path: root/secure/lib/libcrypto/man/man3/OSSL_HTTP_transfer.3

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.\" ========================================================================
.\"
.IX Title "OSSL_HTTP_TRANSFER 3ossl"
.TH OSSL_HTTP_TRANSFER 3ossl "2023-09-19" "3.0.11" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
OSSL_HTTP_open,
OSSL_HTTP_bio_cb_t,
OSSL_HTTP_proxy_connect,
OSSL_HTTP_set1_request,
OSSL_HTTP_exchange,
OSSL_HTTP_get,
OSSL_HTTP_transfer,
OSSL_HTTP_close
\&\-  HTTP client high\-level functions
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/http.h>
\&
\& typedef BIO *(*OSSL_HTTP_bio_cb_t)(BIO *bio, void *arg,
\&                                    int connect, int detail);
\& OSSL_HTTP_REQ_CTX *OSSL_HTTP_open(const char *server, const char *port,
\&                                   const char *proxy, const char *no_proxy,
\&                                   int use_ssl, BIO *bio, BIO *rbio,
\&                                   OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
\&                                   int buf_size, int overall_timeout);
\& int OSSL_HTTP_proxy_connect(BIO *bio, const char *server, const char *port,
\&                             const char *proxyuser, const char *proxypass,
\&                             int timeout, BIO *bio_err, const char *prog);
\& int OSSL_HTTP_set1_request(OSSL_HTTP_REQ_CTX *rctx, const char *path,
\&                            const STACK_OF(CONF_VALUE) *headers,
\&                            const char *content_type, BIO *req,
\&                            const char *expected_content_type, int expect_asn1,
\&                            size_t max_resp_len, int timeout, int keep_alive);
\& BIO *OSSL_HTTP_exchange(OSSL_HTTP_REQ_CTX *rctx, char **redirection_url);
\& BIO *OSSL_HTTP_get(const char *url, const char *proxy, const char *no_proxy,
\&                    BIO *bio, BIO *rbio,
\&                    OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
\&                    int buf_size, const STACK_OF(CONF_VALUE) *headers,
\&                    const char *expected_content_type, int expect_asn1,
\&                    size_t max_resp_len, int timeout);
\& BIO *OSSL_HTTP_transfer(OSSL_HTTP_REQ_CTX **prctx,
\&                         const char *server, const char *port,
\&                         const char *path, int use_ssl,
\&                         const char *proxy, const char *no_proxy,
\&                         BIO *bio, BIO *rbio,
\&                         OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
\&                         int buf_size, const STACK_OF(CONF_VALUE) *headers,
\&                         const char *content_type, BIO *req,
\&                         const char *expected_content_type, int expect_asn1,
\&                         size_t max_resp_len, int timeout, int keep_alive);
\& int OSSL_HTTP_close(OSSL_HTTP_REQ_CTX *rctx, int ok);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBOSSL_HTTP_open()\fR initiates an \s-1HTTP\s0 session using the \fIbio\fR argument if not
\&\s-1NULL,\s0 else by connecting to a given \fIserver\fR optionally via a \fIproxy\fR.
.PP
Typically the OpenSSL build supports sockets and the \fIbio\fR parameter is \s-1NULL.\s0
In this case \fIrbio\fR must be \s-1NULL\s0 as well and the \fIserver\fR must be non-NULL.
The function creates a network \s-1BIO\s0 internally using \fBBIO_new_connect\fR\|(3)
for connecting to the given server and the optionally given \fIport\fR,
defaulting to 80 for \s-1HTTP\s0 or 443 for \s-1HTTPS.\s0
Then this internal \s-1BIO\s0 is used for setting up a connection
and for exchanging one or more request and response.
If \fIbio\fR is given and \fIrbio\fR is \s-1NULL\s0 then this \fIbio\fR is used instead.
If both \fIbio\fR and \fIrbio\fR are given (which may be memory BIOs for instance)
then no explicit connection is set up, but
\&\fIbio\fR is used for writing requests and \fIrbio\fR for reading responses.
As soon as the client has flushed \fIbio\fR the server must be ready to provide
a response or indicate a waiting condition via \fIrbio\fR.
.PP
If \fIbio\fR is given, it is an error to provide \fIproxy\fR or \fIno_proxy\fR arguments,
while \fIserver\fR and \fIport\fR arguments may be given to support diagnostic output.
If \fIbio\fR is \s-1NULL\s0 the optional \fIproxy\fR parameter can be used to set an
\&\s-1HTTP\s0(S) proxy to use (unless overridden by \*(L"no_proxy\*(R" settings).
