print received messages

Author: srittau

README.md

@@ -3,7 +3,10 @@
 [![Build Status](https://travis-ci.org/srittau/FakeSMTPd.svg?branch=master)](https://travis-ci.org/srittau/FakeSMTPd)
 
 FakeSMTPd is an SMTP server for testing mail functionality. Any mail sent via
-this server will be printed to stdout, but will not be forwarded any further.
+this server will be saved, but will not be forwarded any further.
+
+Mail is printed to stdout by default in default mbox format, as defined in
+[RFC 4155](https://www.ietf.org/rfc/rfc4155.txt).
 
 Usage
 -----

fakesmtpd/commands.py

@@ -34,14 +34,15 @@ def handle_helo(state: State, arguments: str) -> Reply:
 
 
 def handle_mail(state: State, arguments: str) -> Reply:
-    if not re.match(r"^FROM:<.*>", arguments, re.IGNORECASE):
+    m = re.match(r"^FROM:<(.*)>", arguments, re.IGNORECASE)
+    if not m:
         return handle_wrong_arguments()
     if not state.greeted:
         return handle_no_greeting()
     if not state.mail_allowed:
         return handle_bad_command_sequence()
     state.clear()
-    state.reverse_path = ""
+    state.reverse_path = m.group(1)
     return SMTPStatus.OK, "Sender OK"
 
 
@@ -57,11 +58,12 @@ def handle_quit(state: State, arguments: str) -> Reply:
 
 
 def handle_rcpt(state: State, arguments: str) -> Reply:
-    if not re.match(r"^TO:<.*>", arguments, re.IGNORECASE):
+    m = re.match(r"^TO:<(.*)>", arguments, re.IGNORECASE)
+    if not m:
         return handle_wrong_arguments()
     if not state.rcpt_allowed:
         return handle_bad_command_sequence()
-    state.forward_path = []
+    state.add_forward_path(m.group(1))
     return SMTPStatus.OK, "Receiver OK"
 
 

fakesmtpd/connection.py

@@ -1,7 +1,8 @@
+import datetime
 from asyncio.streams import StreamReader, StreamWriter
 import logging
 from socket import getfqdn
-from typing import Tuple
+from typing import Tuple, Callable
 
 from fakesmtpd.commands import handle_command
 from fakesmtpd.smtp import SMTPStatus
@@ -15,9 +16,11 @@ class UnexpectedEOFError(Exception):
 
 class ConnectionHandler:
 
-    def __init__(self, reader: StreamReader, writer: StreamWriter) -> None:
+    def __init__(self, reader: StreamReader, writer: StreamWriter,
+                 print_mail: Callable[[State], None]) -> None:
         self.reader = reader
         self.writer = writer
+        self.print_mail = print_mail
         self.state = State()
 
     async def handle(self) -> None:
@@ -51,22 +54,20 @@ async def _handle_mail_text(self):
             pass
         else:
             self._write_reply(SMTPStatus.OK, "OK")
-            self.state.clear()
+            self.state.date = datetime.datetime.utcnow()
+            state = self.state
+            self.print_mail(state)
+            self.state = State()
+            self.state.greeted = state.greeted
 
-    async def _read_mail_text(self) -> str:
-        text = ""
+    async def _read_mail_text(self) -> None:
         while not self.reader.at_eof():
             line = await self.reader.readline()
             if line == b".\r\n":
-                return text
-            text += line.decode("ascii")
+                return
+            self.state.add_line(line.decode("ascii"))
         raise UnexpectedEOFError()
 
     def _write_reply(self, code: SMTPStatus, text: str) -> None:
         full_line = f"{code.value} {text}\r\n"
         self.writer.write(full_line.encode("ascii"))
-
-
-async def handle_connection(reader: StreamReader, writer: StreamWriter) \
-        -> None:
-    await ConnectionHandler(reader, writer).handle()

fakesmtpd/mbox.py

@@ -0,0 +1,9 @@
+from fakesmtpd.state import State
+
+
+def print_mbox_mail(stream, state: State) -> None:
+    """Print a mail in RFC 4155 default mbox format."""
+    stream.write(f"From {state.reverse_path} {state.date.ctime()}\n")
+    stream.write(state.mail_data.replace("\r\n", "\n"))
+    stream.write("\n")
+    stream.flush()

fakesmtpd/server.py

@@ -1,11 +1,15 @@
 import asyncio
+from asyncio.streams import StreamReader, StreamWriter
 import logging
 import signal
 import sys
 from typing import Optional
 
+from functools import partial
+
 from fakesmtpd.args import parse_args
-from fakesmtpd.connection import handle_connection
+from fakesmtpd.connection import ConnectionHandler
+from fakesmtpd.mbox import print_mbox_mail
 
 
 def main() -> None:
@@ -25,3 +29,9 @@ def run_server(host: Optional[str], port: int) -> None:
     s = asyncio.start_server(handle_connection, host=host, port=port)
     loop.run_until_complete(s)
     loop.run_forever()
+
+
+async def handle_connection(reader: StreamReader, writer: StreamWriter) \
+        -> None:
+    print_it = partial(print_mbox_mail, sys.stdout)
+    await ConnectionHandler(reader, writer, print_it).handle()

fakesmtpd/state.py

@@ -1,16 +1,33 @@
+import datetime
+from typing import Optional, List
+
+
 class State:
 
     def __init__(self) -> None:
         self.greeted = False
-        self.clear()
+        self.date: Optional[datetime.datetime] = None
+        self.reverse_path: Optional[str] = None
+        self.forward_path: Optional[List[str]] = None
+        self.mail_data: Optional[str] = None
 
     def clear(self) -> None:
-        self.reverse_path = None
-        self.forward_path = None
-        self.mail_data = None
+        self.reverse_path: Optional[str] = None
+        self.forward_path: Optional[List[str]] = None
+        self.mail_data: Optional[str] = None
+
+    def add_forward_path(self, path: str) -> None:
+        if self.forward_path is None:
+            self.forward_path = []
+        self.forward_path.append(path)
+
+    def add_line(self, line: str) -> None:
+        if self.mail_data is None:
+            self.mail_data = ""
+        self.mail_data += line
 
