108 lines
4.2 KiB
Groff
108 lines
4.2 KiB
Groff
.\" **************************************************************************
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.\" * _ _ ____ _
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.\" * Project ___| | | | _ \| |
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.\" * / __| | | | |_) | |
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.\" * | (__| |_| | _ <| |___
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.\" * \___|\___/|_| \_\_____|
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.\" *
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.\" * Copyright (C) Max Dymond, <max.dymond@microsoft.com>, et al.
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.\" *
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.\" * This software is licensed as described in the file COPYING, which
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.\" * you should have received as part of this distribution. The terms
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.\" * are also available at https://curl.se/docs/copyright.html.
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.\" *
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.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
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.\" * copies of the Software, and permit persons to whom the Software is
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.\" * furnished to do so, under the terms of the COPYING file.
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.\" *
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.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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.\" * KIND, either express or implied.
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.\" *
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.\" * SPDX-License-Identifier: curl
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.\" *
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.\" **************************************************************************
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.\"
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.TH CURLOPT_PREREQFUNCTION 3 "2 Aug 2021" libcurl libcurl
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.SH NAME
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CURLOPT_PREREQFUNCTION \- user callback called when a connection has been
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established, but before a request has been made.
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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/* These are the return codes for the pre-request callback. */
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#define CURL_PREREQFUNC_OK 0
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#define CURL_PREREQFUNC_ABORT 1 /* fail the entire transfer */
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int prereq_callback(void *clientp,
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char *conn_primary_ip,
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char *conn_local_ip,
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int conn_primary_port,
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int conn_local_port);
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PREREQFUNCTION, prereq_callback);
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.SH DESCRIPTION
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Pass a pointer to your callback function, which should match the prototype
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shown above.
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This function gets called by libcurl after a connection has been established
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or a connection has been reused (including any SSL handshaking), but before any
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request is actually made on the connection. For example, for HTTP, this
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callback is called once a connection has been established to the server, but
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before a GET/HEAD/POST/etc request has been sent.
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This function may be called multiple times if redirections are enabled and are
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being followed (see \fICURLOPT_FOLLOWLOCATION(3)\fP).
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The callback function must return \fICURL_PREREQFUNC_OK\fP on success, or
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\fICURL_PREREQFUNC_ABORT\fP to cause the transfer to fail.
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This function is passed the following arguments:
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.IP conn_primary_ip
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A null-terminated pointer to a C string containing the primary IP of the
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remote server established with this connection. For FTP, this is the IP for
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the control connection. IPv6 addresses are represented without surrounding
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brackets.
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.IP conn_local_ip
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A null-terminated pointer to a C string containing the originating IP for this
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connection. IPv6 addresses are represented without surrounding brackets.
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.IP conn_primary_port
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The primary port number on the remote server established with this connection.
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For FTP, this is the port for the control connection. This can be a TCP or a
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UDP port number depending on the protocol.
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.IP conn_local_port
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The originating port number for this connection. This can be a TCP or a UDP
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port number depending on the protocol.
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.IP clientp
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The pointer you set with \fICURLOPT_PREREQDATA(3)\fP.
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.SH DEFAULT
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By default, this is NULL and unused.
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.SH PROTOCOLS
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ALL
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.SH EXAMPLE
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.nf
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static int prereq_callback(void *clientp,
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char *conn_primary_ip,
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char *conn_local_ip,
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int conn_primary_port,
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int conn_local_port)
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{
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printf("Connection made to %s:%s\\n", conn_primary_ip, conn_primary_port);
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return CURL_PREREQFUNC_OK;
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}
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{
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struct data prereq_data;
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curl_easy_setopt(CURL *handle, CURLOPT_PREREQFUNCTION, prereq_callback);
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curl_easy_setopt(CURL *handle, CURLOPT_PREREQDATA, &prereq_data);
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}
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.fi
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.SH AVAILABILITY
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Added in 7.80.0
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.SH RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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.SH "SEE ALSO"
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.BR CURLINFO_PRIMARY_IP (3),
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.BR CURLINFO_PRIMARY_PORT (3),
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.BR CURLOPT_PREREQDATA (3)
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