add description and external ip printing

Author: delthas

README.md

@@ -1,9 +1,41 @@
 # proxypunch
 
-To run:
-Make sure to setup your Go environment, and to add $GOPATH/bin to your PATH, then:
-```
-go get github.com/delthas/proxypunch
-go install github.com/delthas/proxypunch
-proxypunch
-```
+**This program lets you host & connect to friends to play peer-to-peer games without having to open or redirect any port.**
+
+*Technical details: proxypunch creates a user-friendly UDP proxy/tunnel between two peers by hole punching the user's NAT with a custom STUN-like server which additionally "matchmakes" users based on their internal port rather than their NAT-ed port.*  
+
+## How to use
+
+- Download the [latest version for Windows 64 bits](https://github.com/delthas/proxypunch/releases/latest/download/proxypunch.win64.exe) (for other OS check the [latest release page](https://github.com/delthas/proxypunch/releases/latest/))
+- Simply double-click the downloaded executable file to run it; there is no setup or anything so put the file somewhere you'll remember
+- If a Windows Security Alert popup appears, check all checkboxes and click on "Allow access"
+- If prompted for an update, press `Enter` to accept the update; proxypunch will update and restart automatically
+- Choose between **server** (hosting) and **client** (connecting to a host) by typing `s` or `c`, then pressing `Enter`
+- Instructions continue below depending on your choice
+
+##### Server / Hosting
+
+- When prompted for a port, choose any port (if you're not sure, choose any randon number between 10000 and 60000), type it and press `Enter`
+- In your game, start your server / start hosting on the port you chose
+- Ask your peer to connect to the shown host and port, **the peer must connect with proxypunch as explained below, not directly**
+- Wait for the peer to connect, then play & profit
+- When you're done playing with this peer, stop hosting, and close the proxypunch window (start it again and repeat the process to play with someone else)
+- Next time you run proxypunch, you can simply press `Enter` to use the same settings as last time you connected
+
+##### Client / Connecting to a host
+
+- Wait for the person hosting to send you a host and port to connect to
+- Enter the host and port when prompted to by typing it and pressing `Enter`
+- In your game, connect to the shown host and port (**not the host and port your peer gave you**) 
+- Profit & play
+- When you're done playing with this peer, disconnect, and close the proxypunch window (start it again and repeat the process to play with someone else)
+- Next time you run proxypunch, you can simply press `Enter` to use the same settings as last time you connected
+
+##### Troubleshooting
+
+- If you experience any issue when restarting proxypunch to play with someone else, try to use a different port every time your run proxypunch
+- If you have any other issue or feedback, either contact me on Discord at `cc#6439` or [open an issue on Github](https://github.com/delthas/proxypunch/issues/new) 
+
+## Advanced usage
+
+- Command-line flags are available for quick/unattended start, run `proxypunch -help` to review the flags

go.mod

@@ -0,0 +1,3 @@
+module github.com/delthas/proxypunch
+
+require gopkg.in/yaml.v2 v2.2.2

go.sum

@@ -0,0 +1,4 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

@@ -48,7 +48,7 @@ func client(host string, port int) {
 	defer c.Close()
 
 	localPort := c.LocalAddr().(*net.UDPAddr).Port
-	fmt.Println("Listening, connect to 127.0.0.1:" + strconv.Itoa(localPort))
+	fmt.Println("Listening, connect to 127.0.0.1 on port " + strconv.Itoa(localPort))
 
 	relayAddr, err := net.ResolveUDPAddr("udp4", relayHost)
 	if err != nil {
@@ -109,6 +109,7 @@ func client(host string, port int) {
 	}()
 	defer close(chPunch)
 
+	foundPeer := false
 	var localAddr net.UDPAddr
 	for {
 		n, addr, err := c.ReadFromUDP(buffer[1:])
@@ -124,6 +125,10 @@ func client(host string, port int) {
 			continue
 		}
 		if addr.IP.Equal(remoteAddr.IP) && addr.Port == remoteAddr.Port {
+			if !foundPeer {
+				foundPeer = true
+				fmt.Println("Connected to peer")
+			}
 			if n != 0 && localAddr.Port != 0 && buffer[1] == 0xCC {
 				c.WriteToUDP(buffer[2:n+1], &localAddr)
 			}
@@ -142,7 +147,8 @@ func server(port int) {
 	}
 	defer c.Close()
 
-	fmt.Println("Listening, host at " + strconv.Itoa(port))
+	fmt.Println("Listening, start hosting on port " + strconv.Itoa(port))
+	fmt.Println("Connecting...")
 
 	localAddr := &net.UDPAddr{
 		IP:   net.IPv4(127, 0, 0, 1),
@@ -172,6 +178,7 @@ func server(port int) {
 	var remoteAddr net.UDPAddr
 	buffer := make([]byte, 4096)
 
+	receivedIp := false
 	for {
 		n, addr, err := c.ReadFromUDP(buffer)
 		if err != nil {
@@ -181,6 +188,14 @@ func server(port int) {
 		if !addr.IP.Equal(relayAddr.IP) || addr.Port != relayAddr.Port {
 			continue
 		}
+		if n == 4 {
+			if !receivedIp {
+				receivedIp = true
+				ip := net.IP(buffer[:4])
+				fmt.Println("Connected. Ask your peer to connect to " + ip.String() + " on port " + strconv.Itoa(port) + " with proxypunch")
+			}
+			continue
+		}
 		if n != 6 {
 			fmt.Fprintln(os.Stderr, "Error received packet of wrong size from relay. (size:"+strconv.Itoa(n)+")")
 			continue
@@ -209,6 +224,7 @@ func server(port int) {
 	}()
 	defer close(chPunch)
 
+	foundPeer := false
 	for {
 		n, addr, err := c.ReadFromUDP(buffer[1:])
 		if err != nil {
@@ -223,6 +239,10 @@ func server(port int) {
 			continue
 		}
 		if addr.IP.Equal(remoteAddr.IP) && addr.Port == remoteAddr.Port {
+			if !foundPeer {
+				foundPeer = true
+				fmt.Println("Connected to peer")
+			}
 			if n != 0 && buffer[1] == 0xCC {
 				c.WriteToUDP(buffer[2:n+1], localAddr)
 			}
@@ -370,7 +390,7 @@ func main() {
 	if ProgramVersion == "" {
 		ProgramVersion = "[Custom Build]"
 	}
-	fmt.Println("ProxyPunch " + ProgramVersion + " by delthas")
+	fmt.Println("proxypunch " + ProgramVersion + " by delthas")
 	fmt.Println()
 
 	if runtime.GOOS == "windows" {

proxypunch-server/main.go renamed to proxypunch-relay/main.go

@@ -32,11 +32,11 @@ type serverValue struct {
 }
 
 func main() {
-	fmt.Println("ProxyPunch Server v" + version)
+	fmt.Println("proxypunch relay v" + version)
 	fmt.Println()
 
 	var port int
-	flag.IntVar(&port, "port", defaultPort, "server listen port")
+	flag.IntVar(&port, "port", defaultPort, "relay listen port")
 	flag.Parse()
 
 	c, err := net.ListenUDP("udp4", &net.UDPAddr{
@@ -94,6 +94,8 @@ func main() {
 			if val, ok := clients[key]; ok {
 				serverPayload := append([]byte{byte(val.natPort >> 8), byte(val.natPort)}, val.localIp[:]...)
 				c.WriteToUDP(serverPayload, addr)
+			} else {
+				c.WriteToUDP(senderIp[:], addr)
 			}
 		} else if n == 6 {
 			var ip [4]byte