Add server module (#1067)

* add server module

* modify example

* fix travis errors

* add queuing and blocking, fix requests

* add server.rst, change accepter to daemon

* fix import in server.rst

* added server entry in sockets.rst

* fix import in sockets.rst

docs/source/tubes/sockets.rst

@@ -1,6 +1,7 @@
 .. testsetup:: *
 
    from pwn import *
+   from pwnlib.tubes.server import server
 
 :mod:`pwnlib.tubes.sock` --- Sockets
 ===========================================================
@@ -23,3 +24,9 @@
    .. autoclass:: pwnlib.tubes.listen.listen
       :members:
       :show-inheritance:
+
+.. automodule:: pwnlib.tubes.server
+
+   .. autoclass:: pwnlib.tubes.server.server
+      :members:
+      :show-inheritance:

pwnlib/tubes/server.py

@@ -0,0 +1,162 @@
+from __future__ import absolute_import
+
+import errno
+import socket
+import threading
+
+from pwnlib.context import context
+from pwnlib.log import getLogger
+from pwnlib.tubes.sock import sock
+from pwnlib.tubes.remote import remote
+
+log = getLogger(__name__)
+
+class server(sock):
+    r"""Creates an TCP or UDP-server to listen for connections. It supports
+    both IPv4 and IPv6.
+
+    Arguments:
+        port(int): The port to connect to.
+            Defaults to a port auto-selected by the operating system.
+        bindaddr(str): The address to bind to.
+            Defaults to ``0.0.0.0`` / `::`.
+        fam: The string "any", "ipv4" or "ipv6" or an integer to pass to :func:`socket.getaddrinfo`.
+        typ: The string "tcp" or "udp" or an integer to pass to :func:`socket.getaddrinfo`.
+        callback: A function to be started on incoming connections. It should take a :class:`pwnlib.tubes.remote` as its only argument.
+
+    Examples:
+
+        >>> s = server(8888)
+        >>> client_conn = remote('localhost', s.lport)
+        >>> server_conn = s.next_connection()
+        >>> client_conn.sendline('Hello')
+        >>> server_conn.recvline()
+        'Hello\n'
+        >>> def cb(r):
+        ...     client_input = r.readline()
+        ...     r.send(client_input[::-1])
+        ...
+        >>> t = server(8889, callback=cb)
+        >>> client_conn = remote('localhost', t.lport)
+        >>> client_conn.sendline('callback')
+        >>> client_conn.recv()
+        '\nkcabllac'
+    """
+
+    #: Local port
+    lport = 0
+
+    #: Local host
+    lhost = None
+
+    #: Socket type (e.g. socket.SOCK_STREAM)
+    type = None
+
+    #: Socket family
+    family = None
+
+    #: Socket protocol
+    protocol = None
+
+    #: Canonical name of the listening interface
+    canonname = None
+
+    #: Sockaddr structure that is being listened on
+    sockaddr = None
+
+    _accepter = None
+
+    def __init__(self, port=0, bindaddr = "0.0.0.0", fam = "any", typ = "tcp",
+                 callback = None, blocking = False, *args, **kwargs):
+        super(server, self).__init__(*args, **kwargs)
+
+        port = int(port)
+        fam  = {socket.AF_INET: 'ipv4',
+                socket.AF_INET6: 'ipv6'}.get(fam, fam)
+
+        fam = self._get_family(fam)
+        typ = self._get_type(typ)
+
+        if fam == socket.AF_INET6 and bindaddr == '0.0.0.0':
+            bindaddr = '::'
+
+        h = self.waitfor('Trying to bind to %s on port %d' % (bindaddr, port))
+
+        for res in socket.getaddrinfo(bindaddr, port, fam, typ, 0, socket.AI_PASSIVE):
+            self.family, self.type, self.proto, self.canonname, self.sockaddr = res
+
+            if self.type not in [socket.SOCK_STREAM, socket.SOCK_DGRAM]:
+                continue
+
+            h.status("Trying %s" % self.sockaddr[0])
+            listen_sock = socket.socket(self.family, self.type, self.proto)
+            listen_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            listen_sock.bind(self.sockaddr)
+            self.lhost, self.lport = listen_sock.getsockname()[:2]
+            if self.type == socket.SOCK_STREAM:
+                listen_sock.listen(1)
+            break
+        else:
+            h.failure()
+            self.error("Could not bind to %s on port %d" % (bindaddr, port))
+
+        h.success()
+
+        self.sock = listen_sock
+        self.connections_waiting = threading.Event()
+        self.connections = []
+        def accepter():
+            while True:
+                h = self.waitfor('Waiting for connections on %s:%s' % (self.lhost, self.lport))
+                while True:
+                    try:
+                        if self.type == socket.SOCK_STREAM:
+                            sock, rhost = listen_sock.accept()
+                        else:
+                            data, rhost = listen_sock.recvfrom(4096)
+                            listen_sock.connect(rhost)
+                            sock = listen_sock
+                            sock.unrecv(data)
+                        sock.settimeout(self.timeout)
+                        break
+                    except socket.error as e:
+                        if e.errno == errno.EINTR:
+                            continue
+                        h.failure()
+                        self.exception("Socket failure while waiting for connection")
+                        sock = None
+                        return
+
+                self.rhost, self.rport = rhost[:2]
+                r = remote(self.rhost, self.rport, sock = sock)
+                h.success('Got connection from %s on port %d' % (self.rhost, self.rport))
+                if callback:
+                    if not blocking:
+                        t = context.Thread(target = callback, args = (r,))
+                        t.daemon = True
+                        t.start()
+                    else:
+                        callback(r)
+                else:
+                    self.connections.append(r)
+                    if not self.connections_waiting.is_set():
+                        self.connections_waiting.set()
+
+        self._accepter = context.Thread(target = accepter)
+        self._accepter.daemon = True
+        self._accepter.start()
+
+    def next_connection(self):
+        if not self.connections_waiting.is_set():
+            self.connections_waiting.wait()
+        conn = self.connections.pop(0)
+        if not self.connections:
+            self.connections_waiting.clear()
+        return conn
+
+    def close(self):
+        # since `close` is scheduled to run on exit we must check that we got
+        # a connection or the program will hang in the `join` call above
+        if self._accepter and self._accepter.is_alive():
+            return
+        super(server, self).close()