CURLINFO_ACTIVESOCKET doc is misleading

[jay]

I did this

While investigating a mailing list question I observed that CURLINFO_ACTIVESOCKET does not actually return the active socket until after the transfer is done. This appears to be due to legacy reasons, since it is a replacement for CURLINFO_LASTSOCKET.

The socket can only be retrieved via ACTIVESOCKET after lastconnect is set, which only happens in multi_done:

curl/lib/multi.c

Lines 661 to 676 in b81e0b0

	msnprintf(buffer, sizeof(buffer),
	"Connection #%ld to host %s left intact",
	conn->connection_id,
	conn->bits.socksproxy ? conn->socks_proxy.host.dispname :
	conn->bits.httpproxy ? conn->http_proxy.host.dispname :
	conn->bits.conn_to_host ? conn->conn_to_host.dispname :
	conn->host.dispname);
	/* the connection is no longer in use by this transfer */
	CONN_UNLOCK(data);
	if(Curl_conncache_return_conn(data, conn)) {
	/* remember the most recently used connection */
	data->state.lastconnect = conn;
	infof(data, "%s\n", buffer);
	}
	else
	data->state.lastconnect = NULL;

curl/lib/connect.c

Lines 1373 to 1413 in b81e0b0

	/*
	* Used to extract socket and connectdata struct for the most recent
	* transfer on the given Curl_easy.
	*
	* The returned socket will be CURL_SOCKET_BAD in case of failure!
	*/
	curl_socket_t Curl_getconnectinfo(struct Curl_easy *data,
	struct connectdata **connp)
	{
	DEBUGASSERT(data);
	/* this works for an easy handle:
	* - that has been used for curl_easy_perform()
	* - that is associated with a multi handle, and whose connection
	* was detached with CURLOPT_CONNECT_ONLY
	*/
	if(data->state.lastconnect && (data->multi_easy || data->multi)) {
	struct connectdata *c = data->state.lastconnect;
	struct connfind find;
	find.tofind = data->state.lastconnect;
	find.found = FALSE;
	Curl_conncache_foreach(data, data->multi_easy?
	&data->multi_easy->conn_cache:
	&data->multi->conn_cache, &find, conn_is_conn);
	if(!find.found) {
	data->state.lastconnect = NULL;
	return CURL_SOCKET_BAD;
	}
	if(connp) {
	/* only store this if the caller cares for it */
	*connp = c;
	c->data = data;
	}
	return c->sock[FIRSTSOCKET];
	}
	else
	return CURL_SOCKET_BAD;
	}

I expected the following

The documentation says "Pass a pointer to a curl_socket_t to receive the active socket used by this curl session." That implies the socket is available before the session is done.

curl/libcurl version

master branch

curl 7.70.0-DEV (i386-pc-win32) libcurl/7.70.0-DEV Schannel WinIDN
Release-Date: [unreleased]
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
Features: AsynchDNS Debug IDN IPv6 Kerberos Largefile NTLM SPNEGO SSL SSPI UnixSockets

operating system

Windows 7

[bagder]

We can certainly improve the phrasing. We generally never promise any results reliably from curl_easy_getinfo until post-transfer.