include/openssl/bio.h

// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef OPENSSL_HEADER_BIO_H
#define OPENSSL_HEADER_BIO_H

#include <openssl/base.h>   // IWYU pragma: export

#include <stdio.h>  // For FILE

#include <openssl/buffer.h>
#include <openssl/err.h>  // for ERR_print_errors_fp
#include <openssl/ex_data.h>
#include <openssl/stack.h>

#if defined(__cplusplus)
extern "C" {
#endif


// BIO abstracts over a file-descriptor like interface.


// Allocation and freeing.

DEFINE_STACK_OF(BIO)

// BIO_new creates a new BIO with the given method and a reference count of one.
// It returns the fresh `BIO`, or NULL on error.
OPENSSL_EXPORT BIO *BIO_new(const BIO_METHOD *method);

// BIO_free decrements the reference count of `bio`. If the reference count
// drops to zero, it calls the destroy callback, if present, on the method and
// frees `bio` itself. If `bio` is part of a chain (see `BIO_push`), this will
// also free the next `BIO` in the chain, and so on.
//
// It returns one if `bio` was NULL or freed. It returns zero if `bio` was
// shared and some other owner still owns a reference count to it.
//
// WARNING: Do not use the return value. Returning zero is not a sign of an
// error, nor an indication to retry the operation. `BIO` is a reference-counted
// type. A given `BIO` object may be shared between multiple parts of an
// application. To correctly track the reference count, without leaks or
// use-after-free, each part of the application must release only the reference
// counts it owns.
OPENSSL_EXPORT int BIO_free(BIO *bio);

// BIO_vfree performs the same actions as `BIO_free`, but has a void return
// value. This is provided for API-compat.
//
// TODO(fork): remove.
OPENSSL_EXPORT void BIO_vfree(BIO *bio);

// BIO_up_ref increments the reference count of `bio` and returns one.
OPENSSL_EXPORT int BIO_up_ref(BIO *bio);


// Basic I/O.

// BIO_read attempts to read `len` bytes into `data`. It returns the number of
// bytes read, zero on EOF, or a negative number on error.
OPENSSL_EXPORT int BIO_read(BIO *bio, void *data, int len);

// BIO_gets reads a line from `bio` and writes at most `size` bytes into `buf`.
// It returns the number of bytes read or a negative number on error. This
// function's output always includes a trailing NUL byte, so it will read at
// most `size - 1` bytes.
//
// If the function read a complete line, the output will include the newline
// character, '\n'. If no newline was found before `size - 1` bytes or EOF, it
// outputs the bytes which were available.
OPENSSL_EXPORT int BIO_gets(BIO *bio, char *buf, int size);

// BIO_write writes `len` bytes from `data` to `bio`. It returns the number of
// bytes written or a negative number on error.
OPENSSL_EXPORT int BIO_write(BIO *bio, const void *data, int len);

// BIO_write_all writes `len` bytes from `data` to `bio`, looping as necessary.
// It returns one if all bytes were successfully written and zero on error.
OPENSSL_EXPORT int BIO_write_all(BIO *bio, const void *data, size_t len);

// BIO_puts writes a NUL terminated string from `buf` to `bio`. It returns the
// number of bytes written or a negative number on error.
OPENSSL_EXPORT int BIO_puts(BIO *bio, const char *buf);

// BIO_flush flushes any buffered output. It returns one on success and zero
// otherwise.
OPENSSL_EXPORT int BIO_flush(BIO *bio);


// Low-level control functions.
//
// These are generic functions for sending control requests to a BIO. In
// general one should use the wrapper functions like `BIO_get_close`.

// BIO_ctrl sends the control request `cmd` to `bio`. The `cmd` argument should
// be one of the `BIO_C_*` values.
OPENSSL_EXPORT long BIO_ctrl(BIO *bio, int cmd, long larg, void *parg);

// BIO_ptr_ctrl acts like `BIO_ctrl` but passes the address of a `void*`
// pointer as `parg` and returns the value that is written to it, or NULL if
// the control request returns <= 0.
OPENSSL_EXPORT char *BIO_ptr_ctrl(BIO *bp, int cmd, long larg);

// BIO_int_ctrl acts like `BIO_ctrl` but passes the address of a copy of `iarg`
// as `parg`.
OPENSSL_EXPORT long BIO_int_ctrl(BIO *bp, int cmd, long larg, int iarg);

// BIO_reset resets `bio` to its initial state, the precise meaning of which
// depends on the concrete type of `bio`. It normally returns one on success and
// <= 0 otherwise. However, for file and fd BIOs, it returns zero on success and
// a negative number on error.
//
// WARNING: This function's return value conventions differs from most functions
// in this library.
OPENSSL_EXPORT int BIO_reset(BIO *bio);

// BIO_eof returns non-zero when `bio` has reached end-of-file. The precise
// meaning of which depends on the concrete type of `bio`. Note that in the
// case of BIO_pair this always returns non-zero.
OPENSSL_EXPORT int BIO_eof(BIO *bio);

// BIO_set_flags ORs `flags` with `bio->flags`. Unless otherwise documented,
// flags are private to either BoringSSL or the custom `BIO_METHOD`.
OPENSSL_EXPORT void BIO_set_flags(BIO *bio, int flags);

// BIO_clear_flags ANDs `bio->flags` with the bitwise-complement of `flags`.
// Unless otherwise documented, flags are private to either BoringSSL or the
// custom `BIO_METHOD`.
OPENSSL_EXPORT void BIO_clear_flags(BIO *bio, int flags);

// BIO_test_flags returns `bio->flags` AND `flags`.
OPENSSL_EXPORT int BIO_test_flags(const BIO *bio, int flags);

// BIO_should_read returns non-zero if `bio` encountered a temporary error
// while reading (i.e. EAGAIN), indicating that the caller should retry the
// read.
OPENSSL_EXPORT int BIO_should_read(const BIO *bio);

// BIO_should_write returns non-zero if `bio` encountered a temporary error
// while writing (i.e. EAGAIN), indicating that the caller should retry the
// write.
OPENSSL_EXPORT int BIO_should_write(const BIO *bio);

