learning, learning, learning... and doing it the hard way

chatserver.go

@@ -1,23 +1,56 @@
 package main
 
+// Lot's of learning right out of the gate:
+// https://stackoverflow.com/questions/51472020/how-to-get-the-size-of-available-tcp-data
+
 import (
+  "bufio"
   "flag"
   "fmt"
   "io"
   "net"
   "os"
   "strconv"
+  "sync"
   "time"
 )
 
+type bufferedConn struct {
+	r    *bufio.Reader
+	rout io.Reader
+	net.Conn
+}
+
+func newBufferedConn(c net.Conn) bufferedConn {
+	return bufferedConn{bufio.NewReader(c), nil, c}
+}
+
+func (b bufferedConn) Peek(n int) ([]byte, error) {
+	return b.r.Peek(n)
+}
+
+func (b bufferedConn) Buffered() (int) {
+	return b.r.Buffered()
+}
+
+func (b bufferedConn) Read(p []byte) (int, error) {
+	if b.rout != nil {
+		return b.rout.Read(p)
+	}
+	return b.r.Read(p)
+}
+
 type myMsg struct {
   sender net.Conn
   bytes []byte
   receivedAt time.Time
 }
 
+var firstMsgs chan myMsg
 var myMsgs chan myMsg
-var myConns map[net.Conn]bool
+var myUnsortedConns map[net.Conn]bool
+var myRawConns map[net.Conn]bool
+var newConns chan net.Conn
 
 func usage() {
   fmt.Fprintf(os.Stderr, "\nusage: go run chatserver.go\n")
@@ -27,14 +60,11 @@ func usage() {
   os.Exit(1)
 }
 
-func handleConnection(conn net.Conn) {
-  // Why don't these work?
-  //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")
+func handleRaw(conn bufferedConn) {
+  // Handle all subsequent packets
   buf := make([]byte, 1024)
   for {
+    fmt.Fprintf(os.Stdout, "[raw] Waiting for message...\n");
     count, err := conn.Read(buf)
     if nil != err {
       if io.EOF != err {
@@ -43,8 +73,54 @@ func handleConnection(conn net.Conn) {
       fmt.Fprintf(os.Stdout, "Ending socket\n")
       break
     }
-    // not so sure about why this case exists
-    // we'll just ignore it for now...
+    // Fun fact: if the buffer's current length (not capacity) is 0
+    // then the Read returns 0 without error
+    if 0 == count {
+      fmt.Fprintf(os.Stdout, "Weird")
+      continue
+    }
+    fmt.Fprintf(os.Stdout, "Queing message...\n");
+    myMsgs <- myMsg{
+      receivedAt: time.Now(),
+      sender: conn,
+      bytes: buf[0:count],
+    }
+  }
+}
+
+func handleSorted(conn bufferedConn) {
+  // at this piont we've already at least one byte via Peek()
+  // so the first packet is available in the buffer
+  n := conn.Buffered()
+  firstMsg, err := conn.Peek(n)
+  if nil != err {
+    panic(err)
+  }
+  firstMsgs <- myMsg{
+    receivedAt: time.Now(),
+    sender: conn,
+    bytes: firstMsg,
+  }
+
+  // TODO
+  // * TCP-CHAT
+  // * HTTP
+  // * TLS
+
+  // Handle all subsequent packets
+  buf := make([]byte, 1024)
+  for {
+    fmt.Fprintf(os.Stdout, "[sortable] Waiting for message...\n");
+    count, err := conn.Read(buf)
+    if nil != err {
+      if io.EOF != err {
+        fmt.Fprintf(os.Stderr, "Non-EOF socket error: %s\n", err)
+      }
+      fmt.Fprintf(os.Stdout, "Ending socket\n")
+      break
+    }
+    // Fun fact: if the buffer's current length (not capacity) is 0
+    // then the Read returns 0 without error
     if 0 == count {
       // fmt.Fprintf(os.Stdout, "Weird")
       continue
@@ -57,9 +133,57 @@ func handleConnection(conn net.Conn) {
   }
 }
 
