.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2021, Daniel Stenberg, , 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.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 curl_easy_send 3 "29 April 2008" "libcurl 7.18.2" "libcurl Manual" .SH NAME curl_easy_send - sends raw data over an "easy" connection .SH SYNOPSIS .nf #include CURLcode curl_easy_send(CURL *curl, const void *buffer, size_t buflen, size_t *n); .fi .SH DESCRIPTION This function sends arbitrary data over the established connection. You may use it together with \fIcurl_easy_recv(3)\fP to implement custom protocols using libcurl. This functionality can be particularly useful if you use proxies and/or SSL encryption: libcurl will take care of proxy negotiation and connection set-up. \fBbuffer\fP is a pointer to the data of length \fBbuflen\fP that you want sent. The variable \fBn\fP points to will receive the number of sent bytes. To establish the connection, set \fICURLOPT_CONNECT_ONLY(3)\fP option before calling \fIcurl_easy_perform(3)\fP or \fIcurl_multi_perform(3)\fP. Note that \fIcurl_easy_send(3)\fP will not work on connections that were created without this option. The call will return \fBCURLE_AGAIN\fP if it's not possible to send data right now - the socket is used in non-blocking mode internally. When \fBCURLE_AGAIN\fP is returned, use your operating system facilities like \fIselect(2)\fP to wait until the socket is writable. The socket may be obtained using \fIcurl_easy_getinfo(3)\fP with \fICURLINFO_ACTIVESOCKET(3)\fP. Furthermore if you wait on the socket and it tells you it's writable, \fIcurl_easy_send(3)\fP may return \fBCURLE_AGAIN\fP if the only data that was sent was for internal SSL processing, and no other data could be sent. .SH EXAMPLE .nf curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); /* Do not do the transfer - only connect to host */ curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L); res = curl_easy_perform(curl); if(res == CURLE_OK) { /* Extract the socket from the curl handle - we will need it for waiting. */ res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd); /* send data */ res = curl_easy_send(curl, "hello", 5, &sent); } .fi .SH AVAILABILITY Added in 7.18.2. .SH RETURN VALUE On success, returns \fBCURLE_OK\fP and stores the number of bytes actually sent into \fB*n\fP. Note that this may be less than the amount you wanted to send. On failure, returns the appropriate error code. This function may return \fBCURLE_AGAIN\fP. In this case, use your operating system facilities to wait until the socket is writable, and retry. If there's no socket available to use from the previous transfer, this function returns \fBCURLE_UNSUPPORTED_PROTOCOL\fP. .SH "SEE ALSO" .BR curl_easy_setopt "(3), " curl_easy_perform "(3), " curl_easy_getinfo "(3), " .BR curl_easy_recv "(3) "