If \s-1TLS\s0 is not used this defaults to the environment variable \f(CW\*(C`http_proxy\*(C'\fR
if set, else \f(CW\*(C`HTTP_PROXY\*(C'\fR.
If \fIuse_ssl\fR != 0 it defaults to \f(CW\*(C`https_proxy\*(C'\fR if set, else \f(CW\*(C`HTTPS_PROXY\*(C'\fR.
An empty proxy string \f(CW""\fR forbids using a proxy.
Else the format is
\&\f(CW\*(C`[http[s]://][userinfo@]host[:port][/path][?query][#fragment]\*(C'\fR,
where any userinfo, path, query, and fragment given is ignored.
The default proxy port number is 80, or 443 in case \*(L"https:\*(R" is given.
The \s-1HTTP\s0 client functions connect via the given proxy unless the \fIserver\fR
is found in the optional list \fIno_proxy\fR of proxy hostnames (if not \s-1NULL\s0;
default is the environment variable \f(CW\*(C`no_proxy\*(C'\fR if set, else \f(CW\*(C`NO_PROXY\*(C'\fR).
Proxying plain \s-1HTTP\s0 is supported directly,
while using a proxy for \s-1HTTPS\s0 connections requires a suitable callback function
such as \fBOSSL_HTTP_proxy_connect()\fR, described below.
.PP
If \fIuse_ssl\fR is nonzero a \s-1TLS\s0 connection is requested
and the \fIbio_update_fn\fR parameter must be provided.
.PP
The parameter \fIbio_update_fn\fR, which is optional if \fIuse_ssl\fR is 0,
may be used to modify the connection \s-1BIO\s0 used by the \s-1HTTP\s0 client,
but cannot be used when both \fIbio\fR and \fIrbio\fR are given.
\&\fIbio_update_fn\fR is a \s-1BIO\s0 connect/disconnect callback function with prototype
.PP
.Vb 1
\& BIO *(*OSSL_HTTP_bio_cb_t)(BIO *bio, void *arg, int connect, int detail)
.Ve
.PP
The callback function may modify the \s-1BIO\s0 provided in the \fIbio\fR argument,
whereby it may make use of a custom defined argument \fIarg\fR,
which may for instance point to an \fB\s-1SSL_CTX\s0\fR structure.
During connection establishment, just after calling \fBBIO_do_connect_retry()\fR, the
callback function is invoked with the \fIconnect\fR argument being 1 and
\&\fIdetail\fR being 1 if \fIuse_ssl\fR is nonzero (i.e., \s-1HTTPS\s0 is requested), else 0.
On disconnect \fIconnect\fR is 0 and \fIdetail\fR is 1 if no error occurred, else 0.
For instance, on connect the callback may push an \s-1SSL BIO\s0 to implement \s-1HTTPS\s0;
after disconnect it may do some diagnostic output and pop and free the \s-1SSL BIO.\s0
.PP
The callback function must return either the potentially modified \s-1BIO\s0 \fIbio\fR.
or \s-1NULL\s0 to indicate failure, in which case it should not modify the \s-1BIO.\s0
.PP
Here is a simple example that supports \s-1TLS\s0 connections (but not via a proxy):
.PP
.Vb 5
\& BIO *http_tls_cb(BIO *bio, void *arg, int connect, int detail)
\& {
\&     if (connect && detail) { /* connecting with TLS */
\&         SSL_CTX *ctx = (SSL_CTX *)arg;
\&         BIO *sbio = BIO_new_ssl(ctx, 1);
\&
\&         bio = sbio != NULL ? BIO_push(sbio, bio) : NULL;
\&     } else if (!connect) { /* disconnecting */
\&         BIO *hbio;
\&
\&         if (!detail) { /* an error has occurred */
\&             /* optionally add diagnostics here */
\&         }
\&         BIO_ssl_shutdown(bio);
\&         hbio = BIO_pop(bio);
\&         BIO_free(bio); /* SSL BIO */
\&         bio = hbio;
\&     }
\&     return bio;
\& }
.Ve
.PP
After disconnect the modified \s-1BIO\s0 will be deallocated using \fBBIO_free_all()\fR.
.PP
The \fIbuf_size\fR parameter specifies the response header maximum line length.
A value <= 0 means that the \fB\s-1OSSL_HTTP_DEFAULT_MAX_LINE_LEN\s0\fR (4KiB) is used.
\&\fIbuf_size\fR is also used as the number of content bytes that are read at a time.
.PP
If the \fIoverall_timeout\fR parameter is > 0 this indicates the maximum number of
seconds the overall \s-1HTTP\s0 transfer (i.e., connection setup if needed,
sending requests, and receiving responses) is allowed to take until completion.
A value <= 0 enables waiting indefinitely, i.e., no timeout.
