path: root/src/utils/http.py

import asyncio, ipaddress, re, signal, socket, traceback, typing
import urllib.error, urllib.parse
import json as _json
import bs4, netifaces, requests
import tornado.httpclient
from src import utils

REGEX_URL = re.compile("https?://\S+", re.I)

PAIRED_CHARACTERS = ["<>", "()"]

# best-effort tidying up of URLs
def url_sanitise(url: str):
    if not urllib.parse.urlparse(url).scheme:
        url = "http://%s" % url

    for pair_start, pair_end in PAIRED_CHARACTERS:
        # trim ")" from the end only if there's not a "(" to match it
        # google.com/) -> google.com/
        # google.com/() -> google.com/()
        # google.com/()) -> google.com/()
        if url.endswith(pair_end):
            if pair_start in url:
                open_index = url.rfind("(")
                other_index = url.rfind(")", 0, len(url)-1)
                if not other_index == -1 and other_index < open_index:
                    url = url[:-1]
            else:
                url = url[:-1]
    return url

USER_AGENT = ("Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 "
    "(KHTML, like Gecko) Chrome/49.0.2623.87 Safari/537.36")

RESPONSE_MAX = (1024*1024)*100
SOUP_CONTENT_TYPES = ["text/html", "text/xml", "application/xml"]
DECODE_CONTENT_TYPES = ["text/plain"]+SOUP_CONTENT_TYPES

class HTTPException(Exception):
    pass
class HTTPTimeoutException(HTTPException):
    def __init__(self):
        Exception.__init__(self, "HTTP request timed out")
class HTTPParsingException(HTTPException):
    def __init__(self, message: str, data: str=None):
        Exception.__init__(self, message or "HTTP parsing failed")
class HTTPWrongContentTypeException(HTTPException):
    def __init__(self, message: str=None):
        Exception.__init__(self,
            message or "HTTP request gave wrong content type")

def throw_timeout():
    raise HTTPTimeoutException()

class Request(object):
    def __init__(self, url: str, method: str="GET",
            get_params: typing.Dict[str, str]={}, post_data: typing.Any=None,
            headers: typing.Dict[str, str]={},

            json: bool=False, allow_redirects: bool=True,
            check_content_type: bool=True, parse: bool=False,
            detect_encoding: bool=True,

            parser: str="lxml", fallback_encoding="iso-8859-1",
            content_type: str=None,

            **kwargs):
        self.set_url(url)
        self.method = method.upper()
        self.get_params = get_params
        self.post_data = post_data
        self.headers = headers

        self.json = json
        self.allow_redirects = allow_redirects
        self.check_content_type = check_content_type
        self.parse = parse
        self.detect_encoding = detect_encoding

        self.parser = parser
        self.fallback_encoding = fallback_encoding
        self.content_type = content_type

        if kwargs:
            if method == "POST":
                self.post_data = kwargs
            else:
                self.get_params.update(kwargs)

    def set_url(self, url: str):
        if not urllib.parse.urlparse(url).scheme:
            url = "http://%s" % url
        self.url = url

    def get_headers(self) -> typing.Dict[str, str]:
        headers = self.headers.copy()
        if not "Accept-Language" in headers:
            headers["Accept-Language"] = "en-GB"
        if not "User-Agent" in headers:
            headers["User-Agent"] = USER_AGENT
        if not "Content-Type" in headers and self.content_type:
            headers["Content-Type"] = self.content_type
        return headers

    def get_body(self) -> typing.Any:
        if self.content_type == "application/json":
            return _json.dumps(self.post_data)
        else:
            return self.post_data

class Response(object):
    def __init__(self, code: int, data: typing.Any,
            headers: typing.Dict[str, str]):
        self.code = code
        self.data = data
        self.headers = headers

def _meta_content(s: str) -> typing.Dict[str, str]:
    out = {}
    for keyvalue in s.split(";"):
        key, _, value = keyvalue.strip().partition("=")
        out[key] = value
    return out

def _find_encoding(soup: bs4.BeautifulSoup) -> typing.Optional[str]:
    if not soup.meta == None:
        meta_charset = soup.meta.get("charset")
        if not meta_charset == None:
            return meta_charset

