curl_easy_recv(3) receives raw data on an easy connection


#include <curl/easy.h>

CURLcode curl_easy_recv( CURL *curl, void *buffer, size_t buflen, size_t *n);


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 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. The variable n points to will receive the number of received 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_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_ACTIVESOCKET(3) 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.

Reading exactly 0 bytes would indicate a closed connection.

If there's no socket available to use from the previous transfer, this function returns CURLE_UNSUPPORTED_PROTOCOL.


See sendrecv.c in docs/examples directory for usage example.