1curl_easy_send(3)               libcurl Manual               curl_easy_send(3)
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NAME

6       curl_easy_send - sends raw data over an "easy" connection
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SYNOPSIS

9       #include <curl/easy.h>
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11       CURLcode curl_easy_send(CURL *curl, const void *buffer,
12                               size_t buflen, size_t *n);
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DESCRIPTION

15       This function sends arbitrary data over the established connection. You
16       may use it together with curl_easy_recv(3) to implement  custom  proto‐
17       cols  using  libcurl.  This functionality can be particularly useful if
18       you use proxies and/or SSL encryption: libcurl will take care of  proxy
19       negotiation and connection setup.
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21       buffer  is  a  pointer to the data of length buflen that you want sent.
22       The variable n points to will receive the number of sent bytes.
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24       To establish the connection, set CURLOPT_CONNECT_ONLY(3) option  before
25       calling   curl_easy_perform(3)   or  curl_multi_perform(3).  Note  that
26       curl_easy_send(3) will not work on connections that were created  with‐
27       out this option.
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29       The  call  will  return  CURLE_AGAIN  if it's not possible to send data
30       right now - the socket is used in non-blocking  mode  internally.  When
31       CURLE_AGAIN  is returned, use your operating system facilities like se‐
32       lect(2) to wait until the socket is writable. The  socket  may  be  ob‐
33       tained using curl_easy_getinfo(3) with CURLINFO_ACTIVESOCKET(3).
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35       Furthermore  if  you wait on the socket and it tells you it's writable,
36       curl_easy_send(3) may return CURLE_AGAIN if the only data that was sent
37       was for internal SSL processing, and no other data could be sent.
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EXAMPLE

40        curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
41        /* Do not do the transfer - only connect to host */
42        curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
43        res = curl_easy_perform(curl);
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45        if(res == CURLE_OK) {
46          /* Extract the socket from the curl handle -
47             we will need it for waiting. */
48          res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
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50          /* send data */
51          res = curl_easy_send(curl, "hello", 5, &sent);
52        }
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AVAILABILITY

55       Added in 7.18.2.
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RETURN VALUE

58       On  success,  returns  CURLE_OK and stores the number of bytes actually
59       sent into *n. Note that this may be less than the amount you wanted  to
60       send.
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62       On failure, returns the appropriate error code.
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64       This  function may return CURLE_AGAIN. In this case, use your operating
65       system facilities to wait until the socket is writable, and retry.
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67       If there's no socket available to use from the previous transfer,  this
68       function returns CURLE_UNSUPPORTED_PROTOCOL.
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SEE ALSO

71       curl_easy_setopt(3),     curl_easy_perform(3),    curl_easy_getinfo(3),
72       curl_easy_recv(3)
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76libcurl 8.0.1                  January 02, 2023              curl_easy_send(3)
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