wip: Initial commit

go.mod

@@ -0,0 +1,3 @@
+module tgmail
+
+go 1.15

main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"log"
+	"net"
+	"tgmail/server"
+)
+
+func main() {
+	l, err := net.Listen("tcp", "0.0.0.0:2525")
+	if err != nil {
+		panic(err)
+	}
+	defer l.Close()
+
+	log.Println("Listening!")
+
+	for {
+		c, err := l.Accept()
+		if err != nil {
+			log.Println(err)
+			return
+		}
+		go server.Handle(c)
+	}
+}

server/conn_wrapper.go

@@ -0,0 +1,49 @@
+package server
+
+import (
+	"bufio"
+	"log"
+	"net"
+	"strconv"
+	"strings"
+)
+
+type wrapper struct {
+	net.Conn
+	r *bufio.Reader
+}
+
+func (w *wrapper) cmd(code int64, msgs ...string) error {
+	for i, msg := range msgs {
+		sep := "-"
+		if i == len(msgs)-1 {
+			sep = " "
+		}
+		err := w.send(strconv.FormatInt(code, 10) + sep + msg)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (w *wrapper) send(message string) error {
+	log.Println("+", message)
+	// fuck some MTAs
+	_, err := w.Write([]byte(message + "\r\n"))
+	return err
+}
+
+func (w *wrapper) recv() (string, error) {
+	if w.r == nil {
+		w.r = bufio.NewReader(w)
+	}
+	//log.Println("* recv called")
+	msg, err := w.r.ReadString('\n')
+	if err != nil {
+		return "", err
+	}
+	msg = strings.TrimRight(msg, " \t\r\n")
+	log.Println("-", msg)
+	return msg, nil
+}

server/server.go

@@ -0,0 +1,95 @@
+package server
+
+import (
+	"bytes"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/mail"
+	"strings"
+)
+
+const response = "uwu"
+
+func Handle(conn net.Conn) {
+	c := wrapper{Conn: conn}
+	log.Println("Connection received from", c.RemoteAddr().String())
+	c.cmd(220, response+" ESMTP")
+
+	for {
+		msg, err := c.recv()
+		if err != nil {
+			log.Println(err)
+			c.Close()
+			return
+		}
+
+		cmd := strings.ToUpper(strings.Split(msg, " ")[0])
+
+		if cmd == "EHLO" {
+			c.cmd(250,
+				response,
+				"8BITMIME",
+				"SMTPUTF8",
+				"SIZE 104857600")
+			continue
+		}
+
+		if cmd == "DATA" {
+			c.cmd(354, response)
+
+			data, err := readContent(c)
+			if err != nil {
+				log.Println(err)
+				c.Close()
+				return
+			}
+
+			go handleMessage(data)
+
+			continue
+		}
+
+		if cmd == "QUIT" {
+			c.cmd(221, response)
+			c.Close()
+			break
+		}
+
+		c.cmd(250, response)
+	}
+	c.Close()
+}
+
+func readContent(c wrapper) (string, error) {
+	data := ""
+	for {
+		msg, err := c.recv()
+		if err != nil {
+			return "", err
+		}
+		if msg == "." {
+			break
+		}
+		data += msg + "\r\n"
+	}
+	c.cmd(250, response)
+	return data, nil
+}
+
+func handleMessage(data string) {
+	msg, err := mail.ReadMessage(bytes.NewReader([]byte(data)))
+	if err != nil {
+		log.Println(err)
+		return
+	}
+
+	body, err := ioutil.ReadAll(msg.Body)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+
+	log.Println("FROM: ", msg.Header.Get("From"))
+	log.Println(string(body))
+}

test.js

@@ -0,0 +1,16 @@
+const net = require('net')
+
+const server = net.createServer(c => {
+    console.log('Connected')
+    c.on('data', d => {
+        console.log('data', d.toString())
+    })
+    c.on('end', () => {
+        console.log('client disconnected')
+    })
+    c.write('220 uwu ESMTP\n')
+})
+
+server.listen(2525, () => {
+    console.log('works')
+})