// BIO_should_retry returns non-zero if the reason that caused a failed I/O
// operation is temporary and thus the operation should be retried. Otherwise,
// it was a permanent error and it returns zero.
OPENSSL_EXPORT int BIO_should_retry(const BIO *bio);

// BIO_should_io_special returns non-zero if `bio` encountered a temporary
// error while performing a special I/O operation, indicating that the caller
// should retry. The operation that caused the error is returned by
// `BIO_get_retry_reason`.
OPENSSL_EXPORT int BIO_should_io_special(const BIO *bio);

// BIO_RR_CONNECT indicates that a connect would have blocked
#define BIO_RR_CONNECT 0x02

// BIO_RR_ACCEPT indicates that an accept would have blocked
#define BIO_RR_ACCEPT 0x03

// BIO_get_retry_reason returns the special I/O operation that needs to be
// retried. The return value is one of the `BIO_RR_*` values.
OPENSSL_EXPORT int BIO_get_retry_reason(const BIO *bio);

// BIO_set_retry_reason sets the special I/O operation that needs to be retried
// to `reason`, which should be one of the `BIO_RR_*` values.
OPENSSL_EXPORT void BIO_set_retry_reason(BIO *bio, int reason);

// BIO_set_retry_read sets the `BIO_FLAGS_READ` and `BIO_FLAGS_SHOULD_RETRY`
// flags on `bio`.
OPENSSL_EXPORT void BIO_set_retry_read(BIO *bio);

// BIO_set_retry_write sets the `BIO_FLAGS_WRITE` and `BIO_FLAGS_SHOULD_RETRY`
// flags on `bio`.
OPENSSL_EXPORT void BIO_set_retry_write(BIO *bio);

// BIO_get_retry_flags gets the `BIO_FLAGS_READ`, `BIO_FLAGS_WRITE`,
// `BIO_FLAGS_IO_SPECIAL` and `BIO_FLAGS_SHOULD_RETRY` flags from `bio`.
OPENSSL_EXPORT int BIO_get_retry_flags(BIO *bio);

// BIO_clear_retry_flags clears the `BIO_FLAGS_READ`, `BIO_FLAGS_WRITE`,
// `BIO_FLAGS_IO_SPECIAL` and `BIO_FLAGS_SHOULD_RETRY` flags from `bio`.
OPENSSL_EXPORT void BIO_clear_retry_flags(BIO *bio);

// BIO_method_type returns the type of `bio`, which is one of the `BIO_TYPE_*`
// values.
OPENSSL_EXPORT int BIO_method_type(const BIO *bio);

typedef int BIO_info_cb(BIO *, int, int);

// BIO_callback_ctrl allows the callback function to be manipulated. The `cmd`
// arg will generally be `BIO_CTRL_SET_CALLBACK` but arbitrary command values
// can be interpreted by the `BIO`.
OPENSSL_EXPORT long BIO_callback_ctrl(BIO *bio, int cmd, BIO_info_cb *fp);

// BIO_pending returns the number of bytes pending to be read.
OPENSSL_EXPORT size_t BIO_pending(const BIO *bio);

// BIO_ctrl_pending calls `BIO_pending` and exists only for compatibility with
// OpenSSL.
OPENSSL_EXPORT size_t BIO_ctrl_pending(const BIO *bio);

// BIO_wpending returns the number of bytes pending to be written.
OPENSSL_EXPORT size_t BIO_wpending(const BIO *bio);

// BIO_set_close sets the close flag for `bio`. The meaning of which depends on
// the type of `bio` but, for example, a memory BIO interprets the close flag
// as meaning that it owns its buffer. It returns one on success and zero
// otherwise.
OPENSSL_EXPORT int BIO_set_close(BIO *bio, int close_flag);

// BIO_number_read returns the number of bytes that have been read from
// `bio`.
OPENSSL_EXPORT uint64_t BIO_number_read(const BIO *bio);

// BIO_number_written returns the number of bytes that have been written to
// `bio`.
OPENSSL_EXPORT uint64_t BIO_number_written(const BIO *bio);


// Managing chains of BIOs.
//
// BIOs can be put into chains where the output of one is used as the input of
// the next etc. The most common case is a buffering BIO, which accepts and
// buffers writes until flushed into the next BIO in the chain.

// BIO_push adds `appended_bio` to the end of the chain with `bio` at the head.
// It returns `bio`. Note that `appended_bio` may be the head of a chain itself
// and thus this function can be used to join two chains.
//
// BIO_push takes ownership of the caller's reference to `appended_bio`.
OPENSSL_EXPORT BIO *BIO_push(BIO *bio, BIO *appended_bio);

// BIO_pop removes `bio` from the head of a chain and returns the next BIO in
// the chain, or NULL if there is no next BIO.
//
// The caller takes ownership of the chain's reference to `bio`.
OPENSSL_EXPORT BIO *BIO_pop(BIO *bio);

// BIO_next returns the next BIO in the chain after `bio`, or NULL if there is
// no such BIO.
OPENSSL_EXPORT BIO *BIO_next(BIO *bio);

// BIO_find_type walks a chain of BIOs and returns the first that matches
// `type`, which is one of the `BIO_TYPE_*` values.
//
// If `type & 0xff` is non-zero, i.e. `type` is a complete type and contains an
// "index" component, the function looks for an exact match. If `type & 0xff` is
// zero, i.e. `type` just specifies `BIO_TYPE_DESCRIPTOR`, `BIO_TYPE_FILTER`,
// and `BIO_TYPE_SOURCE_SINK` bits, the function looks for any BIO whose type
// contains at least one of those bits.
OPENSSL_EXPORT BIO *BIO_find_type(BIO *bio, int type);

// BIO_copy_next_retry sets the retry flags and `retry_reason` of `bio` from
// the next BIO in the chain.
OPENSSL_EXPORT void BIO_copy_next_retry(BIO *bio);


// Printf functions.

// BIO_printf behaves like `printf` but outputs to `bio` rather than a `FILE`.
// It returns the number of bytes written or a negative number on error.
OPENSSL_EXPORT int BIO_printf(BIO *bio, const char *format, ...)
    OPENSSL_PRINTF_FORMAT_FUNC(2, 3);


// Utility functions.

