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from __future__ import (absolute_import, print_function, division)
from netlib.http.http1 import HTTP1Protocol
from netlib.http.http2 import HTTP2Protocol
from .rawtcp import RawTcpLayer
from .tls import TlsLayer, is_tls_record_magic
from .http import Http1Layer, Http2Layer
class RootContext(object):
"""
The outmost context provided to the root layer.
As a consequence, every layer has .client_conn, .channel, .next_layer() and .config.
"""
def __init__(self, client_conn, config, channel):
self.client_conn = client_conn # Client Connection
self.channel = channel # provides .ask() method to communicate with FlowMaster
self.config = config # Proxy Configuration
def next_layer(self, top_layer):
"""
This function determines the next layer in the protocol stack.
Arguments:
top_layer: the current top layer.
Returns:
The next layer
"""
# 1. Check for --ignore.
if self.config.check_ignore(top_layer.server_conn.address):
return RawTcpLayer(top_layer, logging=False)
# 2. Check for TLS
# 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
d = top_layer.client_conn.rfile.peek(3)
if is_tls_record_magic(d):
return TlsLayer(top_layer, True, True)
# 3. Check for --tcp
if self.config.check_tcp(top_layer.server_conn.address):
return RawTcpLayer(top_layer)
# 4. Check for TLS ALPN (HTTP1/HTTP2)
if isinstance(top_layer, TlsLayer):
alpn = top_layer.client_conn.get_alpn_proto_negotiated()
if alpn == HTTP2Protocol.ALPN_PROTO_H2:
return Http2Layer(top_layer, 'transparent')
if alpn == HTTP1Protocol.ALPN_PROTO_HTTP1:
return Http1Layer(top_layer, 'transparent')
# 5. Assume HTTP1 by default
return Http1Layer(top_layer, 'transparent')
# In a future version, we want to implement TCP passthrough as the last fallback,
# but we don't have the UI part ready for that.
#
# d = top_layer.client_conn.rfile.peek(3)
# is_ascii = (
# len(d) == 3 and
# # better be safe here and don't expect uppercase...
# all(x in string.ascii_letters for x in d)
# )
# # TODO: This could block if there are not enough bytes available?
# d = top_layer.client_conn.rfile.peek(len(HTTP2Protocol.CLIENT_CONNECTION_PREFACE))
# is_http2_magic = (d == HTTP2Protocol.CLIENT_CONNECTION_PREFACE)
@property
def layers(self):
return []
def __repr__(self):
return "RootContext"
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