Update vendor (#1265)

vendor/github.com/wiggin77/srslog/net_conn.go

@@ -0,0 +1,76 @@
+package srslog
+
+import (
+	"io"
+	"net"
+	"time"
+)
+
+// netConn has an internal net.Conn and adheres to the serverConn interface,
+// allowing us to send syslog messages over the network.
+type netConn struct {
+	conn net.Conn
+	done chan interface{}
+}
+
+// newNetConn creates a netConn instance that is monitored for unexpected socket closure.
+func newNetConn(conn net.Conn) *netConn {
+	nc := &netConn{conn: conn, done: make(chan interface{})}
+	go monitor(nc.conn, nc.done)
+	return nc
+}
+
+// writeString formats syslog messages using time.RFC3339 and includes the
+// hostname, and sends the message to the connection.
+func (n *netConn) writeString(framer Framer, formatter Formatter, p Priority, hostname, tag, msg string) error {
+	if framer == nil {
+		framer = DefaultFramer
+	}
+	if formatter == nil {
+		formatter = DefaultFormatter
+	}
+	formattedMessage := framer(formatter(p, hostname, tag, msg))
+	_, err := n.conn.Write([]byte(formattedMessage))
+	return err
+}
+
+// close the network connection
+func (n *netConn) close() error {
+	// signal monitor goroutine to exit
+	close(n.done)
+	// wake up monitor blocked on read (close usually is enough)
+	_ = n.conn.SetReadDeadline(time.Now())
+	// close the connection
+	return n.conn.Close()
+}
+
+// monitor continuously tries to read from the connection to detect socket close.
+// This is needed because syslog server uses a write only socket and Linux systems
+// take a long time to detect a loss of connectivity on a socket when only writing;
+// the writes simply fail without an error returned.
+func monitor(conn net.Conn, done chan interface{}) {
+	defer Logger.Println("monitor exit")
+
+	buf := make([]byte, 1)
+	for {
+		Logger.Println("monitor loop")
+
+		select {
+		case <-done:
+			return
+		case <-time.After(1 * time.Second):
+		}
+
+		err := conn.SetReadDeadline(time.Now().Add(time.Second * 30))
+		if err != nil {
+			continue
+		}
+
+		_, err = conn.Read(buf)
+		Logger.Println("monitor -- ", err)
+		if err == io.EOF {
+			Logger.Println("monitor close conn")
+			conn.Close()
+		}
+	}
+}