WSDD: added protocol trace

log.go

@@ -8,14 +8,29 @@
 package main
 
 import (
+	"archive/tar"
 	"bytes"
 	"fmt"
 	"os"
+	"sync"
 )
 
 // Debug enables or disables debugging
 var Debug = false
 
+// Trace enables or disables protocol trace
+var Trace = true
+
+// Trace file name
+const traceName = "trace.tar"
+
+// Trace file handle, opened on demand
+var (
+	traceFile  *tar.Writer
+	traceLock  sync.Mutex
+	traceIndex int
+)
+
 // LogMessage represents a multiline log message
 type LogMessage struct {
 	prefix string   // Per-line prefix
@@ -54,6 +69,44 @@ func LogBegin(prefix string) *LogMessage {
 	}
 }
 
+// Add record to the protocol trace
+func LogTrace(name string, data []byte) {
+	// Trace enabled?
+	if !Trace {
+		return
+	}
+
+	// Acquire trace lock
+	traceLock.Lock()
+	defer traceLock.Unlock()
+
+	// Open trace file on demand
+	if traceFile == nil {
+		file, err := os.OpenFile(traceName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+		if err != nil {
+			LogError("%s: %s", traceName, err)
+			return
+		}
+
+		traceFile = tar.NewWriter(file)
+	}
+
+	// Build full name
+	name = fmt.Sprintf("%.3d-%s.xml", traceIndex, name)
+	traceIndex++
+
+	// Write file header and data
+	hdr := &tar.Header{
+		Name: name,
+		Mode: 0644,
+		Size: int64(len(data)),
+	}
+
+	traceFile.WriteHeader(hdr)
+	traceFile.Write(data)
+	traceFile.Flush()
+}
+
 // Debug appends line to the LogMessage
 func (m *LogMessage) Debug(format string, args ...interface{}) *LogMessage {
 	if Debug {

main.go

@@ -19,6 +19,7 @@ const usage = `Usage:
 
 Options are:
     -d   enable debug mode
+    -t   enable protocol trace
     -h   print help page
 `
 
@@ -33,6 +34,9 @@ func main() {
 		switch arg {
 		case "-d":
 			Debug = true
+		case "-t":
+			Debug = true
+			Trace = true
 		case "-h":
 			fmt.Printf(usage, os.Args[0])
 			os.Exit(0)

wsdd.go

@@ -206,6 +206,8 @@ func getMetadata(log *LogMessage, address, xaddr string) []Endpoint {
 	resp, err := http.Post(xaddr, "application/soap+xml; charset=utf-8",
 		bytes.NewBuffer(([]byte)(msg)))
 
+	LogTrace("http-request", []byte(msg))
+
 	if err != nil {
 		log.Debug("HTTP: %s", err)
 		return nil
@@ -219,6 +221,8 @@ func getMetadata(log *LogMessage, address, xaddr string) []Endpoint {
 		return nil
 	}
 
+	LogTrace("http-response", response)
+
 	// Parse response XML
 	elements, err := XMLDecode(wsddNsMap, bytes.NewBuffer(response))
 	if err != nil {
@@ -386,6 +390,8 @@ func recvUDPMessages(conn *net.UDPConn, zone string, outchan chan Endpoint) {
 			msg := buf[:n]
 
 			LogDebug("%s: UDP message received", from)
+			LogTrace(fmt.Sprintf("udp-from-%s", from), msg)
+
 			log := LogBegin(fmt.Sprintf("%s", from))
 			handleUDPMessage(log, msg, zone, outchan)
 			log.Commit()
@@ -449,6 +455,7 @@ func WSSDDiscover(outchan chan Endpoint) {
 			msg := fmt.Sprintf(probeTemplate, u)
 			conn.WriteTo([]byte(msg), dest)
 			LogDebug("%s: UDP message sent", dest)
+			LogTrace(fmt.Sprintf("udp-to-%s", dest), []byte(msg))
 		}
 
 		time.Sleep(250 * time.Millisecond)