From 58f9bd0aaef309d695dafe1e5d1ddc5c1d43776c Mon Sep 17 00:00:00 2001
From: AJ ONeal <coolaj86@gmail.com>
Date: Sat, 21 Jul 2018 21:58:05 -0600
Subject: [PATCH] TCP chat works with multiple telnet clients

---
 README.md     | 22 +++++++++++++++++++++-
 chatserver.go | 46 ++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 0a14fe9..a5764de 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,23 @@
 # chat.go
 
-Rudimentary go chat server as a fun project. 
\ No newline at end of file
+Rudimentary go chat server as a fun project.
+
+# Install
+
+```bash
+git clone https://git.coolaj86.com/coolaj86/chat.go.git
+```
+
+# Usage
+
+Start the server
+
+```bash
+go run chatserver.go
+```
+
+Connect with another client or three.
+
+```bash
+telnet localhost 4080
+```
diff --git a/chatserver.go b/chatserver.go
index 9c6e2e5..121a739 100644
--- a/chatserver.go
+++ b/chatserver.go
@@ -7,8 +7,18 @@ import (
   "net"
   "os"
   "strconv"
+  "time"
 )
 
+type myMsg struct {
+  sender net.Conn
+  bytes []byte
+  receivedAt time.Time
+}
+
+var myMsgs chan myMsg
+var myConns map[net.Conn]bool
+
 func usage() {
   fmt.Fprintf(os.Stderr, "\nusage: go run chatserver.go\n")
   flag.PrintDefaults();
@@ -22,6 +32,7 @@ func handleConnection(conn net.Conn) {
   //buf := make([]byte, 0, 1024)
   //buf := []byte{}
   // But this does
+  fmt.Fprintf(conn, "Welcome! This is an open relay chat server. There is no security yet.\n")
   buf := make([]byte, 1024)
   for {
     count, err := conn.Read(buf)
@@ -38,18 +49,24 @@ func handleConnection(conn net.Conn) {
       // fmt.Fprintf(os.Stdout, "Weird")
       continue
     }
-    fmt.Fprintf(os.Stdout, "Message:\n%s\n", buf[0:count])
+    myMsgs <- myMsg{
+      receivedAt: time.Now(),
+      sender: conn,
+      bytes: buf[0:count],
+    }
   }
 }
 
 func main() {
+  myMsgs = make(chan myMsg, 128)
+  myConns = make(map[net.Conn]bool)
   flag.Usage = usage
   port:= flag.Uint("telnet-port", 4080, "tcp telnet chat port")
   flag.Parse()
   addr := ":" + strconv.Itoa(int(*port))
 
 
-  // https://golang.org/pkg/net/
+  // https://golang.org/pkg/net/#Conn
   sock, err := net.Listen("tcp", addr)
   if nil != err {
 		fmt.Fprintf(os.Stderr, "Couldn't bind to TCP socket %q: %s\n", addr, err)
@@ -57,6 +74,30 @@ func main() {
   }
   fmt.Println("Listening on", addr);
 
+  go func() {
+    for {
+      fmt.Fprintf(os.Stdout, "Waiting for message...\n");
+      msg := <- myMsgs
+      ts, err := msg.receivedAt.MarshalJSON()
+      if nil != err {
+        fmt.Fprintf(os.Stderr, "[Error] %s\n", err)
+      }
+      fmt.Fprintf(os.Stdout, "[Timestamp] %s\n", ts)
+      fmt.Fprintf(os.Stdout, "[Remote] %s\n", msg.sender.RemoteAddr().String())
+      fmt.Fprintf(os.Stdout, "[Message] %s\n", msg.bytes);
+      for conn, _ := range myConns {
+        if msg.sender == conn {
+          continue
+        }
+        // backlogged connections could prevent a next write,
+        // so this should be refactored into a goroutine
+        // And what to do about slow clients that get behind (or DoS)?
+        // SetDeadTime and Disconnect them?
+        conn.Write(msg.bytes)
+      }
+    }
+  }()
+
   for {
     conn, err := sock.Accept()
     if err != nil {
@@ -65,6 +106,7 @@ func main() {
       fmt.Fprintf(os.Stderr, "Error accepting connection:\n%s\n", err)
     }
     fmt.Fprintf(os.Stdout, "Accepting socket\n")
+    myConns[conn] = true
     go handleConnection(conn)
   }
 }