1=pod 2 3=head1 NAME 4 5OSSL_HTTP_open, 6OSSL_HTTP_bio_cb_t, 7OSSL_HTTP_proxy_connect, 8OSSL_HTTP_set1_request, 9OSSL_HTTP_exchange, 10OSSL_HTTP_get, 11OSSL_HTTP_transfer, 12OSSL_HTTP_close 13- HTTP client high-level functions 14 15=head1 SYNOPSIS 16 17 #include <openssl/http.h> 18 19 typedef BIO *(*OSSL_HTTP_bio_cb_t)(BIO *bio, void *arg, 20 int connect, int detail); 21 OSSL_HTTP_REQ_CTX *OSSL_HTTP_open(const char *server, const char *port, 22 const char *proxy, const char *no_proxy, 23 int use_ssl, BIO *bio, BIO *rbio, 24 OSSL_HTTP_bio_cb_t bio_update_fn, void *arg, 25 int buf_size, int overall_timeout); 26 int OSSL_HTTP_proxy_connect(BIO *bio, const char *server, const char *port, 27 const char *proxyuser, const char *proxypass, 28 int timeout, BIO *bio_err, const char *prog); 29 int OSSL_HTTP_set1_request(OSSL_HTTP_REQ_CTX *rctx, const char *path, 30 const STACK_OF(CONF_VALUE) *headers, 31 const char *content_type, BIO *req, 32 const char *expected_content_type, int expect_asn1, 33 size_t max_resp_len, int timeout, int keep_alive); 34 BIO *OSSL_HTTP_exchange(OSSL_HTTP_REQ_CTX *rctx, char **redirection_url); 35 BIO *OSSL_HTTP_get(const char *url, const char *proxy, const char *no_proxy, 36 BIO *bio, BIO *rbio, 37 OSSL_HTTP_bio_cb_t bio_update_fn, void *arg, 38 int buf_size, const STACK_OF(CONF_VALUE) *headers, 39 const char *expected_content_type, int expect_asn1, 40 size_t max_resp_len, int timeout); 41 BIO *OSSL_HTTP_transfer(OSSL_HTTP_REQ_CTX **prctx, 42 const char *server, const char *port, 43 const char *path, int use_ssl, 44 const char *proxy, const char *no_proxy, 45 BIO *bio, BIO *rbio, 46 OSSL_HTTP_bio_cb_t bio_update_fn, void *arg, 47 int buf_size, const STACK_OF(CONF_VALUE) *headers, 48 const char *content_type, BIO *req, 49 const char *expected_content_type, int expect_asn1, 50 size_t max_resp_len, int timeout, int keep_alive); 51 int OSSL_HTTP_close(OSSL_HTTP_REQ_CTX *rctx, int ok); 52 53=head1 DESCRIPTION 54 55OSSL_HTTP_open() initiates an HTTP session using the I<bio> argument if not 56NULL, else by connecting to a given I<server> optionally via a I<proxy>. 57 58Typically the OpenSSL build supports sockets and the I<bio> parameter is NULL. 59In this case I<rbio> must be NULL as well and the I<server> must be non-NULL. 60The function creates a network BIO internally using L<BIO_new_connect(3)> 61for connecting to the given server and the optionally given I<port>, 62defaulting to 80 for HTTP or 443 for HTTPS. 63Then this internal BIO is used for setting up a connection 64and for exchanging one or more request and response. 65If I<bio> is given and I<rbio> is NULL then this I<bio> is used instead. 66If both I<bio> and I<rbio> are given (which may be memory BIOs for instance) 67then no explicit connection is set up, but 68I<bio> is used for writing requests and I<rbio> for reading responses. 69As soon as the client has flushed I<bio> the server must be ready to provide 70a response or indicate a waiting condition via I<rbio>. 71 72If I<bio> is given, it is an error to provide I<proxy> or I<no_proxy> arguments, 73while I<server> and I<port> arguments may be given to support diagnostic output. 74If I<bio> is NULL the optional I<proxy> parameter can be used to set an 75HTTP(S) proxy to use (unless overridden by "no_proxy" settings). 76If TLS is not used this defaults to the environment variable C<http_proxy> 77if set, else C<HTTP_PROXY>. 78If I<use_ssl> != 0 it defaults to C<https_proxy> if set, else C<HTTPS_PROXY>. 79An empty proxy string C<""> forbids using a proxy. 80Else the format is 81C<[http[s]://][userinfo@]host[:port][/path][?query][#fragment]>, 82where any userinfo, path, query, and fragment given is ignored. 83The default proxy port number is 80, or 443 in case "https:" is given. 