Files
CN2021/client/ResponseHandler.py
2021-03-21 13:10:57 +01:00

308 lines
9.9 KiB
Python

import logging
import os
import re
from abc import ABC, abstractmethod
from typing import Dict
from urllib.parse import urlparse
from bs4 import BeautifulSoup
from client.Retriever import Retriever
from client.httpclient import HTTPClient, UnsupportedEncoding, FORMAT, InvalidResponse, InvalidStatusLine
class ResponseHandler(ABC):
client: HTTPClient
headers: Dict[str, str]
status_code: int
url: str
retriever: Retriever
def __init__(self, retriever: Retriever, client: HTTPClient, headers: Dict[str, str], url: str):
self.client = client
self.headers = headers
self.url = url
self.retriever = retriever
pass
@abstractmethod
def handle(self):
pass
@staticmethod
def create(client: HTTPClient, headers, status_code, url):
# only chunked transfer-encoding is supported
transfer_encoding = headers.get("transfer-encoding")
if transfer_encoding and transfer_encoding != "chunked":
raise UnsupportedEncoding("transfer-encoding", transfer_encoding)
chunked = transfer_encoding
# content-encoding is not supported
content_encoding = headers.get("content-encoding")
if content_encoding:
raise UnsupportedEncoding("content-encoding", content_encoding)
retriever = Retriever.create(client, headers)
content_type = headers.get("content-type")
if content_type and "text/html" in content_type:
return HTMLDownloadHandler(retriever, client, headers, url)
return RawDownloadHandler(retriever, client, headers, url)
@staticmethod
def get_status_line(client: HTTPClient):
line = client.read_line()
split = list(filter(None, line.split(" ")))
if len(split) < 3:
raise InvalidStatusLine(line)
# Check HTTP version
http_version = split.pop(0)
if len(http_version) < 8 or http_version[4] != "/":
raise InvalidStatusLine(line)
(name, version) = http_version[:4], http_version[5:]
if name != "HTTP" or not re.match(r"1\.[0|1]", version):
raise InvalidStatusLine(line)
status = split.pop(0)
if not re.match(r"\d{3}", status):
raise InvalidStatusLine(line)
status = int(status)
if status < 100 or status > 999:
raise InvalidStatusLine(line)
reason = split.pop(0)
return version, status, reason
@staticmethod
def get_headers(client: HTTPClient):
headers = []
# first header after the status-line may not contain a space
while True:
line = client.read_line()
if line[0].isspace():
continue
else:
break
while True:
if line in ("\r\n", "\n", " "):
break
if line[0].isspace():
headers[-1] = headers[-1].rstrip("\r\n")
headers.append(line.lstrip())
line = client.read_line()
result = {}
header_str = "".join(headers)
for line in header_str.splitlines():
pos = line.find(":")
if pos <= 0 or pos >= len(line) - 1:
continue
(header, value) = map(str.strip, line.split(":", 1))
ResponseHandler.check_next_header(result, header, value)
result[header.lower()] = value.lower()
return result
@staticmethod
def check_next_header(headers, next_header: str, next_value: str):
if next_header == "content-length":
if "content-length" in headers:
logging.error("Multiple content-length headers specified")
raise InvalidResponse()
if not next_value.isnumeric() or int(next_value) <= 0:
logging.error("Invalid content-length value: %r", next_value)
raise InvalidResponse()
@staticmethod
def parse_uri(uri: str):
parsed = urlparse(uri)
# If there is no netloc, the url is invalid, so prepend `//` and try again
if parsed.netloc == "":
parsed = urlparse("//" + uri)
host = parsed.netloc
path = parsed.path
if len(path) == 0 or path[0] != '/':
path = "/" + path
return host, path
class DownloadHandler(ResponseHandler, ABC):
path: str
def __init__(self, retriever: Retriever, client: HTTPClient, headers: Dict[str, str], url: str, dir=None):
super().__init__(retriever, client, headers, url)
if not dir:
dir = self._create_directory()
self.path = self._get_duplicate_name(os.path.join(dir, self.get_filename()))
@staticmethod
def create(retriever: Retriever, client: HTTPClient, headers: Dict[str, str], url: str, dir=None):
content_type = headers.get("content-type")
if content_type and "text/html" in content_type:
return HTMLDownloadHandler(retriever, client, headers, url, dir)
return RawDownloadHandler(retriever, client, headers, url, dir)
def _create_directory(self):
path = self._get_duplicate_name(os.path.abspath(self.client.host))
os.mkdir(path)
return path
def _get_duplicate_name(self, path):
tmp_path = path
i = 0
while os.path.exists(tmp_path):
i += 1
tmp_path = "{path}.{counter}".format(path=path, counter=i)
return tmp_path
def get_filename(self):
"""Returns the filename to download the payload to.
