1 =pod 2 3 =head1 NAME 4 5 BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset, 6 BIO_seek, BIO_tell, BIO_flush, BIO_eof, BIO_set_close, BIO_get_close, 7 BIO_pending, BIO_wpending, BIO_ctrl_pending, BIO_ctrl_wpending, 8 BIO_get_info_callback, BIO_set_info_callback, BIO_info_cb, BIO_get_ktls_send, 9 BIO_get_ktls_recv, BIO_set_conn_mode, BIO_get_conn_mode, BIO_set_tfo 10 - BIO control operations 11 12 =head1 SYNOPSIS 13 14 #include <openssl/bio.h> 15 16 typedef int BIO_info_cb(BIO *b, int state, int res); 17 18 long BIO_ctrl(BIO *bp, int cmd, long larg, void *parg); 19 long BIO_callback_ctrl(BIO *b, int cmd, BIO_info_cb *cb); 20 void *BIO_ptr_ctrl(BIO *bp, int cmd, long larg); 21 long BIO_int_ctrl(BIO *bp, int cmd, long larg, int iarg); 22 23 int BIO_reset(BIO *b); 24 int BIO_seek(BIO *b, int ofs); 25 int BIO_tell(BIO *b); 26 int BIO_flush(BIO *b); 27 int BIO_eof(BIO *b); 28 int BIO_set_close(BIO *b, long flag); 29 int BIO_get_close(BIO *b); 30 int BIO_pending(BIO *b); 31 int BIO_wpending(BIO *b); 32 size_t BIO_ctrl_pending(BIO *b); 33 size_t BIO_ctrl_wpending(BIO *b); 34 35 int BIO_get_info_callback(BIO *b, BIO_info_cb **cbp); 36 int BIO_set_info_callback(BIO *b, BIO_info_cb *cb); 37 38 int BIO_get_ktls_send(BIO *b); 39 int BIO_get_ktls_recv(BIO *b); 40 41 int BIO_set_conn_mode(BIO *b, int mode); 42 int BIO_get_conn_mode(BIO *b); 43 44 int BIO_set_tfo(BIO *b, int onoff); 45 46 =head1 DESCRIPTION 47 48 BIO_ctrl(), BIO_callback_ctrl(), BIO_ptr_ctrl() and BIO_int_ctrl() 49 are BIO "control" operations taking arguments of various types. 50 These functions are not normally called directly, various macros 51 are used instead. The standard macros are described below, macros 52 specific to a particular type of BIO are described in the specific 53 BIOs manual page as well as any special features of the standard 54 calls. 55 56 BIO_reset() typically resets a BIO to some initial state, in the case 57 of file related BIOs for example it rewinds the file pointer to the 58 start of the file. 59 60 BIO_seek() resets a file related BIO's (that is file descriptor and 61 FILE BIOs) file position pointer to B<ofs> bytes from start of file. 62 63 BIO_tell() returns the current file position of a file related BIO. 64 65 BIO_flush() normally writes out any internally buffered data, in some 66 cases it is used to signal EOF and that no more data will be written. 67 68 BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of 69 "EOF" varies according to the BIO type. 70 71 BIO_set_close() sets the BIO B<b> close flag to B<flag>. B<flag> can 72 take the value BIO_CLOSE or BIO_NOCLOSE. Typically BIO_CLOSE is used 73 in a source/sink BIO to indicate that the underlying I/O stream should 74 be closed when the BIO is freed. 75 76 BIO_get_close() returns the BIOs close flag. 77 78 BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() 79 return the number of pending characters in the BIOs read and write buffers. 80 Not all BIOs support these calls. BIO_ctrl_pending() and BIO_ctrl_wpending() 81 return a size_t type and are functions, BIO_pending() and BIO_wpending() are 82 macros which call BIO_ctrl(). 83 84 BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for 85 sending. Otherwise, it returns zero. 86 BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for 87 receiving. Otherwise, it returns zero. 88 89 BIO_get_conn_mode() returns the BIO connection mode. BIO_set_conn_mode() sets 90 the BIO connection mode. 91 92 BIO_set_tfo() disables TCP Fast Open when B<onoff> is 0, and enables TCP Fast 93 Open when B<onoff> is nonzero. Setting the value to 1 is equivalent to setting 94 B<BIO_SOCK_TFO> in BIO_set_conn_mode(). 95 96 =head1 RETURN VALUES 97 98 BIO_reset() normally returns 1 for success and <=0 for failure. File 99 BIOs are an exception, they return 0 for success and -1 for failure. 