Return to CURLMOPT_PUSHFUNCTION.3 CVS log

Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / curl / docs / libcurl / opts

Annotation of embedaddon/curl/docs/libcurl/opts/CURLMOPT_PUSHFUNCTION.3, revision 1.1

1.1     ! misho       1: .\" **************************************************************************
        !             2: .\" *                                  _   _ ____  _
        !             3: .\" *  Project                     ___| | | |  _ \| |
        !             4: .\" *                             / __| | | | |_) | |
        !             5: .\" *                            | (__| |_| |  _ <| |___
        !             6: .\" *                             \___|\___/|_| \_\_____|
        !             7: .\" *
        !             8: .\" * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
        !             9: .\" *
        !            10: .\" * This software is licensed as described in the file COPYING, which
        !            11: .\" * you should have received as part of this distribution. The terms
        !            12: .\" * are also available at https://curl.haxx.se/docs/copyright.html.
        !            13: .\" *
        !            14: .\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
        !            15: .\" * copies of the Software, and permit persons to whom the Software is
        !            16: .\" * furnished to do so, under the terms of the COPYING file.
        !            17: .\" *
        !            18: .\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
        !            19: .\" * KIND, either express or implied.
        !            20: .\" *
        !            21: .\" **************************************************************************
        !            22: .\"
        !            23: .TH CURLMOPT_PUSHFUNCTION 3 "March 23, 2020" "libcurl 7.70.0" "curl_multi_setopt options"
        !            24: 
        !            25: .SH NAME
        !            26: CURLMOPT_PUSHFUNCTION \- callback that approves or denies server pushes
        !            27: .SH SYNOPSIS
        !            28: .nf
        !            29: #include <curl/curl.h>
        !            30: 
        !            31: char *curl_pushheader_bynum(struct curl_pushheaders *h, size_t num);
        !            32: char *curl_pushheader_byname(struct curl_pushheaders *h, const char *name);
        !            33: 
        !            34: int curl_push_callback(CURL *parent,
        !            35:                        CURL *easy,
        !            36:                        size_t num_headers,
        !            37:                        struct curl_pushheaders *headers,
        !            38:                        void *userp);
        !            39: 
        !            40: CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_PUSHFUNCTION,
        !            41:                             curl_push_callback func);
        !            42: .fi
        !            43: .SH DESCRIPTION
        !            44: This callback gets called when a new HTTP/2 stream is being pushed by the
        !            45: server (using the PUSH_PROMISE frame). If no push callback is set, all offered
        !            46: pushes will be denied automatically.
        !            47: .SH CALLBACK DESCRIPTION
        !            48: The callback gets its arguments like this:
        !            49: 
        !            50: \fIparent\fP is the handle of the stream on which this push arrives. The new
        !            51: handle has been duphandle()d from the parent, meaning that it has gotten all
        !            52: its options inherited. It is then up to the application to alter any options
        !            53: if desired.
        !            54: 
        !            55: \fIeasy\fP is a newly created handle that represents this upcoming transfer.
        !            56: 
        !            57: \fInum_headers\fP is the number of name+value pairs that was received and can
        !            58: be accessed
        !            59: 
        !            60: \fIheaders\fP is a handle used to access push headers using the accessor
        !            61: functions described below. This only accesses and provides the PUSH_PROMISE
        !            62: headers, the normal response headers will be provided in the header callback
        !            63: as usual.
        !            64: 
        !            65: \fIuserp\fP is the pointer set with \fICURLMOPT_PUSHDATA(3)\fP
        !            66: 
        !            67: If the callback returns CURL_PUSH_OK, the 'easy' handle will be added to the
        !            68: multi handle, the callback must not do that by itself.
        !            69: 
        !            70: The callback can access PUSH_PROMISE headers with two accessor
        !            71: functions. These functions can only be used from within this callback and they
        !            72: can only access the PUSH_PROMISE headers. The normal response headers will be
        !            73: passed to the header callback for pushed streams just as for normal streams.
        !            74: .IP curl_pushheader_bynum
        !            75: Returns the header at index 'num' (or NULL). The returned pointer points to a
        !            76: "name:value" string that will be freed when this callback returns.
        !            77: .IP curl_pushheader_byname
        !            78: Returns the value for the given header name (or NULL). This is a shortcut so
        !            79: that the application doesn't have to loop through all headers to find the one
        !            80: it is interested in. The data pointed will be freed when this callback
        !            81: returns. If more than one header field use the same name, this returns only
        !            82: the first one.
        !            83: .SH CALLBACK RETURN VALUE
        !            84: .IP "CURL_PUSH_OK (0)"
        !            85: The application has accepted the stream and it can now start receiving data,
        !            86: the ownership of the CURL handle has been taken over by the application.
        !            87: .IP "CURL_PUSH_DENY (1)"
        !            88: The callback denies the stream and no data for this will reach the
        !            89: application, the easy handle will be destroyed by libcurl.
        !            90: .IP *
        !            91: All other return codes are reserved for future use.
        !            92: .SH DEFAULT
        !            93: NULL, no callback
        !            94: .SH PROTOCOLS
        !            95: HTTP(S) (HTTP/2 only)
        !            96: .SH EXAMPLE
        !            97: .nf
        !            98: /* only allow pushes for file names starting with "push-" */
        !            99: int push_callback(CURL *parent,
        !           100:                   CURL *easy,
        !           101:                   size_t num_headers,
        !           102:                   struct curl_pushheaders *headers,
        !           103:                   void *userp)
        !           104: {
        !           105:   char *headp;
        !           106:   int *transfers = (int *)userp;
        !           107:   FILE *out;
        !           108:   headp = curl_pushheader_byname(headers, ":path");
        !           109:   if(headp && !strncmp(headp, "/push-", 6)) {
        !           110:     fprintf(stderr, "The PATH is %s\\n", headp);
        !           111: 
        !           112:     /* save the push here */
        !           113:     out = fopen("pushed-stream", "wb");
        !           114: 
        !           115:     /* write to this file */
        !           116:     curl_easy_setopt(easy, CURLOPT_WRITEDATA, out);
        !           117: 
        !           118:     (*transfers)++; /* one more */
        !           119: 
        !           120:     return CURL_PUSH_OK;
        !           121:   }
        !           122:   return CURL_PUSH_DENY;
        !           123: }
        !           124: 
        !           125: curl_multi_setopt(multi, CURLMOPT_PUSHFUNCTION, push_callback);
        !           126: curl_multi_setopt(multi, CURLMOPT_PUSHDATA, &counter);
        !           127: .fi
        !           128: .SH AVAILABILITY
        !           129: Added in 7.44.0
        !           130: .SH RETURN VALUE
        !           131: Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not.
        !           132: .SH "SEE ALSO"
        !           133: .BR CURLMOPT_PUSHDATA "(3), " CURLMOPT_PIPELINING "(3), " CURLOPT_PIPEWAIT "(3), "
        !           134: .BR RFC 7540