From ecf8fcf32cb78e80032a23b05769d215a4294711 Mon Sep 17 00:00:00 2001
From: mkwcat <cat@mkw.re>
Date: Fri, 20 Oct 2023 03:36:51 -0400
Subject: [PATCH] Matchmaking: Handle server list command

---
 matchmaking/main.go   |  7 ++--
 matchmaking/server.go | 91 +++++++++++++++++++++++++++++++++----------
 2 files changed, 73 insertions(+), 25 deletions(-)

diff --git a/matchmaking/main.go b/matchmaking/main.go
index b21a425..94caab9 100644
--- a/matchmaking/main.go
+++ b/matchmaking/main.go
@@ -79,9 +79,6 @@ func handleRequest(conn net.Conn) {
 		fmt.Printf("Unable to set keepalive - %s", err)
 	}
 
-	// log.Printf("%s: Connection established from %s. Sending challenge.", aurora.Green("[NOTICE]"), aurora.Yellow(conn.RemoteAddr()))
-	// conn.Write([]byte(fmt.Sprintf(`\lc\1\challenge\%s\id\1\final\`, challenge)))
-
 	// Here we go into the listening loop
 	for {
 		buffer := make([]byte, 1024)
@@ -95,11 +92,13 @@ func handleRequest(conn net.Conn) {
 
 		switch buffer[2] {
 		case ServerList:
+			logging.Notice(ModuleName, "Command:", aurora.Yellow("SERVER_LIST").String())
+
 			serverList(conn, buffer)
 			break
 
 		default:
-			logging.Notice(ModuleName, "Command:", aurora.Yellow(buffer[2]).String())
+			logging.Notice(ModuleName, "Unknown command:", aurora.Yellow(buffer[2]).String())
 			break
 		}
 	}
diff --git a/matchmaking/server.go b/matchmaking/server.go
index ed829ef..f85e5ff 100644
--- a/matchmaking/server.go
+++ b/matchmaking/server.go
@@ -2,6 +2,7 @@ package matchmaking
 
 import (
 	"encoding/binary"
+	"github.com/logrusorgru/aurora/v3"
 	"net"
 	"strconv"
 	"strings"
@@ -9,29 +10,36 @@ import (
 	"wwfc/logging"
 )
 
+func popString(buffer []byte, index int) (string, int) {
+	str := common.GetString(buffer[index:])
+	return str, index + len(str) + 1
+}
+
+func popBytes(buffer []byte, index int, size int) ([]byte, int) {
+	return buffer[index : index+size], index + size
+}
+
+func popUint32(buffer []byte, index int) (uint32, int) {
+	return binary.BigEndian.Uint32(buffer[index:]), index + 4
+}
+
 func serverList(conn net.Conn, buffer []byte) {
-	logging.Notice(ModuleName, "Received server list command")
+	const (
+		FlagNoServerList      = 1 << 1 // 0x02
+		FlagAlternateSourceIP = 1 << 3 // 0x08
+		FlagLimitResultCount  = 1 << 7 // 0x80
+	)
 
 	index := 9
-	queryGame := common.GetString(buffer[index:])
-	index += len(queryGame) + 1
-	gameName := common.GetString(buffer[index:])
-	index += len(gameName) + 1
+	queryGame, index := popString(buffer, index)
+	gameName, index := popString(buffer, index)
+	challenge, index := popBytes(buffer, index, 8)
+	filter, index := popString(buffer, index)
+	fields, index := popString(buffer, index)
+	flags, index := popUint32(buffer, index)
 
-	challenge := buffer[index : index+8]
-	index += 8
+	logging.Notice(ModuleName, "queryGame:", aurora.Cyan(queryGame).String(), "- gameName:", aurora.Cyan(gameName).String(), "- filter:", aurora.Cyan(filter).String(), "- fields:", aurora.Cyan(fields).String())
 
-	filter := common.GetString(buffer[index:])
-	index += len(filter) + 1
-	fields := common.GetString(buffer[index:])
-	index += len(fields) + 1
-
-	options := binary.BigEndian.Uint32(buffer[index:])
-	index += 4
-
-	logging.Notice(ModuleName, "Values", queryGame, gameName, string(challenge), string(options))
-
-	// TODO: Find a game if possible, but there is nobody to do that with yet!
 	var output []byte
 	for _, s := range strings.Split(strings.Split(conn.RemoteAddr().String(), ":")[0], ".") {
 		val, err := strconv.Atoi(s)
@@ -42,8 +50,49 @@ func serverList(conn net.Conn, buffer []byte) {
 		output = append(output, byte(val))
 	}
 
-	output = binary.BigEndian.AppendUint16(output, 6500)
+	var fieldList []string
+	for _, field := range strings.Split(fields, "\\") {
+		if len(field) == 0 || field == " " {
+			continue
+		}
 
-	encrypted := common.EncryptTypeX([]byte("9r3Rmy"), challenge, output)
-	conn.Write(encrypted)
+		fieldList = append(fieldList, field)
+	}
+
+	if flags&FlagNoServerList != 0 || len(fieldList) == 0 {
+		// The client requests its own public IP and game port
+		logging.Notice(ModuleName, "Reply without server list", aurora.Cyan(conn.RemoteAddr()).String())
+
+		// The default game port 6500
+		output = binary.BigEndian.AppendUint16(output, 6500)
+
+		// Write the encrypted reply
+		conn.Write(common.EncryptTypeX([]byte("9r3Rmy"), challenge, output))
+		return
+	}
+
+	logging.Notice(ModuleName, "Reply with server list", aurora.Cyan(conn.RemoteAddr()).String())
+
+	// The client's port
+	port, err := strconv.Atoi(strings.Split(conn.RemoteAddr().String(), ":")[1])
+	if err != nil {
+		panic(err)
+	}
+	output = binary.BigEndian.AppendUint16(output, uint16(port))
+
+	output = append(output, byte(len(fieldList)))
+	for _, field := range fieldList {
+		output = append(output, 0x00) // Value?
+		output = append(output, []byte(field)...)
+		output = append(output, 0x00) // String end
+	}
+	output = append(output, 0x00) // Zero length string to end the list
+
+	// TODO: Send server list here
+
+	// Server with no flags and -1 tells the client the message has ended
+	output = append(output, []byte{0x00, 0xff, 0xff, 0xff, 0xff}...)
+
+	// Write the encrypted reply
+	conn.Write(common.EncryptTypeX([]byte("9r3Rmy"), challenge, output))
 }