Switch t1_lib, tls_record, and tls13_both to C++. This leaves just the TLS 1.3 handshake code. Bug: 132 Change-Id: I2bd87b0ecd0ae7d6ea1302bc62c67aec5ca1dccb Reviewed-on: https://boringssl-review.googlesource.com/17767 Reviewed-by: Steven Valdez <svaldez@google.com>
diff --git a/ssl/t1_lib.cc b/ssl/t1_lib.cc new file mode 100644 index 0000000..fb0c8dd --- /dev/null +++ b/ssl/t1_lib.cc
@@ -0,0 +1,3545 @@ +/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) + * All rights reserved. + * + * This package is an SSL implementation written + * by Eric Young (eay@cryptsoft.com). + * The implementation was written so as to conform with Netscapes SSL. + * + * This library is free for commercial and non-commercial use as long as + * the following conditions are aheared to. The following conditions + * apply to all code found in this distribution, be it the RC4, RSA, + * lhash, DES, etc., code; not just the SSL code. The SSL documentation + * included with this distribution is covered by the same copyright terms + * except that the holder is Tim Hudson (tjh@cryptsoft.com). + * + * Copyright remains Eric Young's, and as such any Copyright notices in + * the code are not to be removed. + * If this package is used in a product, Eric Young should be given attribution + * as the author of the parts of the library used. + * This can be in the form of a textual message at program startup or + * in documentation (online or textual) provided with the package. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * "This product includes cryptographic software written by + * Eric Young (eay@cryptsoft.com)" + * The word 'cryptographic' can be left out if the rouines from the library + * being used are not cryptographic related :-). + * 4. If you include any Windows specific code (or a derivative thereof) from + * the apps directory (application code) you must include an acknowledgement: + * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" + * + * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * The licence and distribution terms for any publically available version or + * derivative of this code cannot be changed. i.e. this code cannot simply be + * copied and put under another distribution licence + * [including the GNU Public Licence.] + */ +/* ==================================================================== + * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * 3. All advertising materials mentioning features or use of this + * software must display the following acknowledgment: + * "This product includes software developed by the OpenSSL Project + * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" + * + * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to + * endorse or promote products derived from this software without + * prior written permission. For written permission, please contact + * openssl-core@openssl.org. + * + * 5. Products derived from this software may not be called "OpenSSL" + * nor may "OpenSSL" appear in their names without prior written + * permission of the OpenSSL Project. + * + * 6. Redistributions of any form whatsoever must retain the following + * acknowledgment: + * "This product includes software developed by the OpenSSL Project + * for use in the OpenSSL Toolkit (http://www.openssl.org/)" + * + * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY + * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR + * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * ==================================================================== + * + * This product includes cryptographic software written by Eric Young + * (eay@cryptsoft.com). This product includes software written by Tim + * Hudson (tjh@cryptsoft.com). */ + +#include <openssl/ssl.h> + +#include <assert.h> +#include <limits.h> +#include <stdlib.h> +#include <string.h> + +#include <openssl/bytestring.h> +#include <openssl/digest.h> +#include <openssl/err.h> +#include <openssl/evp.h> +#include <openssl/hmac.h> +#include <openssl/mem.h> +#include <openssl/nid.h> +#include <openssl/rand.h> +#include <openssl/type_check.h> + +#include "internal.h" +#include "../crypto/internal.h" + + +static int ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs); + +static int compare_uint16_t(const void *p1, const void *p2) { + uint16_t u1 = *((const uint16_t *)p1); + uint16_t u2 = *((const uint16_t *)p2); + if (u1 < u2) { + return -1; + } else if (u1 > u2) { + return 1; + } else { + return 0; + } +} + +/* Per http://tools.ietf.org/html/rfc5246#section-7.4.1.4, there may not be + * more than one extension of the same type in a ClientHello or ServerHello. + * This function does an initial scan over the extensions block to filter those + * out. */ +static int tls1_check_duplicate_extensions(const CBS *cbs) { + CBS extensions = *cbs; + size_t num_extensions = 0, i = 0; + uint16_t *extension_types = NULL; + int ret = 0; + + /* First pass: count the extensions. */ + while (CBS_len(&extensions) > 0) { + uint16_t type; + CBS extension; + + if (!CBS_get_u16(&extensions, &type) || + !CBS_get_u16_length_prefixed(&extensions, &extension)) { + goto done; + } + + num_extensions++; + } + + if (num_extensions == 0) { + return 1; + } + + extension_types = + (uint16_t *)OPENSSL_malloc(sizeof(uint16_t) * num_extensions); + if (extension_types == NULL) { + OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); + goto done; + } + + /* Second pass: gather the extension types. */ + extensions = *cbs; + for (i = 0; i < num_extensions; i++) { + CBS extension; + + if (!CBS_get_u16(&extensions, &extension_types[i]) || + !CBS_get_u16_length_prefixed(&extensions, &extension)) { + /* This should not happen. */ + goto done; + } + } + assert(CBS_len(&extensions) == 0); + + /* Sort the extensions and make sure there are no duplicates. */ + qsort(extension_types, num_extensions, sizeof(uint16_t), compare_uint16_t); + for (i = 1; i < num_extensions; i++) { + if (extension_types[i - 1] == extension_types[i]) { + goto done; + } + } + + ret = 1; + +done: + OPENSSL_free(extension_types); + return ret; +} + +int ssl_client_hello_init(SSL *ssl, SSL_CLIENT_HELLO *out, const uint8_t *in, + size_t in_len) { + OPENSSL_memset(out, 0, sizeof(*out)); + out->ssl = ssl; + out->client_hello = in; + out->client_hello_len = in_len; + + CBS client_hello, random, session_id; + CBS_init(&client_hello, out->client_hello, out->client_hello_len); + if (!CBS_get_u16(&client_hello, &out->version) || + !CBS_get_bytes(&client_hello, &random, SSL3_RANDOM_SIZE) || + !CBS_get_u8_length_prefixed(&client_hello, &session_id) || + CBS_len(&session_id) > SSL_MAX_SSL_SESSION_ID_LENGTH) { + return 0; + } + + out->random = CBS_data(&random); + out->random_len = CBS_len(&random); + out->session_id = CBS_data(&session_id); + out->session_id_len = CBS_len(&session_id); + + /* Skip past DTLS cookie */ + if (SSL_is_dtls(out->ssl)) { + CBS cookie; + if (!CBS_get_u8_length_prefixed(&client_hello, &cookie) || + CBS_len(&cookie) > DTLS1_COOKIE_LENGTH) { + return 0; + } + } + + CBS cipher_suites, compression_methods; + if (!CBS_get_u16_length_prefixed(&client_hello, &cipher_suites) || + CBS_len(&cipher_suites) < 2 || (CBS_len(&cipher_suites) & 1) != 0 || + !CBS_get_u8_length_prefixed(&client_hello, &compression_methods) || + CBS_len(&compression_methods) < 1) { + return 0; + } + + out->cipher_suites = CBS_data(&cipher_suites); + out->cipher_suites_len = CBS_len(&cipher_suites); + out->compression_methods = CBS_data(&compression_methods); + out->compression_methods_len = CBS_len(&compression_methods); + + /* If the ClientHello ends here then it's valid, but doesn't have any + * extensions. (E.g. SSLv3.) */ + if (CBS_len(&client_hello) == 0) { + out->extensions = NULL; + out->extensions_len = 0; + return 1; + } + + /* Extract extensions and check it is valid. */ + CBS extensions; + if (!CBS_get_u16_length_prefixed(&client_hello, &extensions) || + !tls1_check_duplicate_extensions(&extensions) || + CBS_len(&client_hello) != 0) { + return 0; + } + + out->extensions = CBS_data(&extensions); + out->extensions_len = CBS_len(&extensions); + + return 1; +} + +int ssl_client_hello_get_extension(const SSL_CLIENT_HELLO *client_hello, + CBS *out, uint16_t extension_type) { + CBS extensions; + CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len); + while (CBS_len(&extensions) != 0) { + /* Decode the next extension. */ + uint16_t type; + CBS extension; + if (!CBS_get_u16(&extensions, &type) || + !CBS_get_u16_length_prefixed(&extensions, &extension)) { + return 0; + } + + if (type == extension_type) { + *out = extension; + return 1; + } + } + + return 0; +} + +int SSL_early_callback_ctx_extension_get(const SSL_CLIENT_HELLO *client_hello, + uint16_t extension_type, + const uint8_t **out_data, + size_t *out_len) { + CBS cbs; + if (!ssl_client_hello_get_extension(client_hello, &cbs, extension_type)) { + return 0; + } + + *out_data = CBS_data(&cbs); + *out_len = CBS_len(&cbs); + return 1; +} + +static const uint16_t kDefaultGroups[] = { + SSL_CURVE_X25519, + SSL_CURVE_SECP256R1, + SSL_CURVE_SECP384R1, +}; + +void tls1_get_grouplist(SSL *ssl, const uint16_t **out_group_ids, + size_t *out_group_ids_len) { + *out_group_ids = ssl->supported_group_list; + *out_group_ids_len = ssl->supported_group_list_len; + if (!*out_group_ids) { + *out_group_ids = kDefaultGroups; + *out_group_ids_len = OPENSSL_ARRAY_SIZE(kDefaultGroups); + } +} + +int tls1_get_shared_group(SSL_HANDSHAKE *hs, uint16_t *out_group_id) { + SSL *const ssl = hs->ssl; + assert(ssl->server); + + const uint16_t *groups, *pref, *supp; + size_t groups_len, pref_len, supp_len; + tls1_get_grouplist(ssl, &groups, &groups_len); + + /* Clients are not required to send a supported_groups extension. In this + * case, the server is free to pick any group it likes. See RFC 4492, + * section 4, paragraph 3. + * + * However, in the interests of compatibility, we will skip ECDH if the + * client didn't send an extension because we can't be sure that they'll + * support our favoured group. Thus we do not special-case an emtpy + * |peer_supported_group_list|. */ + + if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) { + pref = groups; + pref_len = groups_len; + supp = hs->peer_supported_group_list; + supp_len = hs->peer_supported_group_list_len; + } else { + pref = hs->peer_supported_group_list; + pref_len = hs->peer_supported_group_list_len; + supp = groups; + supp_len = groups_len; + } + + for (size_t i = 0; i < pref_len; i++) { + for (size_t j = 0; j < supp_len; j++) { + if (pref[i] == supp[j]) { + *out_group_id = pref[i]; + return 1; + } + } + } + + return 0; +} + +int tls1_set_curves(uint16_t **out_group_ids, size_t *out_group_ids_len, + const int *curves, size_t ncurves) { + uint16_t *group_ids = (uint16_t *)OPENSSL_malloc(ncurves * sizeof(uint16_t)); + if (group_ids == NULL) { + return 0; + } + + for (size_t i = 0; i < ncurves; i++) { + if (!ssl_nid_to_group_id(&group_ids[i], curves[i])) { + OPENSSL_free(group_ids); + return 0; + } + } + + OPENSSL_free(*out_group_ids); + *out_group_ids = group_ids; + *out_group_ids_len = ncurves; + + return 1; +} + +int tls1_set_curves_list(uint16_t **out_group_ids, size_t *out_group_ids_len, + const char *curves) { + uint16_t *group_ids = NULL; + size_t ncurves = 0; + + const char *col; + const char *ptr = curves; + + do { + col = strchr(ptr, ':'); + + uint16_t group_id; + if (!ssl_name_to_group_id(&group_id, ptr, + col ? (size_t)(col - ptr) : strlen(ptr))) { + goto err; + } + + uint16_t *new_group_ids = (uint16_t *)OPENSSL_realloc( + group_ids, (ncurves + 1) * sizeof(uint16_t)); + if (new_group_ids == NULL) { + goto err; + } + group_ids = new_group_ids; + + group_ids[ncurves] = group_id; + ncurves++; + + if (col) { + ptr = col + 1; + } + } while (col); + + OPENSSL_free(*out_group_ids); + *out_group_ids = group_ids; + *out_group_ids_len = ncurves; + + return 1; + +err: + OPENSSL_free(group_ids); + return 0; +} + +int tls1_check_group_id(SSL *ssl, uint16_t group_id) { + const uint16_t *groups; + size_t groups_len; + tls1_get_grouplist(ssl, &groups, &groups_len); + for (size_t i = 0; i < groups_len; i++) { + if (groups[i] == group_id) { + return 1; + } + } + + return 0; +} + +/* kVerifySignatureAlgorithms is the default list of accepted signature + * algorithms for verifying. + * + * For now, RSA-PSS signature algorithms are not enabled on Android's system + * BoringSSL. Once the change in Chrome has stuck and the values are finalized, + * restore them. */ +static const uint16_t kVerifySignatureAlgorithms[] = { + /* List our preferred algorithms first. */ + SSL_SIGN_ED25519, + SSL_SIGN_ECDSA_SECP256R1_SHA256, +#if !defined(BORINGSSL_ANDROID_SYSTEM) + SSL_SIGN_RSA_PSS_SHA256, +#endif + SSL_SIGN_RSA_PKCS1_SHA256, + + /* Larger hashes are acceptable. */ + SSL_SIGN_ECDSA_SECP384R1_SHA384, +#if !defined(BORINGSSL_ANDROID_SYSTEM) + SSL_SIGN_RSA_PSS_SHA384, +#endif + SSL_SIGN_RSA_PKCS1_SHA384, + + /* TODO(davidben): Remove this. */ +#if defined(BORINGSSL_ANDROID_SYSTEM) + SSL_SIGN_ECDSA_SECP521R1_SHA512, +#endif +#if !defined(BORINGSSL_ANDROID_SYSTEM) + SSL_SIGN_RSA_PSS_SHA512, +#endif + SSL_SIGN_RSA_PKCS1_SHA512, + + /* For now, SHA-1 is still accepted but least preferable. */ + SSL_SIGN_RSA_PKCS1_SHA1, + +}; + +/* kSignSignatureAlgorithms is the default list of supported signature + * algorithms for signing. + * + * For now, RSA-PSS signature algorithms are not enabled on Android's system + * BoringSSL. Once the change in Chrome has stuck and the values are finalized, + * restore them. */ +static const uint16_t kSignSignatureAlgorithms[] = { + /* List our preferred algorithms first. */ + SSL_SIGN_ED25519, + SSL_SIGN_ECDSA_SECP256R1_SHA256, +#if !defined(BORINGSSL_ANDROID_SYSTEM) + SSL_SIGN_RSA_PSS_SHA256, +#endif + SSL_SIGN_RSA_PKCS1_SHA256, + + /* If needed, sign larger hashes. + * + * TODO(davidben): Determine which of these may be pruned. */ + SSL_SIGN_ECDSA_SECP384R1_SHA384, +#if !defined(BORINGSSL_ANDROID_SYSTEM) + SSL_SIGN_RSA_PSS_SHA384, +#endif + SSL_SIGN_RSA_PKCS1_SHA384, + + SSL_SIGN_ECDSA_SECP521R1_SHA512, +#if !defined(BORINGSSL_ANDROID_SYSTEM) + SSL_SIGN_RSA_PSS_SHA512, +#endif + SSL_SIGN_RSA_PKCS1_SHA512, + + /* If the peer supports nothing else, sign with SHA-1. */ + SSL_SIGN_ECDSA_SHA1, + SSL_SIGN_RSA_PKCS1_SHA1, +}; + +void SSL_CTX_set_ed25519_enabled(SSL_CTX *ctx, int enabled) { + ctx->ed25519_enabled = !!enabled; +} + +int tls12_add_verify_sigalgs(const SSL *ssl, CBB *out) { + const uint16_t *sigalgs = kVerifySignatureAlgorithms; + size_t num_sigalgs = OPENSSL_ARRAY_SIZE(kVerifySignatureAlgorithms); + if (ssl->ctx->num_verify_sigalgs != 0) { + sigalgs = ssl->ctx->verify_sigalgs; + num_sigalgs = ssl->ctx->num_verify_sigalgs; + } + + for (size_t i = 0; i < num_sigalgs; i++) { + if (sigalgs == kVerifySignatureAlgorithms && + sigalgs[i] == SSL_SIGN_ED25519 && + !ssl->ctx->ed25519_enabled) { + continue; + } + if (!CBB_add_u16(out, sigalgs[i])) { + return 0; + } + } + + return 1; +} + +int tls12_check_peer_sigalg(SSL *ssl, uint8_t *out_alert, uint16_t sigalg) { + const uint16_t *sigalgs = kVerifySignatureAlgorithms; + size_t num_sigalgs = OPENSSL_ARRAY_SIZE(kVerifySignatureAlgorithms); + if (ssl->ctx->num_verify_sigalgs != 0) { + sigalgs = ssl->ctx->verify_sigalgs; + num_sigalgs = ssl->ctx->num_verify_sigalgs; + } + + for (size_t i = 0; i < num_sigalgs; i++) { + if (sigalgs == kVerifySignatureAlgorithms && + sigalgs[i] == SSL_SIGN_ED25519 && + !ssl->ctx->ed25519_enabled) { + continue; + } + if (sigalg == sigalgs[i]) { + return 1; + } + } + + OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; +} + +/* tls_extension represents a TLS extension that is handled internally. The + * |init| function is called for each handshake, before any other functions of + * the extension. Then the add and parse callbacks are called as needed. + * + * The parse callbacks receive a |CBS| that contains the contents of the + * extension (i.e. not including the type and length bytes). If an extension is + * not received then the parse callbacks will be called with a NULL CBS so that + * they can do any processing needed to handle the absence of an extension. + * + * The add callbacks receive a |CBB| to which the extension can be appended but + * the function is responsible for appending the type and length bytes too. + * + * All callbacks return one for success and zero for error. If a parse function + * returns zero then a fatal alert with value |*out_alert| will be sent. If + * |*out_alert| isn't set, then a |decode_error| alert will be sent. */ +struct tls_extension { + uint16_t value; + void (*init)(SSL_HANDSHAKE *hs); + + int (*add_clienthello)(SSL_HANDSHAKE *hs, CBB *out); + int (*parse_serverhello)(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents); + + int (*parse_clienthello)(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents); + int (*add_serverhello)(SSL_HANDSHAKE *hs, CBB *out); +}; + +static int forbid_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + if (contents != NULL) { + /* Servers MUST NOT send this extension. */ + *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; + OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); + return 0; + } + + return 1; +} + +static int ignore_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + /* This extension from the client is handled elsewhere. */ + return 1; +} + +static int dont_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + return 1; +} + +/* Server name indication (SNI). + * + * https://tools.ietf.org/html/rfc6066#section-3. */ + +static int ext_sni_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl->tlsext_hostname == NULL) { + return 1; + } + + CBB contents, server_name_list, name; + if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &server_name_list) || + !CBB_add_u8(&server_name_list, TLSEXT_NAMETYPE_host_name) || + !CBB_add_u16_length_prefixed(&server_name_list, &name) || + !CBB_add_bytes(&name, (const uint8_t *)ssl->tlsext_hostname, + strlen(ssl->tlsext_hostname)) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_sni_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + if (CBS_len(contents) != 0) { + return 0; + } + + assert(ssl->tlsext_hostname != NULL); + + if (ssl->session == NULL) { + OPENSSL_free(hs->new_session->tlsext_hostname); + hs->new_session->tlsext_hostname = BUF_strdup(ssl->tlsext_hostname); + if (!hs->new_session->tlsext_hostname) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + } + + return 1; +} + +static int ext_sni_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + if (contents == NULL) { + return 1; + } + + CBS server_name_list, host_name; + uint8_t name_type; + if (!CBS_get_u16_length_prefixed(contents, &server_name_list) || + !CBS_get_u8(&server_name_list, &name_type) || + /* Although the server_name extension was intended to be extensible to + * new name types and multiple names, OpenSSL 1.0.x had a bug which meant + * different name types will cause an error. Further, RFC 4366 originally + * defined syntax inextensibly. RFC 6066 corrected this mistake, but + * adding new name types is no longer feasible. + * + * Act as if the extensibility does not exist to simplify parsing. */ + !CBS_get_u16_length_prefixed(&server_name_list, &host_name) || + CBS_len(&server_name_list) != 0 || + CBS_len(contents) != 0) { + return 0; + } + + if (name_type != TLSEXT_NAMETYPE_host_name || + CBS_len(&host_name) == 0 || + CBS_len(&host_name) > TLSEXT_MAXLEN_host_name || + CBS_contains_zero_byte(&host_name)) { + *out_alert = SSL_AD_UNRECOGNIZED_NAME; + return 0; + } + + /* Copy the hostname as a string. */ + if (!CBS_strdup(&host_name, &hs->hostname)) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + hs->should_ack_sni = 1; + return 1; +} + +static int ext_sni_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + if (hs->ssl->s3->session_reused || + !hs->should_ack_sni) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + + +/* Renegotiation indication. + * + * https://tools.ietf.org/html/rfc5746 */ + +static int ext_ri_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + /* Renegotiation indication is not necessary in TLS 1.3. */ + if (hs->min_version >= TLS1_3_VERSION) { + return 1; + } + + assert(ssl->s3->initial_handshake_complete == + (ssl->s3->previous_client_finished_len != 0)); + + CBB contents, prev_finished; + if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u8_length_prefixed(&contents, &prev_finished) || + !CBB_add_bytes(&prev_finished, ssl->s3->previous_client_finished, + ssl->s3->previous_client_finished_len) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_ri_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents != NULL && ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + /* Servers may not switch between omitting the extension and supporting it. + * See RFC 5746, sections 3.5 and 4.2. */ + if (ssl->s3->initial_handshake_complete && + (contents != NULL) != ssl->s3->send_connection_binding) { + *out_alert = SSL_AD_HANDSHAKE_FAILURE; + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); + return 0; + } + + if (contents == NULL) { + /* Strictly speaking, if we want to avoid an attack we should *always* see + * RI even on initial ServerHello because the client doesn't see any + * renegotiation during an attack. However this would mean we could not + * connect to any server which doesn't support RI. + * + * OpenSSL has |SSL_OP_LEGACY_SERVER_CONNECT| to control this, but in + * practical terms every client sets it so it's just assumed here. */ + return 1; + } + + const size_t expected_len = ssl->s3->previous_client_finished_len + + ssl->s3->previous_server_finished_len; + + /* Check for logic errors */ + assert(!expected_len || ssl->s3->previous_client_finished_len); + assert(!expected_len || ssl->s3->previous_server_finished_len); + assert(ssl->s3->initial_handshake_complete == + (ssl->s3->previous_client_finished_len != 0)); + assert(ssl->s3->initial_handshake_complete == + (ssl->s3->previous_server_finished_len != 0)); + + /* Parse out the extension contents. */ + CBS renegotiated_connection; + if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) || + CBS_len(contents) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + /* Check that the extension matches. */ + if (CBS_len(&renegotiated_connection) != expected_len) { + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); + *out_alert = SSL_AD_HANDSHAKE_FAILURE; + return 0; + } + + const uint8_t *d = CBS_data(&renegotiated_connection); + int ok = CRYPTO_memcmp(d, ssl->s3->previous_client_finished, + ssl->s3->previous_client_finished_len) == 0; +#if defined(BORINGSSL_UNSAFE_FUZZER_MODE) + ok = 1; +#endif + if (!ok) { + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); + *out_alert = SSL_AD_HANDSHAKE_FAILURE; + return 0; + } + d += ssl->s3->previous_client_finished_len; + + ok = CRYPTO_memcmp(d, ssl->s3->previous_server_finished, + ssl->s3->previous_server_finished_len) == 0; +#if defined(BORINGSSL_UNSAFE_FUZZER_MODE) + ok = 1; +#endif + if (!ok) { + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + ssl->s3->send_connection_binding = 1; + + return 1; +} + +static int ext_ri_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + /* Renegotiation isn't