84The HTTP client functions connect via the given proxy unless the I<server> 85is found in the optional list I<no_proxy> of proxy hostnames (if not NULL; 86default is the environment variable C<no_proxy> if set, else C<NO_PROXY>). 87Proxying plain HTTP is supported directly, 88while using a proxy for HTTPS connections requires a suitable callback function 89such as OSSL_HTTP_proxy_connect(), described below. 90 91If I<use_ssl> is nonzero a TLS connection is requested 92and the I<bio_update_fn> parameter must be provided. 93 94The parameter I<bio_update_fn>, which is optional if I<use_ssl> is 0, 95may be used to modify the connection BIO used by the HTTP client, 96but cannot be used when both I<bio> and I<rbio> are given. 97I<bio_update_fn> is a BIO connect/disconnect callback function with prototype 98 99 BIO *(*OSSL_HTTP_bio_cb_t)(BIO *bio, void *arg, int connect, int detail) 100 101The callback function may modify the BIO provided in the I<bio> argument, 102whereby it may use an optional custom defined argument I<arg>, 103which can for instance point to an B<SSL_CTX> structure. 104During connection establishment, just after calling BIO_do_connect_retry(), the 105callback function is invoked with the I<connect> argument being 1 and 106I<detail> being 1 if I<use_ssl> is nonzero (i.e., HTTPS is requested), else 0. 107On disconnect I<connect> is 0 and I<detail> is 1 if no error occurred, else 0. 108For instance, on connect the callback may push an SSL BIO to implement HTTPS; 109after disconnect it may do some diagnostic output and pop and free the SSL BIO. 110 111The callback function must return either the potentially modified BIO I<bio> 112or NULL to indicate failure, in which case it should not modify the BIO. 113 114Here is a simple example that supports TLS connections (but not via a proxy): 115 116 BIO *http_tls_cb(BIO *bio, void *arg, int connect, int detail) 117 { 118 if (connect && detail) { /* connecting with TLS */ 119 SSL_CTX *ctx = (SSL_CTX *)arg; 120 BIO *sbio = BIO_new_ssl(ctx, 1); 121 122 bio = sbio != NULL ? BIO_push(sbio, bio) : NULL; 123 } else if (!connect) { /* disconnecting */ 124 BIO *hbio; 125 126 if (!detail) { /* an error has occurred */ 127 /* optionally add diagnostics here */ 128 } 129 BIO_ssl_shutdown(bio); 130 hbio = BIO_pop(bio); 131 BIO_free(bio); /* SSL BIO */ 132 bio = hbio; 133 } 134 return bio; 135 } 136 137After disconnect the modified BIO will be deallocated using BIO_free_all(). 138The optional callback function argument I<arg> is not consumed, 139so must be freed by the caller when not needed any more. 140 141The I<buf_size> parameter specifies the response header maximum line length. 142A value <= 0 means that the B<OSSL_HTTP_DEFAULT_MAX_LINE_LEN> (4KiB) is used. 143I<buf_size> is also used as the number of content bytes that are read at a time. 144 145If the I<overall_timeout> parameter is > 0 this indicates the maximum number of 146seconds the overall HTTP transfer (i.e., connection setup if needed, 147sending requests, and receiving responses) is allowed to take until completion. 148A value <= 0 enables waiting indefinitely, i.e., no timeout. 149 150OSSL_HTTP_proxy_connect() may be used by an above BIO connect callback function 151to set up an SSL/TLS connection via an HTTPS proxy. 152It promotes the given BIO I<bio> representing a connection 153pre-established with a TLS proxy using the HTTP CONNECT method, 154optionally using proxy client credentials I<proxyuser> and I<proxypass>, 155to connect with TLS protection ultimately to I<server> and I<port>. 156If the I<port> argument is NULL or the empty string it defaults to "443". 157If the I<timeout> parameter is > 0 this indicates the maximum number of 158seconds the connection setup is allowed to take. 159A value <= 0 enables waiting indefinitely, i.e., no timeout. 