     @property
-    def mail_allowed(self):
+    def mail_allowed(self) -> bool:
         return (
             self.greeted and
             self.reverse_path is None and
@@ -19,15 +36,15 @@ def mail_allowed(self):
         )
 
     @property
-    def rcpt_allowed(self):
+    def rcpt_allowed(self) -> bool:
         return (
             self.greeted and
             self.reverse_path is not None and
             self.mail_data is None
         )
 
     @property
-    def data_allowed(self):
+    def data_allowed(self) -> bool:
         return (
             self.greeted and
             self.reverse_path is not None and

fakesmtpd_test/connection.py

@@ -1,12 +1,14 @@
 import asyncio
-from typing import List
-from unittest.case import TestCase
+from typing import List, Optional
+from unittest import TestCase
 from unittest.mock import patch
 
-from asserts import assert_equal, assert_greater_equal, fail
+from asserts import assert_equal, assert_greater_equal, fail, \
+    assert_is_not_none, assert_datetime_about_now_utc
 
-from fakesmtpd.connection import handle_connection
+from fakesmtpd.connection import ConnectionHandler
 from fakesmtpd.smtp import SMTPStatus
+from fakesmtpd.state import State
 
 FAKE_HOST = "mail.example.com"
 
@@ -78,15 +80,19 @@ def setUp(self):
             patch("fakesmtpd.commands.getfqdn", lambda: FAKE_HOST)
         self._getfqdn_patch1.start()
         self._getfqdn_patch2.start()
+        self.printed_state: Optional[State] = None
 
     def tearDown(self):
         self._getfqdn_patch1.stop()
         self._getfqdn_patch2.stop()
 
     def _handle(self):
         loop = asyncio.get_event_loop()
-        c = handle_connection(self.reader, self.writer)
-        loop.run_until_complete(c)
+        handler = ConnectionHandler(self.reader, self.writer, self._print_mail)
+        loop.run_until_complete(handler.handle())
+
+    def _print_mail(self, state: State) -> None:
+        self.printed_state = state
 
     def test_greeting(self):
         self._handle()
@@ -311,7 +317,7 @@ def test_complete_mail(self):
             "From: foo@example.com",
             "To: bar@example.com",
             "Subject: Foobar",
-            ""
+            "",
             "Line 1",
             "Line 2",
             ".",
@@ -328,7 +334,7 @@ def test_two_transactions(self):
             "From: foo@example.com",
             "To: bar@example.com",
             "Subject: Foobar",
-            ""
+            "",
             ".",
             "MAIL FROM:<foo@example.com>",
         ]
@@ -376,3 +382,33 @@ def test_vrfy(self):
         self._handle()
         self.writer.assert_last_reply(
             SMTPStatus.CANNOT_VRFY, "Verify not allowed")
+
+    def test_mail_printed(self):
+        self.reader.lines = [
+            "EHLO client.example.com",
+            "MAIL FROM:<foo@example.com>",
+            "RCPT TO:<bar1@example.com>",
+            "RCPT TO:<bar2@example.com>",
+            "DATA",
+            "From: foo@example.com",
+            "To: bar@example.com",
+            "Subject: Foobar",
+            "",
+            "Line 1  ",
+            "Line 2",
+            ".",
+        ]
+        self._handle()
+        assert_is_not_none(self.printed_state)
+        assert_datetime_about_now_utc(self.printed_state.date)
+        assert_equal("foo@example.com", self.printed_state.reverse_path)
+        assert_equal(["bar1@example.com", "bar2@example.com"],
+                     self.printed_state.forward_path)
+        assert_equal(
+            "From: foo@example.com\r\n"
+            "To: bar@example.com\r\n"
+            "Subject: Foobar\r\n"
+            "\r\n"
+            "Line 1  \r\n"
+            "Line 2\r\n",
+            self.printed_state.mail_data)

fakesmtpd_test/mbox.py

@@ -0,0 +1,25 @@
+import datetime
+
+from asserts import assert_equal
+from io import StringIO
+from unittest import TestCase
+
+from fakesmtpd.mbox import print_mbox_mail
+from fakesmtpd.state import State
+
+
+class PrintMboxMailTest(TestCase):
+
+    def test_print(self):
+        out = StringIO()
+        state = State()
+        state.date = datetime.datetime(2017, 6, 4, 14, 34, 15)
+        state.reverse_path = "sender@example.com"
+        state.forward_path = ["receiver1@example.com", "receiver2@example.com"]
+        state.mail_data = "Subject: Foo\r\n\r\nText\r\n"
+        print_mbox_mail(out, state)
+        assert_equal("From sender@example.com Sun Jun  4 14:34:15 2017\n"
+                     "Subject: Foo\n"
+                     "\n"
+                     "Text\n"
+                     "\n", out.getvalue())