From 1985c0df4f3f55a2499700b3934d5e13fc0fab18 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krist=C3=B3f=20T=C3=B3th?= <mrtoth@strongds.hu>
Date: Thu, 30 Apr 2020 02:14:51 +0200
Subject: [PATCH] Refactor existing networking bits

---
 connection/listen.go   | 80 ++++++++++++++++++++++++++++++++++++++++++
 main.go                | 29 ++++++++++-----
 socketops/socketops.go | 51 ---------------------------
 3 files changed, 100 insertions(+), 60 deletions(-)
 create mode 100644 connection/listen.go
 delete mode 100644 socketops/socketops.go

diff --git a/connection/listen.go b/connection/listen.go
new file mode 100644
index 0000000..a7a8376
--- /dev/null
+++ b/connection/listen.go
@@ -0,0 +1,80 @@
+package connection
+
+import (
+	"net"
+	"io"
+)
+
+const defaultBufSize = 1 * 1024
+
+
+// Connection represents a recv-only network connection.
+type Connection struct {
+	BufSize int
+	conn *net.TCPConn
+	recvChan chan []byte
+	stopFlag bool
+}
+
+// NewListen starts listening for a single connection on the given address.
+// This method blocks until this is done.
+func NewListen(address string) (*Connection, error) {
+	conn, err := listenAndAcceptTCP(address)
+	if err != nil {
+		return nil, err
+	}
+	return &Connection{
+		conn: conn,
+		BufSize: defaultBufSize,
+		stopFlag: false,
+	}, nil
+}
+
+func listenAndAcceptTCP(address string) (*net.TCPConn, error) {
+	addr, err := net.ResolveTCPAddr("tcp", address)
+	if err != nil {
+		return nil, err
+	}
+	sock, err := net.ListenTCP("tcp", addr)
+	if err != nil {
+		return nil, err
+	}
+	conn, err := sock.AcceptTCP()
+	if err != nil {
+		return nil, err
+	}
+	conn.SetNoDelay(true)
+	return conn, nil
+}
+
+// Recv returns a read-only channel of byte slices and starts
+// receiving and pushing data into it asynchronously.
+// The channel is closed when the sender closes the connection.
+// Use this to read bytes from the network connection.
+func (c *Connection) Recv() <-chan []byte {
+	c.recvChan = make(chan []byte)
+	go c.recvLoop()
+	return c.recvChan
+}
+
+func (c *Connection) recvLoop() {
+	buf := make([]byte, c.BufSize)
+	for !c.stopFlag {
+		n, err := io.ReadFull(c.conn, buf)
+		if err != nil {
+			c.stopFlag = true
+		}
+		// the underlying memory of the buffer
+		// must be copied for thread safety
+		sendBuf := make([]byte, n)
+		copy(sendBuf, buf)
+		c.recvChan <- sendBuf
+	}
+	close(c.recvChan)
+}
+
+// Close closes the connection
+func (c *Connection) Close() {
+	c.stopFlag = true
+	c.conn.Close()
+}
diff --git a/main.go b/main.go
index 242a1df..6661a4b 100644
--- a/main.go
+++ b/main.go
@@ -2,26 +2,37 @@ package main
 
 import (
 	"fmt"
-	"os"
 	"io"
-	"time"
-	"remote-mic/socketops"
+	"os"
 	"remote-mic/audio"
+	"remote-mic/connection"
+	"time"
 )
 
 
 func socketExample() {
-	fmt.Print("Listening for TCP connection on port 8080... ")
-	conn, err := socketops.AcceptConn(":8080")
+	fmt.Print("Listening for connection on port 8080... ")
+	conn, err := connection.NewListen(":8080")
 	if err != nil {
 		panic(err)
 	}
 	defer conn.Close()
 	fmt.Println("Connection accepted!")
 
-	data := make(chan []byte, 10)
-	go socketops.HandleConn(conn, data)
-	socketops.HandleData(data)
+	recvChan := conn.Recv()
+	go func()  {
+		time.Sleep(30 * time.Second)
+		conn.Close()
+	}()
+	for {
+		buf, open := <-recvChan
+		if !open {
+			break
+		}
+		fmt.Printf("Bytes read: %d\n", len(buf))
+		fmt.Printf("Buf: %v\n", buf)
+		fmt.Printf("%v\n", string(buf))		
+	}
 
 	fmt.Println("Exiting.")
 }
@@ -53,5 +64,5 @@ func micStreamExample() {
 }
 
 func main() {
-	micStreamExample()
+	socketExample()
 }
diff --git a/socketops/socketops.go b/socketops/socketops.go
deleted file mode 100644
index 79f3e38..0000000
--- a/socketops/socketops.go
+++ /dev/null
@@ -1,51 +0,0 @@
-package socketops
-
-import (
-	"fmt"
-	"net"
-)
-
-const bufSize = 1024
-
-
-func AcceptConn(connstr string) (net.Conn, error) {
-	addr, err := net.ResolveTCPAddr("tcp", connstr)
-	if err != nil {
-		return nil, err
-	}
-	sock, err := net.ListenTCP("tcp", addr)
-	if err != nil {
-		return nil, err
-	}
-	conn, err := sock.AcceptTCP()
-	if err != nil {
-		return nil, err
-	}
-	conn.SetNoDelay(true)
-	return conn, nil
-}
-
-func HandleConn(conn net.Conn, out chan<- []byte) {
-	buf := make([]byte, bufSize)
-	for {
-		n, err := conn.Read(buf)
-		if err != nil {
-			close(out)
-			break
-		}
-		if n > 0 {
-			out <- buf[:n]
-			fmt.Printf("Bytes read: %d\n", n)
-		}
-	}
-}
-
-func HandleData(data <-chan []byte) {
-	for {
-		buf, open := <-data
-		if !open {
-			break
-		}
-		fmt.Printf("%v\n", string(buf))
-	}
-}