curl_easy_recv
Section: libcurl Manual (3)
Updated: December 18, 2016
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NAME
curl_easy_recv - receives raw data on an "easy" connection
SYNOPSIS
#include <curl/easy.h>
CURLcode curl_easy_recv( CURL *curl, void *buffer,
size_t buflen, size_t *n);
DESCRIPTION
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.
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(3) with
CURLINFO_ACTIVESOCKET(3).
Wait on the socket only if curl_easy_recv(3) 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(3) 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(3) 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, stores the received data into
buffer, and the number of bytes it actually read into
*n.
On failure, returns the appropriate error code.
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's no socket available to use from the previous transfer, this function
returns CURLE_UNSUPPORTED_PROTOCOL.
EXAMPLE
See
sendrecv.c in
docs/examples directory for usage example.
SEE ALSO
curl_easy_setopt(3),
curl_easy_perform(3),
curl_easy_getinfo(3),
curl_easy_send(3)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- AVAILABILITY
-
- RETURN VALUE
-
- EXAMPLE
-
- SEE ALSO
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