1OSSL_HTTP_REQ_CTX(3ossl) OpenSSL OSSL_HTTP_REQ_CTX(3ossl)
2
6 OSSL_HTTP_REQ_CTX, OSSL_HTTP_REQ_CTX_new, OSSL_HTTP_REQ_CTX_free,
7 OSSL_HTTP_REQ_CTX_set_request_line, OSSL_HTTP_REQ_CTX_add1_header,
8 OSSL_HTTP_REQ_CTX_set_expected, OSSL_HTTP_REQ_CTX_set1_req,
9 OSSL_HTTP_REQ_CTX_nbio, OSSL_HTTP_REQ_CTX_nbio_d2i,
10 OSSL_HTTP_REQ_CTX_exchange, OSSL_HTTP_REQ_CTX_get0_mem_bio,
11 OSSL_HTTP_REQ_CTX_get_resp_len,
12 OSSL_HTTP_REQ_CTX_set_max_response_length, OSSL_HTTP_is_alive - HTTP
13 client low-level functions
14
16 #include <openssl/http.h>
17 typedef struct ossl_http_req_ctx_st OSSL_HTTP_REQ_CTX;
19 OSSL_HTTP_REQ_CTX *OSSL_HTTP_REQ_CTX_new(BIO *wbio, BIO *rbio, int buf_size);
21 void OSSL_HTTP_REQ_CTX_free(OSSL_HTTP_REQ_CTX *rctx);
22 int OSSL_HTTP_REQ_CTX_set_request_line(OSSL_HTTP_REQ_CTX *rctx, int method_POST,
24 const char *server, const char *port,
25 const char *path);
26 int OSSL_HTTP_REQ_CTX_add1_header(OSSL_HTTP_REQ_CTX *rctx,
27 const char *name, const char *value);
28 int OSSL_HTTP_REQ_CTX_set_expected(OSSL_HTTP_REQ_CTX *rctx,
30 const char *content_type, int asn1,
31 int timeout, int keep_alive);
32 int OSSL_HTTP_REQ_CTX_set1_req(OSSL_HTTP_REQ_CTX *rctx, const char *content_type,
33 const ASN1_ITEM *it, const ASN1_VALUE *req);
34 int OSSL_HTTP_REQ_CTX_nbio(OSSL_HTTP_REQ_CTX *rctx);
35 int OSSL_HTTP_REQ_CTX_nbio_d2i(OSSL_HTTP_REQ_CTX *rctx,
36 ASN1_VALUE **pval, const ASN1_ITEM *it);
37 BIO *OSSL_HTTP_REQ_CTX_exchange(OSSL_HTTP_REQ_CTX *rctx);
38 BIO *OSSL_HTTP_REQ_CTX_get0_mem_bio(const OSSL_HTTP_REQ_CTX *rctx);
40 size_t OSSL_HTTP_REQ_CTX_get_resp_len(const OSSL_HTTP_REQ_CTX *rctx);
41 void OSSL_HTTP_REQ_CTX_set_max_response_length(OSSL_HTTP_REQ_CTX *rctx,
42 unsigned long len);
43 int OSSL_HTTP_is_alive(const OSSL_HTTP_REQ_CTX *rctx);
45
47 OSSL_HTTP_REQ_CTX is a context structure for an HTTP request and
48 response, used to collect all the necessary data to perform that
49 request.
50 This file documents low-level HTTP functions rarely used directly.
52 High-level HTTP client functions like OSSL_HTTP_get(3) and
53 OSSL_HTTP_transfer(3) should be preferred.
54 OSSL_HTTP_REQ_CTX_new() allocates a new HTTP request context structure,
56 which gets populated with the BIO to write/send the request to (wbio),
57 the BIO to read/receive the response from (rbio, which may be equal to
58 wbio), and the maximum expected response header line length buf_size.
59 A value <= 0 indicates that the OSSL_HTTP_DEFAULT_MAX_LINE_LEN of 4KiB
60 should be used. buf_size is also used as the number of content bytes
61 that are read at a time. The allocated context structure includes an
62 internal memory BIO, which collects the HTTP request header lines.
63 OSSL_HTTP_REQ_CTX_free() frees up the HTTP request context rctx. The
65 rbio is not free'd, wbio will be free'd if free_wbio is set.
66 OSSL_HTTP_REQ_CTX_set_request_line() adds the HTTP request line to the
68 context. The HTTP method is determined by method_POST, which should be
69 1 to indicate "POST" or 0 to indicate "GET". server and port may be
70 set to indicate a proxy server and port that the request should go
71 through, otherwise they should be left NULL. path is the HTTP request
72 path; if left NULL, "/" is used.
