curl_easy_send(3) libcurl Manual curl_easy_send(3)
NAME
curl_easy_send - sends raw data over an "easy" connection
SYNOPSIS
#include <curl/easy.h>
CURLcode curl_easy_send(CURL *curl, const void *buffer,
size_t buflen, size_t *n);
DESCRIPTION
This function sends arbitrary data over the established connection. You
may use it together with curl_easy_recv(3) to implement custom proto-
cols 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.
buffer is a pointer to the data of length buflen that you want sent.
The variable n points to will receive the number of sent bytes.
To establish the connection, set CURLOPT_CONNECT_ONLY(3) option before
calling curl_easy_perform(3) or curl_multi_perform(3). Note that
curl_easy_send(3) will not work on connections that were created with-
out this option.
The call will return CURLE_AGAIN if it's not possible to send data
right now - the socket is used in non-blocking mode internally. When
CURLE_AGAIN is returned, use your operating system facilities like se-
lect(2) to wait until the socket is writable. The socket may be ob-
tained using curl_easy_getinfo(3) with CURLINFO_ACTIVESOCKET(3).
Furthermore if you wait on the socket and it tells you it's writable,
curl_easy_send(3) may return CURLE_AGAIN if the only data that was sent
was for internal SSL processing, and no other data could be sent.
EXAMPLE
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);
}
AVAILABILITY
Added in 7.18.2.
RETURN VALUE
On success, returns CURLE_OK and stores the number of bytes actually
sent into *n. Note that this may be less than the amount you wanted to
send.
On failure, returns the appropriate error code.
This function may return CURLE_AGAIN. 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 CURLE_UNSUPPORTED_PROTOCOL.
SEE ALSO
curl_easy_setopt(3), curl_easy_perform(3), curl_easy_getinfo(3),
curl_easy_recv(3)
libcurl 7.81.0 November 26, 2021 curl_easy_send(3)
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