.PP
\&\fBOSSL_HTTP_proxy_connect()\fR may be used by an above \s-1BIO\s0 connect callback function
to set up an \s-1SSL/TLS\s0 connection via an \s-1HTTPS\s0 proxy.
It promotes the given \s-1BIO\s0 \fIbio\fR representing a connection
pre-established with a \s-1TLS\s0 proxy using the \s-1HTTP CONNECT\s0 method,
optionally using proxy client credentials \fIproxyuser\fR and \fIproxypass\fR,
to connect with \s-1TLS\s0 protection ultimately to \fIserver\fR and \fIport\fR.
If the \fIport\fR argument is \s-1NULL\s0 or the empty string it defaults to \*(L"443\*(R".
If the \fItimeout\fR parameter is > 0 this indicates the maximum number of
seconds the connection setup is allowed to take.
A value <= 0 enables waiting indefinitely, i.e., no timeout.
Since this function is typically called by applications such as
\&\fBopenssl\-s_client\fR\|(1) it uses the \fIbio_err\fR and \fIprog\fR parameters (unless
\&\s-1NULL\s0) to print additional diagnostic information in a user-oriented way.
.PP
\&\fBOSSL_HTTP_set1_request()\fR sets up in \fIrctx\fR the request header and content data
and expectations on the response using the following parameters.
If <rctx> indicates using a proxy for \s-1HTTP\s0 (but not \s-1HTTPS\s0), the server host
(and optionally port) needs to be placed in the header; thus it must be present
in \fIrctx\fR.
For backward compatibility, the server (and optional port) may also be given in
the \fIpath\fR argument beginning with \f(CW\*(C`http://\*(C'\fR (thus giving an absoluteURI).
If \fIpath\fR is \s-1NULL\s0 it defaults to \*(L"/\*(R".
If \fIreq\fR is \s-1NULL\s0 the \s-1HTTP GET\s0 method will be used to send the request
else \s-1HTTP POST\s0 with the contents of \fIreq\fR and optional \fIcontent_type\fR, where
the length of the data in \fIreq\fR does not need to be determined in advance: the
\&\s-1BIO\s0 will be read on-the-fly while sending the request, which supports streaming.
The optional list \fIheaders\fR may contain additional custom \s-1HTTP\s0 header lines.
If the parameter \fIexpected_content_type\fR
is not \s-1NULL\s0 then the client will check that the given content type string
is included in the \s-1HTTP\s0 header of the response and return an error if not.
If the \fIexpect_asn1\fR parameter is nonzero,
a structure in \s-1ASN.1\s0 encoding will be expected as response content.
The \fImax_resp_len\fR parameter specifies the maximum allowed
response content length, where the value 0 indicates no limit.
If the \fItimeout\fR parameter is > 0 this indicates the maximum number of seconds
the subsequent \s-1HTTP\s0 transfer (sending the request and receiving a response)
is allowed to take.
A value of 0 enables waiting indefinitely, i.e., no timeout.
A value < 0 indicates that the \fIoverall_timeout\fR parameter value given
when opening the \s-1HTTP\s0 transfer will be used instead.
If \fIkeep_alive\fR is 0 the connection is not kept open
after receiving a response, which is the default behavior for \s-1HTTP 1.0.\s0
If the value is 1 or 2 then a persistent connection is requested.
If the value is 2 then a persistent connection is required,
i.e., an error occurs in case the server does not grant it.
.PP
\&\fBOSSL_HTTP_exchange()\fR exchanges any form of \s-1HTTP\s0 request and response
as specified by \fIrctx\fR, which must include both connection and request data,
typically set up using \fBOSSL_HTTP_open()\fR and \fBOSSL_HTTP_set1_request()\fR.
It implements the core of the functions described below.
If the \s-1HTTP\s0 method is \s-1GET\s0 and \fIredirection_url\fR
is not \s-1NULL\s0 the latter pointer is used to provide any new location that
the server may return with \s-1HTTP\s0 code 301 (\s-1MOVED_PERMANENTLY\s0) or 302 (\s-1FOUND\s0).
In this case the function returns \s-1NULL\s0 and the caller is
responsible for deallocating the \s-1URL\s0 with \fBOPENSSL_free\fR\|(3).
If the response header contains one or more \*(L"Content-Length\*(R" header lines and/or
an \s-1ASN\s0.1\-encoded response is expected, which should include a total length,
the length indications received are checked for consistency
and for not exceeding any given maximum response length.
If an \s-1ASN\s0.1\-encoded response is expected, the function returns on success
the contents buffered in a memory \s-1BIO,\s0 which does not support streaming.