73 OSSL_HTTP_REQ_CTX_add1_header() adds header name with value value to
75 the context rctx. It can be called more than once to add multiple
76 header lines. For example, to add a "Host" header for "example.com"
77 you would call:
78 OSSL_HTTP_REQ_CTX_add1_header(ctx, "Host", "example.com");
80 OSSL_HTTP_REQ_CTX_set_expected() optionally sets in rctx some
82 expectations of the HTTP client on the response. Due to the structure
83 of an HTTP request, if the keep_alive argument is nonzero the function
84 must be used before calling OSSL_HTTP_REQ_CTX_set1_req(). If the
85 content_type parameter is not NULL then the client will check that the
86 given content type string is included in the HTTP header of the
87 response and return an error if not. If the asn1 parameter is nonzero
88 a structure in ASN.1 encoding will be expected as the response content
89 and input streaming is disabled. This means that an ASN.1 sequence
90 header is required, its length field is checked, and
91 OSSL_HTTP_REQ_CTX_get0_mem_bio() should be used to get the buffered
92 response. Otherwise (by default) any input format is allowed without
93 length checks. In this case the BIO given as rbio argument to
94 OSSL_HTTP_REQ_CTX_new() should be used directly to read the response
95 contents, which may support streaming. If the timeout parameter is > 0
96 this indicates the maximum number of seconds the subsequent HTTP
97 transfer (sending the request and receiving a response) is allowed to
98 take. timeout == 0 enables waiting indefinitely, i.e., no timeout can
99 occur. This is the default. timeout < 0 takes over any value set via
100 the overall_timeout argument of OSSL_HTTP_open(3) with the default
101 being 0, which means no timeout. If the keep_alive parameter is 0,
102 which is the default, the connection is not kept open after receiving a
103 response. This is the default behavior for HTTP 1.0. If the value is 1
104 or 2 then a persistent connection is requested. If the value is 2 then
105 a persistent connection is required, i.e., an error occurs in case the
106 server does not grant it.
107 OSSL_HTTP_REQ_CTX_set1_req() finalizes the HTTP request context. It is
109 needed if the method_POST parameter in the
110 OSSL_HTTP_REQ_CTX_set_request_line() call was 1 and an ASN.1-encoded
111 request should be sent. It must also be used when requesting "keep-
112 alive", even if a GET request is going to be sent, in which case req
113 must be NULL. Unless req is NULL, the function adds the DER encoding
114 of req using the ASN.1 template it to do the encoding (which does not
115 support streaming). The HTTP header "Content-Length" is filled out
116 with the length of the request. content_type must be NULL if req is
117 NULL. If content_type isn't NULL, the HTTP header "Content-Type" is
118 also added with the given string value. The header lines are added to
119 the internal memory BIO for the request header.
120 OSSL_HTTP_REQ_CTX_nbio() attempts to send the request prepared in rctx
122 and to gather the response via HTTP, using the wbio and rbio that were
123 given when calling OSSL_HTTP_REQ_CTX_new(). The function may need to
124 be called again if its result is -1, which indicates
125 BIO_should_retry(3). In such a case it is advisable to sleep a little
126 in between, using BIO_wait(3) on the read BIO to prevent a busy loop.
127 OSSL_HTTP_REQ_CTX_nbio_d2i() is like OSSL_HTTP_REQ_CTX_nbio() but on
129 success in addition parses the response, which must be a DER-encoded
130 ASN.1 structure, using the ASN.1 template it and places the result in
131 *pval.
132 OSSL_HTTP_REQ_CTX_exchange() calls OSSL_HTTP_REQ_CTX_nbio() as often as
134 needed in order to exchange a request and response or until a timeout
135 is reached. On success it returns a pointer to the BIO that can be
136 used to read the result. If an ASN.1-encoded response was expected,
137 this is the BIO returned by OSSL_HTTP_REQ_CTX_get0_mem_bio() when
138 called after the exchange. This memory BIO does not support streaming.
139 Otherwise the returned BIO is the rbio given to
140 OSSL_HTTP_REQ_CTX_new(), which may support streaming. When this BIO is
141 returned, it has been read past the end of the response header, such
142 that the actual response body can be read from it. The returned BIO
143 pointer MUST NOT be freed by the caller.
144 OSSL_HTTP_REQ_CTX_get0_mem_bio() returns the internal memory BIO.
146 Before the HTTP request is sent, this could be used to adapt its header
147 lines. Use with caution! After receiving a response via HTTP, the BIO
148 represents the current state of reading the response header. If the
149 response was expected to be ASN.1 encoded, its contents can be read via
150 this BIO, which does not support streaming. The returned BIO pointer
151 must not be freed by the caller.
152 OSSL_HTTP_REQ_CTX_get_resp_len() returns the size of the response
154 contents in rctx if provided by the server as <Content-Length> header
155 field, else 0.
