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Diffstat (limited to 'docs/libcurl/opts/CURLMOPT_PUSHFUNCTION.3')
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diff --git a/docs/libcurl/opts/CURLMOPT_PUSHFUNCTION.3 b/docs/libcurl/opts/CURLMOPT_PUSHFUNCTION.3 new file mode 100644 index 00000000..9fe02f8d --- /dev/null +++ b/docs/libcurl/opts/CURLMOPT_PUSHFUNCTION.3 @@ -0,0 +1,133 @@ +.\" ************************************************************************** +.\" * _ _ ____ _ +.\" * Project ___| | | | _ \| | +.\" * / __| | | | |_) | | +.\" * | (__| |_| | _ <| |___ +.\" * \___|\___/|_| \_\_____| +.\" * +.\" * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al. +.\" * +.\" * This software is licensed as described in the file COPYING, which +.\" * you should have received as part of this distribution. The terms +.\" * are also available at https://curl.haxx.se/docs/copyright.html. +.\" * +.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell +.\" * copies of the Software, and permit persons to whom the Software is +.\" * furnished to do so, under the terms of the COPYING file. +.\" * +.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY +.\" * KIND, either express or implied. +.\" * +.\" ************************************************************************** +.\" +.TH CURLMOPT_PUSHFUNCTION 3 "1 Jun 2015" "libcurl 7.44.0" "curl_multi_setopt options" +.SH NAME +CURLMOPT_PUSHFUNCTION \- callback that approves or denies server pushes +.SH SYNOPSIS +.nf +#include <curl/curl.h> + +char *curl_pushheader_bynum(struct curl_pushheaders *h, size_t num); +char *curl_pushheader_byname(struct curl_pushheaders *h, const char *name); + +int curl_push_callback(CURL *parent, + CURL *easy, + size_t num_headers, + struct curl_pushheaders *headers, + void *userp); + +CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_PUSHFUNCTION, + curl_push_callback func); +.fi +.SH DESCRIPTION +This callback gets called when a new HTTP/2 stream is being pushed by the +server (using the PUSH_PROMISE frame). If no push callback is set, all offered +pushes will be denied automatically. +.SH CALLBACK DESCRIPTION +The callback gets its arguments like this: + +\fIparent\fP is the handle of the stream on which this push arrives. The new +handle has been duphandle()d from the parent, meaning that it has gotten all +its options inherited. It is then up to the application to alter any options +if desired. + +\fIeasy\fP is a newly created handle that represents this upcoming transfer. + +\fInum_headers\fP is the number of name+value pairs that was received and can +be accessed + +\fIheaders\fP is a handle used to access push headers using the accessor +functions described below. This only accesses and provides the PUSH_PROMISE +headers, the normal response headers will be provided in the header callback +as usual. + +\fIuserp\fP is the pointer set with \fICURLMOPT_PUSHDATA(3)\fP + +If the callback returns CURL_PUSH_OK, the 'easy' handle will be added to the +multi handle, the callback must not do that by itself. + +The callback can access PUSH_PROMISE headers with two accessor +functions. These functions can only be used from within this callback and they +can only access the PUSH_PROMISE headers. The normal response headers will be +passed to the header callback for pushed streams just as for normal streams. +.IP curl_pushheader_bynum +Returns the header at index 'num' (or NULL). The returned pointer points to a +"name:value" string that will be freed when this callback returns. +.IP curl_pushheader_byname +Returns the value for the given header name (or NULL). This is a shortcut so +that the application doesn't have to loop through all headers to find the one +it is interested in. The data pointed will be freed when this callback +returns. If more than one header field use the same name, this returns only +the first one. +.SH CALLBACK RETURN VALUE +.IP "CURL_PUSH_OK (0)" +The application has accepted the stream and it can now start receiving data, +the ownership of the CURL handle has been taken over by the application. +.IP "CURL_PUSH_DENY (1)" +The callback denies the stream and no data for this will reach the +application, the easy handle will be destroyed by libcurl. +.IP * +All other return codes are reserved for future use. +.SH DEFAULT +NULL, no callback +.SH PROTOCOLS +HTTP(S) (HTTP/2 only) +.SH EXAMPLE +.nf +/* only allow pushes for file names starting with "push-" */ +int push_callback(CURL *parent, + CURL *easy, + size_t num_headers, + struct curl_pushheaders *headers, + void *userp) +{ + char *headp; + int *transfers = (int *)userp; + FILE *out; + headp = curl_pushheader_byname(headers, ":path"); + if(headp && !strncmp(headp, "/push-", 6)) { + fprintf(stderr, "The PATH is %s\\n", headp); + + /* save the push here */ + out = fopen("pushed-stream", "wb"); + + /* write to this file */ + curl_easy_setopt(easy, CURLOPT_WRITEDATA, out); + + (*transfers)++; /* one more */ + + return CURL_PUSH_OK; + } + return CURL_PUSH_DENY; +} + +curl_multi_setopt(multi, CURLMOPT_PUSHFUNCTION, push_callback); +curl_multi_setopt(multi, CURLMOPT_PUSHDATA, &counter); +.fi +.SH AVAILABILITY +Added in 7.44.0 +.SH RETURN VALUE +Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not. +.SH "SEE ALSO" +.BR CURLMOPT_PUSHDATA "(3), " CURLMOPT_PIPELINING "(3), " CURLOPT_PIPEWAIT "(3), " +.BR RFC 7540 |