// BIO_indent prints min(`indent`, `max_indent`) spaces. It returns one on
// success and zero otherwise.
OPENSSL_EXPORT int BIO_indent(BIO *bio, unsigned indent, unsigned max_indent);

// BIO_hexdump writes a hex dump of `data` to `bio`. Each line will be indented
// by `indent` spaces. It returns one on success and zero otherwise.
OPENSSL_EXPORT int BIO_hexdump(BIO *bio, const uint8_t *data, size_t len,
                               unsigned indent);

// ERR_print_errors prints the current contents of the error stack to `bio`
// using human readable strings where possible.
OPENSSL_EXPORT void ERR_print_errors(BIO *bio);

// BIO_read_asn1 reads a single ASN.1 object from `bio`. If successful it sets
// `*out` to be an allocated buffer (that should be freed with `OPENSSL_free`),
// `*out_size` to the length, in bytes, of that buffer and returns one.
// Otherwise it returns zero.
//
// If the length of the object is greater than `max_len` or 2^32 then the
// function will fail. Long-form tags are not supported. If the length of the
// object is indefinite the full contents of `bio` are read, unless it would be
// greater than `max_len`, in which case the function fails.
//
// If the function fails then some unknown amount of data may have been read
// from `bio`.
OPENSSL_EXPORT int BIO_read_asn1(BIO *bio, uint8_t **out, size_t *out_len,
                                 size_t max_len);


// Memory BIOs.
//
// Memory BIOs can be used as a read-only source (with `BIO_new_mem_buf`) or a
// writable sink (with `BIO_new`, `BIO_s_mem` and `BIO_mem_contents`). Data
// written to a writable, memory BIO can be recalled by reading from it.
//
// Calling `BIO_reset` on a read-only BIO resets it to the original contents.
// On a writable BIO, it clears any data.
//
// If the close flag is set to `BIO_NOCLOSE` (not the default) then the
// underlying `BUF_MEM` will not be freed when the `BIO` is freed.
//
// Memory BIOs support `BIO_gets` and `BIO_puts`.
//
// `BIO_ctrl_pending` returns the number of bytes currently stored.

// BIO_NOCLOSE and `BIO_CLOSE` can be used as symbolic arguments when a "close
// flag" is passed to a BIO function.
#define BIO_NOCLOSE 0
#define BIO_CLOSE 1

// BIO_s_mem returns a `BIO_METHOD` that uses a in-memory buffer.
OPENSSL_EXPORT const BIO_METHOD *BIO_s_mem(void);

// BIO_new_mem_buf creates read-only BIO that reads from `len` bytes at `buf`.
// It returns the BIO or NULL on error. This function does not copy or take
// ownership of `buf`. The caller must ensure the memory pointed to by `buf`
// outlives the `BIO`.
//
// If `len` is negative, then `buf` is treated as a NUL-terminated string, but
// don't depend on this in new code.
OPENSSL_EXPORT BIO *BIO_new_mem_buf(const void *buf, ossl_ssize_t len);

// BIO_mem_contents sets `*out_contents` to point to the current contents of
// `bio` and `*out_len` to contain the length of that data. It returns one on
// success and zero otherwise.
OPENSSL_EXPORT int BIO_mem_contents(const BIO *bio,
                                    const uint8_t **out_contents,
                                    size_t *out_len);

// BIO_get_mem_data sets `*contents` to point to the current contents of `bio`
// and returns the length of the data.
//
// WARNING: don't use this, use `BIO_mem_contents`. A return value of zero from
// this function can mean either that it failed or that the memory buffer is
// empty.
OPENSSL_EXPORT long BIO_get_mem_data(BIO *bio, char **contents);

// BIO_get_mem_ptr sets `*out` to a BUF_MEM containing the current contents of
// `bio`. It returns one on success or zero on error.
OPENSSL_EXPORT int BIO_get_mem_ptr(BIO *bio, BUF_MEM **out);

// BIO_set_mem_buf sets `b` as the contents of `bio`. If `take_ownership` is
// non-zero, then `b` will be freed when `bio` is closed. Returns one on
// success or zero otherwise.
OPENSSL_EXPORT int BIO_set_mem_buf(BIO *bio, BUF_MEM *b, int take_ownership);

// BIO_set_mem_eof_return sets the value that will be returned from reading
// `bio` when empty. If `eof_value` is zero then an empty memory BIO will
// return EOF (that is it will return zero and `BIO_should_retry` will be
// false). If `eof_value` is non zero then it will return `eof_value` when it
// is empty and it will set the read retry flag (that is `BIO_read_retry` is
// true). To avoid ambiguity with a normal positive return value, `eof_value`
// should be set to a negative value, typically -1.
//
// For a read-only BIO, the default is zero (EOF). For a writable BIO, the
// default is -1 so that additional data can be written once exhausted.
OPENSSL_EXPORT int BIO_set_mem_eof_return(BIO *bio, int eof_value);


// File descriptor BIOs.
//
// File descriptor BIOs are wrappers around the system's `read` and `write`
// functions. If the close flag is set then then `close` is called on the
// underlying file descriptor when the BIO is freed.
//
// `BIO_reset` attempts to seek the file pointer to the start of file using
// `lseek`.