        meta_content_type = soup.findAll("meta",
            {"http-equiv": lambda v: (v or "").lower() == "content-type"})
        if meta_content_type:
            return _meta_content(meta_content_type[0].get("content"))["charset"]

    doctype = [item for item in soup.contents if isinstance(item,
        bs4.Doctype)] or None
    if doctype and doctype[0] == "html":
        return "utf8"

    return None

def request(request_obj: typing.Union[str, Request], **kwargs) -> Response:
    if type(request_obj) == str:
        request_obj = Request(request_obj, **kwargs)
    return _request(request_obj)

def _request(request_obj: Request) -> Response:
    headers = request_obj.get_headers()

    with utils.deadline(seconds=5):
        try:
            response = requests.request(
                request_obj.method,
                request_obj.url,
                headers=headers,
                params=request_obj.get_params,
                data=request_obj.get_body(),
                allow_redirects=request_obj.allow_redirects,
                stream=True
            )
            response_content = response.raw.read(RESPONSE_MAX,
                decode_content=True)
            if not response_content or not response.raw.read(1) == b"":
                # response too large!
                pass
        except utils.DeadlineExceededException:
            raise HTTPTimeoutException()

    response_headers = utils.CaseInsensitiveDict(dict(response.headers))
    content_type = response.headers.get("Content-Type", "").split(";", 1)[0]

    encoding = response.encoding or request_obj.fallback_encoding
    if (request_obj.detect_encoding and
            content_type and content_type in SOUP_CONTENT_TYPES):
        souped = bs4.BeautifulSoup(response_content, request_obj.parser)
        encoding = _find_encoding(souped) or encoding

    def _decode_data():
        return response_content.decode(encoding)

    if request_obj.parse:
        if (not request_obj.check_content_type or
                content_type in SOUP_CONTENT_TYPES):
            souped = bs4.BeautifulSoup(_decode_data(), request_obj.parser)
            return Response(response.status_code, souped, response_headers)
        else:
            raise HTTPWrongContentTypeException(
                "Tried to soup non-html/non-xml data (%s)" % content_type)

    if request_obj.json and response_content:
        data = _decode_data()
        try:
            return Response(response.status_code, _json.loads(data),
                response_headers)
        except _json.decoder.JSONDecodeError as e:
            raise HTTPParsingException(str(e), data)

    if content_type in DECODE_CONTENT_TYPES:
        return Response(response.status_code, _decode_data(), response_headers)
    else:
        return Response(response.status_code, response_content,
            response_headers)

def request_many(urls: typing.List[str]) -> typing.Dict[str, Response]:
    responses = {}

    async def _request(url):
        client = tornado.httpclient.AsyncHTTPClient()
        request = tornado.httpclient.HTTPRequest(url, method="GET",
            connect_timeout=2, request_timeout=2)

        response = await client.fetch(request)

        headers = utils.CaseInsensitiveDict(dict(response.headers))
        data = response.body.decode("utf8")
        responses[url] = Response(response.code, data, headers)

    loop = asyncio.new_event_loop()
    awaits = []
    for url in urls:
        awaits.append(_request(url))
    task = asyncio.wait(awaits, loop=loop, timeout=5)
    loop.run_until_complete(task)
    loop.close()

    return responses

def strip_html(s: str) -> str:
    return bs4.BeautifulSoup(s, "lxml").get_text()

def resolve_hostname(hostname: str) -> typing.List[str]:
    try:
        addresses = socket.getaddrinfo(hostname, None, 0, socket.SOCK_STREAM)
    except:
        return []
    return [address[-1][0] for address in addresses]

def is_ip(addr: str) -> bool:
    try:
        ipaddress.ip_address(addr)
    except ValueError:
        return False
    return True

def is_localhost(hostname: str) -> bool:
    if is_ip(hostname):
        ips = [ipaddress.ip_address(hostname)]
    else:
        ips = [ipaddress.ip_address(ip) for ip in resolve_hostname(hostname)]

    for interface in netifaces.interfaces():
        links = netifaces.ifaddresses(interface)

        for link in links.get(netifaces.AF_INET, []
                )+links.get(netifaces.AF_INET6, []):
            address = ipaddress.ip_address(link["addr"].split("%", 1)[0])
            if address in ips:
                return True

    return False