from __future__ import absolute_import, print_function, division import time import sys import re from netlib.http import request from netlib.http import response from netlib.http import headers from netlib.http import url from netlib import utils from netlib import exceptions def get_header_tokens(headers, key): """ Retrieve all tokens for a header key. A number of different headers follow a pattern where each header line can containe comma-separated tokens, and headers can be set multiple times. """ if key not in headers: return [] tokens = headers[key].split(",") return [token.strip() for token in tokens] def read_request(rfile, body_size_limit=None): request = read_request_head(rfile) expected_body_size = expected_http_body_size(request) request.data.content = b"".join(read_body(rfile, expected_body_size, limit=body_size_limit)) request.timestamp_end = time.time() return request def read_request_head(rfile): """ Parse an HTTP request head (request line + headers) from an input stream Args: rfile: The input stream Returns: The HTTP request object (without body) Raises: exceptions.HttpReadDisconnect: No bytes can be read from rfile. exceptions.HttpSyntaxException: The input is malformed HTTP. exceptions.HttpException: Any other error occured. """ timestamp_start = time.time() if hasattr(rfile, "reset_timestamps"): rfile.reset_timestamps() form, method, scheme, host, port, path, http_version = _read_request_line(rfile) headers = _read_headers(rfile) if hasattr(rfile, "first_byte_timestamp"): # more accurate timestamp_start timestamp_start = rfile.first_byte_timestamp return request.Request( form, method, scheme, host, port, path, http_version, headers, None, timestamp_start ) def read_response(rfile, request, body_size_limit=None): response = read_response_head(rfile) expected_body_size = expected_http_body_size(request, response) response.data.content = b"".join(read_body(rfile, expected_body_size, body_size_limit)) response.timestamp_end = time.time() return response def read_response_head(rfile): """ Parse an HTTP response head (response line + headers) from an input stream Args: rfile: The input stream Returns: The HTTP request object (without body) Raises: exceptions.HttpReadDisconnect: No bytes can be read from rfile. exceptions.HttpSyntaxException: The input is malformed HTTP. exceptions.HttpException: Any other error occured. """ timestamp_start = time.time() if hasattr(rfile, "reset_timestamps"): rfile.reset_timestamps() http_version, status_code, message = _read_response_line(rfile) headers = _read_headers(rfile) if hasattr(rfile, "first_byte_timestamp"): # more accurate timestamp_start timestamp_start = rfile.first_byte_timestamp return response.Response(http_version, status_code, message, headers, None, timestamp_start) def read_body(rfile, expected_size, limit=None, max_chunk_size=4096): """ Read an HTTP message body Args: rfile: The input stream expected_size: The expected body size (see :py:meth:`expected_body_size`) limit: Maximum body size max_chunk_size: Maximium chunk size that gets yielded Returns: A generator that yields byte chunks of the content. Raises: exceptions.HttpException, if an error occurs Caveats: max_chunk_size is not considered if the transfer encoding is chunked. """ if not limit or limit < 0: limit = sys.maxsize if not max_chunk_size: max_chunk_size = limit if expected_size is None: for x in _read_chunked(rfile, limit): yield x elif expected_size >= 0: if limit is not None and expected_size > limit: raise exceptions.HttpException( "HTTP Body too large. " "Limit is {}, content length was advertised as {}".format(limit, expected_size) ) bytes_left = expected_size while bytes_left: chunk_size = min(bytes_left, max_chunk_size) content = rfile.read(chunk_size) if len(content) < chunk_size: raise exceptions.HttpException("Unexpected EOF") yield content bytes_left -= chunk_size else: bytes_left = limit while bytes_left: chunk_size = min(bytes_left, max_chunk_size) content = rfile.read(chunk_size) if not content: return yield content bytes_left -= chunk_size not_done = rfile.read(1) if not_done: raise exceptions.HttpException("HTTP body too large. Limit is {}.".format(limit)) def connection_close(http_version, headers): """ Checks the message to see if the client connection should be closed according to RFC 2616 Section 8.1. """ # At first, check if we have an explicit Connection header. if "connection" in headers: tokens = get_header_tokens(headers, "connection") if "close" in tokens: return True elif "keep-alive" in tokens: return False # If we don't have a Connection header, HTTP 1.1 connections are assumed to # be persistent return http_version != "HTTP/1.1" and http_version != b"HTTP/1.1" # FIXME: Remove one case. def expected_http_body_size(request, response=None): """ Returns: The expected body length: - a positive integer, if the size is