"""
filename = "index.html"
parsed = urlparse(self.url)
# If there is no netloc, the url is invalid, so prepend `//` and try again
if parsed.netloc == "":
parsed = urlparse("//" + self.url)
# If the path contains a `/` get only the last part and use it as filename
# If the path end with a `/`, it's a directory so ignore it.
if len(parsed.path) != 0:
index = parsed.path.rfind("/")
if index == -1:
filename = parsed.path
elif parsed.path[-1] != "/":
filename = parsed.path[index:]
result = os.path.basename(filename).strip()
if any(letter.isalnum() for letter in result):
return result
return "index.html"
def _handle_sub_request(self, client, url):
(version, status, _) = self.get_status_line(client)
logging.debug("Parsed status-line: version: %s, status: %s", version, status)
headers = self.get_headers(client)
logging.debug("Parsed headers: %r", headers)
if status != 200:
raise InvalidResponse("Status not expected 200: " + str(status))
retriever = Retriever.create(client, headers)
handler = RawDownloadHandler(retriever, client, headers, url, os.path.dirname(self.path))
return handler.handle()
class RawDownloadHandler(DownloadHandler):
def __init__(self, retriever: Retriever, client: HTTPClient, headers: Dict[str, str], url: str, dir=None):
super().__init__(retriever, client, headers, url, dir)
def handle(self) -> str:
logging.debug("Retrieving payload")
file = open(self.path, "wb")
for buffer in self.retriever.retrieve():
file.write(buffer)
file.close()
return self.path
class HTMLDownloadHandler(DownloadHandler):
def __init__(self, retriever: Retriever, client: HTTPClient, headers: Dict[str, str], url: str, dir=None):
super().__init__(retriever, client, headers, url, dir)
def handle(self) -> str:
(dir, file) = os.path.split(self.path)
tmp_filename = ".{file}.tmp".format(file=file)
tmp_path = os.path.join(dir, tmp_filename)
file = open(tmp_path, "wb")
for buffer in self.retriever.retrieve():
file.write(buffer)
file.close()
self.__download_images(tmp_path, self.path)
os.remove(tmp_path)
return self.path
def __download_images(self, tmp_filename, target_filename):
(host, path) = ResponseHandler.parse_uri(self.url)
with open(tmp_filename, "rb") as fp:
soup = BeautifulSoup(fp, 'html.parser')
base_url = self.url
base_element = soup.find("base")
if base_element:
base_url = base_element["href"]
for tag in soup.find_all("img"):
try:
tag["src"] = self.__download_image(tag["src"], host, base_url)
except Exception as e:
logging.debug(e)
logging.error("Failed to download image: %s, skipping...", tag["src"])
with open(target_filename, 'w') as file:
file.write(str(soup))
def __download_image(self, img_src, host, base_url):
parsed = urlparse(img_src)
logging.debug("Downloading image: %s", img_src)
if len(parsed.netloc) == 0 and parsed.path != "/":
# relative url, append base_url
img_src = os.path.join(os.path.dirname(base_url), parsed.path)
parsed = urlparse(img_src)
# Check if the image is located on the same server
if len(parsed.netloc) == 0 or parsed.netloc == host:
same_host = True
img_host = host
img_path = parsed.path
else:
same_host = False
(img_host, img_path) = ResponseHandler.parse_uri(img_src)
message = "GET {path} HTTP/1.1\r\n".format(path=img_path)
message += "Accept: */*\r\nAccept-Encoding: identity\r\n"
message += "Host: {host}\r\n\r\n".format(host=host)
message = message.encode(FORMAT)
if same_host:
client = self.client
client.reset_request()
else:
client = HTTPClient(img_src)
client.connect((img_host, 80))
client.sendall(message)
filename = self._handle_sub_request(client, img_host + img_path)
if not same_host:
client.close()
return filename