supported as a server so this function should never be + * called after the initial handshake. */ + assert(!ssl->s3->initial_handshake_complete); + + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + return 1; + } + + if (contents == NULL) { + return 1; + } + + CBS renegotiated_connection; + if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) || + CBS_len(contents) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR); + return 0; + } + + /* Check that the extension matches. We do not support renegotiation as a + * server, so this must be empty. */ + if (CBS_len(&renegotiated_connection) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH); + *out_alert = SSL_AD_HANDSHAKE_FAILURE; + return 0; + } + + ssl->s3->send_connection_binding = 1; + + return 1; +} + +static int ext_ri_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + /* Renegotiation isn't supported as a server so this function should never be + * called after the initial handshake. */ + assert(!ssl->s3->initial_handshake_complete); + + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) || + !CBB_add_u16(out, 1 /* length */) || + !CBB_add_u8(out, 0 /* empty renegotiation info */)) { + return 0; + } + + return 1; +} + + +/* Extended Master Secret. + * + * https://tools.ietf.org/html/rfc7627 */ + +static int ext_ems_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + /* Extended master secret is not necessary in TLS 1.3. */ + if (hs->min_version >= TLS1_3_VERSION || hs->max_version <= SSL3_VERSION) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + +static int ext_ems_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + + if (contents != NULL) { + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION || + ssl->version == SSL3_VERSION || + CBS_len(contents) != 0) { + return 0; + } + + hs->extended_master_secret = 1; + } + + /* Whether EMS is negotiated may not change on renegotiation. */ + if (ssl->s3->established_session != NULL && + hs->extended_master_secret != + ssl->s3->established_session->extended_master_secret) { + OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_EMS_MISMATCH); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + return 1; +} + +static int ext_ems_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + uint16_t version = ssl3_protocol_version(hs->ssl); + if (version >= TLS1_3_VERSION || + version == SSL3_VERSION) { + return 1; + } + + if (contents == NULL) { + return 1; + } + + if (CBS_len(contents) != 0) { + return 0; + } + + hs->extended_master_secret = 1; + return 1; +} + +static int ext_ems_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + if (!hs->extended_master_secret) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + + +/* Session tickets. + * + * https://tools.ietf.org/html/rfc5077 */ + +static int ext_ticket_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + /* TLS 1.3 uses a different ticket extension. */ + if (hs->min_version >= TLS1_3_VERSION || + SSL_get_options(ssl) & SSL_OP_NO_TICKET) { + return 1; + } + + const uint8_t *ticket_data = NULL; + int ticket_len = 0; + + /* Renegotiation does not participate in session resumption. However, still + * advertise the extension to avoid potentially breaking servers which carry + * over the state from the previous handshake, such as OpenSSL servers + * without upstream's 3c3f0259238594d77264a78944d409f2127642c4. */ + if (!ssl->s3->initial_handshake_complete && + ssl->session != NULL && + ssl->session->tlsext_tick != NULL && + /* Don't send TLS 1.3 session tickets in the ticket extension. */ + SSL_SESSION_protocol_version(ssl->session) < TLS1_3_VERSION) { + ticket_data = ssl->session->tlsext_tick; + ticket_len = ssl->session->tlsext_ticklen; + } + + CBB ticket; + if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) || + !CBB_add_u16_length_prefixed(out, &ticket) || + !CBB_add_bytes(&ticket, ticket_data, ticket_len) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_ticket_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + return 0; + } + + /* If |SSL_OP_NO_TICKET| is set then no extension will have been sent and + * this function should never be called, even if the server tries to send the + * extension. */ + assert((SSL_get_options(ssl) & SSL_OP_NO_TICKET) == 0); + + if (CBS_len(contents) != 0) { + return 0; + } + + hs->ticket_expected = 1; + return 1; +} + +static int ext_ticket_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + if (!hs->ticket_expected) { + return 1; + } + + /* If |SSL_OP_NO_TICKET| is set, |ticket_expected| should never be true. */ + assert((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) == 0); + + if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + + +/* Signature Algorithms. + * + * https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1 */ + +static int ext_sigalgs_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (hs->max_version < TLS1_2_VERSION) { + return 1; + } + + CBB contents, sigalgs_cbb; + if (!CBB_add_u16(out, TLSEXT_TYPE_signature_algorithms) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &sigalgs_cbb) || + !tls12_add_verify_sigalgs(ssl, &sigalgs_cbb) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_sigalgs_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + OPENSSL_free(hs->peer_sigalgs); + hs->peer_sigalgs = NULL; + hs->num_peer_sigalgs = 0; + + if (contents == NULL) { + return 1; + } + + CBS supported_signature_algorithms; + if (!CBS_get_u16_length_prefixed(contents, &supported_signature_algorithms) || + CBS_len(contents) != 0 || + CBS_len(&supported_signature_algorithms) == 0 || + !tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) { + return 0; + } + + return 1; +} + + +/* OCSP Stapling. + * + * https://tools.ietf.org/html/rfc6066#section-8 */ + +static int ext_ocsp_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (!ssl->ocsp_stapling_enabled) { + return 1; + } + + CBB contents; + if (!CBB_add_u16(out, TLSEXT_TYPE_status_request) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) || + !CBB_add_u16(&contents, 0 /* empty responder ID list */) || + !CBB_add_u16(&contents, 0 /* empty request extensions */) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_ocsp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + /* TLS 1.3 OCSP responses are included in the Certificate extensions. */ + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + return 0; + } + + /* OCSP stapling is forbidden on non-certificate ciphers. */ + if (CBS_len(contents) != 0 || + !ssl_cipher_uses_certificate_auth(hs->new_cipher)) { + return 0; + } + + /* Note this does not check for resumption in TLS 1.2. Sending + * status_request here does not make sense, but OpenSSL does so and the + * specification does not say anything. Tolerate it but ignore it. */ + + hs->certificate_status_expected = 1; + return 1; +} + +static int ext_ocsp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + if (contents == NULL) { + return 1; + } + + uint8_t status_type; + if (!CBS_get_u8(contents, &status_type)) { + return 0; + } + + /* We cannot decide whether OCSP stapling will occur yet because the correct + * SSL_CTX might not have been selected. */ + hs->ocsp_stapling_requested = status_type == TLSEXT_STATUSTYPE_ocsp; + + return 1; +} + +static int ext_ocsp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION || + !hs->ocsp_stapling_requested || + ssl->cert->ocsp_response == NULL || + ssl->s3->session_reused || + !ssl_cipher_uses_certificate_auth(hs->new_cipher)) { + return 1; + } + + hs->certificate_status_expected = 1; + + return CBB_add_u16(out, TLSEXT_TYPE_status_request) && + CBB_add_u16(out, 0 /* length */); +} + + +/* Next protocol negotiation. + * + * https://htmlpreview.github.io/?https://github.com/agl/technotes/blob/master/nextprotoneg.html */ + +static int ext_npn_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl->s3->initial_handshake_complete || + ssl->ctx->next_proto_select_cb == NULL || + SSL_is_dtls(ssl)) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + +static int ext_npn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + return 0; + } + + /* If any of these are false then we should never have sent the NPN + * extension in the ClientHello and thus this function should never have been + * called. */ + assert(!ssl->s3->initial_handshake_complete); + assert(!SSL_is_dtls(ssl)); + assert(ssl->ctx->next_proto_select_cb != NULL); + + if (ssl->s3->alpn_selected != NULL) { + /* NPN and ALPN may not be negotiated in the same connection. */ + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN); + return 0; + } + + const uint8_t *const orig_contents = CBS_data(contents); + const size_t orig_len = CBS_len(contents); + + while (CBS_len(contents) != 0) { + CBS proto; + if (!CBS_get_u8_length_prefixed(contents, &proto) || + CBS_len(&proto) == 0) { + return 0; + } + } + + uint8_t *selected; + uint8_t selected_len; + if (ssl->ctx->next_proto_select_cb( + ssl, &selected, &selected_len, orig_contents, orig_len, + ssl->ctx->next_proto_select_cb_arg) != SSL_TLSEXT_ERR_OK) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + OPENSSL_free(ssl->s3->next_proto_negotiated); + ssl->s3->next_proto_negotiated = + (uint8_t *)BUF_memdup(selected, selected_len); + if (ssl->s3->next_proto_negotiated == NULL) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + ssl->s3->next_proto_negotiated_len = selected_len; + hs->next_proto_neg_seen = 1; + + return 1; +} + +static int ext_npn_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + return 1; + } + + if (contents != NULL && CBS_len(contents) != 0) { + return 0; + } + + if (contents == NULL || + ssl->s3->initial_handshake_complete || + ssl->ctx->next_protos_advertised_cb == NULL || + SSL_is_dtls(ssl)) { + return 1; + } + + hs->next_proto_neg_seen = 1; + return 1; +} + +static int ext_npn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + /* |next_proto_neg_seen| might have been cleared when an ALPN extension was + * parsed. */ + if (!hs->next_proto_neg_seen) { + return 1; + } + + const uint8_t *npa; + unsigned npa_len; + + if (ssl->ctx->next_protos_advertised_cb( + ssl, &npa, &npa_len, ssl->ctx->next_protos_advertised_cb_arg) != + SSL_TLSEXT_ERR_OK) { + hs->next_proto_neg_seen = 0; + return 1; + } + + CBB contents; + if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_bytes(&contents, npa, npa_len) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + + +/* Signed certificate timestamps. + * + * https://tools.ietf.org/html/rfc6962#section-3.3.1 */ + +static int ext_sct_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (!ssl->signed_cert_timestamps_enabled) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + +static int ext_sct_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + /* TLS 1.3 SCTs are included in the Certificate extensions. */ + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + /* If this is false then we should never have sent the SCT extension in the + * ClientHello and thus this function should never have been called. */ + assert(ssl->signed_cert_timestamps_enabled); + + if (!ssl_is_sct_list_valid(contents)) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + /* Session resumption uses the original session information. The extension + * should not be sent on resumption, but RFC 6962 did not make it a + * requirement, so tolerate this. + * + * TODO(davidben): Enforce this anyway. */ + if (!ssl->s3->session_reused && + !CBS_stow(contents, &hs->new_session->tlsext_signed_cert_timestamp_list, + &hs->new_session->tlsext_signed_cert_timestamp_list_length)) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + return 1; +} + +static int