This function receives raw data from the established connection. You may use
it together with curl_easy_send(3) 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
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. The variable n points to will receive the number of received
To establish the connection, set CURLOPT_CONNECT_ONLY option before
calling curl_easy_perform(3). Note that curl_easy_recv(3) does not
work on connections that were created without this option.
You must ensure that the socket has data to read before calling
curl_easy_recv(3), otherwise the call will return CURLE_AGAIN -
the socket is used in non-blocking mode internally. Use
curl_easy_getinfo(3) with CURLINFO_LASTSOCKET to obtain the
socket; use your operating system facilities like select(2) to check if
it has any data you can read.
Added in 7.18.2.
On success, returns CURLE_OK, stores the received data into
buffer, and the number of bytes it actually read into *n.
On failure, returns the appropriate error code.
If there is no data to read, the function returns CURLE_AGAIN. Use
your operating system facilities to wait until the data is ready, and retry.
See sendrecv.c in docs/examples directory for usage example.