From 7de900fb1cdd7ef2a35ed476e0fd23ff5bea28cb Mon Sep 17 00:00:00 2001
From: Simone Lazzaris <slazzaris@gmail.com>
Date: Mon, 29 Mar 2021 17:40:28 +0200
Subject: [PATCH] First working release

---
 .gitignore       |   7 ++
 db.py            |  71 +++++++++++++++++
 main.py          |  16 ++++
 pop3.py          | 193 +++++++++++++++++++++++++++++++++++++++++++++++
 requirements.txt |   2 +
 smtp.py          |  76 +++++++++++++++++++
 6 files changed, 365 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 db.py
 create mode 100644 main.py
 create mode 100644 pop3.py
 create mode 100644 requirements.txt
 create mode 100644 smtp.py

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3c73035
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+__pycache__
+bin
+data
+immudb
+lib
+lib64
+pyvenv.cfg
diff --git a/db.py b/db.py
new file mode 100644
index 0000000..d8a9f35
--- /dev/null
+++ b/db.py
@@ -0,0 +1,71 @@
+import immudb.client
+import time,string,random,re
+
+IMMUDB_USER="immudb"
+IMMUDB_PASS="immudb"
+IMMUDB_HOST="localhost"
+IMMUDB_PORT="3322"
+
+def rndstring(size):
+	chars=string.ascii_uppercase + string.digits
+	return ''.join(random.choice(chars) for _ in range(size))
+
+
+class db:
+	def __init__(self):
+		self.cli=immudb.client.ImmudbClient("{}:{}".format(IMMUDB_HOST,IMMUDB_PORT))
+		self.cli.login(IMMUDB_USER,IMMUDB_PASS)
+		
+	def validUser(self, username):
+		k="USER:{}".format(username).encode('utf8')
+		try:
+			u=self.cli.safeGet(k)
+			return u.verified
+		except:
+			return False
+		
+	def validLogin(self, username, password):
+		k="USER:{}".format(username).encode('utf8')
+		try:
+			u=self.cli.safeGet(k)
+			return u.verified and u.value==password
+		except:
+			return False
+
+	def storeEmail(self, username, message):
+		uniq="{}.{}".format(time.time(), rndstring(8))
+		k="MAIL:{}:{}:S{}".format(username, uniq,len(message))
+		self.cli.safeSet(k.encode('utf8'), message)
+
+	def listEmail(self, username):
+		prefix="MAIL:{}:".format(username).encode('utf8')
+		ret=[]
+		prev=None
+		rx=re.compile(r"MAIL:.*:(.+):S([0-9]+)")
+		while True:
+			sc=self.cli.scan(prev, prefix, False, 10)
+			if len(sc)==0:
+				break
+			for i in sc.keys():
+				prev=i
+				m=rx.match(i.decode('utf8'))
+				if m!=None:
+					ret.append((m.group(1),int(m.group(2))))
+		return ret
+
+	def getEmail(self, username, idx):
+		prefix="MAIL:{}:".format(username).encode('utf8')
+		ret=[]
+		prev=None
+		rx=re.compile(r"MAIL:.*:(.+):S([0-9]+)")
+		curr=0
+		while True:
+			sc=self.cli.scan(prev, prefix, False, 10)
+			if len(sc)==0:
+				break
+			for i in sc.keys():
+				curr+=1
+				prev=i
+				if curr==idx:
+					return sc[i]
+		return None
diff --git a/main.py b/main.py
new file mode 100644
index 0000000..9991bbd
--- /dev/null
+++ b/main.py
@@ -0,0 +1,16 @@
+from twisted.internet import protocol, reactor, endpoints
+import logging
+import smtp
+import pop3
+import db
+
+logging.basicConfig(level=logging.DEBUG)
+immudb=db.db()
+
+smtp_endpoint=endpoints.serverFromString(reactor,"tcp:7125")
+pop3_endpoint=endpoints.serverFromString(reactor,"tcp:7110")
+
+smtp_endpoint.listen(smtp.SMTPFactory(immudb))
+pop3_endpoint.listen(pop3.POP3Factory(immudb))
+
+reactor.run()
diff --git a/pop3.py b/pop3.py
new file mode 100644
index 0000000..979b999
--- /dev/null
+++ b/pop3.py
@@ -0,0 +1,193 @@
+from twisted.internet import protocol, reactor, endpoints
+from twisted.protocols.basic import LineReceiver
+import logging
+logging.basicConfig(level=logging.DEBUG)
+
+class POP3Protocol(LineReceiver):
+	def __init__(self):
+		self.user=None
+		self.auth=False
+		
+	def connectionMade(self):
+		logging.info("Incoming pop3 connection")
+		greeting="+OK mailsafe ready."