156 OSSL_HTTP_REQ_CTX_set_max_response_length() sets the maximum allowed
158 response content length for rctx to len. If not set or len is 0 then
159 the OSSL_HTTP_DEFAULT_MAX_RESP_LEN is used, which currently is 100 KiB.
160 If the "Content-Length" header is present and exceeds this value or the
161 content is an ASN.1 encoded structure with a length exceeding this
162 value or both length indications are present but disagree then an error
163 occurs.
164 OSSL_HTTP_is_alive() can be used to query if the HTTP connection given
166 by rctx is still alive, i.e., has not been closed. It returns 0 if
167 rctx is NULL.
168 If the client application requested or required a persistent connection
170 and this was granted by the server, it can keep rctx as long as it
171 wants to send further requests and OSSL_HTTP_is_alive() returns
172 nonzero, else it should call OSSL_HTTP_REQ_CTX_free(rctx) or
173 OSSL_HTTP_close(3). In case the client application keeps rctx but the
174 connection then dies for any reason at the server side, it will notice
175 this obtaining an I/O error when trying to send the next request via
176 rctx.
177
179 The server's response may be unexpected if the hostname that was used
180 to create the wbio, any "Host" header, and the host specified in the
181 request URL do not match.
182 Many of these functions must be called in a certain order.
184 First, the HTTP request context must be allocated:
186 OSSL_HTTP_REQ_CTX_new().
187 Then, the HTTP request must be prepared with request data:
189 1. Calling OSSL_HTTP_REQ_CTX_set_request_line().
191 2. Adding extra header lines with OSSL_HTTP_REQ_CTX_add1_header().
193 This is optional and may be done multiple times with different
194 names.
195 3. Finalize the request using OSSL_HTTP_REQ_CTX_set1_req(). This may
197 be omitted if the GET method is used and "keep-alive" is not
198 requested.
199 When the request context is fully prepared, the HTTP exchange may be
201 performed with OSSL_HTTP_REQ_CTX_nbio() or
202 OSSL_HTTP_REQ_CTX_exchange().
203
205 When built with tracing enabled, OSSL_HTTP_REQ_CTX_nbio() and all
206 functions using it, such as OSSL_HTTP_REQ_CTX_exchange() and
207 OSSL_HTTP_transfer(3), may be traced using OSSL_TRACE_CATEGORY_HTTP.
208 See also OSSL_trace_enabled(3) and "ENVIRONMENT" in openssl(1).
209
211 OSSL_HTTP_REQ_CTX_new() returns a pointer to a OSSL_HTTP_REQ_CTX, or
212 NULL on error.
213 OSSL_HTTP_REQ_CTX_free() and
215 OSSL_HTTP_REQ_CTX_set_max_response_length() do not return values.
216 OSSL_HTTP_REQ_CTX_set_request_line(), OSSL_HTTP_REQ_CTX_add1_header(),
218 OSSL_HTTP_REQ_CTX_set1_req(), and OSSL_HTTP_REQ_CTX_set_expected()
219 return 1 for success and 0 for failure.
220 OSSL_HTTP_REQ_CTX_nbio() and OSSL_HTTP_REQ_CTX_nbio_d2i() return 1 for
222 success, 0 on error or redirection, -1 if retry is needed.
223 OSSL_HTTP_REQ_CTX_exchange() and OSSL_HTTP_REQ_CTX_get0_mem_bio()
225 return a pointer to a BIO on success as described above or NULL on
226 failure. The returned BIO must not be freed by the caller.
227 OSSL_HTTP_REQ_CTX_get_resp_len() returns the size of the response
229 contents or 0 if not available or an error occurred.
230 OSSL_HTTP_is_alive() returns 1 if its argument is non-NULL and the
232 client requested a persistent connection and the server did not
233 disagree on keeping the connection open, else 0.
234
236 BIO_should_retry(3), BIO_wait(3), ASN1_item_d2i_bio(3),
237 ASN1_item_i2d_mem_bio(3), OSSL_HTTP_open(3), OSSL_HTTP_get(3),
238 OSSL_HTTP_transfer(3), OSSL_HTTP_close(3), OSSL_trace_enabled(3)
239
241 The functions described here were added in OpenSSL 3.0.
242
244 Copyright 2015-2022 The OpenSSL Project Authors. All Rights Reserved.
245 Licensed under the Apache License 2.0 (the "License"). You may not use
247 this file except in compliance with the License. You can obtain a copy
248 in the file LICENSE in the source distribution or at
249 <https://www.openssl.org/source/license.html>.
2503.1.1 2023-08-31 OSSL_HTTP_REQ_CTX(3ossl)