---
name: "curl_easy_recv"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/curl_easy_recv"
---

# curl\_easy\_recv(3)

receives raw data on an "easy" connection

## NAME

curl\_easy\_recv - receives raw data on an "easy" connection

## SYNOPSIS

```
#include <curl/curl.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)](/curl_easy_send/3.md)* to implement custom protocols using libcurl. This functionality can be particularly useful if you use proxies and/or SSL encryption: libcurl takes care of proxy negotiation and connection setup.

**buffer** is a pointer to your buffer memory that gets populated by the received data. **buflen** is the maximum amount of data you can get in that buffer. The variable **n** points to receives the number of received bytes.

To establish the connection, set *[CURLOPT\_CONNECT\_ONLY(3)](/CURLOPT_CONNECT_ONLY/3.md)* option before calling *[curl\_easy\_perform(3)](/curl_easy_perform/3.md)* or *[curl\_multi\_perform(3)](/curl_multi_perform/3.md)*. Note that *[curl\_easy\_recv(3)](/curl_easy_recv/3.md)* does not work on connections that were created without this option.

The call returns **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)](/select/2.md)* to wait for data. The socket may be obtained using *[curl\_easy\_getinfo(3)](/curl_easy_getinfo/3.md)* with *[CURLINFO\_ACTIVESOCKET(3)](/CURLINFO_ACTIVESOCKET/3.md)*.

Wait on the socket only if *[curl\_easy\_recv(3)](/curl_easy_recv/3.md)* 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)](/curl_easy_recv/3.md)* 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)](/curl_easy_recv/3.md)* may return **CURLE\_AGAIN** if the only data that was read was for internal SSL processing, and no other data is available.

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    /* Do not do the transfer - only connect to host */
    curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
    res = curl_easy_perform(curl);
    if(res == CURLE_OK) {
      char buf[256];
      size_t nread;
      long sockfd;
      /* Extract the socket from the curl handle - we need it for waiting. */
      res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
      /* read data */
      res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
    }
  }
}
```

## 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 is no socket available to use from the previous transfer, this function returns **CURLE\_UNSUPPORTED\_PROTOCOL**.

## SEE ALSO

[**curl\_easy\_getinfo**(3)](/curl_easy_getinfo/3.md), [**curl\_easy\_perform**(3)](/curl_easy_perform/3.md), [**curl\_easy\_send**(3)](/curl_easy_send/3.md), [**curl\_easy\_setopt**(3)](/curl_easy_setopt/3.md)