ext_sct_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + if (contents == NULL) { + return 1; + } + + if (CBS_len(contents) != 0) { + return 0; + } + + hs->scts_requested = 1; + return 1; +} + +static int ext_sct_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + /* The extension shouldn't be sent when resuming sessions. */ + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION || + ssl->s3->session_reused || + ssl->cert->signed_cert_timestamp_list == NULL) { + return 1; + } + + CBB contents; + return CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) && + CBB_add_u16_length_prefixed(out, &contents) && + CBB_add_bytes( + &contents, + CRYPTO_BUFFER_data(ssl->cert->signed_cert_timestamp_list), + CRYPTO_BUFFER_len(ssl->cert->signed_cert_timestamp_list)) && + CBB_flush(out); +} + + +/* Application-level Protocol Negotiation. + * + * https://tools.ietf.org/html/rfc7301 */ + +static int ext_alpn_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl->alpn_client_proto_list == NULL || + ssl->s3->initial_handshake_complete) { + return 1; + } + + CBB contents, proto_list; + if (!CBB_add_u16(out, TLSEXT_TYPE_application_layer_protocol_negotiation) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &proto_list) || + !CBB_add_bytes(&proto_list, ssl->alpn_client_proto_list, + ssl->alpn_client_proto_list_len) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_alpn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + assert(!ssl->s3->initial_handshake_complete); + assert(ssl->alpn_client_proto_list != NULL); + + if (hs->next_proto_neg_seen) { + /* NPN and ALPN may not be negotiated in the same connection. */ + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN); + return 0; + } + + /* The extension data consists of a ProtocolNameList which must have + * exactly one ProtocolName. Each of these is length-prefixed. */ + CBS protocol_name_list, protocol_name; + if (!CBS_get_u16_length_prefixed(contents, &protocol_name_list) || + CBS_len(contents) != 0 || + !CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) || + /* Empty protocol names are forbidden. */ + CBS_len(&protocol_name) == 0 || + CBS_len(&protocol_name_list) != 0) { + return 0; + } + + if (!ssl->ctx->allow_unknown_alpn_protos) { + /* Check that the protocol name is one of the ones we advertised. */ + int protocol_ok = 0; + CBS client_protocol_name_list, client_protocol_name; + CBS_init(&client_protocol_name_list, ssl->alpn_client_proto_list, + ssl->alpn_client_proto_list_len); + while (CBS_len(&client_protocol_name_list) > 0) { + if (!CBS_get_u8_length_prefixed(&client_protocol_name_list, + &client_protocol_name)) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + if (CBS_len(&client_protocol_name) == CBS_len(&protocol_name) && + OPENSSL_memcmp(CBS_data(&client_protocol_name), + CBS_data(&protocol_name), + CBS_len(&protocol_name)) == 0) { + protocol_ok = 1; + break; + } + } + + if (!protocol_ok) { + OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + } + + if (!CBS_stow(&protocol_name, &ssl->s3->alpn_selected, + &ssl->s3->alpn_selected_len)) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + return 1; +} + +int ssl_negotiate_alpn(SSL_HANDSHAKE *hs, uint8_t *out_alert, + const SSL_CLIENT_HELLO *client_hello) { + SSL *const ssl = hs->ssl; + CBS contents; + if (ssl->ctx->alpn_select_cb == NULL || + !ssl_client_hello_get_extension( + client_hello, &contents, + TLSEXT_TYPE_application_layer_protocol_negotiation)) { + /* Ignore ALPN if not configured or no extension was supplied. */ + return 1; + } + + /* ALPN takes precedence over NPN. */ + hs->next_proto_neg_seen = 0; + + CBS protocol_name_list; + if (!CBS_get_u16_length_prefixed(&contents, &protocol_name_list) || + CBS_len(&contents) != 0 || + CBS_len(&protocol_name_list) < 2) { + OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT); + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + /* Validate the protocol list. */ + CBS protocol_name_list_copy = protocol_name_list; + while (CBS_len(&protocol_name_list_copy) > 0) { + CBS protocol_name; + + if (!CBS_get_u8_length_prefixed(&protocol_name_list_copy, &protocol_name) || + /* Empty protocol names are forbidden. */ + CBS_len(&protocol_name) == 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT); + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + } + + const uint8_t *selected; + uint8_t selected_len; + if (ssl->ctx->alpn_select_cb( + ssl, &selected, &selected_len, CBS_data(&protocol_name_list), + CBS_len(&protocol_name_list), + ssl->ctx->alpn_select_cb_arg) == SSL_TLSEXT_ERR_OK) { + OPENSSL_free(ssl->s3->alpn_selected); + ssl->s3->alpn_selected = (uint8_t *)BUF_memdup(selected, selected_len); + if (ssl->s3->alpn_selected == NULL) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + ssl->s3->alpn_selected_len = selected_len; + } + + return 1; +} + +static int ext_alpn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl->s3->alpn_selected == NULL) { + return 1; + } + + CBB contents, proto_list, proto; + if (!CBB_add_u16(out, TLSEXT_TYPE_application_layer_protocol_negotiation) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &proto_list) || + !CBB_add_u8_length_prefixed(&proto_list, &proto) || + !CBB_add_bytes(&proto, ssl->s3->alpn_selected, + ssl->s3->alpn_selected_len) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + + +/* Channel ID. + * + * https://tools.ietf.org/html/draft-balfanz-tls-channelid-01 */ + +static void ext_channel_id_init(SSL_HANDSHAKE *hs) { + hs->ssl->s3->tlsext_channel_id_valid = 0; +} + +static int ext_channel_id_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (!ssl->tlsext_channel_id_enabled || + SSL_is_dtls(ssl)) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + +static int ext_channel_id_parse_serverhello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + assert(!SSL_is_dtls(ssl)); + assert(ssl->tlsext_channel_id_enabled); + + if (CBS_len(contents) != 0) { + return 0; + } + + ssl->s3->tlsext_channel_id_valid = 1; + return 1; +} + +static int ext_channel_id_parse_clienthello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL || + !ssl->tlsext_channel_id_enabled || + SSL_is_dtls(ssl)) { + return 1; + } + + if (CBS_len(contents) != 0) { + return 0; + } + + ssl->s3->tlsext_channel_id_valid = 1; + return 1; +} + +static int ext_channel_id_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (!ssl->s3->tlsext_channel_id_valid) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) || + !CBB_add_u16(out, 0 /* length */)) { + return 0; + } + + return 1; +} + + +/* Secure Real-time Transport Protocol (SRTP) extension. + * + * https://tools.ietf.org/html/rfc5764 */ + + +static void ext_srtp_init(SSL_HANDSHAKE *hs) { + hs->ssl->srtp_profile = NULL; +} + +static int ext_srtp_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + STACK_OF(SRTP_PROTECTION_PROFILE) *profiles = SSL_get_srtp_profiles(ssl); + if (profiles == NULL) { + return 1; + } + const size_t num_profiles = sk_SRTP_PROTECTION_PROFILE_num(profiles); + if (num_profiles == 0) { + return 1; + } + + CBB contents, profile_ids; + if (!CBB_add_u16(out, TLSEXT_TYPE_srtp) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &profile_ids)) { + return 0; + } + + for (size_t i = 0; i < num_profiles; i++) { + if (!CBB_add_u16(&profile_ids, + sk_SRTP_PROTECTION_PROFILE_value(profiles, i)->id)) { + return 0; + } + } + + if (!CBB_add_u8(&contents, 0 /* empty use_mki value */) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_srtp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + /* The extension consists of a u16-prefixed profile ID list containing a + * single uint16_t profile ID, then followed by a u8-prefixed srtp_mki field. + * + * See https://tools.ietf.org/html/rfc5764#section-4.1.1 */ + CBS profile_ids, srtp_mki; + uint16_t profile_id; + if (!CBS_get_u16_length_prefixed(contents, &profile_ids) || + !CBS_get_u16(&profile_ids, &profile_id) || + CBS_len(&profile_ids) != 0 || + !CBS_get_u8_length_prefixed(contents, &srtp_mki) || + CBS_len(contents) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); + return 0; + } + + if (CBS_len(&srtp_mki) != 0) { + /* Must be no MKI, since we never offer one. */ + OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_MKI_VALUE); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + STACK_OF(SRTP_PROTECTION_PROFILE) *profiles = SSL_get_srtp_profiles(ssl); + + /* Check to see if the server gave us something we support (and presumably + * offered). */ + for (size_t i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(profiles); i++) { + const SRTP_PROTECTION_PROFILE *profile = + sk_SRTP_PROTECTION_PROFILE_value(profiles, i); + + if (profile->id == profile_id) { + ssl->srtp_profile = profile; + return 1; + } + } + + OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; +} + +static int ext_srtp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + CBS profile_ids, srtp_mki; + if (!CBS_get_u16_length_prefixed(contents, &profile_ids) || + CBS_len(&profile_ids) < 2 || + !CBS_get_u8_length_prefixed(contents, &srtp_mki) || + CBS_len(contents) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST); + return 0; + } + /* Discard the MKI value for now. */ + + const STACK_OF(SRTP_PROTECTION_PROFILE) *server_profiles = + SSL_get_srtp_profiles(ssl); + + /* Pick the server's most preferred profile. */ + for (size_t i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(server_profiles); i++) { + const SRTP_PROTECTION_PROFILE *server_profile = + sk_SRTP_PROTECTION_PROFILE_value(server_profiles, i); + + CBS profile_ids_tmp; + CBS_init(&profile_ids_tmp, CBS_data(&profile_ids), CBS_len(&profile_ids)); + + while (CBS_len(&profile_ids_tmp) > 0) { + uint16_t profile_id; + if (!CBS_get_u16(&profile_ids_tmp, &profile_id)) { + return 0; + } + + if (server_profile->id == profile_id) { + ssl->srtp_profile = server_profile; + return 1; + } + } + } + + return 1; +} + +static int ext_srtp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl->srtp_profile == NULL) { + return 1; + } + + CBB contents, profile_ids; + if (!CBB_add_u16(out, TLSEXT_TYPE_srtp) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &profile_ids) || + !CBB_add_u16(&profile_ids, ssl->srtp_profile->id) || + !CBB_add_u8(&contents, 0 /* empty MKI */) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + + +/* EC point formats. + * + * https://tools.ietf.org/html/rfc4492#section-5.1.2 */ + +static int ext_ec_point_add_extension(SSL_HANDSHAKE *hs, CBB *out) { + CBB contents, formats; + if (!CBB_add_u16(out, TLSEXT_TYPE_ec_point_formats) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u8_length_prefixed(&contents, &formats) || + !CBB_add_u8(&formats, TLSEXT_ECPOINTFORMAT_uncompressed) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_ec_point_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + /* The point format extension is unneccessary in TLS 1.3. */ + if (hs->min_version >= TLS1_3_VERSION) { + return 1; + } + + return ext_ec_point_add_extension(hs, out); +} + +static int ext_ec_point_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + if (contents == NULL) { + return 1; + } + + if (ssl3_protocol_version(hs->ssl) >= TLS1_3_VERSION) { + return 0; + } + + CBS ec_point_format_list; + if (!CBS_get_u8_length_prefixed(contents, &ec_point_format_list) || + CBS_len(contents) != 0) { + return 0; + } + + /* Per RFC 4492, section 5.1.2, implementations MUST support the uncompressed + * point format. */ + if (OPENSSL_memchr(CBS_data(&ec_point_format_list), + TLSEXT_ECPOINTFORMAT_uncompressed, + CBS_len(&ec_point_format_list)) == NULL) { + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + return 1; +} + +static int