# badserverext.py - Extension making servers behave badly

#

# Copyright 2017 Gregory Szorc <gregory.szorc@gmail.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

# no-check-code

"""Extension to make servers behave badly.

This extension is useful for testing Mercurial behavior when various network

events occur.

Various config options in the [badserver] section influence behavior:

close-before-accept

   If true, close() the server socket when a new connection arrives before

   accept() is called. The server will then exit.

close-after-accept

   If true, the server will close() the client socket immediately after

   accept().

close-after-recv-bytes

   If defined, close the client socket after receiving this many bytes.

   (The value is a list, multiple values can use used to close a series of requests

   request)

close-after-recv-patterns

   If defined, the `close-after-recv-bytes` values only start counting after the

   `read` operation that encountered the defined patterns.

   (The value is a list, multiple values can use used to close a series of requests

   request)

close-after-send-bytes

   If defined, close the client socket after sending this many bytes.

   (The value is a list, multiple values can use used to close a series of requests

   request)

close-after-send-patterns

   If defined, close the client socket after the configured regexp is seen.

   (The value is a list, multiple values can use used to close a series of requests

   request)

"""

import re

import socket

from mercurial import (

    registrar,

)

from mercurial.hgweb import server

configtable = {}

configitem = registrar.configitem(configtable)

configitem(

    b'badserver',

    b'close-after-accept',

    default=False,

)

configitem(

    b'badserver',

    b'close-after-recv-bytes',

    default=b'0',

)

configitem(

    b'badserver',

    b'close-after-recv-patterns',

    default=b'',

)

configitem(

    b'badserver',

    b'close-after-send-bytes',

    default=b'0',

)

configitem(

    b'badserver',

    b'close-after-send-patterns',

    default=b'',

)

configitem(

    b'badserver',

    b'close-before-accept',

    default=False,

)

class ConditionTracker:

    def __init__(

        self,

        close_after_recv_bytes,

        close_after_recv_patterns,

        close_after_send_bytes,

        close_after_send_patterns,

    ):

        self._all_close_after_recv_bytes = close_after_recv_bytes

        self._all_close_after_recv_patterns = close_after_recv_patterns

        self._all_close_after_send_bytes = close_after_send_bytes

        self._all_close_after_send_patterns = close_after_send_patterns

        self.target_recv_bytes = None

        self.remaining_recv_bytes = None

        self.recv_patterns = None

        self.recv_data = b''

        self.target_send_bytes = None

        self.remaining_send_bytes = None

        self.send_pattern = None

        self.send_data = b''

    def start_next_request(self):

        """move to the next set of close condition"""

        if self._all_close_after_recv_bytes:

            self.target_recv_bytes = self._all_close_after_recv_bytes.pop(0)

            self.remaining_recv_bytes = self.target_recv_bytes

        else:

            self.target_recv_bytes = None

            self.remaining_recv_bytes = None

        self.recv_data = b''

        if self._all_close_after_recv_patterns:

            self.recv_pattern = self._all_close_after_recv_patterns.pop(0)

        else:

            self.recv_pattern = None

        if self._all_close_after_send_bytes:

            self.target_send_bytes = self._all_close_after_send_bytes.pop(0)

            self.remaining_send_bytes = self.target_send_bytes

        else:

            self.target_send_bytes = None

            self.remaining_send_bytes = None

        self.send_data = b''

        if self._all_close_after_send_patterns:

            self.send_pattern = self._all_close_after_send_patterns.pop(0)

        else:

            self.send_pattern = None

    def might_close(self):

        """True, if any processing will be needed"""

        if self.remaining_recv_bytes is not None:

            return True

        if self.recv_pattern is not None:

            return True

        if self.remaining_send_bytes is not None:

            return True

        if self.send_pattern is not None:

            return True

        return False

    def forward_write(self, obj, method, data, *args, **kwargs):

        """call an underlying write function until condition are met

        When the condition are met the socket is closed

        """

        remaining = self.remaining_send_bytes

        pattern = self.send_pattern

        orig = object.__getattribute__(obj, '_orig')

        bmethod = method.encode('ascii')

        func = getattr(orig, method)

        if pattern:

            self.send_data += data

            pieces = pattern.split(self.send_data, maxsplit=1)

            if len(pieces) > 1:

                dropped = len(pieces[-1])

                remaining = len(data) - dropped

        if remaining:

            remaining = max(0, remaining)

        if not remaining:

            newdata = data

        else:

            if remaining < len(data):

                newdata = data[0:remaining]

            else:

                newdata = data

            remaining -= len(newdata)

            self.remaining_send_bytes = remaining

        result = func(newdata, *args, **kwargs)

        if remaining is None:

            obj._writelog(b'%s(%d) -> %s' % (bmethod, len(data), data))

        else:

            msg = b'%s(%d from %d) -> (%d) %s'

            msg %= (bmethod, len(newdata), len(data), remaining, newdata)

            obj._writelog(msg)

        if remaining is not None and remaining <= 0:

            obj._writelog(b'write limit reached; closing socket')

            object.__getattribute__(obj, '_cond_close')()

            raise Exception('connection closed after sending N bytes')

        return result

    def forward_read(self, obj, method, size=-1):

