curl_easy_recv

Definition: include builtins\libcurl.e

{CURLcode res, atom buffer, integer len} = curl_easy_recv(atom curl, atom buffer, integer buflen)
Description: Receives raw data on an "easy" connection.

This function receives raw data from the established connection.
You may use it together with curl_easy_send 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.

buffer is a pointer to your buffer that will get the received data.
buflen is the maximum amount of data you can get in that buffer.

To establish the connection, set CURLOPT_CONNECT_ONLY option before calling curl_easy_perform or curl_multi_perform.
Note that curl_easy_recv does not work on connections that were created without this option.

The call will return CURLE_AGAIN if there is no data to read - the socket is used in non-blocking mode internally.
When CURLE_AGAIN is returned, use your operating system facilities like select(2) to wait for data.
The socket may be obtained using curl_easy_getinfo with CURLINFO_ACTIVESOCKET.

Wait on the socket only if curl_easy_recv returns CURLE_AGAIN.
The reason for this is libcurl or the SSL library may internally cache some data, therefore you should call curl_easy_recv until all data is read which would include any cached data.

Furthermore if you wait on the socket and it tells you there is data to read, curl_easy_recv may return CURLE_AGAIN if the only data that was read was for internal SSL processing, and no other data is available.

Availability: Added in 7.18.2.

Return value: On success, returns CURLE_OK, the data buffer, and the number of bytes it actually read.
On failure, returns the appropriate error code as the first element of the result.

The function may return CURLE_AGAIN. In this case, use your operating system facilities to wait until data can be read, and retry.

Reading exactly 0 bytes indicates a closed connection.

If there is no socket available to use from the previous transfer, this function returns CURLE_UNSUPPORTED_PROTOCOL.
See Also: curl_easy_setopt, curl_easy_perform, curl_easy_getinfo, curl_easy_send