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. 80Otherwise, the format is 81C<[http[s]://][userinfo@]host[:port][/path][?query][#fragment]>, 82where any userinfo, path, query, and fragment given is ignored. 83If the host string is an IPv6 address, it must be enclosed in C<[> and C<]>. 84The default proxy port number is 80, or 443 in case "https:" is given. 85The HTTP client functions connect via the given proxy unless the I<server> 86is found in the optional list I<no_proxy> of proxy hostnames or IP addresses 87separated by C<,> and/or whitespace (if not NULL; 88default is the environment variable C<no_proxy> if set, else C<NO_PROXY>). 89Proxying plain HTTP is supported directly, 90while using a proxy for HTTPS connections requires a suitable callback function 91such as OSSL_HTTP_proxy_connect(), described below. 92 93If I<use_ssl> is nonzero a TLS connection is requested 94and the I<bio_update_fn> parameter must be provided. 95 96The parameter I<bio_update_fn>, which is optional if I<use_ssl> is 0, 97may be used to modify the connection BIO used by the HTTP client, 98but cannot be used when both I<bio> and I<rbio> are given. 99I<bio_update_fn> is a BIO connect/disconnect callback function with prototype 100 101 BIO *(*OSSL_HTTP_bio_cb_t)(BIO *bio, void *arg, int connect, int detail) 102 103The callback function may modify the BIO provided in the I<bio> argument, 104whereby it may make use of a custom defined argument I<arg>, 105which may for instance point to an B<SSL_CTX> structure. 106During connection establishment, just after calling BIO_do_connect_retry(), the 107callback function is invoked with the I<connect> argument being 1 and 108I<detail> being 1 if I<use_ssl> is nonzero (i.e., HTTPS is requested), else 0. 109On disconnect I<connect> is 0 and I<detail> is 1 if no error occurred, else 0. 110For instance, on connect the callback may push an SSL BIO to implement HTTPS; 111after disconnect it may do some diagnostic output and pop and free the SSL BIO. 112 113The callback function must return either the potentially modified BIO I<bio>. 114or NULL to indicate failure, in which case it should not modify the BIO. 115 116Here is a simple example that supports TLS connections (but not via a proxy): 117 118 BIO *http_tls_cb(BIO *bio, void *arg, int connect, int detail) 119 { 120 if (connect && detail) { /* connecting with TLS */ 121 SSL_CTX *ctx = (SSL_CTX *)arg; 122 BIO *sbio = BIO_new_ssl(ctx, 1); 123 124 bio = sbio != NULL ? BIO_push(sbio, bio) : NULL; 125 } else if (!connect) { /* disconnecting */ 126 BIO *hbio; 127 128 if (!detail) { /* an error has occurred */ 129 /* optionally add diagnostics here */ 130 } 131 BIO_ssl_shutdown(bio); 132 hbio = BIO_pop(bio); 133 BIO_free(bio); /* SSL BIO */ 134 bio = hbio; 135 } 136 return bio; 137 } 138 139After disconnect the modified BIO will be deallocated using BIO_free_all(). 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. 177If the parameter I<expected_content_type> 178is not NULL then the client will check that the given content type string 179is included in the HTTP header of the response and return an error if not. 180If the I<expect_asn1> parameter is nonzero, 181a structure in ASN.1 encoding will be expected as response content. 182The I<max_resp_len> parameter specifies the maximum allowed 183response content length, where the value 0 indicates no limit. 184If the I<timeout> parameter is > 0 this indicates the maximum number of seconds 185the subsequent HTTP transfer (sending the request and receiving a response) 186is allowed to take. 187A value of 0 enables waiting indefinitely, i.e., no timeout. 188A value < 0 indicates that the I<overall_timeout> parameter value given 189when opening the HTTP transfer will be used instead. 190If I<keep_alive> is 0 the connection is not kept open 191after receiving a response, which is the default behavior for HTTP 1.0. 192If the value is 1 or 2 then a persistent connection is requested. 193If the value is 2 then a persistent connection is required, 194i.e., an error occurs in case the server does not grant it. 195 196OSSL_HTTP_exchange() exchanges any form of HTTP request and response 197as specified by I<rctx>, which must include both connection and request data, 198typically set up using OSSL_HTTP_open() and OSSL_HTTP_set1_request(). 199It implements the core of the functions described below. 200If the HTTP method is GET and I<redirection_url> 201is not NULL the latter pointer is used to provide any new location that 202the server may return with HTTP code 301 (MOVED_PERMANENTLY) or 302 (FOUND). 