1=pod 2 3=head1 NAME 4 5OSSL_HTTP_REQ_CTX, 6OSSL_HTTP_REQ_CTX_new, 7OSSL_HTTP_REQ_CTX_free, 8OSSL_HTTP_REQ_CTX_set_request_line, 9OSSL_HTTP_REQ_CTX_add1_header, 10OSSL_HTTP_REQ_CTX_set_expected, 11OSSL_HTTP_REQ_CTX_set1_req, 12OSSL_HTTP_REQ_CTX_nbio, 13OSSL_HTTP_REQ_CTX_nbio_d2i, 14OSSL_HTTP_REQ_CTX_exchange, 15OSSL_HTTP_REQ_CTX_get0_mem_bio, 16OSSL_HTTP_REQ_CTX_get_resp_len, 17OSSL_HTTP_REQ_CTX_set_max_response_length, 18OSSL_HTTP_is_alive 19- HTTP client low-level functions 20 21=head1 SYNOPSIS 22 23 #include <openssl/http.h> 24 25 typedef struct ossl_http_req_ctx_st OSSL_HTTP_REQ_CTX; 26 27 OSSL_HTTP_REQ_CTX *OSSL_HTTP_REQ_CTX_new(BIO *wbio, BIO *rbio, int buf_size); 28 void OSSL_HTTP_REQ_CTX_free(OSSL_HTTP_REQ_CTX *rctx); 29 30 int OSSL_HTTP_REQ_CTX_set_request_line(OSSL_HTTP_REQ_CTX *rctx, int method_POST, 31 const char *server, const char *port, 32 const char *path); 33 int OSSL_HTTP_REQ_CTX_add1_header(OSSL_HTTP_REQ_CTX *rctx, 34 const char *name, const char *value); 35 36 int OSSL_HTTP_REQ_CTX_set_expected(OSSL_HTTP_REQ_CTX *rctx, 37 const char *content_type, int asn1, 38 int timeout, int keep_alive); 39 int OSSL_HTTP_REQ_CTX_set1_req(OSSL_HTTP_REQ_CTX *rctx, const char *content_type, 40 const ASN1_ITEM *it, const ASN1_VALUE *req); 41 int OSSL_HTTP_REQ_CTX_nbio(OSSL_HTTP_REQ_CTX *rctx); 42 int OSSL_HTTP_REQ_CTX_nbio_d2i(OSSL_HTTP_REQ_CTX *rctx, 43 ASN1_VALUE **pval, const ASN1_ITEM *it); 44 BIO *OSSL_HTTP_REQ_CTX_exchange(OSSL_HTTP_REQ_CTX *rctx); 45 46 BIO *OSSL_HTTP_REQ_CTX_get0_mem_bio(const OSSL_HTTP_REQ_CTX *rctx); 47 size_t OSSL_HTTP_REQ_CTX_get_resp_len(const OSSL_HTTP_REQ_CTX *rctx); 48 void OSSL_HTTP_REQ_CTX_set_max_response_length(OSSL_HTTP_REQ_CTX *rctx, 49 unsigned long len); 50 51 int OSSL_HTTP_is_alive(const OSSL_HTTP_REQ_CTX *rctx); 52 53=head1 DESCRIPTION 54 55B<OSSL_HTTP_REQ_CTX> is a context structure for an HTTP request and response, 56used to collect all the necessary data to perform that request. 57 58This file documents low-level HTTP functions rarely used directly. High-level 59HTTP client functions like L<OSSL_HTTP_get(3)> and L<OSSL_HTTP_transfer(3)> 60should be preferred. 61 62OSSL_HTTP_REQ_CTX_new() allocates a new HTTP request context structure, 63which gets populated with the B<BIO> to write/send the request to (I<wbio>), 64the B<BIO> to read/receive the response from (I<rbio>, which may be equal to 65I<wbio>), and the maximum expected response header line length I<buf_size>. 66A value <= 0 indicates that 67the B<OSSL_HTTP_DEFAULT_MAX_LINE_LEN> of 4KiB should be used. 68I<buf_size> is also used as the number of content bytes that are read at a time. 69The allocated context structure includes an internal memory B<BIO>, 70which collects the HTTP request header lines. 71 72OSSL_HTTP_REQ_CTX_free() frees up the HTTP request context I<rctx>. 73The I<rbio> is not free'd, I<wbio> will be free'd if I<free_wbio> is set. 74 75OSSL_HTTP_REQ_CTX_set_request_line() adds the 1st HTTP request line to I<rctx>. 76The HTTP method is determined by I<method_POST>, 77which should be 1 to indicate C<POST> or 0 to indicate C<GET>. 78I<server> and I<port> may be set to give the server and the optional port that 79an HTTP proxy shall forward the request to, otherwise they must be left NULL. 80I<path> provides the HTTP request path; if left NULL, C</> is used. 81For backward compatibility, I<path> may begin with C<http://> and thus convey 82an absoluteURI. In this case it indicates HTTP proxy use and provides also the 83server (and optionally the port) that the proxy shall forward the request to. 84In this case the I<server> and I<port> arguments must be NULL. 85 86OSSL_HTTP_REQ_CTX_add1_header() adds header I<name> with value I<value> to the 87context I<rctx>. It can be called more than once to add multiple header lines. 88For example, to add a C<Host> header for C<example.com> you would call: 89 90 OSSL_HTTP_REQ_CTX_add1_header(ctx, "Host", "example.com"); 91 92OSSL_HTTP_REQ_CTX_set_expected() optionally sets in I<rctx> some expectations 93of the HTTP client on the response. 94Due to the structure of an HTTP request, if the I<keep_alive> argument is 95nonzero the function must be used before calling OSSL_HTTP_REQ_CTX_set1_req(). 