#if !defined(OPENSSL_NO_POSIX_IO)
// BIO_s_fd returns a `BIO_METHOD` for file descriptor fds.
OPENSSL_EXPORT const BIO_METHOD *BIO_s_fd(void);

// BIO_new_fd creates a new file descriptor BIO wrapping `fd`. If `close_flag`
// is non-zero, then `fd` will be closed when the BIO is.
OPENSSL_EXPORT BIO *BIO_new_fd(int fd, int close_flag);
#endif

// BIO_set_fd sets the file descriptor of `bio` to `fd`. If `close_flag` is
// non-zero then `fd` will be closed when `bio` is. It returns one on success
// or zero on error.
//
// This function may also be used with socket BIOs (see `BIO_s_socket` and
// `BIO_new_socket`).
OPENSSL_EXPORT int BIO_set_fd(BIO *bio, int fd, int close_flag);

// BIO_get_fd returns the file descriptor currently in use by `bio` or -1 if
// `bio` does not wrap a file descriptor. If there is a file descriptor and
// `out_fd` is not NULL, it also sets `*out_fd` to the file descriptor.
//
// This function may also be used with socket BIOs (see `BIO_s_socket` and
// `BIO_new_socket`).
OPENSSL_EXPORT int BIO_get_fd(BIO *bio, int *out_fd);


// File BIOs.
//
// File BIOs are wrappers around a C `FILE` object.
//
// `BIO_flush` on a file BIO calls `fflush` on the wrapped stream.
//
// `BIO_reset` attempts to seek the file pointer to the start of file using
// `fseek`.
//
// Setting the close flag causes `fclose` to be called on the stream when the
// BIO is freed.

// BIO_s_file returns a BIO_METHOD that wraps a `FILE`.
OPENSSL_EXPORT const BIO_METHOD *BIO_s_file(void);

// BIO_new_file creates a file BIO by opening `filename` with the given mode.
// See the `fopen` manual page for details of the mode argument. On Windows,
// files may be opened in either binary or text mode so, as in `fopen`, callers
// must specify the desired option in `mode`.
OPENSSL_EXPORT BIO *BIO_new_file(const char *filename, const char *mode);

// BIO_FP_TEXT indicates the `FILE` should be switched to text mode on Windows.
// It has no effect on non-Windows platforms.
#define BIO_FP_TEXT 0x10

// BIO_new_fp creates a new file BIO that wraps `file`. If `flags` contains
// `BIO_CLOSE`, then `fclose` will be called on `file` when the BIO is closed.
//
// On Windows, if `flags` contains `BIO_FP_TEXT`, this function will
// additionally switch `file` to text mode. This is not recommended, but may be
// required for OpenSSL compatibility. If `file` was not already in text mode,
// mode changes can cause unflushed data in `file` to be written in unexpected
// ways. See `_setmode` in Windows documentation for details.
//
// Unlike OpenSSL, if `flags` does not contain `BIO_FP_TEXT`, the translation
// mode of `file` is left as-is. In OpenSSL, `file` will be set to binary, with
// the same pitfalls as above. BoringSSL does not do this so that wrapping a
// `FILE` in a `BIO` will not inadvertently change its state.
//
// To avoid these pitfalls, callers should set the desired translation mode when
// opening the file. If targeting just BoringSSL, this is sufficient. If
// targeting both OpenSSL and BoringSSL, callers should set `BIO_FP_TEXT` to
// match the desired state of the file.
OPENSSL_EXPORT BIO *BIO_new_fp(FILE *file, int flags);

// BIO_get_fp sets `*out_file` to the current `FILE` for `bio`. It returns one
// on success and zero otherwise.
OPENSSL_EXPORT int BIO_get_fp(BIO *bio, FILE **out_file);

// BIO_set_fp sets the `FILE` for `bio`. If `flags` contains `BIO_CLOSE` then
// `fclose` will be called on `file` when `bio` is closed. It returns one on
// success and zero otherwise.
//
// On Windows, if `flags` contains `BIO_FP_TEXT`, this function will
// additionally switch `file` to text mode. This is not recommended, but may be
// required for OpenSSL compatibility. If `file` was not already in text mode,
// mode changes can cause unflushed data in `file` to be written in unexpected
// ways. See `_setmode` in Windows documentation for details.
//
// Unlike OpenSSL, if `flags` does not contain `BIO_FP_TEXT`, the translation
// mode of `file` is left as-is. In OpenSSL, `file` will be set to binary, with
// the same pitfalls as above. BoringSSL does not do this so that wrapping a
// `FILE` in a `BIO` will not inadvertently change its state.
//
// To avoid these pitfalls, callers should set the desired translation mode when
// opening the file. If targeting just BoringSSL, this is sufficient. If
// targeting both OpenSSL and BoringSSL, callers should set `BIO_FP_TEXT` to
// match the desired state of the file.
OPENSSL_EXPORT int BIO_set_fp(BIO *bio, FILE *file, int flags);

// BIO_read_filename opens `filename` for reading and sets the result as the
// `FILE` for `bio`. It returns one on success and zero otherwise. The `FILE`
// will be closed when `bio` is freed. On Windows, the file is opened in binary
// mode.
OPENSSL_EXPORT int BIO_read_filename(BIO *bio, const char *filename);

// BIO_write_filename opens `filename` for writing and sets the result as the
// `FILE` for `bio`. It returns one on success and zero otherwise. The `FILE`
// will be closed when `bio` is freed. On Windows, the file is opened in binary
// mode.
OPENSSL_EXPORT int BIO_write_filename(BIO *bio, const char *filename);

// BIO_append_filename opens `filename` for appending and sets the result as
// the `FILE` for `bio`. It returns one on success and zero otherwise. The
// `FILE` will be closed when `bio` is freed. On Windows, the file is opened in
// binary mode.
OPENSSL_EXPORT int BIO_append_filename(BIO *bio, const char *filename);

// BIO_rw_filename opens `filename` for reading and writing and sets the result
// as the `FILE` for `bio`. It returns one on success and zero otherwise. The
// `FILE` will be closed when `bio` is freed. On Windows, the file is opened in
// binary mode.
OPENSSL_EXPORT int BIO_rw_filename(BIO *bio, const char *filename);

// BIO_tell returns the file offset of `bio`, or a negative number on error or
// if `bio` does not support the operation.
//
// TODO(crbug.com/42290329): On platforms where `long` is 32-bit, this function
// cannot report 64-bit offsets.
OPENSSL_EXPORT long BIO_tell(BIO *bio);

// BIO_seek sets the file offset of `bio` to `offset`. It returns a non-negative
// number on success and a negative number on error. If `bio` is a file
// descriptor `BIO`, it returns the resulting file offset on success. If `bio`
// is a file `BIO`, it returns zero on success.
//
// WARNING: This function's return value conventions differs from most functions
// in this library.
//
// TODO(crbug.com/42290329): On platforms where `long` is 32-bit, this function
// cannot handle 64-bit offsets.
OPENSSL_EXPORT long BIO_seek(BIO *bio, long offset);


// Socket BIOs.
//
// Socket BIOs behave like file descriptor BIOs but, on Windows systems, wrap
// the system's `recv` and `send` functions instead of `read` and `write`. On
// Windows, file descriptors are provided by C runtime and are not
// interchangeable with sockets.
//
// Socket BIOs may be used with `BIO_set_fd` and `BIO_get_fd`.
//
// TODO(davidben): Add separate APIs and fix the internals to use `SOCKET`s
// around rather than rely on int casts.