203In this case the function returns NULL and the caller is 204responsible for deallocating the URL with L<OPENSSL_free(3)>. 205If the response header contains one or more "Content-Length" header lines and/or 206an ASN.1-encoded response is expected, which should include a total length, 207the length indications received are checked for consistency 208and for not exceeding any given maximum response length. 209If an ASN.1-encoded response is expected, the function returns on success 210the contents buffered in a memory BIO, which does not support streaming. 211Otherwise it returns directly the read BIO that holds the response contents, 212which allows a response of indefinite length and may support streaming. 213The caller is responsible for freeing the BIO pointer obtained. 214 215OSSL_HTTP_get() uses HTTP GET to obtain data from I<bio> if non-NULL, 216else from the server contained in the I<url>, and returns it as a BIO. 217It supports redirection via HTTP status code 301 or 302. It is meant for 218transfers with a single round trip, so does not support persistent connections. 219If I<bio> is non-NULL, any host and port components in the I<url> are not used 220for connecting but the hostname is used, as usual, for the C<Host> header. 221Any userinfo and fragment components in the I<url> are ignored. 222Any query component is handled as part of the path component. 223If the scheme component of the I<url> is C<https> a TLS connection is requested 224and the I<bio_update_fn>, as described for OSSL_HTTP_open(), must be provided. 225Also the remaining parameters are interpreted as described for OSSL_HTTP_open() 226and OSSL_HTTP_set1_request(), respectively. 227The caller is responsible for freeing the BIO pointer obtained. 228 229OSSL_HTTP_transfer() exchanges an HTTP request and response 230over a connection managed via I<prctx> without supporting redirection. 231It combines OSSL_HTTP_open(), OSSL_HTTP_set1_request(), OSSL_HTTP_exchange(), 232and OSSL_HTTP_close(). 233If I<prctx> is not NULL it reuses any open connection represented by a non-NULL 234I<*prctx>. It keeps the connection open if a persistent connection is requested 235or required and this was granted by the server, else it closes the connection 236and assigns NULL to I<*prctx>. 237The remaining parameters are interpreted as described for OSSL_HTTP_open() 238and OSSL_HTTP_set1_request(), respectively. 239The caller is responsible for freeing the BIO pointer obtained. 240 241OSSL_HTTP_close() closes the connection and releases I<rctx>. 242The I<ok> parameter is passed to any BIO update function 243given during setup as described above for OSSL_HTTP_open(). 244It must be 1 if no error occurred during the HTTP transfer and 0 otherwise. 245 246=head1 NOTES 247 248The names of the environment variables used by this implementation: 249C<http_proxy>, C<HTTP_PROXY>, C<https_proxy>, C<HTTPS_PROXY>, C<no_proxy>, and 250C<NO_PROXY>, have been chosen for maximal compatibility with 251other HTTP client implementations such as wget, curl, and git. 252 253=head1 RETURN VALUES 254 255OSSL_HTTP_open() returns on success a B<OSSL_HTTP_REQ_CTX>, else NULL. 256 257OSSL_HTTP_proxy_connect() and OSSL_HTTP_set1_request() 258return 1 on success, 0 on error. 259 260On success, OSSL_HTTP_exchange(), OSSL_HTTP_get(), and OSSL_HTTP_transfer() 261return a memory BIO that buffers all the data received if an ASN.1-encoded 262response is expected, otherwise a BIO that may support streaming. 263The BIO must be freed by the caller. 264On failure, they return NULL. 265Failure conditions include connection/transfer timeout, parse errors, etc. 266The caller is responsible for freeing the BIO pointer obtained. 267 268OSSL_HTTP_close() returns 0 if anything went wrong while disconnecting, else 1. 269 270=head1 SEE ALSO 271 272L<OSSL_HTTP_parse_url(3)>, L<BIO_new_connect(3)>, 273L<ASN1_item_i2d_mem_bio(3)>, L<ASN1_item_d2i_bio(3)>, 274L<OSSL_HTTP_is_alive(3)> 275 276=head1 HISTORY 277 278All the functions described here were added in OpenSSL 3.0. 279 280=head1 COPYRIGHT 281 282Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved. 283 284Licensed under the Apache License 2.0 (the "License"). You may not use 285this file except in compliance with the License. You can obtain a copy 286in the file LICENSE in the source distribution or at 287L<https://www.openssl.org/source/license.html>. 288 289=cut 290