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| .TH CURLOPT_PREREQFUNCTION 3 "November 04, 2021" "libcurl 7.80.0" "curl_easy_setopt options" |
| |
| .SH NAME |
| CURLOPT_PREREQFUNCTION \- user callback called when a connection has been |
| established, but before a request has been made. |
| .SH SYNOPSIS |
| .nf |
| #include <curl/curl.h> |
| |
| /* These are the return codes for the pre-request callback. */ |
| #define CURL_PREREQFUNC_OK 0 |
| #define CURL_PREREQFUNC_ABORT 1 /* fail the entire transfer */ |
| |
| int prereq_callback(void *clientp, |
| char *conn_primary_ip, |
| char *conn_local_ip, |
| int conn_primary_port, |
| int conn_local_port); |
| |
| CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PREREQFUNCTION, prereq_callback); |
| .SH DESCRIPTION |
| Pass a pointer to your callback function, which should match the prototype |
| shown above. |
| |
| This function gets called by libcurl after a connection has been established |
| or a connection has been reused (including any SSL handshaking), but before any |
| request is actually made on the connection. For example, for HTTP, this |
| callback is called once a connection has been established to the server, but |
| before a GET/HEAD/POST/etc request has been sent. |
| |
| This function may be called multiple times if redirections are enabled and are |
| being followed (see \fICURLOPT_FOLLOWLOCATION(3)\fP). |
| |
| This function is passed the following information: |
| .IP conn_primary_ip |
| A nul-terminated pointer to a C string containing the primary IP of the remote |
| server established with this connection. For FTP, this is the IP for the control |
| connection. IPv6 addresses are represented without surrounding brackets. |
| .IP conn_local_ip |
| A nul-terminated pointer to a C string containing the originating IP for this |
| connection. IPv6 addresses are represented without surrounding brackets. |
| .IP conn_primary_port |
| The primary port number on the remote server established with this connection. |
| For FTP, this is the port for the control connection. This can be a TCP or a |
| UDP port number dependending on the protocol. |
| .IP conn_local_port |
| The originating port number for this connection. This can be a TCP or a UDP port |
| number dependending on the protocol. |
| .RE |
| |
| \fIclientp\fP is the pointer you set with \fICURLOPT_PREREQDATA(3)\fP. |
| |
| The callback function must return \fICURL_PREREQFUNC_OK\fP on success, or |
| \fICURL_PREREQFUNC_ABORT\fP to cause the transfer to fail. |
| |
| .SH DEFAULT |
| By default, this is NULL and unused. |
| .SH PROTOCOLS |
| ALL |
| .SH EXAMPLE |
| .nf |
| static int prereq_callback(void *clientp, |
| char *conn_primary_ip, |
| char *conn_local_ip, |
| int conn_primary_port, |
| int conn_local_port) |
| { |
| printf("Connection made to %s:%s\\n", conn_primary_ip, conn_primary_port); |
| return CURL_PREREQFUNC_OK; |
| } |
| |
| { |
| struct data prereq_data; |
| curl_easy_setopt(CURL *handle, CURLOPT_PREREQFUNCTION, prereq_callback); |
| curl_easy_setopt(CURL *handle, CURLOPT_PREREQDATA, &prereq_data); |
| } |
| .fi |
| .SH AVAILABILITY |
| Added in 7.80.0 |
| .SH RETURN VALUE |
| Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. |
| .SH "SEE ALSO" |
| .BR CURLOPT_PREREQDATA "(3) " |