diff options
Diffstat (limited to 'libmproxy/protocol2/tls.py')
| -rw-r--r-- | libmproxy/protocol2/tls.py | 288 |
1 files changed, 0 insertions, 288 deletions
diff --git a/libmproxy/protocol2/tls.py b/libmproxy/protocol2/tls.py deleted file mode 100644 index 73bb12f3..00000000 --- a/libmproxy/protocol2/tls.py +++ /dev/null @@ -1,288 +0,0 @@ -from __future__ import (absolute_import, print_function, division) - -import struct - -from construct import ConstructError - -from netlib.tcp import NetLibError, NetLibInvalidCertificateError -from netlib.http.http1 import HTTP1Protocol -from ..contrib.tls._constructs import ClientHello -from ..exceptions import ProtocolException -from .layer import Layer - - -def is_tls_record_magic(d): - """ - Returns: - True, if the passed bytes start with the TLS record magic bytes. - False, otherwise. - """ - d = d[:3] - - # TLS ClientHello magic, works for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 - # http://www.moserware.com/2009/06/first-few-milliseconds-of-https.html#client-hello - return ( - len(d) == 3 and - d[0] == '\x16' and - d[1] == '\x03' and - d[2] in ('\x00', '\x01', '\x02', '\x03') - ) - - -class TlsLayer(Layer): - def __init__(self, ctx, client_tls, server_tls): - self.client_sni = None - self.client_alpn_protocols = None - - super(TlsLayer, self).__init__(ctx) - self._client_tls = client_tls - self._server_tls = server_tls - - self._sni_from_server_change = None - - def __call__(self): - """ - The strategy for establishing SSL is as follows: - First, we determine whether we need the server cert to establish ssl with the client. - If so, we first connect to the server and then to the client. - If not, we only connect to the client and do the server_ssl lazily on a Connect message. - - An additional complexity is that establish ssl with the server may require a SNI value from the client. - In an ideal world, we'd do the following: - 1. Start the SSL handshake with the client - 2. Check if the client sends a SNI. - 3. Pause the client handshake, establish SSL with the server. - 4. Finish the client handshake with the certificate from the server. - There's just one issue: We cannot get a callback from OpenSSL if the client doesn't send a SNI. :( - Thus, we manually peek into the connection and parse the ClientHello message to obtain both SNI and ALPN values. - - Further notes: - - OpenSSL 1.0.2 introduces a callback that would help here: - https://www.openssl.org/docs/ssl/SSL_CTX_set_cert_cb.html - - The original mitmproxy issue is https://github.com/mitmproxy/mitmproxy/issues/427 - """ - - client_tls_requires_server_cert = ( - self._client_tls and self._server_tls and not self.config.no_upstream_cert - ) - - if self._client_tls: - self._parse_client_hello() - - if client_tls_requires_server_cert: - self._establish_tls_with_client_and_server() - elif self._client_tls: - self._establish_tls_with_client() - - layer = self.ctx.next_layer(self) - layer() - - def __repr__(self): - if self._client_tls and self._server_tls: - return "TlsLayer(client and server)" - elif self._client_tls: - return "TlsLayer(client)" - elif self._server_tls: - return "TlsLayer(server)" - else: - return "TlsLayer(inactive)" - - def _get_client_hello(self): - """ - Peek into the socket and read all records that contain the initial client hello message. - - Returns: - The raw handshake packet bytes, without TLS record header(s). - """ - client_hello = "" - client_hello_size = 1 - offset = 0 - while len(client_hello) < client_hello_size: - record_header = self.client_conn.rfile.peek(offset + 5)[offset:] - if not is_tls_record_magic(record_header) or len(record_header) != 5: - raise ProtocolException('Expected TLS record, got "%s" instead.' % record_header) - record_size = struct.unpack("!H", record_header[3:])[0] + 5 - record_body = self.client_conn.rfile.peek(offset + record_size)[offset + 5:] - if len(record_body) != record_size - 5: - raise ProtocolException("Unexpected EOF in TLS handshake: %s" % record_body) - client_hello += record_body - offset += record_size - client_hello_size = struct.unpack("!I", '\x00' + client_hello[1:4])[0] + 4 - return client_hello - - def _parse_client_hello(self): - """ - Peek into the connection, read the initial client hello and parse it to obtain ALPN values. - """ - try: - raw_client_hello = self._get_client_hello()[4:] # exclude handshake header. - except ProtocolException as e: - self.log("Cannot parse Client Hello: %s" % repr(e), "error") - return - - try: - client_hello = ClientHello.parse(raw_client_hello) - except ConstructError as e: - self.log("Cannot parse Client Hello: %s" % repr(e), "error") - self.log("Raw Client Hello:\r\n:%s" % raw_client_hello.encode("hex"), "debug") - return - - for extension in client_hello.extensions: - if extension.type == 0x00: - if len(extension.server_names) != 1 or extension.server_names[0].type != 0: - self.log("Unknown Server Name Indication: %s" % extension.server_names, "error") - self.client_sni = extension.server_names[0].name - elif extension.type == 0x10: - self.client_alpn_protocols = list(extension.alpn_protocols) - - self.log( - "Parsed Client Hello: sni=%s, alpn=%s" % (self.client_sni, self.client_alpn_protocols), - "debug" - ) - - def connect(self): - if not self.server_conn: - self.ctx.connect() - if self._server_tls and not self.server_conn.tls_established: - self._establish_tls_with_server() - - def reconnect(self): - self.ctx.reconnect() - if self._server_tls and not self.server_conn.tls_established: - self._establish_tls_with_server() - - def set_server(self, address, server_tls=None, sni=None, depth=1): - self.ctx.set_server(address, server_tls, sni, depth) - if depth == 1 and server_tls is not None: - self._sni_from_server_change = sni - self._server_tls = server_tls - - @property - def sni_for_server_connection(self): - if self._sni_from_server_change is False: - return None - else: - return self._sni_from_server_change or self.client_sni - - @property - def alpn_for_client_connection(self): - return self.server_conn.get_alpn_proto_negotiated() - - def __alpn_select_callback(self, conn_, options): - """ - Once the client signals the alternate protocols it supports, - we reconnect upstream with the same list and pass the server's choice down to the client. - """ - - # This gets triggered if we haven't established an upstream connection yet. - default_alpn = HTTP1Protocol.ALPN_PROTO_HTTP1 - # alpn_preference = netlib.http.http2.HTTP2Protocol.ALPN_PROTO_H2 - - if self.alpn_for_client_connection in options: - choice = bytes(self.alpn_for_client_connection) - elif default_alpn in options: - choice = bytes(default_alpn) - else: - choice = options[0] - self.log("ALPN for client: %s" % choice, "debug") - return choice - - def _establish_tls_with_client_and_server(self): - self.ctx.connect() - - # If establishing TLS with the server fails, we try to establish TLS with the client nonetheless - # to send an error message over TLS. - try: - self._establish_tls_with_server() - except Exception as e: - try: - self._establish_tls_with_client() - except: - pass - raise e - - self._establish_tls_with_client() - - def _establish_tls_with_client(self): - self.log("Establish TLS with client", "debug") - cert, key, chain_file = self._find_cert() - - try: - self.client_conn.convert_to_ssl( - cert, key, - method=self.config.openssl_method_client, - options=self.config.openssl_options_client, - cipher_list=self.config.ciphers_client, - dhparams=self.config.certstore.dhparams, - chain_file=chain_file, - alpn_select_callback=self.__alpn_select_callback, - ) - except NetLibError as e: - raise ProtocolException("Cannot establish TLS with client: %s" % repr(e), e) - - def _establish_tls_with_server(self): - self.log("Establish TLS with server", "debug") - try: - # We only support http/1.1 and h2. - # If the server only supports spdy (next to http/1.1), it may select that - # and mitmproxy would enter TCP passthrough mode, which we want to avoid. - deprecated_http2_variant = lambda x: x.startswith("h2-") or x.startswith("spdy") - if self.client_alpn_protocols: - alpn = filter(lambda x: not deprecated_http2_variant(x), self.client_alpn_protocols) - else: - alpn = None - - self.server_conn.establish_ssl( - self.config.clientcerts, - self.sni_for_server_connection, - method=self.config.openssl_method_server, - options=self.config.openssl_options_server, - verify_options=self.config.openssl_verification_mode_server, - ca_path=self.config.openssl_trusted_cadir_server, - ca_pemfile=self.config.openssl_trusted_ca_server, - cipher_list=self.config.ciphers_server, - alpn_protos=alpn, - ) - tls_cert_err = self.server_conn.ssl_verification_error - if tls_cert_err is not None: - self.log( - "TLS verification failed for upstream server at depth %s with error: %s" % - (tls_cert_err['depth'], tls_cert_err['errno']), - "error") - self.log("Ignoring server verification error, continuing with connection", "error") - except NetLibInvalidCertificateError as e: - tls_cert_err = self.server_conn.ssl_verification_error - self.log( - "TLS verification failed for upstream server at depth %s with error: %s" % - (tls_cert_err['depth'], tls_cert_err['errno']), - "error") - self.log("Aborting connection attempt", "error") - raise ProtocolException("Cannot establish TLS with server: %s" % repr(e), e) - except NetLibError as e: - raise ProtocolException("Cannot establish TLS with server: %s" % repr(e), e) - - self.log("ALPN selected by server: %s" % self.alpn_for_client_connection, "debug") - - def _find_cert(self): - host = self.server_conn.address.host - sans = set() - # Incorporate upstream certificate - use_upstream_cert = ( - self.server_conn and - self.server_conn.tls_established and - (not self.config.no_upstream_cert) - ) - if use_upstream_cert: - upstream_cert = self.server_conn.cert - sans.update(upstream_cert.altnames) - if upstream_cert.cn: - sans.add(host) - host = upstream_cert.cn.decode("utf8").encode("idna") - # Also add SNI values. - if self.client_sni: - sans.add(self.client_sni) - if self._sni_from_server_change: - sans.add(self._sni_from_server_change) - - sans.discard(host) - return self.config.certstore.get_cert(host, list(sans)) |