+// TODO https://github.com/polvi/sni
+func handleConnection(conn net.Conn) {
+  fmt.Fprintf(os.Stdout, "Accepting socket\n")
+
+  m := sync.Mutex{}
+  virgin := true
+  myUnsortedConns[conn] = true
+
+  // Why don't these work?
+  //buf := make([]byte, 0, 1024)
+  //buf := []byte{}
+  // But this does
+
+	bufConn := newBufferedConn(conn)
+  go func() {
+    // Handle First Packet
+    fmsg, err := bufConn.Peek(1)
+    if nil != err {
+      panic(err)
+    }
+    fmt.Fprintf(os.Stdout, "[First Byte] %s\n", fmsg)
+
+    m.Lock();
+    if virgin {
+      virgin = false
+      go handleSorted(bufConn)
+    } else {
+      go handleRaw(bufConn)
+    }
+    m.Unlock();
+  }()
+
+  time.Sleep(250 * 1000000)
+  // If we still haven't received data from the client
+  // assume that the client must be expecting a welcome from us
+  m.Lock()
+  if virgin {
+    virgin = false
+    // don't block for this
+    // let it be handled after the unlock
+    defer fmt.Fprintf(conn, "Welcome! This is an open relay chat server. There is no security yet.\n")
+  }
+  m.Unlock()
+}
+
 func main() {
+  firstMsgs = make(chan myMsg, 128)
   myMsgs = make(chan myMsg, 128)
-  myConns = make(map[net.Conn]bool)
+  newConns = make(chan net.Conn, 128)
+  myRawConns = make(map[net.Conn]bool)
+  myUnsortedConns = make(map[net.Conn]bool)
   flag.Usage = usage
   port:= flag.Uint("telnet-port", 4080, "tcp telnet chat port")
   flag.Parse()
@@ -76,8 +200,21 @@ func main() {
 
   go func() {
     for {
-      fmt.Fprintf(os.Stdout, "Waiting for message...\n");
-      msg := <- myMsgs
+      conn, err := sock.Accept()
+      if err != nil {
+        // Not sure what kind of error this could be or how it could happen.
+        // Could a connection abort or end before it's handled?
+        fmt.Fprintf(os.Stderr, "Error accepting connection:\n%s\n", err)
+      }
+      newConns <- conn
+    }
+  }()
+
+  for {
+    select {
+    case conn := <- newConns:
+      go handleConnection(conn)
+    case msg := <- myMsgs:
       ts, err := msg.receivedAt.MarshalJSON()
       if nil != err {
         fmt.Fprintf(os.Stderr, "[Error] %s\n", err)
@@ -85,7 +222,7 @@ func main() {
       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 {
+      for conn, _ := range myRawConns {
         if msg.sender == conn {
           continue
         }
@@ -95,18 +232,15 @@ func main() {
         // SetDeadTime and Disconnect them?
         conn.Write(msg.bytes)
       }
+    case msg := <- firstMsgs:
+      fmt.Fprintf(os.Stdout, "f [First Message]\n")
+      ts, err := msg.receivedAt.MarshalJSON()
+      if nil != err {
+        fmt.Fprintf(os.Stderr, "f [Error] %s\n", err)
+      }
+      fmt.Fprintf(os.Stdout, "f [Timestamp] %s\n", ts)
+      fmt.Fprintf(os.Stdout, "f [Remote] %s\n", msg.sender.RemoteAddr().String())
+      fmt.Fprintf(os.Stdout, "f [Message] %s\n", msg.bytes);
     }
-  }()
-
-  for {
-    conn, err := sock.Accept()
-    if err != nil {
-      // Not sure what kind of error this could be or how it could happen.
-      // Could a connection abort or end before it's handled?
-      fmt.Fprintf(os.Stderr, "Error accepting connection:\n%s\n", err)
-    }
-    fmt.Fprintf(os.Stdout, "Accepting socket\n")
-    myConns[conn] = true
-    go handleConnection(conn)
   }
 }