160Since this function is typically called by applications such as 161L<openssl-s_client(1)> it uses the I<bio_err> and I<prog> parameters (unless 162NULL) to print additional diagnostic information in a user-oriented way. 163 164OSSL_HTTP_set1_request() sets up in I<rctx> the request header and content data 165and expectations on the response using the following parameters. 166If <rctx> indicates using a proxy for HTTP (but not HTTPS), the server host 167(and optionally port) needs to be placed in the header; thus it must be present 168in I<rctx>. 169For backward compatibility, the server (and optional port) may also be given in 170the I<path> argument beginning with C<http://> (thus giving an absoluteURI). 171If I<path> is NULL it defaults to "/". 172If I<req> is NULL the HTTP GET method will be used to send the request 173else HTTP POST with the contents of I<req> and optional I<content_type>, where 174the length of the data in I<req> does not need to be determined in advance: the 175BIO will be read on-the-fly while sending the request, which supports streaming. 176The optional list I<headers> may contain additional custom HTTP header lines. 177 178If the I<expected_content_type> argument is not NULL, 179the client will check that the specified content-type string 180is included in the HTTP header of the response and return an error if not. 181In the content-type header line the specified string should be present either 182as a whole, or in case the specified string does not include a C<;> character, 183it is sufficient that the specified string appears as a prefix 184in the header line, followed by a C<;> character and any further text. 185For instance, if I<expected_content_type> specifies C<text/html>, 186this is matched by C<text/html>, C<text/html; charset=UTF-8>, etc. 187 188If the I<expect_asn1> parameter is nonzero, 189a structure in ASN.1 encoding will be expected as response content. 190The I<max_resp_len> parameter specifies the maximum allowed 191response content length, where the value 0 indicates no limit. 192If the I<timeout> parameter is > 0 this indicates the maximum number of seconds 193the subsequent HTTP transfer (sending the request and receiving a response) 194is allowed to take. 195A value of 0 enables waiting indefinitely, i.e., no timeout. 196A value < 0 indicates that the I<overall_timeout> parameter value given 197when opening the HTTP transfer will be used instead. 198If I<keep_alive> is 0 the connection is not kept open 199after receiving a response, which is the default behavior for HTTP 1.0. 200If the value is 1 or 2 then a persistent connection is requested. 201If the value is 2 then a persistent connection is required, 202i.e., an error occurs in case the server does not grant it. 203 204OSSL_HTTP_exchange() exchanges any form of HTTP request and response 205as specified by I<rctx>, which must include both connection and request data, 206typically set up using OSSL_HTTP_open() and OSSL_HTTP_set1_request(). 207It implements the core of the functions described below. 208If the HTTP method is GET and I<redirection_url> 209is not NULL the latter pointer is used to provide any new location that 210the server may return with HTTP code 301 (MOVED_PERMANENTLY) or 302 (FOUND). 211In this case the function returns NULL and the caller is 212responsible for deallocating the URL with L<OPENSSL_free(3)>. 213If the response header contains one or more "Content-Length" header lines and/or 214an ASN.1-encoded response is expected, which should include a total length, 215the length indications received are checked for consistency 216and for not exceeding any given maximum response length. 217If an ASN.1-encoded response is expected, the function returns on success 218the contents buffered in a memory BIO, which does not support streaming. 219Otherwise it returns directly the read BIO that holds the response contents, 220which allows a response of indefinite length and may support streaming. 221The caller is responsible for freeing the BIO pointer obtained. 