#if !defined(OPENSSL_NO_SOCK)
OPENSSL_EXPORT const BIO_METHOD *BIO_s_socket(void);

// BIO_new_socket allocates and initialises a fresh BIO which will read and
// write to the socket `fd`. If `close_flag` is `BIO_CLOSE` then closing the
// BIO will close `fd`. It returns the fresh `BIO` or NULL on error.
OPENSSL_EXPORT BIO *BIO_new_socket(int fd, int close_flag);
#endif  // !OPENSSL_NO_SOCK


// Connect BIOs.
//
// A connection BIO creates a network connection and transfers data over the
// resulting socket.

#if !defined(OPENSSL_NO_SOCK)
OPENSSL_EXPORT const BIO_METHOD *BIO_s_connect(void);

// BIO_new_connect returns a BIO that connects to the given hostname and port.
// The `host_and_optional_port` argument should be of the form
// "www.example.com" or "www.example.com:443". If the port is omitted, it must
// be provided with `BIO_set_conn_port`.
//
// It returns the new BIO on success, or NULL on error.
OPENSSL_EXPORT BIO *BIO_new_connect(const char *host_and_optional_port);

// BIO_set_conn_hostname sets `host_and_optional_port` as the hostname and
// optional port that `bio` will connect to. If the port is omitted, it must be
// provided with `BIO_set_conn_port`.
//
// It returns one on success and zero otherwise.
OPENSSL_EXPORT int BIO_set_conn_hostname(BIO *bio,
                                         const char *host_and_optional_port);

// BIO_set_conn_port sets `port_str` as the port or service name that `bio`
// will connect to. It returns one on success and zero otherwise.
OPENSSL_EXPORT int BIO_set_conn_port(BIO *bio, const char *port_str);

// BIO_set_conn_int_port sets `*port` as the port that `bio` will connect to.
// It returns one on success and zero otherwise.
OPENSSL_EXPORT int BIO_set_conn_int_port(BIO *bio, const int *port);

// BIO_set_nbio sets whether `bio` will use non-blocking I/O operations. It
// returns one on success and zero otherwise. This only works for connect BIOs
// and must be called before `bio` is connected to take effect.
//
// For socket and fd BIOs, callers must configure blocking vs. non-blocking I/O
// using the underlying platform APIs.
OPENSSL_EXPORT int BIO_set_nbio(BIO *bio, int on);

// BIO_do_connect connects `bio` if it has not been connected yet. It returns
// one on success and <= 0 otherwise.
OPENSSL_EXPORT int BIO_do_connect(BIO *bio);
#endif  // !OPENSSL_NO_SOCK


// Datagram BIOs.
//
// TODO(fork): not implemented.

#define BIO_CTRL_DGRAM_QUERY_MTU 40  // as kernel for current MTU

#define BIO_CTRL_DGRAM_SET_MTU 42 /* set cached value for  MTU. want to use
                                     this if asking the kernel fails */

#define BIO_CTRL_DGRAM_MTU_EXCEEDED 43 /* check whether the MTU was exceed in
                                          the previous write operation. */

// BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT is unsupported as it is unused by consumers
// and depends on `timeval`, which is not 2038-clean on all platforms.

#define BIO_CTRL_DGRAM_GET_PEER           46

#define BIO_CTRL_DGRAM_GET_FALLBACK_MTU   47


// BIO Pairs.
//
// BIO pairs provide a "loopback" like system: a pair of BIOs where data
// written to one can be read from the other and vice versa.

// BIO_new_bio_pair sets `*out1` and `*out2` to two freshly created BIOs where
// data written to one can be read from the other and vice versa. The
// `writebuf1` argument gives the size of the buffer used in `*out1` and
// `writebuf2` for `*out2`. It returns one on success and zero on error.
OPENSSL_EXPORT int BIO_new_bio_pair(BIO **out1, size_t writebuf1, BIO **out2,
                                    size_t writebuf2);

// BIO_ctrl_get_read_request returns the number of bytes that the other side of
// `bio` tried (unsuccessfully) to read.
OPENSSL_EXPORT size_t BIO_ctrl_get_read_request(BIO *bio);

// BIO_ctrl_get_write_guarantee returns the number of bytes that `bio` (which
// must have been returned by `BIO_new_bio_pair`) will accept on the next
// `BIO_write` call.
OPENSSL_EXPORT size_t BIO_ctrl_get_write_guarantee(BIO *bio);

// BIO_shutdown_wr marks `bio` as closed, from the point of view of the other
// side of the pair. Future `BIO_write` calls on `bio` will fail. It returns
// one on success and zero otherwise.
OPENSSL_EXPORT int BIO_shutdown_wr(BIO *bio);


// Custom BIOs.
//
// Consumers can create custom `BIO`s by filling in a `BIO_METHOD` and using
// low-level control functions to set state.