ext_ec_point_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert, + CBS *contents) { + if (ssl3_protocol_version(hs->ssl) >= TLS1_3_VERSION) { + return 1; + } + + return ext_ec_point_parse_serverhello(hs, out_alert, contents); +} + +static int ext_ec_point_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + return 1; + } + + const uint32_t alg_k = hs->new_cipher->algorithm_mkey; + const uint32_t alg_a = hs->new_cipher->algorithm_auth; + const int using_ecc = (alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA); + + if (!using_ecc) { + return 1; + } + + return ext_ec_point_add_extension(hs, out); +} + + +/* Pre Shared Key + * + * https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.6 */ + +static size_t ext_pre_shared_key_clienthello_length(SSL_HANDSHAKE *hs) { + SSL *const ssl = hs->ssl; + if (hs->max_version < TLS1_3_VERSION || ssl->session == NULL || + SSL_SESSION_protocol_version(ssl->session) < TLS1_3_VERSION) { + return 0; + } + + size_t binder_len = EVP_MD_size(SSL_SESSION_get_digest(ssl->session)); + return 15 + ssl->session->tlsext_ticklen + binder_len; +} + +static int ext_pre_shared_key_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (hs->max_version < TLS1_3_VERSION || ssl->session == NULL || + SSL_SESSION_protocol_version(ssl->session) < TLS1_3_VERSION) { + return 1; + } + + struct OPENSSL_timeval now; + ssl_get_current_time(ssl, &now); + uint32_t ticket_age = 1000 * (now.tv_sec - ssl->session->time); + uint32_t obfuscated_ticket_age = ticket_age + ssl->session->ticket_age_add; + + /* Fill in a placeholder zero binder of the appropriate length. It will be + * computed and filled in later after length prefixes are computed. */ + uint8_t zero_binder[EVP_MAX_MD_SIZE] = {0}; + size_t binder_len = EVP_MD_size(SSL_SESSION_get_digest(ssl->session)); + + CBB contents, identity, ticket, binders, binder; + if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &identity) || + !CBB_add_u16_length_prefixed(&identity, &ticket) || + !CBB_add_bytes(&ticket, ssl->session->tlsext_tick, + ssl->session->tlsext_ticklen) || + !CBB_add_u32(&identity, obfuscated_ticket_age) || + !CBB_add_u16_length_prefixed(&contents, &binders) || + !CBB_add_u8_length_prefixed(&binders, &binder) || + !CBB_add_bytes(&binder, zero_binder, binder_len)) { + return 0; + } + + hs->needs_psk_binder = 1; + return CBB_flush(out); +} + +int ssl_ext_pre_shared_key_parse_serverhello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, + CBS *contents) { + uint16_t psk_id; + if (!CBS_get_u16(contents, &psk_id) || + CBS_len(contents) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + /* We only advertise one PSK identity, so the only legal index is zero. */ + if (psk_id != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND); + *out_alert = SSL_AD_UNKNOWN_PSK_IDENTITY; + return 0; + } + + return 1; +} + +int ssl_ext_pre_shared_key_parse_clienthello( + SSL_HANDSHAKE *hs, CBS *out_ticket, CBS *out_binders, + uint32_t *out_obfuscated_ticket_age, uint8_t *out_alert, CBS *contents) { + /* We only process the first PSK identity since we don't support pure PSK. */ + CBS identities, binders; + if (!CBS_get_u16_length_prefixed(contents, &identities) || + !CBS_get_u16_length_prefixed(&identities, out_ticket) || + !CBS_get_u32(&identities, out_obfuscated_ticket_age) || + !CBS_get_u16_length_prefixed(contents, &binders) || + CBS_len(&binders) == 0 || + CBS_len(contents) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + *out_binders = binders; + + /* Check the syntax of the remaining identities, but do not process them. */ + size_t num_identities = 1; + while (CBS_len(&identities) != 0) { + CBS unused_ticket; + uint32_t unused_obfuscated_ticket_age; + if (!CBS_get_u16_length_prefixed(&identities, &unused_ticket) || + !CBS_get_u32(&identities, &unused_obfuscated_ticket_age)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + num_identities++; + } + + /* Check the syntax of the binders. The value will be checked later if + * resuming. */ + size_t num_binders = 0; + while (CBS_len(&binders) != 0) { + CBS binder; + if (!CBS_get_u8_length_prefixed(&binders, &binder)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + num_binders++; + } + + if (num_identities != num_binders) { + OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_BINDER_COUNT_MISMATCH); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + return 1; +} + +int ssl_ext_pre_shared_key_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + if (!hs->ssl->s3->session_reused) { + return 1; + } + + CBB contents; + if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) || + !CBB_add_u16_length_prefixed(out, &contents) || + /* We only consider the first identity for resumption */ + !CBB_add_u16(&contents, 0) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + + +/* Pre-Shared Key Exchange Modes + * + * https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.7 */ + +static int ext_psk_key_exchange_modes_add_clienthello(SSL_HANDSHAKE *hs, + CBB *out) { + if (hs->max_version < TLS1_3_VERSION) { + return 1; + } + + CBB contents, ke_modes; + if (!CBB_add_u16(out, TLSEXT_TYPE_psk_key_exchange_modes) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u8_length_prefixed(&contents, &ke_modes) || + !CBB_add_u8(&ke_modes, SSL_PSK_DHE_KE)) { + return 0; + } + + return CBB_flush(out); +} + +static int ext_psk_key_exchange_modes_parse_clienthello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, + CBS *contents) { + if (contents == NULL) { + return 1; + } + + CBS ke_modes; + if (!CBS_get_u8_length_prefixed(contents, &ke_modes) || + CBS_len(&ke_modes) == 0 || + CBS_len(contents) != 0) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + /* We only support tickets with PSK_DHE_KE. */ + hs->accept_psk_mode = OPENSSL_memchr(CBS_data(&ke_modes), SSL_PSK_DHE_KE, + CBS_len(&ke_modes)) != NULL; + + return 1; +} + + +/* Early Data Indication + * + * https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.8 */ + +static int ext_early_data_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (ssl->session == NULL || + SSL_SESSION_protocol_version(ssl->session) < TLS1_3_VERSION || + ssl->session->ticket_max_early_data == 0 || + hs->received_hello_retry_request || + !ssl->cert->enable_early_data) { + return 1; + } + + hs->early_data_offered = 1; + + if (!CBB_add_u16(out, TLSEXT_TYPE_early_data) || + !CBB_add_u16(out, 0) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + +static int ext_early_data_parse_serverhello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL) { + return 1; + } + + if (CBS_len(contents) != 0) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + if (!ssl->s3->session_reused) { + *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; + OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); + return 0; + } + + ssl->early_data_accepted = 1; + return 1; +} + +static int ext_early_data_parse_clienthello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, CBS *contents) { + SSL *const ssl = hs->ssl; + if (contents == NULL || + ssl3_protocol_version(ssl) < TLS1_3_VERSION) { + return 1; + } + + if (CBS_len(contents) != 0) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + hs->early_data_offered = 1; + return 1; +} + +static int ext_early_data_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + if (!hs->ssl->early_data_accepted) { + return 1; + } + + if (!CBB_add_u16(out, TLSEXT_TYPE_early_data) || + !CBB_add_u16(out, 0) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + + +/* Key Share + * + * https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.5 */ + +static int ext_key_share_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (hs->max_version < TLS1_3_VERSION) { + return 1; + } + + CBB contents, kse_bytes; + if (!CBB_add_u16(out, TLSEXT_TYPE_key_share) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &kse_bytes)) { + return 0; + } + + uint16_t group_id = hs->retry_group; + if (hs->received_hello_retry_request) { + /* We received a HelloRetryRequest without a new curve, so there is no new + * share to append. Leave |ecdh_ctx| as-is. */ + if (group_id == 0 && + !CBB_add_bytes(&kse_bytes, hs->key_share_bytes, + hs->key_share_bytes_len)) { + return 0; + } + OPENSSL_free(hs->key_share_bytes); + hs->key_share_bytes = NULL; + hs->key_share_bytes_len = 0; + if (group_id == 0) { + return CBB_flush(out); + } + } else { + /* Add a fake group. See draft-davidben-tls-grease-01. */ + if (ssl->ctx->grease_enabled && + (!CBB_add_u16(&kse_bytes, + ssl_get_grease_value(ssl, ssl_grease_group)) || + !CBB_add_u16(&kse_bytes, 1 /* length */) || + !CBB_add_u8(&kse_bytes, 0 /* one byte key share */))) { + return 0; + } + + /* Predict the most preferred group. */ + const uint16_t *groups; + size_t groups_len; + tls1_get_grouplist(ssl, &groups, &groups_len); + if (groups_len == 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_NO_GROUPS_SPECIFIED); + return 0; + } + + group_id = groups[0]; + } + + CBB key_exchange; + if (!CBB_add_u16(&kse_bytes, group_id) || + !CBB_add_u16_length_prefixed(&kse_bytes, &key_exchange) || + !SSL_ECDH_CTX_init(&hs->ecdh_ctx, group_id) || + !SSL_ECDH_CTX_offer(&hs->ecdh_ctx, &key_exchange) || + !CBB_flush(&kse_bytes)) { + return 0; + } + + if (!hs->received_hello_retry_request) { + /* Save the contents of the extension to repeat it in the second + * ClientHello. */ + hs->key_share_bytes_len = CBB_len(&kse_bytes); + hs->key_share_bytes = + (uint8_t *)BUF_memdup(CBB_data(&kse_bytes), CBB_len(&kse_bytes)); + if (hs->key_share_bytes == NULL) { + return 0; + } + } + + return CBB_flush(out); +} + +int ssl_ext_key_share_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t **out_secret, + size_t *out_secret_len, + uint8_t *out_alert, CBS *contents) { + CBS peer_key; + uint16_t group_id; + if (!CBS_get_u16(contents, &group_id) || + !CBS_get_u16_length_prefixed(contents, &peer_key) || + CBS_len(contents) != 0) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + if (SSL_ECDH_CTX_get_id(&hs->ecdh_ctx) != group_id) { + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE); + return 0; + } + + if (!SSL_ECDH_CTX_finish(&hs->ecdh_ctx, out_secret, out_secret_len, out_alert, + CBS_data(&peer_key), CBS_len(&peer_key))) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + hs->new_session->group_id = group_id; + SSL_ECDH_CTX_cleanup(&hs->ecdh_ctx); + return 1; +} + +int ssl_ext_key_share_parse_clienthello(SSL_HANDSHAKE *hs, int *out_found, + uint8_t **out_secret, + size_t *out_secret_len, + uint8_t *out_alert, CBS *contents) { + uint16_t group_id; + CBS key_shares; + if (!tls1_get_shared_group(hs, &group_id)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_GROUP); + *out_alert = SSL_AD_HANDSHAKE_FAILURE; + return 0; + } + + if (!CBS_get_u16_length_prefixed(contents, &key_shares) || + CBS_len(contents) != 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); + return 0; + } + + /* Find the corresponding key share. */ + int found = 0; + CBS peer_key; + while (CBS_len(&key_shares) > 0) { + uint16_t id; + CBS peer_key_tmp; + if (!CBS_get_u16(&key_shares, &id) || + !CBS_get_u16_length_prefixed(&key_shares, &peer_key_tmp)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); + return 0; + } + + if (id == group_id) { + if (found) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_KEY_SHARE); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + found = 1; + peer_key = peer_key_tmp; + /* Continue parsing the structure to keep peers honest. */ + } + } + + if (!found) { + *out_found = 0; + *out_secret = NULL; + *out_secret_len = 0; + return 1; + } + + /* Compute the DH secret. */ + uint8_t *secret = NULL; + size_t