Remove support for RSA premaster logging.

This was replaced by the more general CLIENT_RANDOM scheme that records
the master secret. Support was added in Wireshark 1.8.0, released in
June 2012. At this point, ECDHE is sufficiently widely deployed that
anyone that cares about this feature must have upgraded their Wireshark
by now.

Change-Id: I9b708f245ec8728c1999daf91aca663be7d25661
Reviewed-on: https://boringssl-review.googlesource.com/13263
Reviewed-by: David Benjamin <davidben@google.com>

ssl/handshake_client.c

diff --git a/ssl/handshake_client.c b/ssl/handshake_client.c
index 388d53b..3389d6c 100644
--- a/ssl/handshake_client.c
+++ b/ssl/handshake_client.c
@@ -1578,8 +1578,6 @@
     if (!CBB_reserve(enc_pms, &ptr, RSA_size(rsa)) ||
         !RSA_encrypt(rsa, &enc_pms_len, ptr, RSA_size(rsa), pms, pms_len,
                      RSA_PKCS1_PADDING) ||
-        /* Log the premaster secret, if logging is enabled. */
-        !ssl_log_rsa_client_key_exchange(ssl, ptr, enc_pms_len, pms, pms_len) ||
         !CBB_did_write(enc_pms, enc_pms_len) ||
         !CBB_flush(&body)) {
       goto err;

ssl/internal.h

diff --git a/ssl/internal.h b/ssl/internal.h
index 9557828..a320e72 100644
--- a/ssl/internal.h
+++ b/ssl/internal.h
@@ -1155,15 +1155,6 @@
 
 /* SSLKEYLOGFILE functions. */
 
-/* ssl_log_rsa_client_key_exchange logs |premaster|, if logging is enabled for
- * |ssl|. It returns one on success and zero on failure. The entry is identified
- * by the first 8 bytes of |encrypted_premaster|. */
-int ssl_log_rsa_client_key_exchange(const SSL *ssl,
-                                    const uint8_t *encrypted_premaster,
-                                    size_t encrypted_premaster_len,
-                                    const uint8_t *premaster,
-                                    size_t premaster_len);
-
 /* ssl_log_secret logs |secret| with label |label|, if logging is enabled for
  * |ssl|. It returns one on success and zero on failure. */
 int ssl_log_secret(const SSL *ssl, const char *label, const uint8_t *secret,

ssl/ssl_lib.c

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 1a95bc8..ba1ee8f 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2370,41 +2370,6 @@
   return 1;
 }
 
-int ssl_log_rsa_client_key_exchange(const SSL *ssl,
-                                    const uint8_t *encrypted_premaster,
-                                    size_t encrypted_premaster_len,
-                                    const uint8_t *premaster,
-                                    size_t premaster_len) {
-  if (ssl->ctx->keylog_callback == NULL) {
-    return 1;
-  }
-
-  if (encrypted_premaster_len < 8) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return 0;
-  }
-
-  CBB cbb;
-  uint8_t *out;
-  size_t out_len;
-  if (!CBB_init(&cbb, 4 + 16 + 1 + premaster_len * 2 + 1) ||
-      !CBB_add_bytes(&cbb, (const uint8_t *)"RSA ", 4) ||
-      /* Only the first 8 bytes of the encrypted premaster secret are
-       * logged. */
-      !cbb_add_hex(&cbb, encrypted_premaster, 8) ||
-      !CBB_add_bytes(&cbb, (const uint8_t *)" ", 1) ||
-      !cbb_add_hex(&cbb, premaster, premaster_len) ||
-      !CBB_add_u8(&cbb, 0 /* NUL */) ||
-      !CBB_finish(&cbb, &out, &out_len)) {
-    CBB_cleanup(&cbb);
-    return 0;
-  }
-
-  ssl->ctx->keylog_callback(ssl, (const char *)out);
-  OPENSSL_free(out);
-  return 1;
-}
-
 int ssl_log_secret(const SSL *ssl, const char *label, const uint8_t *secret,
                    size_t secret_len) {
   if (ssl->ctx->keylog_callback == NULL) {