96If the I<content_type> parameter 97is not NULL then the client will check that the given content type string 98is included in the HTTP header of the response and return an error if not. 99If the I<asn1> parameter is nonzero a structure in ASN.1 encoding will be 100expected as the response content and input streaming is disabled. This means 101that an ASN.1 sequence header is required, its length field is checked, and 102OSSL_HTTP_REQ_CTX_get0_mem_bio() should be used to get the buffered response. 103Otherwise (by default) any input format is allowed without length checks. 104In this case the BIO given as I<rbio> argument to OSSL_HTTP_REQ_CTX_new() should 105be used directly to read the response contents, which may support streaming. 106If the I<timeout> parameter is > 0 this indicates the maximum number of seconds 107the subsequent HTTP transfer (sending the request and receiving a response) 108is allowed to take. 109I<timeout> == 0 enables waiting indefinitely, i.e., no timeout can occur. 110This is the default. 111I<timeout> < 0 takes over any value set via the I<overall_timeout> argument of 112L<OSSL_HTTP_open(3)> with the default being 0, which means no timeout. 113If the I<keep_alive> parameter is 0, which is the default, the connection is not 114kept open after receiving a response. This is the default behavior for HTTP 1.0. 115If the value is 1 or 2 then a persistent connection is requested. 116If the value is 2 then a persistent connection is required, 117i.e., an error occurs in case the server does not grant it. 118 119OSSL_HTTP_REQ_CTX_set1_req() finalizes the HTTP request context. 120It is needed if the I<method_POST> parameter in the 121OSSL_HTTP_REQ_CTX_set_request_line() call was 1 122and an ASN.1-encoded request should be sent. 123It must also be used when requesting "keep-alive", 124even if a GET request is going to be sent, in which case I<req> must be NULL. 125Unless I<req> is NULL, the function adds the DER encoding of I<req> using 126the ASN.1 template I<it> to do the encoding (which does not support streaming). 127The HTTP header C<Content-Length> is filled out with the length of the request. 128I<content_type> must be NULL if I<req> is NULL. 129If I<content_type> isn't NULL, 130the HTTP header C<Content-Type> is also added with the given string value. 131The header lines are added to the internal memory B<BIO> for the request header. 132 133OSSL_HTTP_REQ_CTX_nbio() attempts to send the request prepared in I<rctx> 134and to gather the response via HTTP, using the I<wbio> and I<rbio> 135that were given when calling OSSL_HTTP_REQ_CTX_new(). 136The function may need to be called again if its result is -1, which indicates 137L<BIO_should_retry(3)>. In such a case it is advisable to sleep a little in 138between, using L<BIO_wait(3)> on the read BIO to prevent a busy loop. 139 140OSSL_HTTP_REQ_CTX_nbio_d2i() is like OSSL_HTTP_REQ_CTX_nbio() but on success 141in addition parses the response, which must be a DER-encoded ASN.1 structure, 142using the ASN.1 template I<it> and places the result in I<*pval>. 143 144OSSL_HTTP_REQ_CTX_exchange() calls OSSL_HTTP_REQ_CTX_nbio() as often as needed 145in order to exchange a request and response or until a timeout is reached. 146On success it returns a pointer to the BIO that can be used to read the result. 147If an ASN.1-encoded response was expected, this is the BIO 148returned by OSSL_HTTP_REQ_CTX_get0_mem_bio() when called after the exchange. 149This memory BIO does not support streaming. 150Otherwise the returned BIO is the I<rbio> given to OSSL_HTTP_REQ_CTX_new(), 151which may support streaming. 152When this BIO is returned, it has been read past the end of the response header, 153such that the actual response body can be read from it. 154The returned BIO pointer MUST NOT be freed by the caller. 155 156OSSL_HTTP_REQ_CTX_get0_mem_bio() returns the internal memory B<BIO>. 157Before the HTTP request is sent, this could be used to adapt its header lines. 158I<Use with caution!> 159After receiving a response via HTTP, the BIO represents the current state of 160reading the response header. If the response was expected to be ASN.1 encoded, 161its contents can be read via this BIO, which does not support streaming. 