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 make use of a custom defined argument I<arg>, 103which may 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(). 138 139The I<buf_size> parameter specifies the response header maximum line length. 140A value <= 0 means that the B<OSSL_HTTP_DEFAULT_MAX_LINE_LEN> (4KiB) is used. 141I<buf_size> is also used as the number of content bytes that are read at a time. 142 143If the I<overall_timeout> parameter is > 0 this indicates the maximum number of 144seconds the overall HTTP transfer (i.e., connection setup if needed, 145sending requests, and receiving responses) is allowed to take until completion. 146A value <= 0 enables waiting indefinitely, i.e., no timeout. 147 148OSSL_HTTP_proxy_connect() may be used by an above BIO connect callback function 149to set up an SSL/TLS connection via an HTTPS proxy. 150It promotes the given BIO I<bio> representing a connection 151pre-established with a TLS proxy using the HTTP CONNECT method, 152optionally using proxy client credentials I<proxyuser> and I<proxypass>, 153to connect with TLS protection ultimately to I<server> and I<port>. 154If the I<port> argument is NULL or the empty string it defaults to "443". 155If the I<timeout> parameter is > 0 this indicates the maximum number of 156seconds the connection setup is allowed to take. 157A value <= 0 enables waiting indefinitely, i.e., no timeout. 158Since this function is typically called by applications such as 159L<openssl-s_client(1)> it uses the I<bio_err> and I<prog> parameters (unless 160NULL) to print additional diagnostic information in a user-oriented way. 161 162OSSL_HTTP_set1_request() sets up in I<rctx> the request header and content data 163and expectations on the response using the following parameters. 164If <rctx> indicates using a proxy for HTTP (but not HTTPS), the server hostname 165(and optionally port) needs to be placed in the header and thus must be present. 166If I<path> is NULL it defaults to "/". 167If I<req> is NULL the HTTP GET method will be used to send the request 168else HTTP POST with the contents of I<req> and optional I<content_type>, where 169the length of the data in I<req> does not need to be determined in advance: the 170BIO will be read on-the-fly while sending the request, which supports streaming. 171The optional list I<headers> may contain additional custom HTTP header lines. 172If the parameter I<expected_content_type> 173is not NULL then the client will check that the given content type string 174is included in the HTTP header of the response and return an error if not. 175If the I<expect_asn1> parameter is nonzero, 176a structure in ASN.1 encoding will be expected as response content. 177The I<max_resp_len> parameter specifies the maximum allowed 178response content length, where the value 0 indicates no limit. 179If the I<timeout> parameter is > 0 this indicates the maximum number of seconds 180the subsequent HTTP transfer (sending the request and receiving a response) 181is allowed to take. 182A value of 0 enables waiting indefinitely, i.e., no timeout. 183A value < 0 indicates that the I<overall_timeout> parameter value given 184when opening the HTTP transfer will be used instead. 185If I<keep_alive> is 0 the connection is not kept open 186after receiving a response, which is the default behavior for HTTP 1.0. 187If the value is 1 or 2 then a persistent connection is requested. 188If the value is 2 then a persistent connection is required, 189i.e., an error occurs in case the server does not grant it. 190 191OSSL_HTTP_exchange() exchanges any form of HTTP request and response 192as specified by I<rctx>, which must include both connection and request data, 193typically set up using OSSL_HTTP_open() and OSSL_HTTP_set1_request(). 194It implements the core of the functions described below. 195If the HTTP method is GET and I<redirection_url> 196is not NULL the latter pointer is used to provide any new location that 197the server may return with HTTP code 301 (MOVED_PERMANENTLY) or 302 (FOUND). 198In this case the function returns NULL and the caller is 199responsible for deallocating the URL with L<OPENSSL_free(3)>. 