Otherwise it returns directly the read \s-1BIO\s0 that holds the response contents,
which allows a response of indefinite length and may support streaming.
The caller is responsible for freeing the \s-1BIO\s0 pointer obtained.
.PP
\&\fBOSSL_HTTP_get()\fR uses \s-1HTTP GET\s0 to obtain data from \fIbio\fR if non-NULL,
else from the server contained in the \fIurl\fR, and returns it as a \s-1BIO.\s0
It supports redirection via \s-1HTTP\s0 status code 301 or 302.  It is meant for
transfers with a single round trip, so does not support persistent connections.
If \fIbio\fR is non-NULL, any host and port components in the \fIurl\fR are not used
for connecting but the hostname is used, as usual, for the \f(CW\*(C`Host\*(C'\fR header.
Any userinfo and fragment components in the \fIurl\fR are ignored.
Any query component is handled as part of the path component.
If the scheme component of the \fIurl\fR is \f(CW\*(C`https\*(C'\fR a \s-1TLS\s0 connection is requested
and the \fIbio_update_fn\fR, as described for \fBOSSL_HTTP_open()\fR, must be provided.
Also the remaining parameters are interpreted as described for \fBOSSL_HTTP_open()\fR
and \fBOSSL_HTTP_set1_request()\fR, respectively.
The caller is responsible for freeing the \s-1BIO\s0 pointer obtained.
.PP
\&\fBOSSL_HTTP_transfer()\fR exchanges an \s-1HTTP\s0 request and response
over a connection managed via \fIprctx\fR without supporting redirection.
It combines \fBOSSL_HTTP_open()\fR, \fBOSSL_HTTP_set1_request()\fR, \fBOSSL_HTTP_exchange()\fR,
and \fBOSSL_HTTP_close()\fR.
If \fIprctx\fR is not \s-1NULL\s0 it reuses any open connection represented by a non-NULL
\&\fI*prctx\fR.  It keeps the connection open if a persistent connection is requested
or required and this was granted by the server, else it closes the connection
and assigns \s-1NULL\s0 to \fI*prctx\fR.
The remaining parameters are interpreted as described for \fBOSSL_HTTP_open()\fR
and \fBOSSL_HTTP_set1_request()\fR, respectively.
The caller is responsible for freeing the \s-1BIO\s0 pointer obtained.
.PP
\&\fBOSSL_HTTP_close()\fR closes the connection and releases \fIrctx\fR.
The \fIok\fR parameter is passed to any \s-1BIO\s0 update function
given during setup as described above for \fBOSSL_HTTP_open()\fR.
It must be 1 if no error occurred during the \s-1HTTP\s0 transfer and 0 otherwise.
.SH "NOTES"
.IX Header "NOTES"
The names of the environment variables used by this implementation:
\&\f(CW\*(C`http_proxy\*(C'\fR, \f(CW\*(C`HTTP_PROXY\*(C'\fR, \f(CW\*(C`https_proxy\*(C'\fR, \f(CW\*(C`HTTPS_PROXY\*(C'\fR, \f(CW\*(C`no_proxy\*(C'\fR, and
\&\f(CW\*(C`NO_PROXY\*(C'\fR, have been chosen for maximal compatibility with
other \s-1HTTP\s0 client implementations such as wget, curl, and git.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBOSSL_HTTP_open()\fR returns on success a \fB\s-1OSSL_HTTP_REQ_CTX\s0\fR, else \s-1NULL.\s0
.PP
\&\fBOSSL_HTTP_proxy_connect()\fR and \fBOSSL_HTTP_set1_request()\fR
return 1 on success, 0 on error.
.PP
On success, \fBOSSL_HTTP_exchange()\fR, \fBOSSL_HTTP_get()\fR, and \fBOSSL_HTTP_transfer()\fR
return a memory \s-1BIO\s0 that buffers all the data received if an \s-1ASN\s0.1\-encoded
response is expected, otherwise a \s-1BIO\s0 that may support streaming.
The \s-1BIO\s0 must be freed by the caller.
On failure, they return \s-1NULL.\s0
Failure conditions include connection/transfer timeout, parse errors, etc.
The caller is responsible for freeing the \s-1BIO\s0 pointer obtained.
.PP
\&\fBOSSL_HTTP_close()\fR returns 0 if anything went wrong while disconnecting, else 1.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBOSSL_HTTP_parse_url\fR\|(3), \fBBIO_new_connect\fR\|(3),
\&\fBASN1_item_i2d_mem_bio\fR\|(3), \fBASN1_item_d2i_bio\fR\|(3),
\&\fBOSSL_HTTP_is_alive\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
All the functions described here were added in OpenSSL 3.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2019\-2023 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.