known in advance - None, if the size in unknown in advance (chunked encoding) - -1, if all data should be read until end of stream. Raises: exceptions.HttpSyntaxException, if the content length header is invalid """ # Determine response size according to # http://tools.ietf.org/html/rfc7230#section-3.3 if not response: headers = request.headers response_code = None is_request = True else: headers = response.headers response_code = response.status_code is_request = False if is_request: if headers.get("expect", "").lower() == "100-continue": return 0 else: if request.method.upper() == "HEAD": return 0 if 100 <= response_code <= 199: return 0 if response_code == 200 and request.method.upper() == "CONNECT": return 0 if response_code in (204, 304): return 0 if "chunked" in headers.get("transfer-encoding", "").lower(): return None if "content-length" in headers: try: size = int(headers["content-length"]) if size < 0: raise ValueError() return size except ValueError: raise exceptions.HttpSyntaxException("Unparseable Content Length") if is_request: return 0 return -1 def _get_first_line(rfile): try: line = rfile.readline() if line == b"\r\n" or line == b"\n": # Possible leftover from previous message line = rfile.readline() except exceptions.TcpDisconnect: raise exceptions.HttpReadDisconnect("Remote disconnected") if not line: raise exceptions.HttpReadDisconnect("Remote disconnected") return line.strip() def _read_request_line(rfile): try: line = _get_first_line(rfile) except exceptions.HttpReadDisconnect: # We want to provide a better error message. raise exceptions.HttpReadDisconnect("Client disconnected") try: method, path, http_version = line.split(b" ") if path == b"*" or path.startswith(b"/"): form = "relative" scheme, host, port = None, None, None elif method == b"CONNECT": form = "authority" host, port = _parse_authority_form(path) scheme, path = None, None else: form = "absolute" scheme, host, port, path = url.parse(path) _check_http_version(http_version) except ValueError: raise exceptions.HttpSyntaxException("Bad HTTP request line: {}".format(line)) return form, method, scheme, host, port, path, http_version def _parse_authority_form(hostport): """ Returns (host, port) if hostport is a valid authority-form host specification. http://tools.ietf.org/html/draft-luotonen-web-proxy-tunneling-01 section 3.1 Raises: ValueError, if the input is malformed """ try: host, port = hostport.split(b":") port = int(port) if not utils.is_valid_host(host) or not utils.is_valid_port(port): raise ValueError() except ValueError: raise exceptions.HttpSyntaxException("Invalid host specification: {}".format(hostport)) return host, port def _read_response_line(rfile): try: line = _get_first_line(rfile) except exceptions.HttpReadDisconnect: # We want to provide a better error message. raise exceptions.HttpReadDisconnect("Server disconnected") try: parts = line.split(b" ", 2) if len(parts) == 2: # handle missing message gracefully parts.append(b"") http_version, status_code, message = parts status_code = int(status_code) _check_http_version(http_version) except ValueError: raise exceptions.HttpSyntaxException("Bad HTTP response line: {}".format(line)) return http_version, status_code, message def _check_http_version(http_version): if not re.match(br"^HTTP/\d\.\d$", http_version): raise exceptions.HttpSyntaxException("Unknown HTTP version: {}".format(http_version)) def _read_headers(rfile): """ Read a set of headers. Stop once a blank line is reached. Returns: A headers object Raises: exceptions.HttpSyntaxException """ ret = [] while True: line = rfile.readline() if not line or line == b"\r\n" or line == b"\n": break if line[0] in b" \t": if not ret: raise exceptions.HttpSyntaxException("Invalid headers") # continued header ret[-1] = (ret[-1][0], ret[-1][1] + b'\r\n ' + line.strip()) else: try: name, value = line.split(b":", 1) value = value.strip() if not name: raise ValueError() ret.append((name, value)) except ValueError: raise exceptions.HttpSyntaxException( "Invalid header line: %s" % repr(line) ) return headers.Headers(ret) def _read_chunked(rfile, limit=sys.maxsize): """ Read a HTTP body with chunked transfer encoding. Args: rfile: the input file limit: A positive integer """ total = 0 while True: line = rfile.readline(128) if line == b"": raise exceptions.HttpException("Connection closed prematurely") if line != b"\r\n" and line != b"\n": try: length = int(line, 16) except ValueError: raise exceptions.HttpSyntaxException("Invalid chunked encoding length: {}".format(line)) total += length if total > limit: raise exceptions.HttpException( "HTTP Body too large. Limit is {}, " "chunked content longer than {}".format(limit, total) ) chunk = rfile.read(length) suffix = rfile.readline(5) if suffix != b"\r\n": raise exceptions.HttpSyntaxException("Malformed chunked body") if length == 0: return yield chunk