// BIO_get_new_index returns a new "type" value for a custom `BIO`, or -1 on
// error.
OPENSSL_EXPORT int BIO_get_new_index(void);

// BIO_meth_new returns a newly-allocated `BIO_METHOD` or NULL on allocation
// error. The `type` specifies the type that will be returned by
// `BIO_method_type`. If this is unnecessary, this value may be zero. The `name`
// parameter is vestigial and may be NULL.
//
// Use the `BIO_meth_set_*` functions below to initialize the `BIO_METHOD`. The
// function implementations may use `BIO_set_data` and `BIO_get_data` to add
// method-specific state to associated `BIO`s. Additionally, `BIO_set_init` must
// be called after an associated `BIO` is fully initialized. State set via
// `BIO_set_data` may be released by configuring a destructor with
// `BIO_meth_set_destroy`.
OPENSSL_EXPORT BIO_METHOD *BIO_meth_new(int type, const char *name);

// BIO_meth_free releases memory associated with `method`.
OPENSSL_EXPORT void BIO_meth_free(BIO_METHOD *method);

// BIO_meth_set_create sets a function to be called on `BIO_new` for `method`
// and returns one. The function should return one on success and zero on
// error.
OPENSSL_EXPORT int BIO_meth_set_create(BIO_METHOD *method,
                                       int (*create_func)(BIO *));

// BIO_meth_set_destroy sets a function to release data associated with a `BIO`
// and returns one. The function's return value is ignored.
//
// As the `BIO` is about to be destroyed, it is not necessary for `destroy_func`
// to clear the BIO's state with `BIO_set_data` or `BIO_set_init`. There is no
// harm in clearing them, but the `BIO` will not be passed to `BIO` operations,
// unless `destroy_func` itself does so.
OPENSSL_EXPORT int BIO_meth_set_destroy(BIO_METHOD *method,
                                        int (*destroy_func)(BIO *));

// BIO_meth_set_write sets the implementation of `BIO_write` for `method` and
// returns one. `BIO_METHOD`s which implement `BIO_write` should also implement
// `BIO_CTRL_FLUSH`. (See `BIO_meth_set_ctrl`.)
OPENSSL_EXPORT int BIO_meth_set_write(BIO_METHOD *method,
                                      int (*write_func)(BIO *, const char *,
                                                        int));

// BIO_meth_set_read sets the implementation of `BIO_read` for `method` and
// returns one.
OPENSSL_EXPORT int BIO_meth_set_read(BIO_METHOD *method,
                                     int (*read_func)(BIO *, char *, int));

// BIO_meth_set_gets sets the implementation of `BIO_gets` for `method` and
// returns one.
OPENSSL_EXPORT int BIO_meth_set_gets(BIO_METHOD *method,
                                     int (*gets_func)(BIO *, char *, int));

// BIO_meth_set_ctrl sets the implementation of `BIO_ctrl` for `method` and
// returns one.
OPENSSL_EXPORT int BIO_meth_set_ctrl(BIO_METHOD *method,
                                     long (*ctrl_func)(BIO *, int, long,
                                                       void *));

// BIO_meth_set_callback_ctrl sets the implementation of `BIO_callback_ctrl` for
// `method` and returns one.
OPENSSL_EXPORT int BIO_meth_set_callback_ctrl(
    BIO_METHOD *method, long (*callback_ctrl_func)(BIO *, int, BIO_info_cb *));

// BIO_set_data sets custom data on `bio`. It may be retried with
// `BIO_get_data`.
//
// This function should only be called by the implementation of a custom `BIO`.
// In particular, the data pointer of a built-in `BIO` is private to the
// library. For other uses, see `BIO_set_ex_data` and `BIO_set_app_data`.
OPENSSL_EXPORT void BIO_set_data(BIO *bio, void *ptr);

// BIO_get_data returns custom data on `bio` set by `BIO_get_data`.
//
// This function should only be called by the implementation of a custom `BIO`.
// In particular, the data pointer of a built-in `BIO` is private to the
// library. For other uses, see `BIO_get_ex_data` and `BIO_get_app_data`.
OPENSSL_EXPORT void *BIO_get_data(BIO *bio);

// BIO_set_init sets whether `bio` has been fully initialized. Until fully
// initialized, `BIO_read` and `BIO_write` will fail.
OPENSSL_EXPORT void BIO_set_init(BIO *bio, int init);

// BIO_get_init returns whether `bio` has been fully initialized.
OPENSSL_EXPORT int BIO_get_init(BIO *bio);

// These are values of the `cmd` argument to `BIO_ctrl`.

// BIO_CTRL_RESET implements `BIO_reset`. The arguments are unused.
#define BIO_CTRL_RESET 1

// BIO_CTRL_EOF implements `BIO_eof`. The arguments are unused.
#define BIO_CTRL_EOF 2

// BIO_CTRL_INFO is a legacy command that returns information specific to the
// type of `BIO`. It is not safe to call generically and should not be
// implemented in new `BIO` types.
#define BIO_CTRL_INFO 3

// BIO_CTRL_GET_CLOSE returns the close flag set by `BIO_CTRL_SET_CLOSE`. The
// arguments are unused.
#define BIO_CTRL_GET_CLOSE 8

// BIO_CTRL_SET_CLOSE implements `BIO_set_close`. The `larg` argument is the
// close flag.
#define BIO_CTRL_SET_CLOSE 9

// BIO_CTRL_PENDING implements `BIO_pending`. The arguments are unused.
#define BIO_CTRL_PENDING 10

// BIO_CTRL_FLUSH implements `BIO_flush`. The arguments are unused.
#define BIO_CTRL_FLUSH 11

// BIO_CTRL_WPENDING implements `BIO_wpending`. The arguments are unused.
#define BIO_CTRL_WPENDING 13

// BIO_CTRL_SET_CALLBACK sets an informational callback of type
// int cb(BIO *bio, int state, int ret)
#define BIO_CTRL_SET_CALLBACK 14

// BIO_CTRL_GET_CALLBACK returns the callback set by `BIO_CTRL_SET_CALLBACK`.
#define BIO_CTRL_GET_CALLBACK 15

// The following are never used, but are defined to aid porting existing code.
#define BIO_CTRL_SET 4
#define BIO_CTRL_GET 5
#define BIO_CTRL_PUSH 6
#define BIO_CTRL_POP 7
#define BIO_CTRL_DUP 12
#define BIO_CTRL_SET_FILENAME 30


// ex_data functions.
//
// See `ex_data.h` for details.

