Bare minimum required commands to act as a reciever implemented

smtp/connection.go

@@ -20,30 +20,65 @@ package smtp
 
 import (
 	"net"
+	// "fmt"
+	"strings"
 
 	"github.com/rs/zerolog/log"
 )
 
 type Connection struct {
 	connection net.Conn
+
+	ReversePathBuffer *string
+	ForwardPathBuffer *string
+	MailBuffer        *string
 }
 
-func (self Connection) Read() (string, error) {
-	buffer := [64]byte{}
-	read, err := self.connection.Read(buffer[:])
-	if err != nil {
-		return "", err
+func NewConnection(connection net.Conn) Connection {
+	return Connection{
+		connection,
+		nil,
+		nil,
+		nil,
+	}
+}
+
+var buffer = [1024]byte{}
+func (self Connection) Read(delimiter string) (string, error) {
+	var message string
+	for !strings.Contains(message, delimiter) {
+		num_read, err := self.connection.Read(buffer[:])
+		if err != nil {
+			return "", err
+		}
+		message += string(buffer[:num_read])
 	}
 
-	message := string(buffer[:read - 2])
+	lines := strings.Split(message, "\n")
+	for index, line := range lines {
+		if index != len(lines) - 1 || line != "" {
+			if index == 0 {
+				log.Trace().Msgf("%v  -> %v", self.RemoteAddr(), line)
+			} else {
+				log.Trace().Msgf("%v     %v", self.RemoteAddr(), line)
+			}
+		}
+	}
 
-	log.Trace().Msgf("%v  -> %v", self.RemoteAddr(), message)
-
-	return message, nil
+	return message[:len(message) - len(delimiter)], nil
 }
 
 func (self Connection) Write(message string) error {
-	log.Trace().Msgf("%v <-  %v", self.RemoteAddr(), message[:len(message) - 1])
+	lines := strings.Split(message, "\n")
+	for index, line := range lines {
+		if index != len(lines) - 1 || line != "" {
+			if index == 0 {
+				log.Trace().Msgf("%v <-  %v", self.RemoteAddr(), line)
+			} else {
+				log.Trace().Msgf("%v     %v", self.RemoteAddr(), line)
+			}
+		}
+	}
 	_, err := self.connection.Write([]byte(message))
 	return err
 }

smtp/handlers.go

@@ -25,7 +25,7 @@ import (
 
 type Command struct {
 	name string
-	Exec func(Connection)([]Command, error)
+	Exec func(Connection, string)([]Command, error)
 }
 
 func (self Command) Name() string {
@@ -42,7 +42,7 @@ func (self Connection) Chain() error {
 		return err
 	}
 	for {
-		message, err := self.Read()
+		message, err := self.Read("\r\n")
 		if err != nil {
 			return err
 		}
@@ -50,7 +50,7 @@ func (self Connection) Chain() error {
 		command_found := false
 		for _, command := range commands {
 			if command.Check(message) {
-				commands, err = command.Exec(self)
+				commands, err = command.Exec(self, message[len(command.Name()):])
 				if err != nil {
 					return err
 				}
@@ -80,24 +80,105 @@ func Greet(connection Connection) ([]Command, error) {
 		"220 localhost ESMTP diodemail -- Service ready" + "\n",
 	)
 	if err != nil {
-		return nil, err
+		return []Command{}, err
 	}
 
 	return []Command{
-		Command{ "HELO", Hello },
-		Command{ "EHLO", Hello },
+		HELO,
+		EHLO,
 	}, nil
 }
 
 /* --- HELO/EHLO RESPONSE --- */
 
-func Hello(connection Connection) ([]Command, error) {
+var HELO = Command{ "HELO", Hello }
+var EHLO = Command{ "EHLO", Hello }
+func Hello(connection Connection, message string) ([]Command, error) {
 	err := connection.Write(
-		fmt.Sprintf("250 %v is shy", connection.connection.LocalAddr()) + "\n",
+		fmt.Sprintf(
+			"250 %v is shy" + "\r\n",
+			connection.connection.LocalAddr(),
+		),
+	)
+	if err != nil {
+		return []Command{}, err
+	}
+
+	return []Command{
+		MAIL_FROM,
+	}, nil
+}
+
+/* --- MAIL FROM RESPONSE --- */
+
+var MAIL_FROM = Command{ "MAIL FROM:", MailFrom }
+func MailFrom(connection Connection, message string) ([]Command, error) {
+	match := ReversePath.FindStringSubmatch(message)
+	if match == nil {
+		return []Command{}, fmt.Errorf("Invalid forward-path: %v", message)
+	} else if len(match) > 1 {
+		connection.ReversePathBuffer = &match[1]
+	}
+	err := connection.Write(
+		"250 OK\n",
+	)
+	if err != nil {
+		return []Command{}, err
+	}
+
+	return []Command{
+		RCPT_TO,
+	}, nil
+}
+
+var RCPT_TO = Command{ "RCPT TO:", RcptTo }
+func RcptTo(connection Connection, message string) ([]Command, error) {
+	match := ForwardPath.FindStringSubmatch(message)
+	if match == nil {
+		return []Command{}, fmt.Errorf("Invalid forward-path: %v", message)
+	} else {
+		connection.ForwardPathBuffer = &match[1]
+	}
+	err := connection.Write(
+		"250 OK\n",
+	)
+	if err != nil {
+		return []Command{}, err
+	}
+
+	return []Command{
+		DATA,
+	}, nil
+}
+
+var DATA = Command { "DATA", Data }
+func Data(connection Connection, message string) ([]Command, error) {
+	err := connection.Write(
+		"354 Start Input\n",
+	)
+	if err != nil {
+		return []Command{}, err
+	}
+	data, err := connection.Read("\r\n.\r\n")
+	connection.MailBuffer = &data
+	err = connection.Write(
+		"250 OK\n",
 	)
 	if err != nil {
 		return nil, err
 	}
+	return []Command{
+		QUIT,
+	}, nil
+}
 
+var QUIT = Command { "QUIT", Quit }
+func Quit(connection Connection, message string) ([]Command, error) {
+	err := connection.Write(
+		"221 OK\n",
+	)
+	if err != nil {
+		return nil, err
+	}
 	return []Command{}, nil
 }

smtp/parsers.go

@@ -0,0 +1,33 @@
+/* diodemail - send-only smtp server
+ * Copyright (c) 2024 Gnarwhal
+ *
+ * This file is part of SSHare.
+ *
+ * SSHare is free software: you can redistribute it and/or modify it under the terms of
+ * the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * SSHare is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * SSHare. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package smtp
+
+import (
+	"fmt"
+	"regexp"
+)
+
+var ReversePath = regexp.MustCompile(fmt.Sprintf("(?:%v)|<>", path))
+var ForwardPath = regexp.MustCompile(path)
+
+// https://datatracker.ietf.org/doc/html/rfc5321#page-41
+// Is this...legal, m'lord? (no, but ¯\_(ツ)_/¯)
+// ...
+// Ok fine. TODO. Happy now?
+var path = "<(?:.*:)?(\\w+@\\w+(?:\\.\\w+)*)>"

smtp/server.go

@@ -60,7 +60,7 @@ func Run(host string, implicit_tls bool) error {
 			return err
 		}
 
-		go handle(Connection{connection})
+		go handle(NewConnection(connection))
 	}
 }