162The returned BIO pointer must not be freed by the caller. 163 164OSSL_HTTP_REQ_CTX_get_resp_len() returns the size of the response contents 165in I<rctx> if provided by the server as <Content-Length> header field, else 0. 166 167OSSL_HTTP_REQ_CTX_set_max_response_length() sets the maximum allowed 168response content length for I<rctx> to I<len>. If not set or I<len> is 0 169then the B<OSSL_HTTP_DEFAULT_MAX_RESP_LEN> is used, which currently is 100 KiB. 170If the C<Content-Length> header is present and exceeds this value or 171the content is an ASN.1 encoded structure with a length exceeding this value 172or both length indications are present but disagree then an error occurs. 173 174OSSL_HTTP_is_alive() can be used to query if the HTTP connection 175given by I<rctx> is still alive, i.e., has not been closed. 176It returns 0 if I<rctx> is NULL. 177 178If the client application requested or required a persistent connection 179and this was granted by the server, it can keep I<rctx> as long as it wants 180to send further requests and OSSL_HTTP_is_alive() returns nonzero, 181else it should call I<OSSL_HTTP_REQ_CTX_free(rctx)> or L<OSSL_HTTP_close(3)>. 182In case the client application keeps I<rctx> but the connection then dies 183for any reason at the server side, it will notice this obtaining an 184I/O error when trying to send the next request via I<rctx>. 185 186=head1 WARNINGS 187 188The server's response may be unexpected if the hostname that was used to 189create the I<wbio>, any C<Host> header, and the host specified in the 190request URL do not match. 191 192Many of these functions must be called in a certain order. 193 194First, the HTTP request context must be allocated: 195OSSL_HTTP_REQ_CTX_new(). 196 197Then, the HTTP request must be prepared with request data: 198 199=over 4 200 201=item 1. 202 203Calling OSSL_HTTP_REQ_CTX_set_request_line(). 204 205=item 2. 206 207Adding extra header lines with OSSL_HTTP_REQ_CTX_add1_header(). 208This is optional and may be done multiple times with different names. 209 210=item 3. 211 212Finalize the request using OSSL_HTTP_REQ_CTX_set1_req(). 213This may be omitted if the GET method is used and "keep-alive" is not requested. 214 215=back 216 217When the request context is fully prepared, the HTTP exchange may be performed 218with OSSL_HTTP_REQ_CTX_nbio() or OSSL_HTTP_REQ_CTX_exchange(). 219 220=head1 RETURN VALUES 221 222OSSL_HTTP_REQ_CTX_new() returns a pointer to a B<OSSL_HTTP_REQ_CTX>, or NULL 223on error. 224 225OSSL_HTTP_REQ_CTX_free() and OSSL_HTTP_REQ_CTX_set_max_response_length() 226do not return values. 227 228OSSL_HTTP_REQ_CTX_set_request_line(), OSSL_HTTP_REQ_CTX_add1_header(), 229OSSL_HTTP_REQ_CTX_set1_req(), and OSSL_HTTP_REQ_CTX_set_expected() 230return 1 for success and 0 for failure. 231 232OSSL_HTTP_REQ_CTX_nbio() and OSSL_HTTP_REQ_CTX_nbio_d2i() 233return 1 for success, 0 on error or redirection, -1 if retry is needed. 234 235OSSL_HTTP_REQ_CTX_exchange() and OSSL_HTTP_REQ_CTX_get0_mem_bio() 236return a pointer to a B<BIO> on success as described above or NULL on failure. 237The returned BIO must not be freed by the caller. 238 239OSSL_HTTP_REQ_CTX_get_resp_len() returns the size of the response contents 240or 0 if not available or an error occurred. 241 242OSSL_HTTP_is_alive() returns 1 if its argument is non-NULL 243and the client requested a persistent connection 244and the server did not disagree on keeping the connection open, else 0. 245 246=head1 SEE ALSO 247 248L<BIO_should_retry(3)>, 249L<BIO_wait(3)>, 250L<ASN1_item_d2i_bio(3)>, 251L<ASN1_item_i2d_mem_bio(3)>, 252L<OSSL_HTTP_open(3)>, 253L<OSSL_HTTP_get(3)>, 254L<OSSL_HTTP_transfer(3)>, 255L<OSSL_HTTP_close(3)> 256 257=head1 HISTORY 258 259The functions described here were added in OpenSSL 3.0. 260 261=head1 COPYRIGHT 262 263Copyright 2015-2023 The OpenSSL Project Authors. All Rights Reserved. 264 265Licensed under the Apache License 2.0 (the "License"). You may not use 266this file except in compliance with the License. You can obtain a copy 267in the file LICENSE in the source distribution or at 268L<https://www.openssl.org/source/license.html>. 269 270=cut 271