fix authentication when algorithm field is not supported (#558)

(https://github.com/bluenviron/mediamtx/issues/3116)

This fixes authentication issues with some TP-LINK cameras.

pkg/auth/www_authenticate.go

@@ -6,18 +6,44 @@ import (
 )
 
 // GenerateWWWAuthenticate generates a WWW-Authenticate header.
-func GenerateWWWAuthenticate(methods []headers.AuthMethod, realm string, nonce string) base.HeaderValue {
+func GenerateWWWAuthenticate(methods []ValidateMethod, realm string, nonce string) base.HeaderValue {
 	if methods == nil {
-		methods = []headers.AuthMethod{headers.AuthDigestSHA256, headers.AuthDigestMD5, headers.AuthBasic}
+		methods = []ValidateMethod{ValidateMethodBasic, ValidateMethodDigestMD5, ValidateMethodSHA256}
 	}
 
 	var ret base.HeaderValue
+
 	for _, m := range methods {
-		ret = append(ret, headers.Authenticate{
-			Method: m,
-			Realm:  realm,
-			Nonce:  nonce, // used only by digest
-		}.Marshal()...)
+		var a base.HeaderValue
+
+		switch m {
+		case ValidateMethodBasic:
+			a = headers.Authenticate{
+				Method: headers.AuthMethodBasic,
+				Realm:  realm,
+			}.Marshal()
+
+		case ValidateMethodDigestMD5:
+			aa := headers.AuthAlgorithmMD5
+			a = headers.Authenticate{
+				Method:    headers.AuthMethodDigest,
+				Realm:     realm,
+				Nonce:     nonce,
+				Algorithm: &aa,
+			}.Marshal()
+
+		default: // sha256
+			aa := headers.AuthAlgorithmSHA256
+			a = headers.Authenticate{
+				Method:    headers.AuthMethodDigest,
+				Realm:     realm,
+				Nonce:     nonce,
+				Algorithm: &aa,
+			}.Marshal()
+		}
+
+		ret = append(ret, a...)
 	}
+
 	return ret
 }