        """call an underlying read function until condition are met

        When the condition are met the socket is closed

        """

        remaining = self.remaining_recv_bytes

        pattern = self.recv_pattern

        orig = object.__getattribute__(obj, '_orig')

        bmethod = method.encode('ascii')

        func = getattr(orig, method)

        requested_size = size

        actual_size = size

        if pattern is None and remaining:

            if size < 0:

                actual_size = remaining

            else:

                actual_size = min(remaining, requested_size)

        result = func(actual_size)

        if pattern is None and remaining:

            remaining -= len(result)

            self.remaining_recv_bytes = remaining

        if requested_size == 65537:

            requested_repr = b'~'

        else:

            requested_repr = b'%d' % requested_size

        if requested_size == actual_size:

            msg = b'%s(%s) -> (%d) %s'

            msg %= (bmethod, requested_repr, len(result), result)

        else:

            msg = b'%s(%d from %s) -> (%d) %s'

            msg %= (bmethod, actual_size, requested_repr, len(result), result)

        obj._writelog(msg)

        if pattern is not None:

            self.recv_data += result

            if pattern.search(self.recv_data):

                # start counting bytes starting with the next read

                self.recv_pattern = None

        if remaining is not None and remaining <= 0:

            obj._writelog(b'read limit reached; closing socket')

            obj._cond_close()

            # This is the easiest way to abort the current request.

            raise Exception('connection closed after receiving N bytes')

        return result

# We can't adjust __class__ on a socket instance. So we define a proxy type.

class socketproxy:

    __slots__ = ('_orig', '_logfp', '_cond')

    def __init__(self, obj, logfp, condition_tracked):

        object.__setattr__(self, '_orig', obj)

        object.__setattr__(self, '_logfp', logfp)

        object.__setattr__(self, '_cond', condition_tracked)

    def __getattribute__(self, name):

        if name in ('makefile', 'sendall', '_writelog', '_cond_close'):

            return object.__getattribute__(self, name)

        return getattr(object.__getattribute__(self, '_orig'), name)

    def __delattr__(self, name):

        delattr(object.__getattribute__(self, '_orig'), name)

    def __setattr__(self, name, value):

        setattr(object.__getattribute__(self, '_orig'), name, value)

    def _writelog(self, msg):

        msg = msg.replace(b'\r', b'\\r').replace(b'\n', b'\\n')

        object.__getattribute__(self, '_logfp').write(msg)

        object.__getattribute__(self, '_logfp').write(b'\n')

        object.__getattribute__(self, '_logfp').flush()

    def makefile(self, mode, bufsize):

        f = object.__getattribute__(self, '_orig').makefile(mode, bufsize)

        logfp = object.__getattribute__(self, '_logfp')

        cond = object.__getattribute__(self, '_cond')

        return fileobjectproxy(f, logfp, cond)

    def sendall(self, data, flags=0):

        cond = object.__getattribute__(self, '_cond')

        return cond.forward_write(self, 'sendall', data, flags)

    def _cond_close(self):

        object.__getattribute__(self, '_orig').shutdown(socket.SHUT_RDWR)

# We can't adjust __class__ on socket._fileobject, so define a proxy.

class fileobjectproxy:

    __slots__ = ('_orig', '_logfp', '_cond')

    def __init__(self, obj, logfp, condition_tracked):

        object.__setattr__(self, '_orig', obj)

        object.__setattr__(self, '_logfp', logfp)

        object.__setattr__(self, '_cond', condition_tracked)

    def __getattribute__(self, name):

        if name in (

            '_close',

            'read',

            'readline',

            'write',

            '_writelog',

            '_cond_close',

        ):

            return object.__getattribute__(self, name)

        return getattr(object.__getattribute__(self, '_orig'), name)

    def __delattr__(self, name):

        delattr(object.__getattribute__(self, '_orig'), name)

    def __setattr__(self, name, value):

        setattr(object.__getattribute__(self, '_orig'), name, value)

    def _writelog(self, msg):

        msg = msg.replace(b'\r', b'\\r').replace(b'\n', b'\\n')

        object.__getattribute__(self, '_logfp').write(msg)

        object.__getattribute__(self, '_logfp').write(b'\n')

        object.__getattribute__(self, '_logfp').flush()

    def _close(self):

        # We wrap an io.BufferedIO instance.

        self.raw._sock.shutdown(socket.SHUT_RDWR)

    def read(self, size=-1):

        cond = object.__getattribute__(self, '_cond')

        return cond.forward_read(self, 'read', size)

    def readline(self, size=-1):

        cond = object.__getattribute__(self, '_cond')

        return cond.forward_read(self, 'readline', size)

    def write(self, data):

        cond = object.__getattribute__(self, '_cond')

        return cond.forward_write(self, 'write', data)

    def _cond_close(self):

        self._close()

def process_bytes_config(value):

    parts = value.split(b',')

    integers = [int(v) for v in parts if v]

    return [v if v else None for v in integers]

def process_pattern_config(value):

    patterns = []

    for p in value.split(b','):

        if not p:

            p = None

        else:

            p = re.compile(p, re.DOTALL | re.MULTILINE)

        patterns.append(p)

    return patterns

def extsetup(ui):

    # Change the base HTTP server class so various events can be performed.

    # See SocketServer.BaseServer for how the specially named methods work.

    class badserver(server.MercurialHTTPServer):

        def __init__(self, ui, *args, **kwargs):

            self._ui = ui

            super(badserver, self).__init__(ui, *args, **kwargs)

            all_recv_bytes = self._ui.config(

                b'badserver', b'close-after-recv-bytes'

            )