222 223OSSL_HTTP_get() uses HTTP GET to obtain data from I<bio> if non-NULL, 224else from the server contained in the I<url>, and returns it as a BIO. 225It supports redirection via HTTP status code 301 or 302. It is meant for 226transfers with a single round trip, so does not support persistent connections. 227If I<bio> is non-NULL, any host and port components in the I<url> are not used 228for connecting but the hostname is used, as usual, for the C<Host> header. 229Any userinfo and fragment components in the I<url> are ignored. 230Any query component is handled as part of the path component. 231If the scheme component of the I<url> is C<https> a TLS connection is requested 232and the I<bio_update_fn>, as described for OSSL_HTTP_open(), must be provided. 233Also the remaining parameters are interpreted as described for OSSL_HTTP_open() 234and OSSL_HTTP_set1_request(), respectively. 235The caller is responsible for freeing the BIO pointer obtained. 236 237OSSL_HTTP_transfer() exchanges an HTTP request and response 238over a connection managed via I<prctx> without supporting redirection. 239It combines OSSL_HTTP_open(), OSSL_HTTP_set1_request(), OSSL_HTTP_exchange(), 240and OSSL_HTTP_close(). 241If I<prctx> is not NULL it reuses any open connection represented by a non-NULL 242I<*prctx>. It keeps the connection open if a persistent connection is requested 243or required and this was granted by the server, else it closes the connection 244and assigns NULL to I<*prctx>. 245The remaining parameters are interpreted as described for OSSL_HTTP_open() 246and OSSL_HTTP_set1_request(), respectively. 247The caller is responsible for freeing the BIO pointer obtained. 248 249OSSL_HTTP_close() closes the connection and releases I<rctx>. 250The I<ok> parameter is passed to any BIO update function 251given during setup as described above for OSSL_HTTP_open(). 252It must be 1 if no error occurred during the HTTP transfer and 0 otherwise. 253 254=head1 NOTES 255 256The names of the environment variables used by this implementation: 257C<http_proxy>, C<HTTP_PROXY>, C<https_proxy>, C<HTTPS_PROXY>, C<no_proxy>, and 258C<NO_PROXY>, have been chosen for maximal compatibility with 259other HTTP client implementations such as wget, curl, and git. 260 261When built with tracing enabled, OSSL_HTTP_transfer() and all functions using it 262may be traced using B<OSSL_TRACE_CATEGORY_HTTP>. 263See also L<OSSL_trace_enabled(3)> and L<openssl(1)/ENVIRONMENT>. 264 265=head1 RETURN VALUES 266 267OSSL_HTTP_open() returns on success a B<OSSL_HTTP_REQ_CTX>, else NULL. 268 269OSSL_HTTP_proxy_connect() and OSSL_HTTP_set1_request() 270return 1 on success, 0 on error. 271 272On success, OSSL_HTTP_exchange(), OSSL_HTTP_get(), and OSSL_HTTP_transfer() 273return a memory BIO that buffers all the data received if an ASN.1-encoded 274response is expected, otherwise a BIO that may support streaming. 275The BIO must be freed by the caller. 276On failure, they return NULL. 277Failure conditions include connection/transfer timeout, parse errors, etc. 278The caller is responsible for freeing the BIO pointer obtained. 279 280OSSL_HTTP_close() returns 0 if anything went wrong while disconnecting, else 1. 281 282=head1 SEE ALSO 283 284L<OSSL_HTTP_parse_url(3)>, L<BIO_new_connect(3)>, 285L<ASN1_item_i2d_mem_bio(3)>, L<ASN1_item_d2i_bio(3)>, 286L<OSSL_HTTP_is_alive(3)>, 287L<OSSL_trace_enabled(3)> 288 289=head1 HISTORY 290 291All the functions described here were added in OpenSSL 3.0. 292 293=head1 COPYRIGHT 294 295Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved. 296 297Licensed under the Apache License 2.0 (the "License"). You may not use 298this file except in compliance with the License. You can obtain a copy 299in the file LICENSE in the source distribution or at 300L<https://www.openssl.org/source/license.html>. 301 302=cut 303