+		self.sendLine(greeting.encode('utf8'))
+		
+	def lineReceived(self, line):
+		parms=line.split()
+		if len(parms)==0:
+			logging.warn("Unknown command")
+			self.sendLine("-ERR Unknown command.".encode('utf8'))
+			return
+		cmd=parms[0].decode('utf8').upper()
+		if self.auth:
+			prefix="cmd_"
+		else:
+			prefix="auth_"
+		f=getattr(self, prefix+cmd, None)
+		if f==None:
+			logging.warn("Unknown command '%s'",cmd)
+			self.sendLine("-ERR Unknown command.".encode('utf8'))
+			return
+		logging.info("Received command '%s'",cmd)
+		f(line)
+		
+	def auth_CAPA(self, line):
+		self.sendLine("+OK".encode('utf8'))
+		for c in ["TOP", "UIDL", "USER", "IMPLEMENTATION mailsafe"]:
+			self.sendLine(c.encode('utf8'))
+		self.sendLine(".".encode('utf8'))
+		
+	def auth_QUIT(self, line):
+		greeting="+OK See you later alligator".encode('utf8')
+		self.sendLine(greeting)
+		self.transport.loseConnection()
+		
+	def auth_USER(self, line):
+		try:
+			usr=line.split()[1].decode('utf8')
+			self.user=usr
+			greeting="+OK Now enter your password".encode('utf8')
+			self.sendLine(greeting)
+		except:
+			err="-ERR I don't understand".encode('utf8')
+			self.sendLine(err)
+		
+	def auth_PASS(self, line):
+		if self.auth==None:
+			err="-ERR USER first.".encode('utf8')
+			self.sendLine(err)
+			return
+		try:
+			pwd=line.split()[1]
+			if self.db.validLogin(self.user, pwd):
+				self.auth=True
+				greeting="+OK You are now logged in".encode('utf8')
+			else:
+				greeting="-ERR user {} sus".format(self.user).encode('utf8')
+			self.sendLine(greeting)
+		except:
+			err="-ERR I don't understand".encode('utf8')
+			self.sendLine(err)
+		
+		
+	def cmd_QUIT(self, line):
+		greeting="+OK See you later alligator".encode('utf8')
+		self.sendLine(greeting)
+		self.transport.loseConnection()
+		
+	def cmd_NOOP(self, line):
+		greeting="+OK".encode('utf8')
+		self.sendLine(greeting)
+		
+	def cmd_RSET(self, line):
+		greeting="+OK".encode('utf8')
+		self.sendLine(greeting)
+		
+	def cmd_DELE(self, line):
+		msg="-ERR Messages are permanent".encode('utf8')
+		self.sendLine(msg)
+		
+	def cmd_STAT(self, line):
+		msglist=self.db.listEmail(self.user)
+		ttsize=0
+		for i in msglist:
+			ttsize+=i[1]
+		statusLine="+OK {} {}".format(len(msglist),ttsize).encode('utf8')
+		self.sendLine(statusLine)
+		
+	def cmd_RETR(self, line):
+		try:
+			msgnum=int(line.split()[1])
+		except:
+			self.sendLine("-ERR wrong".encode('utf8'))
+			return
+		msg=self.db.getEmail(self.user,msgnum)
+		if msg==None:
+			self.sendLine("-ERR not found".encode('utf8'))
+		else:
+			self.sendLine("+OK {} octets".format(len(msg)).encode('utf8'))
+			for l in msg.split(b"\r\n"):
+				self.sendLine(l)
+		self.sendLine(".".encode('utf8'))
+		
+	def cmd_TOP(self, line):
+		try:
+			msgnum=int(line.split()[1])
+			lines=int(line.split()[2])
+		except:
+			self.sendLine("-ERR wrong".encode('utf8'))
+			return
+		msg=self.db.getEmail(self.user,msgnum)
+		if msg==None:
+			self.sendLine("-ERR not found".encode('utf8'))
+		else:
+			self.sendLine("+OK {} octets".format(len(msg)).encode('utf8'))
+			for i,l in enumerate(msg.split(b"\r\n")):
+				if i>=lines:
+					break
+				self.sendLine(l)
+		self.sendLine(".".encode('utf8'))
+		
+	def cmd_LIST(self, line):
+		parms=line.split()
+		if len(parms)>1:
+			try:
+				msgnum=int(parms[1])-1
+			except:
+				self.sendLine("-ERR wrong".encode('utf8'))
+				return
+		else:
+			msgnum=None
+		msglist=self.db.listEmail(self.user)
+		ttsize=0
+		for i in msglist:
+			ttsize+=i[1]
+		if msgnum==None:
+			statusLine="+OK {} messages ({} octets)".format(len(msglist),ttsize).encode('utf8')
+			self.sendLine(statusLine)
+			i=0
+			for m in msglist:
+				i=i+1
+				self.sendLine("{} {}".format(i,m[1]).encode('utf8'))
+			self.sendLine(".".encode('utf8'))
+		elif len(msglist)>msgnum and msgnum>0:
+			self.sendLine("+OK {} {}".format(msgnum+1,msglist[msgnum][1]).encode('utf8'))
+		else:
+			self.sendLine("-ERR You what?".encode('utf8'))
+		
+	def cmd_UIDL(self, line):
+		parms=line.split()
+		if len(parms)>1:
+			try:
+				msgnum=int(parms[1])-1
+			except:
+				self.sendLine("-ERR wrong".encode('utf8'))
+				return
+		else:
+			msgnum=None
+		msglist=self.db.listEmail(self.user)
+		if msgnum==None:
+			self.sendLine("+OK".encode('utf8'))
+			i=0
+			for m in msglist:
+				i=i+1
+				self.sendLine("{} {}".format(i,m[0]).encode('utf8'))
+			self.sendLine(".".encode('utf8'))
+		elif len(msglist)>msgnum and msgnum>0:
+			self.sendLine("+OK {} {}".format(msgnum+1,msglist[msgnum][0]).encode('utf8'))
+		else:
+			self.sendLine("-ERR You what?".encode('utf8'))
+		
+
+class POP3Factory(protocol.ServerFactory):
+	protocol=POP3Protocol
+
+	def __init__(self, db, *a, **kw):
+		protocol.ServerFactory.__init__(self, *a, **kw)
+		self.db=db
+	
+	def buildProtocol(self, addr):
+		p = protocol.ServerFactory.buildProtocol(self, addr)
+		p.db = self.db
+		return p
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..d238af3
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,2 @@
+immudb-py==0.9.2
+Twisted==21.2.0
diff --git a/smtp.py b/smtp.py
new file mode 100644
index 0000000..b54c3c0
--- /dev/null
+++ b/smtp.py
@@ -0,0 +1,76 @@
+from twisted.internet import protocol, reactor, endpoints, defer
+from twisted.mail import smtp
+from zope.interface import implementer
+from twisted.internet import defer
+import datetime
+import time
+from email import utils
+from email.header import Header
+import logging
+import db
+
+@implementer(smtp.IMessageDelivery)
+class ImmudbMessageDelivery:
+	def __init__(self, db):
+		self.db=db
+		
+	def receivedHeader(self, helo, origin, rcpt):
+		recv="from {hello0} [{hello1}] message to {rcpts}; {date}"
+		rcpts=",".join([str(r.dest) for r in rcpt])
+		date = utils.format_datetime(datetime.datetime.now())
+		hh=Header("Received")
+		hh.append(recv.format(hello0=helo[0].decode('ascii'),
+		     hello1=helo[1].decode('ascii'),
+		     rcpts=rcpts, date=date).encode('ascii'))
+		return hh.encode().encode('ascii')
+
+	def validateFrom(self, helo, origin):
+		logging.info("validating from %s",origin)
+		# All addresses are accepted
+		return origin
+
+	def validateTo(self, user):
+		# Only messages directed to configured users are accepted
+		logging.info("validating to %s",user)
+		if self.db.validUser(user.dest):
+			logging.info("ok")
+			return lambda: ImmudbMessage(self.db, user.dest)
+		raise smtp.SMTPBadRcpt(user)
+
+@implementer(smtp.IMessage)
+class ImmudbMessage:
+	def __init__(self, db, rcpt):
+		self.msg = b''
+		self.db=db
+		self.rcpt=str(rcpt)
+
+	def lineReceived(self, line):
+		self.msg+=line+b"\r\n"
+
+	def eomReceived(self):
+		logging.info("New message received for %s",self.rcpt)
+		self.db.storeEmail(self.rcpt, self.msg)
+		self.lines = None
+		return defer.succeed(None)
+
+	def connectionLost(self):
+		# There was an error, throw away the stored lines
+		self.lines = None
+
+
+class SMTPProtocol(smtp.ESMTP):
+	def connectionMade(self):
+		logging.info("smtp connection")
+		smtp.ESMTP.connectionMade(self)
+
+class SMTPFactory(protocol.ServerFactory):
+	protocol=SMTPProtocol
+	domain="lazzaris.net"
+	def __init__(self, db, *a, **kw):
+		smtp.SMTPFactory.__init__(self, *a, **kw)
+		self.delivery=ImmudbMessageDelivery(db)
+	
+	def buildProtocol(self, addr):
+		p = smtp.SMTPFactory.buildProtocol(self, addr)
+		p.delivery = self.delivery
+		return p