100 101 BIO_seek() and BIO_tell() both return the current file position on success 102 and -1 for failure, except file BIOs which for BIO_seek() always return 0 103 for success and -1 for failure. 104 105 BIO_flush() returns 1 for success and <=0 for failure. 106 107 BIO_eof() returns 1 if EOF has been reached, 0 if not, or negative values for failure. 108 109 BIO_set_close() returns 1 on success or <=0 for failure. 110 111 BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE. It also 112 returns other negative values if an error occurs. 113 114 BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() 115 return the amount of pending data. BIO_pending() and BIO_wpending() return 116 negative value or 0 on error. BIO_ctrl_pending() and BIO_ctrl_wpending() return 117 0 on error. 118 119 BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for 120 sending. Otherwise, it returns zero. 121 BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for 122 receiving. Otherwise, it returns zero. 123 124 BIO_set_conn_mode() returns 1 for success and 0 for failure. BIO_get_conn_mode() 125 returns the current connection mode. Which may contain the bitwise-or of the 126 following flags: 127 128 BIO_SOCK_REUSEADDR 129 BIO_SOCK_V6_ONLY 130 BIO_SOCK_KEEPALIVE 131 BIO_SOCK_NONBLOCK 132 BIO_SOCK_NODELAY 133 BIO_SOCK_TFO 134 135 BIO_set_tfo() returns 1 for success, and 0 for failure. 136 137 =head1 NOTES 138 139 BIO_flush(), because it can write data may return 0 or -1 indicating 140 that the call should be retried later in a similar manner to BIO_write_ex(). 141 The BIO_should_retry() call should be used and appropriate action taken 142 is the call fails. 143 144 The return values of BIO_pending() and BIO_wpending() may not reliably 145 determine the amount of pending data in all cases. For example in the 146 case of a file BIO some data may be available in the FILE structures 147 internal buffers but it is not possible to determine this in a 148 portably way. For other types of BIO they may not be supported. 149 150 Filter BIOs if they do not internally handle a particular BIO_ctrl() 151 operation usually pass the operation to the next BIO in the chain. 152 This often means there is no need to locate the required BIO for 153 a particular operation, it can be called on a chain and it will 154 be automatically passed to the relevant BIO. However, this can cause 155 unexpected results: for example no current filter BIOs implement 156 BIO_seek(), but this may still succeed if the chain ends in a FILE 157 or file descriptor BIO. 158 159 Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl() 160 operation. 161 162 =head1 BUGS 163 164 Some of the return values are ambiguous and care should be taken. In 165 particular a return value of 0 can be returned if an operation is not 166 supported, if an error occurred, if EOF has not been reached and in 167 the case of BIO_seek() on a file BIO for a successful operation. 168 169 In older versions of OpenSSL the BIO_ctrl_pending() and 170 BIO_ctrl_wpending() could return values greater than INT_MAX on error. 171 172 =head1 HISTORY 173 174 The BIO_get_ktls_send() and BIO_get_ktls_recv() macros were added in 175 OpenSSL 3.0. They were modified to never return -1 in OpenSSL 3.0.4. 176 177 The BIO_get_conn_mode(), BIO_set_conn_mode() and BIO_set_tfo() functions 178 were added in OpenSSL 3.2. 179 180 =head1 COPYRIGHT 181 182 Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved. 183 184 Licensed under the Apache License 2.0 (the "License"). You may not use 185 this file except in compliance with the License. You can obtain a copy 186 in the file LICENSE in the source distribution or at 187 L<https://www.openssl.org/source/license.html>. 188 189 =cut 190
Indexes created Mon Mar 02 05:31:46 UTC 2026