[Feature] Add TCP information (RTT and Cwnd) to Logging

This patch adds support for logging the underlying RTT and Cwnd of the
TCP connection used when doing probes. More work to follow in order to
add support for this information on Windows and Darwin.

1 files changed, 11 insertions, 18 deletions

diff --git a/extendedstats/unix.go b/extendedstats/unix.go
index a2d4d30..3db94fc 100644
--- a/extendedstats/unix.go
+++ b/extendedstats/unix.go
@@ -27,20 +27,8 @@ func ExtendedStatsAvailable() bool {
 	return true
 }
 
-func (es *ExtendedStats) IncorporateConnectionStats(rawConn net.Conn) error {
-	tlsConn, ok := rawConn.(*tls.Conn)
-	if !ok {
-		return fmt.Errorf(
-			"OOPS: Could not get the TCP info for the connection (not a TLS connection)",
-		)
-	}
-	tcpConn, ok := tlsConn.NetConn().(*net.TCPConn)
-	if !ok {
-		return fmt.Errorf(
-			"OOPS: Could not get the TCP info for the connection (not a TCP connection)",
-		)
-	}
-	if info, err := getTCPInfo(tcpConn); err != nil {
+func (es *ExtendedStats) IncorporateConnectionStats(basicConn net.Conn) error {
+	if info, err := GetTCPInfo(basicConn); err != nil {
 		return fmt.Errorf("OOPS: Could not get the TCP info for the connection: %v", err)
 	} else {
 		es.MaxPathMtu = utilities.Max(es.MaxPathMtu, uint64(info.Pmtu))
@@ -67,16 +55,21 @@ func (es *ExtendedStats) Repr() string {
 `, es.MaxPathMtu, es.MaxSendMss, es.MaxRecvMss, es.TotalRetransmissions, es.TotalReorderings, es.AverageRtt)
 }
 
-func getTCPInfo(connection net.Conn) (*unix.TCPInfo, error) {
-	tcpConn, ok := connection.(*net.TCPConn)
+func GetTCPInfo(basicConn net.Conn) (*unix.TCPInfo, error) {
+	tlsConn, ok := basicConn.(*tls.Conn)
 	if !ok {
-		return nil, fmt.Errorf("connection is not a net.TCPConn")
+		return nil, fmt.Errorf("OOPS: Outermost connection is not a TLS connection")
+	}
+	tcpConn, ok := tlsConn.NetConn().(*net.TCPConn)
+	if !ok {
+		return nil, fmt.Errorf(
+			"OOPS: Could not get the TCP info for the connection (not a TCP connection)",
+		)
 	}
 	rawConn, err := tcpConn.SyscallConn()
 	if err != nil {
 		return nil, err
 	}
-
 	var info *unix.TCPInfo = nil
 	rawConn.Control(func(fd uintptr) {
 		info, err = unix.GetsockoptTCPInfo(int(fd), unix.SOL_TCP, unix.TCP_INFO)