From f398ea24d19d5b63d56632076608c6c486c51ec1 Mon Sep 17 00:00:00 2001
From: Nicholas Novak <34256932+NickyBoy89@users.noreply.github.com>
Date: Sun, 29 Oct 2023 21:18:58 -0700
Subject: [PATCH] feat: Started on a proxy server to intercept game packets

---
 connector/handle_game_connection.go | 16 ++++++
 connector/listen_port.go            | 77 +++++++++++++++++++++++++++++
 go.mod                              |  1 +
 go.sum                              |  2 +
 main.go                             |  2 +
 5 files changed, 98 insertions(+)
 create mode 100644 connector/handle_game_connection.go
 create mode 100644 connector/listen_port.go

diff --git a/connector/handle_game_connection.go b/connector/handle_game_connection.go
new file mode 100644
index 0000000..b2dc32e
--- /dev/null
+++ b/connector/handle_game_connection.go
@@ -0,0 +1,16 @@
+package connector
+
+import (
+	"io"
+)
+
+// This is the size that Netty apparently uses to read from the incoming
+// connection at a time
+//
+// This is documented in a mod that removes this limit:
+// https://www.curseforge.com/minecraft/mc-mods/xl-packets
+const nettyMaxPacketSize = 2_097_152 // 16MiB
+
+func handleGameConnection(conn io.Reader) {
+	panic("Unhandled game traffic")
+}
diff --git a/connector/listen_port.go b/connector/listen_port.go
new file mode 100644
index 0000000..f2a7e7b
--- /dev/null
+++ b/connector/listen_port.go
@@ -0,0 +1,77 @@
+package connector
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/spf13/cobra"
+)
+
+var (
+	inputPort  int
+	outputPort int
+)
+
+func init() {
+	ProxyPortCommand.Flags().IntVar(&inputPort, "in", -1, "The input port, or the port to listen to a server on")
+	ProxyPortCommand.Flags().IntVar(&outputPort, "out", -1, "The output port, or the port for the client to listen on")
+	ProxyPortCommand.MarkFlagRequired("in")
+	ProxyPortCommand.MarkFlagRequired("out")
+}
+
+var ProxyPortCommand = &cobra.Command{
+	Use:   "proxy",
+	Short: "Proxies the connection between the input and output ports",
+	RunE: func(cmd *cobra.Command, args []string) error {
+
+		// Listen for connections to the local server
+		l, err := net.Listen("tcp", fmt.Sprintf(":%d", inputPort))
+		if err != nil {
+			return err
+		}
+
+		log.Infof("Listening for incoming connections on port %d", inputPort)
+		for {
+			conn, err := l.Accept()
+			if err != nil {
+				return err
+			}
+
+			go handleConn(conn)
+		}
+	},
+}
+
+func handleConn(conn net.Conn) {
+	defer conn.Close()
+	log.Infof("Received connection from %v", conn.RemoteAddr())
+	// Open a connection to the remote server
+	serverConn, err := net.Dial("tcp", fmt.Sprintf(":%d", outputPort))
+	if err != nil {
+		panic(err)
+	}
+	defer serverConn.Close()
+
+	var sidecarServerDataStream bytes.Buffer
+
+	// Divert any data read from the server to be copied into the sidecar data stream
+	serverReader := io.TeeReader(serverConn, &sidecarServerDataStream)
+
+	go handleGameConnection(&sidecarServerDataStream)
+
+	// Start copying data from the server to the client
+	go func() {
+		if _, err := io.Copy(conn, serverReader); err != nil {
+			panic(err)
+		}
+	}()
+
+	// Copy data from the client to the server
+	if _, err := io.Copy(serverConn, conn); err != nil {
+		panic(err)
+	}
+}
diff --git a/go.mod b/go.mod
index 1d6fac8..6559197 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.21.3
 require (
 	github.com/charmbracelet/bubbletea v0.24.2
 	github.com/charmbracelet/lipgloss v0.9.1
+	github.com/sirupsen/logrus v1.9.3
 	github.com/spf13/cobra v1.7.0
 )
 
diff --git a/go.sum b/go.sum
index bd9bd1a..a5930f2 100644
--- a/go.sum
+++ b/go.sum
@@ -34,6 +34,8 @@ github.com/rivo/uniseg v0.1.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJ
 github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
 github.com/spf13/cobra v1.7.0 h1:hyqWnYt1ZQShIddO5kBpj3vu05/++x6tJ6dg8EC572I=
 github.com/spf13/cobra v1.7.0/go.mod h1:uLxZILRyS/50WlhOIKD7W6V5bgeIt+4sICxh6uRMrb0=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
diff --git a/main.go b/main.go
index 275f56d..4e47741 100644
--- a/main.go
+++ b/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"git.nicholasnovak.io/nnovak/spatial-db/connector"
 	"git.nicholasnovak.io/nnovak/spatial-db/visualization"
 	"github.com/spf13/cobra"
 )
@@ -11,6 +12,7 @@ func main() {
 	}
 
 	rootCmd.AddCommand(visualization.VisualizeCommand)
+	rootCmd.AddCommand(connector.ProxyPortCommand)
 
 	if err := rootCmd.Execute(); err != nil {
 		panic(err)