secret_len; + SSL_ECDH_CTX group; + OPENSSL_memset(&group, 0, sizeof(SSL_ECDH_CTX)); + CBB public_key; + if (!CBB_init(&public_key, 32) || + !SSL_ECDH_CTX_init(&group, group_id) || + !SSL_ECDH_CTX_accept(&group, &public_key, &secret, &secret_len, out_alert, + CBS_data(&peer_key), CBS_len(&peer_key)) || + !CBB_finish(&public_key, &hs->ecdh_public_key, + &hs->ecdh_public_key_len)) { + OPENSSL_free(secret); + SSL_ECDH_CTX_cleanup(&group); + CBB_cleanup(&public_key); + *out_alert = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + SSL_ECDH_CTX_cleanup(&group); + + *out_secret = secret; + *out_secret_len = secret_len; + *out_found = 1; + return 1; +} + +int ssl_ext_key_share_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + uint16_t group_id; + CBB kse_bytes, public_key; + if (!tls1_get_shared_group(hs, &group_id) || + !CBB_add_u16(out, TLSEXT_TYPE_key_share) || + !CBB_add_u16_length_prefixed(out, &kse_bytes) || + !CBB_add_u16(&kse_bytes, group_id) || + !CBB_add_u16_length_prefixed(&kse_bytes, &public_key) || + !CBB_add_bytes(&public_key, hs->ecdh_public_key, + hs->ecdh_public_key_len) || + !CBB_flush(out)) { + return 0; + } + + OPENSSL_free(hs->ecdh_public_key); + hs->ecdh_public_key = NULL; + hs->ecdh_public_key_len = 0; + + hs->new_session->group_id = group_id; + return 1; +} + + +/* Supported Versions + * + * https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.1 */ + +static int ext_supported_versions_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + if (hs->max_version <= TLS1_2_VERSION) { + return 1; + } + + CBB contents, versions; + if (!CBB_add_u16(out, TLSEXT_TYPE_supported_versions) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u8_length_prefixed(&contents, &versions)) { + return 0; + } + + /* Add a fake version. See draft-davidben-tls-grease-01. */ + if (ssl->ctx->grease_enabled && + !CBB_add_u16(&versions, ssl_get_grease_value(ssl, ssl_grease_version))) { + return 0; + } + + if (!ssl_add_supported_versions(hs, &versions) || + !CBB_flush(out)) { + return 0; + } + + return 1; +} + + +/* Cookie + * + * https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.2 */ + +static int ext_cookie_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + if (hs->cookie == NULL) { + return 1; + } + + CBB contents, cookie; + if (!CBB_add_u16(out, TLSEXT_TYPE_cookie) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &cookie) || + !CBB_add_bytes(&cookie, hs->cookie, hs->cookie_len) || + !CBB_flush(out)) { + return 0; + } + + /* The cookie is no longer needed in memory. */ + OPENSSL_free(hs->cookie); + hs->cookie = NULL; + hs->cookie_len = 0; + return 1; +} + + +/* Negotiated Groups + * + * https://tools.ietf.org/html/rfc4492#section-5.1.2 + * https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.4 */ + +static int ext_supported_groups_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + CBB contents, groups_bytes; + if (!CBB_add_u16(out, TLSEXT_TYPE_supported_groups) || + !CBB_add_u16_length_prefixed(out, &contents) || + !CBB_add_u16_length_prefixed(&contents, &groups_bytes)) { + return 0; + } + + /* Add a fake group. See draft-davidben-tls-grease-01. */ + if (ssl->ctx->grease_enabled && + !CBB_add_u16(&groups_bytes, + ssl_get_grease_value(ssl, ssl_grease_group))) { + return 0; + } + + const uint16_t *groups; + size_t groups_len; + tls1_get_grouplist(ssl, &groups, &groups_len); + + for (size_t i = 0; i < groups_len; i++) { + if (!CBB_add_u16(&groups_bytes, groups[i])) { + return 0; + } + } + + return CBB_flush(out); +} + +static int ext_supported_groups_parse_serverhello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, + CBS *contents) { + /* This extension is not expected to be echoed by servers in TLS 1.2, but some + * BigIP servers send it nonetheless, so do not enforce this. */ + return 1; +} + +static int ext_supported_groups_parse_clienthello(SSL_HANDSHAKE *hs, + uint8_t *out_alert, + CBS *contents) { + if (contents == NULL) { + return 1; + } + + CBS supported_group_list; + if (!CBS_get_u16_length_prefixed(contents, &supported_group_list) || + CBS_len(&supported_group_list) == 0 || + (CBS_len(&supported_group_list) & 1) != 0 || + CBS_len(contents) != 0) { + return 0; + } + + hs->peer_supported_group_list = + (uint16_t *)OPENSSL_malloc(CBS_len(&supported_group_list)); + if (hs->peer_supported_group_list == NULL) { + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; + } + + const size_t num_groups = CBS_len(&supported_group_list) / 2; + for (size_t i = 0; i < num_groups; i++) { + if (!CBS_get_u16(&supported_group_list, + &hs->peer_supported_group_list[i])) { + goto err; + } + } + + assert(CBS_len(&supported_group_list) == 0); + hs->peer_supported_group_list_len = num_groups; + + return 1; + +err: + OPENSSL_free(hs->peer_supported_group_list); + hs->peer_supported_group_list = NULL; + *out_alert = SSL_AD_INTERNAL_ERROR; + return 0; +} + +static int ext_supported_groups_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) { + /* Servers don't echo this extension. */ + return 1; +} + + +/* kExtensions contains all the supported extensions. */ +static const struct tls_extension kExtensions[] = { + { + TLSEXT_TYPE_renegotiate, + NULL, + ext_ri_add_clienthello, + ext_ri_parse_serverhello, + ext_ri_parse_clienthello, + ext_ri_add_serverhello, + }, + { + TLSEXT_TYPE_server_name, + NULL, + ext_sni_add_clienthello, + ext_sni_parse_serverhello, + ext_sni_parse_clienthello, + ext_sni_add_serverhello, + }, + { + TLSEXT_TYPE_extended_master_secret, + NULL, + ext_ems_add_clienthello, + ext_ems_parse_serverhello, + ext_ems_parse_clienthello, + ext_ems_add_serverhello, + }, + { + TLSEXT_TYPE_session_ticket, + NULL, + ext_ticket_add_clienthello, + ext_ticket_parse_serverhello, + /* Ticket extension client parsing is handled in ssl_session.c */ + ignore_parse_clienthello, + ext_ticket_add_serverhello, + }, + { + TLSEXT_TYPE_signature_algorithms, + NULL, + ext_sigalgs_add_clienthello, + forbid_parse_serverhello, + ext_sigalgs_parse_clienthello, + dont_add_serverhello, + }, + { + TLSEXT_TYPE_status_request, + NULL, + ext_ocsp_add_clienthello, + ext_ocsp_parse_serverhello, + ext_ocsp_parse_clienthello, + ext_ocsp_add_serverhello, + }, + { + TLSEXT_TYPE_next_proto_neg, + NULL, + ext_npn_add_clienthello, + ext_npn_parse_serverhello, + ext_npn_parse_clienthello, + ext_npn_add_serverhello, + }, + { + TLSEXT_TYPE_certificate_timestamp, + NULL, + ext_sct_add_clienthello, + ext_sct_parse_serverhello, + ext_sct_parse_clienthello, + ext_sct_add_serverhello, + }, + { + TLSEXT_TYPE_application_layer_protocol_negotiation, + NULL, + ext_alpn_add_clienthello, + ext_alpn_parse_serverhello, + /* ALPN is negotiated late in |ssl_negotiate_alpn|. */ + ignore_parse_clienthello, + ext_alpn_add_serverhello, + }, + { + TLSEXT_TYPE_channel_id, + ext_channel_id_init, + ext_channel_id_add_clienthello, + ext_channel_id_parse_serverhello, + ext_channel_id_parse_clienthello, + ext_channel_id_add_serverhello, + }, + { + TLSEXT_TYPE_srtp, + ext_srtp_init, + ext_srtp_add_clienthello, + ext_srtp_parse_serverhello, + ext_srtp_parse_clienthello, + ext_srtp_add_serverhello, + }, + { + TLSEXT_TYPE_ec_point_formats, + NULL, + ext_ec_point_add_clienthello, + ext_ec_point_parse_serverhello, + ext_ec_point_parse_clienthello, + ext_ec_point_add_serverhello, + }, + { + TLSEXT_TYPE_key_share, + NULL, + ext_key_share_add_clienthello, + forbid_parse_serverhello, + ignore_parse_clienthello, + dont_add_serverhello, + }, + { + TLSEXT_TYPE_psk_key_exchange_modes, + NULL, + ext_psk_key_exchange_modes_add_clienthello, + forbid_parse_serverhello, + ext_psk_key_exchange_modes_parse_clienthello, + dont_add_serverhello, + }, + { + TLSEXT_TYPE_early_data, + NULL, + ext_early_data_add_clienthello, + ext_early_data_parse_serverhello, + ext_early_data_parse_clienthello, + ext_early_data_add_serverhello, + }, + { + TLSEXT_TYPE_supported_versions, + NULL, + ext_supported_versions_add_clienthello, + forbid_parse_serverhello, + ignore_parse_clienthello, + dont_add_serverhello, + }, + { + TLSEXT_TYPE_cookie, + NULL, + ext_cookie_add_clienthello, + forbid_parse_serverhello, + ignore_parse_clienthello, + dont_add_serverhello, + }, + /* The final extension must be non-empty. WebSphere Application Server 7.0 is + * intolerant to the last extension being zero-length. See + * https://crbug.com/363583. */ + { + TLSEXT_TYPE_supported_groups, + NULL, + ext_supported_groups_add_clienthello, + ext_supported_groups_parse_serverhello, + ext_supported_groups_parse_clienthello, + ext_supported_groups_add_serverhello, + }, +}; + +#define kNumExtensions (sizeof(kExtensions) / sizeof(struct tls_extension)) + +OPENSSL_COMPILE_ASSERT(kNumExtensions <= + sizeof(((SSL_HANDSHAKE *)NULL)->extensions.sent) * 8, + too_many_extensions_for_sent_bitset); +OPENSSL_COMPILE_ASSERT( + kNumExtensions <= sizeof(((SSL_HANDSHAKE *)NULL)->extensions.received) * 8, + too_many_extensions_for_received_bitset); + +static const struct tls_extension *tls_extension_find(uint32_t *out_index, + uint16_t value) { + unsigned i; + for (i = 0; i < kNumExtensions; i++) { + if (kExtensions[i].value == value) { + *out_index = i; + return &kExtensions[i]; + } + } + + return NULL; +} + +int SSL_extension_supported(unsigned extension_value) { + uint32_t index; + return extension_value == TLSEXT_TYPE_padding || + tls_extension_find(&index, extension_value) != NULL; +} + +int ssl_add_clienthello_tlsext(SSL_HANDSHAKE *hs, CBB *out, size_t header_len) { + SSL *const ssl = hs->ssl; + /* Don't add extensions for SSLv3 unless doing secure renegotiation. */ + if (hs->client_version == SSL3_VERSION && + !ssl->s3->send_connection_binding) { + return 1; + } + + CBB extensions; + if (!CBB_add_u16_length_prefixed(out, &extensions)) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + + hs->extensions.sent = 0; + hs->custom_extensions.sent = 0; + + for (size_t i = 0; i < kNumExtensions; i++) { + if (kExtensions[i].init != NULL) { + kExtensions[i].init(hs); + } + } + + uint16_t grease_ext1 = 0; + if (ssl->ctx->grease_enabled) { + /* Add a fake empty extension. See draft-davidben-tls-grease-01. */ + grease_ext1 = ssl_get_grease_value(ssl, ssl_grease_extension1); + if (!CBB_add_u16(&extensions, grease_ext1) || + !CBB_add_u16(&extensions, 0 /* zero length */)) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + } + + for (size_t i = 0; i < kNumExtensions; i++) { + const size_t len_before = CBB_len(&extensions); + if (!kExtensions[i].add_clienthello(hs, &extensions)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION); + ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); + return 0; + } + + if (CBB_len(&extensions) != len_before) { + hs->extensions.sent |= (1u << i); + } + } + + if (!custom_ext_add_clienthello(hs, &extensions)) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + + if (ssl->ctx->grease_enabled) { + /* Add a fake non-empty extension. See draft-davidben-tls-grease-01. */ + uint16_t grease_ext2 = ssl_get_grease_value(ssl, ssl_grease_extension2); + + /* The two fake extensions must not have the same value. GREASE values are + * of the form 0x1a1a, 0x2a2a, 0x3a3a, etc., so XOR to generate a different + * one. */ + if (grease_ext1 == grease_ext2) { + grease_ext2 ^= 0x1010; + } + + if (!CBB_add_u16(&extensions, grease_ext2) || + !CBB_add_u16(&extensions, 1 /* one byte length */) || + !CBB_add_u8(&extensions, 0 /* single zero byte as contents */)) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + } + + if (!SSL_is_dtls(ssl)) { + size_t psk_extension_len = ext_pre_shared_key_clienthello_length(hs); + header_len += 2 + CBB_len(&extensions) + psk_extension_len; + if (header_len > 0xff && header_len < 0x200) { + /* Add padding to workaround bugs in F5 terminators. See RFC 7685. + * + * NB: because this code works out the length of all existing extensions + * it MUST always appear last. */ + size_t padding_len = 0x200 - header_len; + /* Extensions take at least four bytes to encode. Always include at least + * one byte of data if including the extension. WebSphere Application + * Server 7.0 is intolerant to the last extension being zero-length. See + * https://crbug.com/363583. */ + if (padding_len >= 4 + 1) { + padding_len -= 4; + } else { + padding_len = 1; + } + + uint8_t *padding_bytes; + if (!CBB_add_u16(&extensions, TLSEXT_TYPE_padding) || + !CBB_add_u16(&extensions, padding_len) || + !CBB_add_space(&extensions, &padding_bytes, padding_len)) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + + OPENSSL_memset(padding_bytes, 0, padding_len); + } + } + + /* The PSK extension must be last, including after the padding. */ + if (!ext_pre_shared_key_add_clienthello(hs, &extensions)) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + + /* Discard empty extensions blocks. */ + if (CBB_len(&extensions) == 0) { + CBB_discard_child(out); + } + + return CBB_flush(out); +} + +int ssl_add_serverhello_tlsext(SSL_HANDSHAKE *hs, CBB *out) { + SSL *const ssl = hs->ssl; + CBB extensions; + if (!CBB_add_u16_length_prefixed(out, &extensions)) { + goto err; + } + + for (unsigned i = 0; i < kNumExtensions; i++) { + if (!