200If the response header contains one or more "Content-Length" header lines and/or 201an ASN.1-encoded response is expected, which should include a total length, 202the length indications received are checked for consistency 203and for not exceeding any given maximum response length. 204If an ASN.1-encoded response is expected, the function returns on success 205the contents buffered in a memory BIO, which does not support streaming. 206Otherwise it returns directly the read BIO that holds the response contents, 207which allows a response of indefinite length and may support streaming. 208The caller is responsible for freeing the BIO pointer obtained. 209 210OSSL_HTTP_get() uses HTTP GET to obtain data from I<bio> if non-NULL, 211else from the server contained in the I<url>, and returns it as a BIO. 212It supports redirection via HTTP status code 301 or 302. It is meant for 213transfers with a single round trip, so does not support persistent connections. 214If I<bio> is non-NULL, any host and port components in the I<url> are not used 215for connecting but the hostname is used, as usual, for the C<Host> header. 216Any userinfo and fragment components in the I<url> are ignored. 217Any query component is handled as part of the path component. 218If the scheme component of the I<url> is C<https> a TLS connection is requested 219and the I<bio_update_fn>, as described for OSSL_HTTP_open(), must be provided. 220Also the remaining parameters are interpreted as described for OSSL_HTTP_open() 221and OSSL_HTTP_set1_request(), respectively. 222The caller is responsible for freeing the BIO pointer obtained. 223 224OSSL_HTTP_transfer() exchanges an HTTP request and response 225over a connection managed via I<prctx> without supporting redirection. 226It combines OSSL_HTTP_open(), OSSL_HTTP_set1_request(), OSSL_HTTP_exchange(), 227and OSSL_HTTP_close(). 228If I<prctx> is not NULL it reuses any open connection represented by a non-NULL 229I<*prctx>. It keeps the connection open if a persistent connection is requested 230or required and this was granted by the server, else it closes the connection 231and assigns NULL to I<*prctx>. 232The remaining parameters are interpreted as described for OSSL_HTTP_open() 233and OSSL_HTTP_set1_request(), respectively. 234The caller is responsible for freeing the BIO pointer obtained. 235 236OSSL_HTTP_close() closes the connection and releases I<rctx>. 237The I<ok> parameter is passed to any BIO update function 238given during setup as described above for OSSL_HTTP_open(). 239It must be 1 if no error occurred during the HTTP transfer and 0 otherwise. 240 241=head1 NOTES 242 243The names of the environment variables used by this implementation: 244C<http_proxy>, C<HTTP_PROXY>, C<https_proxy>, C<HTTPS_PROXY>, C<no_proxy>, and 245C<NO_PROXY>, have been chosen for maximal compatibility with 246other HTTP client implementations such as wget, curl, and git. 247 248=head1 RETURN VALUES 249 250OSSL_HTTP_open() returns on success a B<OSSL_HTTP_REQ_CTX>, else NULL. 251 252OSSL_HTTP_proxy_connect() and OSSL_HTTP_set1_request() 253return 1 on success, 0 on error. 254 255On success, OSSL_HTTP_exchange(), OSSL_HTTP_get(), and OSSL_HTTP_transfer() 256return a memory BIO that buffers all the data received if an ASN.1-encoded 257response is expected, otherwise a BIO that may support streaming. 258The BIO must be freed by the caller. 259On failure, they return NULL. 260Failure conditions include connection/transfer timeout, parse errors, etc. 261The caller is responsible for freeing the BIO pointer obtained. 262 263OSSL_HTTP_close() returns 0 if anything went wrong while disconnecting, else 1. 264 265=head1 SEE ALSO 266 267L<OSSL_HTTP_parse_url(3)>, L<BIO_new_connect(3)>, 268L<ASN1_item_i2d_mem_bio(3)>, L<ASN1_item_d2i_bio(3)>, 269L<OSSL_HTTP_is_alive(3)> 270 271=head1 HISTORY 272 273All the functions described here were added in OpenSSL 3.0. 274 275=head1 COPYRIGHT 276 277Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved. 278 279Licensed under the Apache License 2.0 (the "License"). You may not use 280this file except in compliance with the License. You can obtain a copy 281in the file LICENSE in the source distribution or at 282L<https://www.openssl.org/source/license.html>. 283 284=cut 285