OPENSSL_EXPORT int BIO_get_ex_new_index(long argl, void *argp,
                                        CRYPTO_EX_unused *unused,
                                        CRYPTO_EX_dup *dup_unused,
                                        CRYPTO_EX_free *free_func);
OPENSSL_EXPORT int BIO_set_ex_data(BIO *bio, int idx, void *arg);
OPENSSL_EXPORT void *BIO_get_ex_data(const BIO *bio, int idx);

#define BIO_set_app_data(bio, arg) (BIO_set_ex_data(bio, 0, (char *)(arg)))
#define BIO_get_app_data(bio) (BIO_get_ex_data(bio, 0))


// Deprecated functions.

// BIO_free_all calls `BIO_free`. Code that targets BoringSSL does not need to
// call a separate free function for `BIO`s that are part of a chain.
OPENSSL_EXPORT void BIO_free_all(BIO *bio);

typedef BIO_info_cb bio_info_cb;

// BIO_f_base64 returns a filter `BIO` that base64-encodes data written into
// it, and decodes data read from it. `BIO_gets` is not supported. Call
// `BIO_flush` when done writing, to signal that no more data are to be
// encoded. The flag `BIO_FLAGS_BASE64_NO_NL` may be set to encode all the data
// on one line.
//
// Use `EVP_EncodeBlock` and `EVP_DecodeBase64` instead.
OPENSSL_EXPORT const BIO_METHOD *BIO_f_base64(void);

OPENSSL_EXPORT void BIO_set_retry_special(BIO *bio);

// BIO_set_write_buffer_size returns zero.
OPENSSL_EXPORT int BIO_set_write_buffer_size(BIO *bio, int buffer_size);

// BIO_set_shutdown sets a method-specific "shutdown" bit on `bio`.
OPENSSL_EXPORT void BIO_set_shutdown(BIO *bio, int shutdown);

// BIO_get_shutdown returns the method-specific "shutdown" bit.
OPENSSL_EXPORT int BIO_get_shutdown(BIO *bio);

// BIO_meth_set_puts returns one. `BIO_puts` is implemented with `BIO_write` in
// BoringSSL.
OPENSSL_EXPORT int BIO_meth_set_puts(BIO_METHOD *method,
                                     int (*puts)(BIO *, const char *));

#if !defined(OPENSSL_NO_SOCK)
// The following functions return function pointers, possibly NULL, which are
// compatible with the corresponding `BIO_meth_set_*` function. `method` must be
// `BIO_s_socket` or the program will abort.
//
// Using these functions is inherently unsafe and fragile. It is not possible to
// use them in a future-proof way. See
// https://github.com/openssl/openssl/issues/26047 for details. BoringSSL
// implements them solely for compatibility with Folly and older versions of
// PostgreSQL. To work around the future-proofing problems, the return values
// may diverge from the true implementation of `BIO_s_socket`.
//
// Caller should not use these functions. They are not necessary to define
// custom `BIO_METHOD`s. Instead, callers should either:
//
// - Define a custom `BIO_METHOD` that owns a socket `BIO` somewhere in the
//   custom data. See `BIO_set_data`.
//
// - Define a custom `BIO_METHOD` that wraps a socket `BIO` as a filter. See
//   `BIO_push` and `BIO_next`.
//
// - Define a custom `BIO_METHOD` without `BIO_s_socket` at all. If not using
//   the built-in read or write functions, `BIO_s_socket` only provides a no-op
//   `BIO_CTRL_FLUSH` implementation. This can be implemented by the caller.
OPENSSL_EXPORT int (*BIO_meth_get_write(const BIO_METHOD *method))(BIO *,
                                                                   const char *,
                                                                   int);
OPENSSL_EXPORT int (*BIO_meth_get_read(const BIO_METHOD *method))(BIO *, char *,
                                                                  int);
OPENSSL_EXPORT int (*BIO_meth_get_gets(const BIO_METHOD *method))(BIO *, char *,
                                                                  int);
OPENSSL_EXPORT int (*BIO_meth_get_puts(const BIO_METHOD *method))(BIO *,
                                                                  const char *);
OPENSSL_EXPORT long (*BIO_meth_get_ctrl(const BIO_METHOD *method))(BIO *, int,
                                                                   long,
                                                                   void *);
OPENSSL_EXPORT int (*BIO_meth_get_create(const BIO_METHOD *method))(BIO *);
OPENSSL_EXPORT int (*BIO_meth_get_destroy(const BIO_METHOD *method))(BIO *);
OPENSSL_EXPORT long (*BIO_meth_get_callback_ctrl(const BIO_METHOD *method))(
    BIO *, int, BIO_info_cb *);
#endif  // !OPENSSL_NO_SOCK


// Private functions

#define BIO_FLAGS_READ 0x01
#define BIO_FLAGS_WRITE 0x02
#define BIO_FLAGS_IO_SPECIAL 0x04
#define BIO_FLAGS_RWS (BIO_FLAGS_READ | BIO_FLAGS_WRITE | BIO_FLAGS_IO_SPECIAL)
#define BIO_FLAGS_SHOULD_RETRY 0x08
#define BIO_FLAGS_BASE64_NO_NL 0x100
// BIO_FLAGS_MEM_RDONLY is used with memory BIOs. It means we shouldn't free up
// or change the data in any way.
#define BIO_FLAGS_MEM_RDONLY 0x200

// BIO_TYPE_DESCRIPTOR denotes that the `BIO` responds to the `BIO_C_SET_FD`
// (`BIO_set_fd`) and `BIO_C_GET_FD` (`BIO_get_fd`) control hooks.
#define BIO_TYPE_DESCRIPTOR 0x0100  // socket, fd, connect or accept
#define BIO_TYPE_FILTER 0x0200
#define BIO_TYPE_SOURCE_SINK 0x0400

