From 7bd3a587de42cc5b7bfa5ecb1393fbc435c7ced4 Mon Sep 17 00:00:00 2001
From: Emir Aganovic <emirfreelance91@gmail.com>
Date: Thu, 17 Oct 2024 09:08:40 +0200
Subject: [PATCH] fix: handle lower case digest algorith #24

---
 client.go      |  6 ++++++
 client_test.go | 15 +++++++++++++++
 sip/utils.go   | 27 +++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/client.go b/client.go
index 17d28bc..717b54c 100644
--- a/client.go
+++ b/client.go
@@ -430,6 +430,9 @@ func digestProxyAuthApply(req *sip.Request, res *sip.Response, opts digest.Optio
 		return fmt.Errorf("fail to parse challenge authHeader=%q: %w", authHeader.Value(), err)
 	}
 
+	// Fix lower case algorithm although not supported by rfc
+	chal.Algorithm = sip.ASCIIToUpper(chal.Algorithm)
+
 	// Reply with digest
 	cred, err := digest.Digest(chal, opts)
 	if err != nil {
@@ -448,6 +451,9 @@ func digestAuthApply(req *sip.Request, res *sip.Response, opts digest.Options) e
 		return fmt.Errorf("fail to parse chalenge wwwauth=%q: %w", wwwAuth.Value(), err)
 	}
 
+	// Fix lower case algorithm although not supported by rfc
+	chal.Algorithm = sip.ASCIIToUpper(chal.Algorithm)
+
 	// Reply with digest
 	cred, err := digest.Digest(chal, opts)
 	if err != nil {
diff --git a/client_test.go b/client_test.go
index bcfda96..ee7b910 100644
--- a/client_test.go
+++ b/client_test.go
@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/emiago/sipgo/sip"
+	"github.com/icholy/digest"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -202,3 +203,17 @@ func TestClientRequestOptions(t *testing.T) {
 	conn, err := tp.ClientRequestConnection(context.TODO(), req)
 }
 */
+
+func TestDigestAuthLowerCase(t *testing.T) {
+	challenge := `Digest username="user", realm="asterisk", nonce="662d65a084b88c6d2a745a9de086fa91", uri="sip:+user@example.com", algorithm=sha-256, response="3681b63e5d9c3bb80e5350e2783d7b88"`
+	chal, err := digest.ParseChallenge(challenge)
+	require.NoError(t, err)
+	chal.Algorithm = sip.ASCIIToUpper(chal.Algorithm)
+
+	_, err = digest.Digest(chal, digest.Options{
+		Method:   "INVITE",
+		Username: "user",
+		URI:      "sip:+user@example.com",
+	})
+	require.NoError(t, err)
+}
diff --git a/sip/utils.go b/sip/utils.go
index 4d6ff21..9cc518d 100644
--- a/sip/utils.go
+++ b/sip/utils.go
@@ -109,6 +109,33 @@ func ASCIIToLowerInPlace(s []byte) {
 	}
 }
 
+func ASCIIToUpper(s string) string {
+	// first check is ascii already up to avoid alloc
+	nonLowInd := -1
+	for i, c := range s {
+		if 'A' <= c && c <= 'Z' {
+			continue
+		}
+		nonLowInd = i
+		break
+	}
+	if nonLowInd < 0 {
+		return s
+	}
+
+	var b strings.Builder
+	b.Grow(len(s))
+	b.WriteString(s[:nonLowInd])
+	for i := nonLowInd; i < len(s); i++ {
+		c := s[i]
+		if 'a' <= c && c <= 'z' {
+			c -= 'a' - 'A'
+		}
+		b.WriteByte(c)
+	}
+	return b.String()
+}
+
 // HeaderToLower is fast ASCII lower string
 func HeaderToLower(s string) string {
 	// Avoid allocations