From 6dfbe636bd67eee77eae967e6b216ce8574e436c Mon Sep 17 00:00:00 2001
From: Evan Burkey <evan@burkey.co>
Date: Thu, 14 Sep 2023 18:40:02 -0700
Subject: [PATCH] mobinthemiddle

---
 cmd/mobinthemiddle/main.go | 125 +++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 cmd/mobinthemiddle/main.go

diff --git a/cmd/mobinthemiddle/main.go b/cmd/mobinthemiddle/main.go
new file mode 100644
index 0000000..fe8f93a
--- /dev/null
+++ b/cmd/mobinthemiddle/main.go
@@ -0,0 +1,125 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net"
+	"strings"
+)
+
+const tonyAddr = "7YWHMfk9JZe0LM0g1ZauHuiSxhI"
+
+func hack(data []byte) []byte {
+	sp := strings.Split(string(data), " ")
+	for i, _ := range sp {
+		if len(sp[i]) == 0 || sp[i][0] != '7' || len(sp[i]) < 26 || len(sp[i]) > 35 {
+			continue
+		}
+		s := sp[i]
+		if sp[i][len(sp[i])-1] == '\n' {
+			sp[i] = tonyAddr + "\n"
+		} else {
+			sp[i] = tonyAddr
+		}
+		fmt.Printf("Rewrote %s to %s\n", s, tonyAddr)
+	}
+	return []byte(strings.Join(sp, " "))
+}
+
+func handleConn(conn net.Conn, c chan []byte, d chan bool) {
+	defer close(c)
+	defer func() { d <- true }()
+
+	data := make([]byte, 1024)
+	var buf bytes.Buffer
+
+	for {
+		n, err := conn.Read(data)
+		if err != nil {
+			if err != io.EOF {
+				fmt.Printf("Error reading from connection: %v\n", err)
+			}
+			return
+		}
+		if n == 0 {
+			return
+		}
+
+		buf.Write(data[:n])
+		if idx := bytes.IndexByte(buf.Bytes(), '\n'); idx != -1 {
+			data = hack(buf.Bytes())
+			c <- data
+			buf.Next(idx + 1)
+		}
+	}
+}
+
+func handleClient(clientConn net.Conn) {
+	defer clientConn.Close()
+
+	// Connect to the upstream server
+	serverConn, err := net.Dial("tcp", "chat.protohackers.com:16963")
+	//serverConn, err := net.Dial("tcp", "localhost:3030")
+	if err != nil {
+		fmt.Println("Failed to connect to upstream server:", err)
+		return
+	}
+	defer serverConn.Close()
+
+	clientToServer := make(chan []byte)
+	serverToClient := make(chan []byte)
+	clientDisconnect := make(chan bool)
+	serverDisconnect := make(chan bool)
+
+	go handleConn(clientConn, clientToServer, clientDisconnect)
+	go handleConn(serverConn, serverToClient, serverDisconnect)
+
+	go func() {
+		for {
+			select {
+			case data, ok := <-clientToServer:
+				if !ok {
+					return
+				}
+				_, err := serverConn.Write(data)
+				if err != nil {
+					fmt.Println("error writing to server: ", err)
+				}
+			case data, ok := <-serverToClient:
+				if !ok {
+					return
+				}
+				_, err := clientConn.Write(data)
+				if err != nil {
+					fmt.Println("error writing to server: ", err)
+				}
+			}
+		}
+	}()
+
+	// Wait for a disconnect
+	select {
+	case <-clientDisconnect:
+	case <-serverDisconnect:
+	}
+}
+
+func main() {
+	listener, err := net.Listen("tcp", ":3030")
+	//listener, err := net.Listen("tcp", ":3031")
+	if err != nil {
+		fmt.Println("Failed to start listener:", err)
+		return
+	}
+	defer listener.Close()
+
+	for {
+		clientConn, err := listener.Accept()
+		if err != nil {
+			fmt.Println("Failed to accept client connection:", err)
+			continue
+		}
+		go handleClient(clientConn)
+	}
+}