// These are the 'types' of BIOs
#define BIO_TYPE_NONE 0
#define BIO_TYPE_MEM (1 | BIO_TYPE_SOURCE_SINK)
#define BIO_TYPE_FILE (2 | BIO_TYPE_SOURCE_SINK)
#define BIO_TYPE_FD (4 | BIO_TYPE_SOURCE_SINK | BIO_TYPE_DESCRIPTOR)
#define BIO_TYPE_SOCKET (5 | BIO_TYPE_SOURCE_SINK | BIO_TYPE_DESCRIPTOR)
#define BIO_TYPE_NULL (6 | BIO_TYPE_SOURCE_SINK)
#define BIO_TYPE_SSL (7 | BIO_TYPE_FILTER)
#define BIO_TYPE_MD (8 | BIO_TYPE_FILTER)
#define BIO_TYPE_BUFFER (9 | BIO_TYPE_FILTER)
#define BIO_TYPE_CIPHER (10 | BIO_TYPE_FILTER)
#define BIO_TYPE_BASE64 (11 | BIO_TYPE_FILTER)
#define BIO_TYPE_CONNECT (12 | BIO_TYPE_SOURCE_SINK | BIO_TYPE_DESCRIPTOR)
#define BIO_TYPE_ACCEPT (13 | BIO_TYPE_SOURCE_SINK | BIO_TYPE_DESCRIPTOR)
#define BIO_TYPE_PROXY_CLIENT (14 | BIO_TYPE_FILTER)
#define BIO_TYPE_PROXY_SERVER (15 | BIO_TYPE_FILTER)
#define BIO_TYPE_NBIO_TEST (16 | BIO_TYPE_FILTER)
#define BIO_TYPE_NULL_FILTER (17 | BIO_TYPE_FILTER)
#define BIO_TYPE_BER (18 | BIO_TYPE_FILTER)       // BER -> bin filter
#define BIO_TYPE_BIO (19 | BIO_TYPE_SOURCE_SINK)  // (half a) BIO pair
#define BIO_TYPE_LINEBUFFER (20 | BIO_TYPE_FILTER)
#define BIO_TYPE_DGRAM (21 | BIO_TYPE_SOURCE_SINK | BIO_TYPE_DESCRIPTOR)
#define BIO_TYPE_ASN1 (22 | BIO_TYPE_FILTER)
#define BIO_TYPE_COMP (23 | BIO_TYPE_FILTER)

// BIO_TYPE_START is the first user-allocated `BIO` type. No pre-defined type,
// flag bits aside, may exceed this value.
#define BIO_TYPE_START 128

#define BIO_C_SET_CONNECT 100
#define BIO_C_DO_STATE_MACHINE 101
#define BIO_C_SET_NBIO 102
#define BIO_C_SET_PROXY_PARAM 103
#define BIO_C_SET_FD 104
#define BIO_C_GET_FD 105
#define BIO_C_SET_FILE_PTR 106
#define BIO_C_GET_FILE_PTR 107
#define BIO_C_SET_FILENAME 108
#define BIO_C_SET_SSL 109
#define BIO_C_SET_MD 111
#define BIO_C_GET_MD 112
#define BIO_C_GET_CIPHER_STATUS 113
#define BIO_C_SET_BUF_MEM 114
#define BIO_C_GET_BUF_MEM_PTR 115
#define BIO_C_GET_BUFF_NUM_LINES 116
#define BIO_C_SET_BUFF_SIZE 117
#define BIO_C_SET_ACCEPT 118
#define BIO_C_SSL_MODE 119
#define BIO_C_GET_MD_CTX 120
#define BIO_C_GET_PROXY_PARAM 121
#define BIO_C_SET_BUFF_READ_DATA 122  // data to read first
#define BIO_C_GET_ACCEPT 124
#define BIO_C_FILE_SEEK 128
#define BIO_C_GET_CIPHER_CTX 129
#define BIO_C_SET_BUF_MEM_EOF_RETURN 130  // return end of input value
#define BIO_C_SET_BIND_MODE 131
#define BIO_C_GET_BIND_MODE 132
#define BIO_C_FILE_TELL 133
#define BIO_C_GET_SOCKS 134
#define BIO_C_SET_SOCKS 135

#define BIO_C_SET_WRITE_BUF_SIZE 136  // for BIO_s_bio
#define BIO_C_GET_WRITE_BUF_SIZE 137
#define BIO_C_GET_WRITE_GUARANTEE 140
#define BIO_C_GET_READ_REQUEST 141
#define BIO_C_SHUTDOWN_WR 142
#define BIO_C_NREAD0 143
#define BIO_C_NREAD 144
#define BIO_C_NWRITE0 145
#define BIO_C_NWRITE 146
#define BIO_C_RESET_READ_REQUEST 147
#define BIO_C_SET_MD_CTX 148

#define BIO_C_SET_PREFIX 149
#define BIO_C_GET_PREFIX 150
#define BIO_C_SET_SUFFIX 151
#define BIO_C_GET_SUFFIX 152

#define BIO_C_SET_EX_ARG 153
#define BIO_C_GET_EX_ARG 154


#if defined(__cplusplus)
}  // extern C

extern "C++" {

BSSL_NAMESPACE_BEGIN

BORINGSSL_MAKE_DELETER(BIO, BIO_free)
BORINGSSL_MAKE_UP_REF(BIO, BIO_up_ref)
BORINGSSL_MAKE_DELETER(BIO_METHOD, BIO_meth_free)

BSSL_NAMESPACE_END

}  // extern C++

#endif

#define BIO_R_BAD_FOPEN_MODE 100
#define BIO_R_BROKEN_PIPE 101
#define BIO_R_CONNECT_ERROR 102
#define BIO_R_ERROR_SETTING_NBIO 103
#define BIO_R_INVALID_ARGUMENT 104
#define BIO_R_IN_USE 105
#define BIO_R_KEEPALIVE 106
#define BIO_R_NBIO_CONNECT_ERROR 107
#define BIO_R_NO_HOSTNAME_SPECIFIED 108
#define BIO_R_NO_PORT_SPECIFIED 109
#define BIO_R_NO_SUCH_FILE 110
#define BIO_R_NULL_PARAMETER 111
#define BIO_R_SYS_LIB 112
#define BIO_R_UNABLE_TO_CREATE_SOCKET 113
#define BIO_R_UNINITIALIZED 114
#define BIO_R_UNSUPPORTED_METHOD 115
#define BIO_R_WRITE_TO_READ_ONLY_BIO 116

#endif  // OPENSSL_HEADER_BIO_H