From 713c2b0f0443202e884cf762996edb8a7979282b Mon Sep 17 00:00:00 2001
From: 45Tatami <tatami@fftatami.cc>
Date: Fri, 31 Dec 2021 15:50:08 +0100
Subject: [PATCH] Add native application

---
 native_application/go.mod  |  3 ++
 native_application/main.go | 93 ++++++++++++++++++++++++++++++++++++++
 native_inserter.json       |  7 +++
 3 files changed, 103 insertions(+)
 create mode 100644 native_application/go.mod
 create mode 100644 native_application/main.go
 create mode 100644 native_inserter.json

diff --git a/native_application/go.mod b/native_application/go.mod
new file mode 100644
index 0000000..eb006f3
--- /dev/null
+++ b/native_application/go.mod
@@ -0,0 +1,3 @@
+module gorecv
+
+go 1.17
diff --git a/native_application/main.go b/native_application/main.go
new file mode 100644
index 0000000..5729031
--- /dev/null
+++ b/native_application/main.go
@@ -0,0 +1,93 @@
+package main
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net"
+)
+
+type Message struct {
+	Body string `json:"body"`
+}
+
+const MSG_SIZE_LIMIT = 1000 * 1000 // Unclear if 1MiB or 1MB, using lower bound
+const LISTEN_INTERFACE = ":30501"
+
+func main() {
+	log.Println("Listening on", LISTEN_INTERFACE)
+
+	l, err := net.Listen("tcp", LISTEN_INTERFACE)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer l.Close()
+
+	msg_pipe := make(chan string)
+
+	// Output routine
+	go func() {
+		for {
+			msg, err := json.Marshal(Message{<-msg_pipe})
+			if err != nil {
+				log.Println("Error encoding message:", err)
+				continue
+			}
+
+			msg_len := len(msg)
+			if msg_len >= MSG_SIZE_LIMIT {
+				log.Println("Message over webextension limit. Discarding")
+				continue
+			}
+
+			len_buf := make([]byte, 4)
+			binary.LittleEndian.PutUint32(len_buf, uint32(msg_len))
+
+			log.Println(len_buf, string(msg))
+			fmt.Print(string(len_buf))
+			fmt.Print(string(msg))
+		}
+	}()
+
+	// Accept connections
+	for {
+		conn, err := l.Accept()
+		if err != nil {
+			log.Println("Error accepting conn:", err)
+		}
+		go conn_hndlr(conn, msg_pipe)
+	}
+}
+
+func conn_hndlr(c net.Conn, ch chan<- string) {
+	defer c.Close()
+	log.Println("Connection opened:", c)
+	for {
+		msg, err := read_msg(c)
+		if err != nil {
+			break
+		}
+		ch <- msg
+	}
+	log.Println("Closing connection:", c)
+}
+
+func read_msg(c net.Conn) (string, error) {
+	len_buf := make([]byte, 4)
+
+	if _, err := io.ReadFull(c, len_buf); err != nil {
+		log.Println("Len read error:", err)
+		return "", err
+	}
+
+	msg_len := binary.LittleEndian.Uint32(len_buf)
+	msg_buf := make([]byte, msg_len)
+	if _, err := io.ReadFull(c, msg_buf); err != nil {
+		log.Println("Msg read error:", err)
+		return "", err
+	}
+
+	return string(msg_buf), nil
+}
diff --git a/native_inserter.json b/native_inserter.json
new file mode 100644
index 0000000..e46f5f1
--- /dev/null
+++ b/native_inserter.json
@@ -0,0 +1,7 @@
+{
+  "name": "native_inserter",
+  "description": "Example host for native messaging",
+  "path": "/usr/local/bin/gorecv",
+  "type": "stdio",
+  "allowed_extensions": [ "@native-inserter" ]
+}