Update PROTOCOL.md

2 files changed, 72 insertions, 1 deletions

diff --git a/PROTOCOL.md b/PROTOCOL.md
index e69de29..d17eded 100644
--- a/PROTOCOL.md
+++ b/PROTOCOL.md
@@ -0,0 +1,40 @@
+# SOLEC protocol specification
+
+## Data format
+
+Everything is big endian. `text` is always null terminated UTF-8.
+Every packet starts with `uint8` denoting type of the rest of remaining data.
+
+## Event types
+
+| Type | Name      |
+|------|-----------|
+| 0x01 | Handshake |
+| 0x02 | Ping      |
+| 0x03 | Pong      |
+
+## Events
+
+### Handshake
+
+Sent after estabilishing TCP connection. First by the client and then by the server.
+If one of the sides uses different protocol version connection should be aborted.
+
+| Type  | Name | Description      |
+|-------|------|------------------|
+| uint8 | ver  | Protocol version |
+
+
+### Ping
+
+Empty.
+
+### Pong
+
+`time` field contains Unix timestamp generated just before sending the packet.
+Timezone should always be UTC.
+
+| Type   | Name | Description      |
+|--------|------|------------------|
+| uint64 | time | Unix timestamp   |
+
diff --git a/cmd/mock/main.go b/cmd/mock/main.go
index cc0a048..8516821 100644
--- a/cmd/mock/main.go
+++ b/cmd/mock/main.go
@@ -1,7 +1,38 @@
 package main
 
-import "log"
+import (
+	"flag"
+	"log"
+	"net"
+)
+
+var listenAddr string
 
 func main() {
+	flag.StringVar(&listenAddr, "a", "localhost:9999", "Listening address:port")
+	flag.Parse()
+
 	log.Print("Starting solec daemon mock")
+	log.Fatal(listen())
+}
+
+func listen() error {
+	ln, err := net.Listen("tcp", listenAddr)
+	if err != nil {
+		return err
+	}
+
+	log.Print("Server is listening on: ", listenAddr)
+
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			log.Print("Cannot accept connection: ", err)
+		}
+		go handle(conn)
+	}
+}
+
+func handle(conn net.Conn) {
+	log.Print("Received connection from: ", conn.RemoteAddr())
 }