curl_easy_recv (3) - Linux Man Pages
curl_easy_recv: receives raw data on an "easy" connection
NAMEcurl_easy_recv - receives raw data on an "easy" connection
DESCRIPTIONThis 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.
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.
AVAILABILITYAdded in 7.18.2.
RETURN VALUEOn 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.