(hs->extensions.received & (1u << i))) { + /* Don't send extensions that were not received. */ + continue; + } + + if (!kExtensions[i].add_serverhello(hs, &extensions)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION); + ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); + goto err; + } + } + + if (!custom_ext_add_serverhello(hs, &extensions)) { + goto err; + } + + /* Discard empty extensions blocks before TLS 1.3. */ + if (ssl3_protocol_version(ssl) < TLS1_3_VERSION && + CBB_len(&extensions) == 0) { + CBB_discard_child(out); + } + + return CBB_flush(out); + +err: + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; +} + +static int ssl_scan_clienthello_tlsext(SSL_HANDSHAKE *hs, + const SSL_CLIENT_HELLO *client_hello, + int *out_alert) { + SSL *const ssl = hs->ssl; + for (size_t i = 0; i < kNumExtensions; i++) { + if (kExtensions[i].init != NULL) { + kExtensions[i].init(hs); + } + } + + hs->extensions.received = 0; + hs->custom_extensions.received = 0; + + CBS extensions; + CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len); + while (CBS_len(&extensions) != 0) { + uint16_t type; + CBS extension; + + /* Decode the next extension. */ + if (!CBS_get_u16(&extensions, &type) || + !CBS_get_u16_length_prefixed(&extensions, &extension)) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + /* RFC 5746 made the existence of extensions in SSL 3.0 somewhat + * ambiguous. Ignore all but the renegotiation_info extension. */ + if (ssl->version == SSL3_VERSION && type != TLSEXT_TYPE_renegotiate) { + continue; + } + + unsigned ext_index; + const struct tls_extension *const ext = + tls_extension_find(&ext_index, type); + + if (ext == NULL) { + if (!custom_ext_parse_clienthello(hs, out_alert, type, &extension)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION); + return 0; + } + continue; + } + + hs->extensions.received |= (1u << ext_index); + uint8_t alert = SSL_AD_DECODE_ERROR; + if (!ext->parse_clienthello(hs, &alert, &extension)) { + *out_alert = alert; + OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION); + ERR_add_error_dataf("extension %u", (unsigned)type); + return 0; + } + } + + for (size_t i = 0; i < kNumExtensions; i++) { + if (hs->extensions.received & (1u << i)) { + continue; + } + + CBS *contents = NULL, fake_contents; + static const uint8_t kFakeRenegotiateExtension[] = {0}; + if (kExtensions[i].value == TLSEXT_TYPE_renegotiate && + ssl_client_cipher_list_contains_cipher(client_hello, + SSL3_CK_SCSV & 0xffff)) { + /* The renegotiation SCSV was received so pretend that we received a + * renegotiation extension. */ + CBS_init(&fake_contents, kFakeRenegotiateExtension, + sizeof(kFakeRenegotiateExtension)); + contents = &fake_contents; + hs->extensions.received |= (1u << i); + } + + /* Extension wasn't observed so call the callback with a NULL + * parameter. */ + uint8_t alert = SSL_AD_DECODE_ERROR; + if (!kExtensions[i].parse_clienthello(hs, &alert, contents)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION); + ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); + *out_alert = alert; + return 0; + } + } + + return 1; +} + +int ssl_parse_clienthello_tlsext(SSL_HANDSHAKE *hs, + const SSL_CLIENT_HELLO *client_hello) { + SSL *const ssl = hs->ssl; + int alert = SSL_AD_DECODE_ERROR; + if (ssl_scan_clienthello_tlsext(hs, client_hello, &alert) <= 0) { + ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); + return 0; + } + + if (ssl_check_clienthello_tlsext(hs) <= 0) { + OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_TLSEXT); + return 0; + } + + return 1; +} + +static int ssl_scan_serverhello_tlsext(SSL_HANDSHAKE *hs, CBS *cbs, + int *out_alert) { + SSL *const ssl = hs->ssl; + /* Before TLS 1.3, ServerHello extensions blocks may be omitted if empty. */ + if (CBS_len(cbs) == 0 && ssl3_protocol_version(ssl) < TLS1_3_VERSION) { + return 1; + } + + /* Decode the extensions block and check it is valid. */ + CBS extensions; + if (!CBS_get_u16_length_prefixed(cbs, &extensions) || + !tls1_check_duplicate_extensions(&extensions)) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + uint32_t received = 0; + while (CBS_len(&extensions) != 0) { + uint16_t type; + CBS extension; + + /* Decode the next extension. */ + if (!CBS_get_u16(&extensions, &type) || + !CBS_get_u16_length_prefixed(&extensions, &extension)) { + *out_alert = SSL_AD_DECODE_ERROR; + return 0; + } + + unsigned ext_index; + const struct tls_extension *const ext = + tls_extension_find(&ext_index, type); + + if (ext == NULL) { + if (!custom_ext_parse_serverhello(hs, out_alert, type, &extension)) { + return 0; + } + continue; + } + + OPENSSL_COMPILE_ASSERT(kNumExtensions <= sizeof(hs->extensions.sent) * 8, + too_many_bits); + + if (!(hs->extensions.sent & (1u << ext_index)) && + type != TLSEXT_TYPE_renegotiate) { + /* If the extension was never sent then it is illegal, except for the + * renegotiation extension which, in SSL 3.0, is signaled via SCSV. */ + OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); + ERR_add_error_dataf("extension :%u", (unsigned)type); + *out_alert = SSL_AD_UNSUPPORTED_EXTENSION; + return 0; + } + + received |= (1u << ext_index); + + uint8_t alert = SSL_AD_DECODE_ERROR; + if (!ext->parse_serverhello(hs, &alert, &extension)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION); + ERR_add_error_dataf("extension %u", (unsigned)type); + *out_alert = alert; + return 0; + } + } + + for (size_t i = 0; i < kNumExtensions; i++) { + if (!(received & (1u << i))) { + /* Extension wasn't observed so call the callback with a NULL + * parameter. */ + uint8_t alert = SSL_AD_DECODE_ERROR; + if (!kExtensions[i].parse_serverhello(hs, &alert, NULL)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION); + ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value); + *out_alert = alert; + return 0; + } + } + } + + return 1; +} + +static int ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs) { + SSL *const ssl = hs->ssl; + int ret = SSL_TLSEXT_ERR_NOACK; + int al = SSL_AD_UNRECOGNIZED_NAME; + + if (ssl->ctx->tlsext_servername_callback != 0) { + ret = ssl->ctx->tlsext_servername_callback(ssl, &al, + ssl->ctx->tlsext_servername_arg); + } else if (ssl->session_ctx->tlsext_servername_callback != 0) { + ret = ssl->session_ctx->tlsext_servername_callback( + ssl, &al, ssl->session_ctx->tlsext_servername_arg); + } + + switch (ret) { + case SSL_TLSEXT_ERR_ALERT_FATAL: + ssl3_send_alert(ssl, SSL3_AL_FATAL, al); + return -1; + + case SSL_TLSEXT_ERR_NOACK: + hs->should_ack_sni = 0; + return 1; + + default: + return 1; + } +} + +int ssl_parse_serverhello_tlsext(SSL_HANDSHAKE *hs, CBS *cbs) { + SSL *const ssl = hs->ssl; + int alert = SSL_AD_DECODE_ERROR; + if (ssl_scan_serverhello_tlsext(hs, cbs, &alert) <= 0) { + ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); + return 0; + } + + return 1; +} + +static enum ssl_ticket_aead_result_t +ssl_decrypt_ticket_with_cipher_ctx(SSL *ssl, uint8_t **out, size_t *out_len, + int *out_renew_ticket, const uint8_t *ticket, + size_t ticket_len) { + const SSL_CTX *const ssl_ctx = ssl->session_ctx; + + bssl::ScopedHMAC_CTX hmac_ctx; + bssl::ScopedEVP_CIPHER_CTX cipher_ctx; + + /* Ensure there is room for the key name and the largest IV + * |tlsext_ticket_key_cb| may try to consume. The real limit may be lower, but + * the maximum IV length should be well under the minimum size for the + * session material and HMAC. */ + if (ticket_len < SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH) { + return ssl_ticket_aead_ignore_ticket; + } + const uint8_t *iv = ticket + SSL_TICKET_KEY_NAME_LEN; + + if (ssl_ctx->tlsext_ticket_key_cb != NULL) { + int cb_ret = ssl_ctx->tlsext_ticket_key_cb( + ssl, (uint8_t *)ticket /* name */, (uint8_t *)iv, cipher_ctx.get(), + hmac_ctx.get(), 0 /* decrypt */); + if (cb_ret < 0) { + return ssl_ticket_aead_error; + } else if (cb_ret == 0) { + return ssl_ticket_aead_ignore_ticket; + } else if (cb_ret == 2) { + *out_renew_ticket = 1; + } + } else { + /* Check the key name matches. */ + if (OPENSSL_memcmp(ticket, ssl_ctx->tlsext_tick_key_name, + SSL_TICKET_KEY_NAME_LEN) != 0) { + return ssl_ticket_aead_ignore_ticket; + } + if (!HMAC_Init_ex(hmac_ctx.get(), ssl_ctx->tlsext_tick_hmac_key, + sizeof(ssl_ctx->tlsext_tick_hmac_key), tlsext_tick_md(), + NULL) || + !EVP_DecryptInit_ex(cipher_ctx.get(), EVP_aes_128_cbc(), NULL, + ssl_ctx->tlsext_tick_aes_key, iv)) { + return ssl_ticket_aead_error; + } + } + size_t iv_len = EVP_CIPHER_CTX_iv_length(cipher_ctx.get()); + + /* Check the MAC at the end of the ticket. */ + uint8_t mac[EVP_MAX_MD_SIZE]; + size_t mac_len = HMAC_size(hmac_ctx.get()); + if (ticket_len < SSL_TICKET_KEY_NAME_LEN + iv_len + 1 + mac_len) { + /* The ticket must be large enough for key name, IV, data, and MAC. */ + return ssl_ticket_aead_ignore_ticket; + } + HMAC_Update(hmac_ctx.get(), ticket, ticket_len - mac_len); + HMAC_Final(hmac_ctx.get(), mac, NULL); + int mac_ok = + CRYPTO_memcmp(mac, ticket + (ticket_len - mac_len), mac_len) == 0; +#if defined(BORINGSSL_UNSAFE_FUZZER_MODE) + mac_ok = 1; +#endif + if (!mac_ok) { + return ssl_ticket_aead_ignore_ticket; + } + + /* Decrypt the session data. */ + const uint8_t *ciphertext = ticket + SSL_TICKET_KEY_NAME_LEN + iv_len; + size_t ciphertext_len = ticket_len - SSL_TICKET_KEY_NAME_LEN - iv_len - + mac_len; + bssl::UniquePtr<uint8_t> plaintext((uint8_t *)OPENSSL_malloc(ciphertext_len)); + if (!plaintext) { + return ssl_ticket_aead_error; + } + size_t plaintext_len; +#if defined(BORINGSSL_UNSAFE_FUZZER_MODE) + OPENSSL_memcpy(plaintext.get(), ciphertext, ciphertext_len); + plaintext_len = ciphertext_len; +#else + if (ciphertext_len >= INT_MAX) { + return ssl_ticket_aead_ignore_ticket; + } + int len1, len2; + if (!EVP_DecryptUpdate(cipher_ctx.get(), plaintext.get(), &len1, ciphertext, + (int)ciphertext_len) || + !EVP_DecryptFinal_ex(cipher_ctx.get(), plaintext.get() + len1, &len2)) { + ERR_clear_error(); + return ssl_ticket_aead_ignore_ticket; + } + plaintext_len = (size_t)(len1) + len2; +#endif + + *out = plaintext.release(); + *out_len = plaintext_len; + return ssl_ticket_aead_success; +} + +static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_method( + SSL *ssl, uint8_t **out, size_t *out_len, int *out_renew_ticket, + const uint8_t *ticket, size_t ticket_len) { + uint8_t *plaintext = (uint8_t *)OPENSSL_malloc(ticket_len); + if (plaintext == NULL) { + OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); + return ssl_ticket_aead_error; + } + + size_t plaintext_len; + const enum ssl_ticket_aead_result_t result = + ssl->session_ctx->ticket_aead_method->open( + ssl, plaintext, &plaintext_len, ticket_len, ticket, ticket_len); + + if (result == ssl_ticket_aead_success) { + *out = plaintext; + plaintext = NULL; + *out_len = plaintext_len; + } + + OPENSSL_free(plaintext); + return result; +} + +enum ssl_ticket_aead_result_t ssl_process_ticket( + SSL *ssl, SSL_SESSION **out_session, int *out_renew_ticket, + const uint8_t *ticket, size_t ticket_len, const uint8_t *session_id, + size_t session_id_len) { + *out_renew_ticket = 0; + *out_session = NULL; + + if ((SSL_get_options(ssl) & SSL_OP_NO_TICKET) || + session_id_len > SSL_MAX_SSL_SESSION_ID_LENGTH) { + return ssl_ticket_aead_ignore_ticket; + } + + uint8_t *plaintext = NULL; + size_t plaintext_len; + enum ssl_ticket_aead_result_t result; + if (ssl->session_ctx->ticket_aead_method != NULL) { + result = ssl_decrypt_ticket_with_method( + ssl, &plaintext, &plaintext_len, out_renew_ticket, ticket, ticket_len); + } else { + result = ssl_decrypt_ticket_with_cipher_ctx( + ssl, &plaintext, &plaintext_len, out_renew_ticket, ticket, ticket_len); + } + + if (result != ssl_ticket_aead_success) { + return result; + } + + /* Decode the session. */ + SSL_SESSION *session = + SSL_SESSION_from_bytes(plaintext, plaintext_len, ssl->ctx); + OPENSSL_free(plaintext); + + if (session == NULL) { + ERR_clear_error(); /* Don't leave an error on the queue. */ + return ssl_ticket_aead_ignore_ticket; + } + + /* Copy the client's session ID into the new session, to denote the ticket has + * been accepted. */ + OPENSSL_memcpy(session->session_id, session_id, session_id_len); + session->session_id_length = session_id_len; + + *out_session = session; + return ssl_ticket_aead_success; +} + +int tls1_parse_peer_sigalgs(SSL_HANDSHAKE *hs, const CBS *in_sigalgs) { + /* Extension ignored for inappropriate versions */ + if (ssl3_protocol_version(hs->ssl) < TLS1_2_VERSION) { + return 1; + } + + OPENSSL_free(hs->peer_sigalgs); + hs->peer_sigalgs = NULL; + hs->num_peer_sigalgs = 0; + + size_t num_sigalgs = CBS_len(in_sigalgs); + if (num_sigalgs % 2 != 0) { + return 0; + } + num_sigalgs /= 2; + + /* supported_signature_algorithms in the certificate request is + * allowed to be empty. */ + if (num_sigalgs == 0) { + return 1; + } + + /* This multiplication doesn't overflow because sizeof(uint16_t) is two + * and we just divided |num_sigalgs| by two. */ + hs->peer_sigalgs = (uint16_t *)OPENSSL_malloc(num_sigalgs * sizeof(uint16_t)); + if (hs->peer_sigalgs == NULL) { + return 0; + } + hs->num_peer_sigalgs = num_sigalgs; + + CBS sigalgs; + CBS_init(&sigalgs, CBS_data(in_sigalgs), CBS_len(in_sigalgs)); + for (size_t i = 0; i < num_sigalgs; i++) { + if (!CBS_get_u16(&sigalgs, &hs->peer_sigalgs[i])) { + return 0; + } + } + + return 1; +} + +int tls1_get_legacy_signature_algorithm(uint16_t *out, const EVP_PKEY *pkey) { + switch (EVP_PKEY_id(pkey)) { + case EVP_PKEY_RSA: + *out = SSL_SIGN_RSA_PKCS1_MD5_SHA1; + return 1; + case EVP_PKEY_EC: + *out = SSL_SIGN_ECDSA_SHA1; + return 1; + default: + return 0; + } +} + +int tls1_choose_signature_algorithm(SSL_HANDSHAKE *hs, uint16_t *out) { + SSL *const ssl = hs->ssl; + CERT *cert = ssl->cert; + + /* Before TLS 1.2, the signature algorithm isn't negotiated as part of the + * handshake. */ + if (ssl3_protocol_version(ssl) < TLS1_2_VERSION) { + if (!tls1_get_legacy_signature_algorithm(out, hs->local_pubkey)) { + OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS); + return 0; + } + return 1; + } + + const uint16_t *sigalgs = cert->sigalgs; + size_t num_sigalgs = cert->num_sigalgs; + if (sigalgs == NULL) { + sigalgs = kSignSignatureAlgorithms; + num_sigalgs = OPENSSL_ARRAY_SIZE(kSignSignatureAlgorithms); + } + + const uint16_t *peer_sigalgs = hs->peer_sigalgs; + size_t num_peer_sigalgs = hs->num_peer_sigalgs; + if (num_peer_sigalgs == 0 && ssl3_protocol_version(ssl) < TLS1_3_VERSION) { + /* If the client didn't specify any signature_algorithms extension then + * we can assume that it supports SHA1. See + * http://tools.ietf.org/html/rfc5246#section-7.4.1.4.1 */ + static const uint16_t kDefaultPeerAlgorithms[] = {SSL_SIGN_RSA_PKCS1_SHA1, + SSL_SIGN_ECDSA_SHA1}; + peer_sigalgs = kDefaultPeerAlgorithms; + num_peer_sigalgs = OPENSSL_ARRAY_SIZE(kDefaultPeerAlgorithms); + } + + for (size_t i = 0; i < num_sigalgs; i++) { + uint16_t sigalg = sigalgs[i]; + /* SSL_SIGN_RSA_PKCS1_MD5_SHA1 is an internal value and should never be + * negotiated. */ + if (sigalg == SSL_SIGN_RSA_PKCS1_MD5_SHA1 || + !ssl_private_key_supports_signature_algorithm(hs, sigalgs[i])) { + continue; + } + + for (size_t j = 0; j < num_peer_sigalgs; j++) { + if (sigalg == peer_sigalgs[j]) { + *out = sigalg; + return 1; + } + } + } + + OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS); + return 0; +} + +int tls1_verify_channel_id(SSL_HANDSHAKE *hs) { + SSL *const ssl = hs->ssl; + uint16_t extension_type; + CBS extension, channel_id; + + /* A Channel ID handshake message is structured to contain multiple + * extensions, but the only one that can be present is Channel ID. */ + CBS_init(&channel_id, ssl->init_msg, ssl->init_num); + if (!CBS_get_u16(&channel_id, &extension_type) || + !CBS_get_u16_length_prefixed(&channel_id, &extension) || + CBS_len(&channel_id) != 0 || + extension_type != TLSEXT_TYPE_channel_id || + CBS_len(&extension) != TLSEXT_CHANNEL_ID_SIZE) { + OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); + ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); + return 0; + } + + bssl::UniquePtr<EC_GROUP> p256( + EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1)); + if (!p256) { + OPENSSL_PUT_ERROR(SSL, SSL_R_NO_P256_SUPPORT); + return 0; + } + + bssl::UniquePtr<ECDSA_SIG> sig(ECDSA_SIG_new()); + bssl::UniquePtr<BIGNUM> x(BN_new()), y(BN_new()); + if (!sig || !x || !y) { + return 0; + } + + const uint8_t *p = CBS_data(&extension); + if (BN_bin2bn(p + 0, 32, x.get()) == NULL || + BN_bin2bn(p + 32, 32, y.get()) == NULL || + BN_bin2bn(p + 64, 32, sig->r) == NULL || + BN_bin2bn(p + 96, 32, sig->s) == NULL) { + return 0; + } + + bssl::UniquePtr<EC_KEY> key(EC_KEY_new()); + bssl::UniquePtr<EC_POINT> point(EC_POINT_new(p256.get())); + if (!key || !point || + !EC_POINT_set_affine_coordinates_GFp(p256.get(), point.get(), x.get(), + y.get(), nullptr) || + !EC_KEY_set_group(key.get(), p256.get()) || + !EC_KEY_set_public_key(key.get(), point.get())) { + return 0; + } + + uint8_t digest[EVP_MAX_MD_SIZE]; + size_t digest_len; + if (!tls1_channel_id_hash(hs, digest, &digest_len)) { + return 0; + } + + int sig_ok = ECDSA_do_verify(digest, digest_len, sig.get(), key.get()); +#if defined(BORINGSSL_UNSAFE_FUZZER_MODE) + sig_ok = 1; +#endif + if (!sig_ok) { + OPENSSL_PUT_ERROR(SSL, SSL_R_CHANNEL_ID_SIGNATURE_INVALID); + ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR); + ssl->s3->tlsext_channel_id_valid = 0; + return 0; + } + + OPENSSL_memcpy(ssl->s3->tlsext_channel_id, p, 64); + return 1; +} + +int tls1_write_channel_id(SSL_HANDSHAKE *hs, CBB *cbb) { + SSL *const ssl = hs->ssl; + uint8_t digest[EVP_MAX_MD_SIZE]; + size_t digest_len; + if (!tls1_channel_id_hash(hs, digest, &digest_len)) { + return 0; + } + + EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(ssl->tlsext_channel_id_private); + if (ec_key == NULL) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + + int ret = 0; + BIGNUM *x = BN_new(); + BIGNUM *y = BN_new(); + ECDSA_SIG *sig = NULL; + if (x == NULL || y == NULL || + !EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(ec_key), + EC_KEY_get0_public_key(ec_key), + x, y, NULL)) { + goto err; + } + + sig = ECDSA_do_sign(digest, digest_len, ec_key); + if (sig == NULL) { + goto err; + } + + CBB child; + if (!CBB_add_u16(cbb, TLSEXT_TYPE_channel_id) || + !CBB_add_u16_length_prefixed(cbb, &child) || + !BN_bn2cbb_padded(&child, 32, x) || + !BN_bn2cbb_padded(&child, 32, y) || + !BN_bn2cbb_padded(&child, 32, sig->r) || + !BN_bn2cbb_padded(&child, 32, sig->s) || + !CBB_flush(cbb)) { + goto err; + } + + ret = 1; + +err: + BN_free(x); + BN_free(y); + ECDSA_SIG_free(sig); + return ret; +} + +int tls1_channel_id_hash(SSL_HANDSHAKE *hs, uint8_t *out, size_t *out_len) { + SSL *const ssl = hs->ssl; + if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) { + uint8_t *msg; + size_t msg_len; + if (!tls13_get_cert_verify_signature_input(hs, &msg, &msg_len, + ssl_cert_verify_channel_id)) { + return 0; + } + SHA256(msg, msg_len, out); + *out_len = SHA256_DIGEST_LENGTH; + OPENSSL_free(msg); + return 1; + } + + SHA256_CTX ctx; + + SHA256_Init(&ctx); + static const char kClientIDMagic[] = "TLS Channel ID signature"; + SHA256_Update(&ctx, kClientIDMagic, sizeof(kClientIDMagic)); + + if (ssl->session != NULL) { + static const char kResumptionMagic[] = "Resumption"; + SHA256_Update(&ctx, kResumptionMagic, sizeof(kResumptionMagic)); + if (ssl->session->original_handshake_hash_len == 0) { + OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); + return 0; + } + SHA256_Update(&ctx, ssl->session->original_handshake_hash, + ssl->session->original_handshake_hash_len); + } + + uint8_t hs_hash[EVP_MAX_MD_SIZE]; + size_t hs_hash_len; + if (!SSL_TRANSCRIPT_get_hash(&hs->transcript, hs_hash, &hs_hash_len)) { + return 0; + } + SHA256_Update(&ctx, hs_hash, (size_t)hs_hash_len); + SHA256_Final(out, &ctx); + *out_len = SHA256_DIGEST_LENGTH; + return 1; +} + +/* tls1_record_handshake_hashes_for_channel_id records the current handshake + * hashes in |hs->new_session| so that Channel ID resumptions can sign that + * data. */ +int tls1_record_handshake_hashes_for_channel_id(SSL_HANDSHAKE *hs) { + SSL *const ssl = hs->ssl; + /* This function should never be called for a resumed session because the + * handshake hashes that we wish to record are for the original, full + * handshake. */ + if (ssl->session != NULL) { + return -1; + } + + OPENSSL_COMPILE_ASSERT( + sizeof(hs->new_session->original_handshake_hash) == EVP_MAX_MD_SIZE, + original_handshake_hash_is_too_small); + + size_t digest_len; + if (!SSL_TRANSCRIPT_get_hash(&hs->transcript, + hs->new_session->original_handshake_hash, + &digest_len)) { + return -1; + } + + OPENSSL_COMPILE_ASSERT(EVP_MAX_MD_SIZE <= 0xff, max_md_size_is_too_large); + hs->new_session->original_handshake_hash_len = (uint8_t)digest_len; + + return 1; +} + +int ssl_do_channel_id_callback(SSL *ssl) { + if (ssl->tlsext_channel_id_private != NULL || + ssl->ctx->channel_id_cb == NULL) { + return 1; + } + + EVP_PKEY *key = NULL; + ssl->ctx->channel_id_cb(ssl, &key); + if (key == NULL) { + /* The caller should try again later. */ + return 1; + } + + int ret = SSL_set1_tls_channel_id(ssl, key); + EVP_PKEY_free(key); + return ret; +} + +int ssl_is_sct_list_valid(const CBS *contents) { + /* Shallow parse the SCT list for sanity. By the RFC + * (https://tools.ietf.org/html/rfc6962#section-3.3) neither the list nor any + * of the SCTs may be empty. */ + CBS copy = *contents; + CBS sct_list; + if (!CBS_get_u16_length_prefixed(©, &sct_list) || + CBS_len(©) != 0 || + CBS_len(&sct_list) == 0) { + return 0; + } + + while (CBS_len(&sct_list) > 0) { + CBS sct; + if (!CBS_get_u16_length_prefixed(&sct_list, &sct) || + CBS_len(&sct) == 0) { + return 0; + } + } + + return 1; +}