Added examples/add with is a simple TLS/SSL enabled service to add 2 …

…numbers

examples/add/README

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+
+This is a simple add service that happens over a TLS connection.
+
+To generate code from the protobuf file:
+cd addservice
+protoc --go_out=. addservice.proto 
+
+To compile the server:
+go build add.go
+
+To compile the client:
+go build client.go
+
+To make test certificates:
+./makecert.sh AnyFakeOrRealEmail@foo.com
+
+To test run add in one window/shell and client in the other.
+
+
+
+

examples/add/add.go

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+package main
+
+import (
+	"flag"
+	"log"
+	"net"
+	"crypto/rand"
+	"crypto/tls"
+	"crypto/x509"
+	"./addservice"
+)
+
+// Add is the type which will implement the addservice.AddService interface
+// and can be called remotely.  In this case, it does not have any state, but
+// it could.
+type Add struct{}
+
+// Add is the function that can be called remotely.  Note that this can be
+// called concurrently, so if the Echo structure did have internal state,
+// it should be designed for concurrent access.
+func (Add) Add(in *addservice.AddMessage, out *addservice.SumMessage) error {
+	log.Printf("server: X=%d", *in.X)
+	log.Printf("server: Y=%d", *in.Y)
+	out.Z = new(int32)
+	*out.Z = *in.X + *in.Y
+	log.Printf("server: Z=%d", *out.Z)
+	return nil
+}
+
+func handleClient(conn net.Conn) {
+	tlscon, ok := conn.(*tls.Conn)
+	if ok {
+		log.Print("server: conn: type assert to TLS succeedded")
+		err := tlscon.Handshake()
+		if err != nil {
+			log.Fatalf("server: handshake failed: %s", err)
+		} else {
+			log.Print("server: conn: Handshake completed")
+		}
+		state := tlscon.ConnectionState()
+// Note we could reject clients if we don't like their public key.		
+		log.Println("Server: client public key is:")
+		for _, v := range state.PeerCertificates {
+			log.Print(x509.MarshalPKIXPublicKey(v.PublicKey))
+		}
+// Now that we have completed SSL/TLS 
+		addservice.ServeAddService(tlscon,Add{})
+	}
+}
+
+func serverTLSListen(service string) {
+
+// Load x509 certificates for our private/public key, makecert.sh will
+// generate them for you.
+
+	cert, err := tls.LoadX509KeyPair("certs/server.pem", "certs/server.key")
+	if err != nil {
+		log.Fatalf("server: loadkeys: %s", err)
+	}
+// Note if we don't tls.RequireAnyClientCert client side certs are ignored.
+	config := tls.Config{Certificates: []tls.Certificate{cert}, ClientAuth: tls.RequireAnyClientCert}
+	config.Rand = rand.Reader
+	listener, err := tls.Listen("tcp", service, &config)
+	if err != nil {
+		log.Fatalf("server: listen: %s", err)
+	}
+	log.Print("server: listening")
+// Keep this loop simple/fast as to be able to handle new connections
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			log.Printf("server: accept: %s", err)
+			break
+		}
+		log.Printf("server: accepted from %s", conn.RemoteAddr())
+// Fire off go routing to handle rest of connection.
+		go handleClient(conn)
+	}
+}
+
+func main() {
+	flag.Parse()
+	serverTLSListen("0.0.0.0:8000")
+}

examples/add/addservice/addservice.proto

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+package addservice;
+
+message add_message {
+	required int32 x=1;
+	required int32 y=2;
+}
+
+message sum_message {
+	required int32 z=1;
+}
+
+service add_service {
+  rpc add (add_message) returns (sum_message);
+}

examples/add/makecert.sh

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+#!/bin/bash
+# call this script with an email address (valid or not).
+# like:
+# ./makecert.sh joe@random.com
+mkdir certs
+rm certs/*
+echo "make server cert"
+openssl req -new -nodes -x509 -out certs/server.pem -keyout certs/server.key -days 3650 -subj "/C=DE/ST=NRW/L=Earth/O=Random Company/OU=IT/CN=www.random.com/emailAddress=$1"
+echo "make client cert"
+openssl req -new -nodes -x509 -out certs/client.pem -keyout certs/client.key -days 3650 -subj "/C=DE/ST=NRW/L=Earth/O=Random Company/OU=IT/CN=www.random.com/emailAddress=$1"