96 lines
2.8 KiB
Markdown
96 lines
2.8 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
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SPDX-License-Identifier: curl
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Title: curl_easy_send
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Section: 3
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Source: libcurl
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See-also:
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- curl_easy_getinfo (3)
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- curl_easy_perform (3)
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- curl_easy_recv (3)
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- curl_easy_setopt (3)
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---
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# NAME
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curl_easy_send - sends raw data over an "easy" connection
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_easy_send(CURL *curl, const void *buffer,
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size_t buflen, size_t *n);
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~~~
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# DESCRIPTION
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This function sends arbitrary data over the established connection. You may
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use it together with curl_easy_recv(3) to implement custom protocols
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using libcurl. This functionality can be particularly useful if you use
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proxies and/or SSL encryption: libcurl takes care of proxy negotiation and
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connection setup.
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**buffer** is a pointer to the data of length **buflen** that you want
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sent. The variable **n** points to receives the number of sent bytes.
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To establish the connection, set CURLOPT_CONNECT_ONLY(3) option before
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calling curl_easy_perform(3) or curl_multi_perform(3). Note that
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curl_easy_send(3) does not work on connections that were created without
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this option.
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The call returns **CURLE_AGAIN** if it is not possible to send data right now
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- the socket is used in non-blocking mode internally. When **CURLE_AGAIN**
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is returned, use your operating system facilities like *select(2)* to wait
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until the socket is writable. The socket may be obtained using
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curl_easy_getinfo(3) with CURLINFO_ACTIVESOCKET(3).
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Furthermore if you wait on the socket and it tells you it is writable,
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curl_easy_send(3) may return **CURLE_AGAIN** if the only data that was sent
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was for internal SSL processing, and no other data could be sent.
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# EXAMPLE
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~~~c
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int main(void)
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{
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CURL *curl = curl_easy_init();
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if(curl) {
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CURLcode res;
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curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
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/* Do not do the transfer - only connect to host */
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curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
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res = curl_easy_perform(curl);
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if(res == CURLE_OK) {
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long sockfd;
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size_t sent;
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/* Extract the socket from the curl handle - we need it for waiting. */
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res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
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/* send data */
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res = curl_easy_send(curl, "hello", 5, &sent);
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}
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}
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}
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~~~
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# AVAILABILITY
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Added in 7.18.2.
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# RETURN VALUE
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On success, returns **CURLE_OK** and stores the number of bytes actually
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sent into ***n**. Note that this may be less than the amount you wanted to
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send.
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On failure, returns the appropriate error code.
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This function may return **CURLE_AGAIN**. In this case, use your operating
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system facilities to wait until the socket is writable, and retry.
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If there is no socket available to use from the previous transfer, this function
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returns **CURLE_UNSUPPORTED_PROTOCOL**.
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