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While developing <a href="http://pieces.openpolitics.com/thunderbayes/">ThunderBayes</a> (an extension for Thunderbird) I wrote this simple POP3 server to serve a message to my ThunderBayes test setup.

Python, 161 lines
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"""pypopper: a file-based pop3 server

Useage:
    python pypopper.py <port> <path_to_message_file>
"""
import logging
import os
import socket
import sys
import traceback

logging.basicConfig(format="%(name)s %(levelname)s - %(message)s")
log = logging.getLogger("pypopper")
log.setLevel(logging.INFO)

class ChatterboxConnection(object):
    END = "\r\n"
    def __init__(self, conn):
        self.conn = conn
    def __getattr__(self, name):
        return getattr(self.conn, name)
    def sendall(self, data, END=END):
        if len(data) < 50:
            log.debug("send: %r", data)
        else:
            log.debug("send: %r...", data[:50])
        data += END
        self.conn.sendall(data)
    def recvall(self, END=END):
        data = []
        while True:
            chunk = self.conn.recv(4096)
            if END in chunk:
                data.append(chunk[:chunk.index(END)])
                break
            data.append(chunk)
            if len(data) > 1:
                pair = data[-2] + data[-1]
                if END in pair:
                    data[-2] = pair[:pair.index(END)]
                    data.pop()
                    break
        log.debug("recv: %r", "".join(data))
        return "".join(data)


class Message(object):
    def __init__(self, filename):
        msg = open(filename, "r")
        try:
            self.data = data = msg.read()
            self.size = len(data)
            self.top, bot = data.split("\r\n\r\n", 1)
            self.bot = bot.split("\r\n")
        finally:
            msg.close()


def handleUser(data, msg):
    return "+OK user accepted"

def handlePass(data, msg):
    return "+OK pass accepted"

def handleStat(data, msg):
    return "+OK 1 %i" % msg.size

def handleList(data, msg):
    return "+OK 1 messages (%i octets)\r\n1 %i\r\n." % (msg.size, msg.size)

def handleTop(data, msg):
    cmd, num, lines = data.split()
    assert num == "1", "unknown message number: %s" % num
    lines = int(lines)
    text = msg.top + "\r\n\r\n" + "\r\n".join(msg.bot[:lines])
    return "+OK top of message follows\r\n%s\r\n." % text

def handleRetr(data, msg):
    log.info("message sent")
    return "+OK %i octets\r\n%s\r\n." % (msg.size, msg.data)

def handleDele(data, msg):
    return "+OK message 1 deleted"

def handleNoop(data, msg):
    return "+OK"

def handleQuit(data, msg):
    return "+OK pypopper POP3 server signing off"

dispatch = dict(
    USER=handleUser,
    PASS=handlePass,
    STAT=handleStat,
    LIST=handleList,
    TOP=handleTop,
    RETR=handleRetr,
    DELE=handleDele,
    NOOP=handleNoop,
    QUIT=handleQuit,
)

def serve(host, port, filename):
    assert os.path.exists(filename)
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind((host, port))
    try:
        if host:
            hostname = host
        else:
            hostname = "localhost"
        log.info("pypopper POP3 serving '%s' on %s:%s", filename, hostname, port)
        while True:
            sock.listen(1)
            conn, addr = sock.accept()
            log.debug('Connected by %s', addr)
            try:
                msg = Message(filename)
                conn = ChatterboxConnection(conn)
                conn.sendall("+OK pypopper file-based pop3 server ready")
                while True:
                    data = conn.recvall()
                    command = data.split(None, 1)[0]
                    try:
                        cmd = dispatch[command]
                    except KeyError:
                        conn.sendall("-ERR unknown command")
                    else:
                        conn.sendall(cmd(data, msg))
                        if cmd is handleQuit:
                            break
            finally:
                conn.close()
                msg = None
    except (SystemExit, KeyboardInterrupt):
        log.info("pypopper stopped")
    except Exception, ex:
        log.critical("fatal error", exc_info=ex)
    finally:
        sock.shutdown(socket.SHUT_RDWR)
        sock.close()

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print "USAGE: [<host>:]<port> <path_to_message_file>"
    else:
        _, port, filename = sys.argv
        if ":" in port:
            host = port[:port.index(":")]
            port = port[port.index(":") + 1:]
        else:
            host = ""
        try:
            port = int(port)
        except Exception:
            print "Unknown port:", port
        else:
            if os.path.exists(filename):
                serve(host, port, filename)
            else:
                print "File not found:", filename

Save the above code in a file named pypopper.py. Then run it with two arguments (server port and file name) something like this:

python pypopper.py 110 message.txt

Which would start the server on localhost port 110 and serve the contents of message.txt every time the client requests new messages. Please note, this server SHOULD NOT BE USED IN PRODUCTION! It is not secure, it is only meant for testing and learning about POP3. It implements a minimal subset of the POP3 protocol; just enough to test ThunderBayes.

1 comment

Valery 13 years ago  # | flag

On Windows, add 'rb' at line 49: msg = open(filename, "r") should be msg = open(filename, "rb")

Valery.