feat: randomize Cseq value #166

Author: emiago

client.go

@@ -2,6 +2,8 @@ package sipgo
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/binary"
 	"fmt"
 	"log/slog"
 	"net"
@@ -389,8 +391,15 @@ func clientRequestBuildReq(c *Client, req *sip.Request) error {
 	}
 
 	if v := req.CSeq(); v == nil {
+		var b [4]byte
+		_, err := rand.Read(b[:])
+		if err != nil {
+			return err
+		}
+		n := binary.BigEndian.Uint32(b[:]) & 0x7FFFFFFF // ensure < 2^31
+		n = max(1<<31-100, n)
 		cseq := sip.CSeqHeader{
-			SeqNo:      1,
+			SeqNo:      n,
 			MethodName: req.Method,
 		}
 		mustHeader = append(mustHeader, &cseq)

client_test.go

@@ -2,6 +2,7 @@ package sipgo
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"net"
 	"os"
@@ -56,7 +57,8 @@ func TestClientRequestBuild(t *testing.T) {
 	assert.NotEmpty(t, callid.Value())
 
 	cseq := req.CSeq()
-	assert.Equal(t, "1 OPTIONS", cseq.Value())
+	assert.True(t, cseq.SeqNo > 1)
+	assert.Equal(t, fmt.Sprintf("%d %s", cseq.SeqNo, "OPTIONS"), cseq.Value())
 
 	maxfwd := req.MaxForwards()
 	assert.Equal(t, "70", maxfwd.Value())