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# client.py
#
# Copyright 2019 Jason McBrayer
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from email.message import EmailMessage
import codecs
import collections
import fnmatch
import io
import mimetypes
import os.path
import random
import shlex
import shutil
import socket
import subprocess
import tempfile
import urllib.parse
import ssl
import sys
import time
class Response:
content = None
content_type = None
charset = None
lang = None
url = None
status = None
status_meta = None
prompt = None
num_bytes = None
error_message = None
def __init__(
self, content=None, content_type=None, charset=None, lang=None, url=None, status=None, status_meta=None, prompt=None, num_bytes=None, error_message=None
):
self.content = content
self.content_type = content_type
self.charset = charset
self.lang = lang
self.url = url
self.status = status
self.status_meta = status_meta
self.prompt = prompt
self.num_bytes = num_bytes
self.error_message = error_message
def fetch(raw_url):
# Do everything which touches the network in one block,
# so we only need to catch exceptions once
url = urllib.parse.urlparse(raw_url, 'gemini')
header = ""
try:
# Is this a local file?
if not url.netloc:
print("ERROR: {} parses with no netloc".format(raw_url))
f.close()
return
else:
address, f = _send_request(url)
# Read response header
header = f.readline(1027)
header = header.decode("UTF-8")
if not header or header[-1] != '\n':
_debug("ERROR: Received invalid header from server!")
return
header = header.strip()
_debug("Response header: %s." % header)
# Catch network errors which may happen on initial connection
except Exception as err:
# Print an error message
if isinstance(err, socket.gaierror):
print("ERROR: DNS error!")
return
elif isinstance(err, ConnectionRefusedError):
print("ERROR: Connection refused!")
return
elif isinstance(err, ConnectionResetError):
print("ERROR: Connection reset!")
return
elif isinstance(err, (TimeoutError, socket.timeout)):
print(
"""ERROR: Connection timed out!
Slow internet connection? Use 'set timeout' to be more patient."""
)
return
else:
print("ERROR: " + str(err))
return
# Validate header
header_split = header.split(maxsplit=1)
if len(header_split) < 1:
print("ERROR: Received invalid header from server!")
f.close()
return
status = header_split[0]
if len(header_split) > 1:
meta = header_split[1]
if len(header) > 1024 or len(status) != 2 or not status.isnumeric():
print("ERROR: Received invalid header from server!")
f.close()
return
# Handle headers. Not all headers are handled yet.
# Input
if status.startswith("1"):
if len(header_split) < 2:
print("ERROR: Input status requires a meta value in header!")
return
return Response(
url=url.geturl(),
status=status,
prompt=meta,
)
# Redirects
elif status.startswith("3"):
if len(header_split) < 2:
print("ERROR: Redirect status requires a meta value in header!")
return
return Response(
url=urllib.parse.urlparse(meta).geturl(),
status=status,
)
# Errors
elif status.startswith("4") or status.startswith("5"):
if len(header_split) < 2:
print("ERROR: Error status requires a meta value in header!")
return
return Response(
status=status,
error_message=meta,
)
return
# Client cert
elif status.startswith("6"):
print("ERROR: The requested resource requires client-certificate")
return
# Invalid status
elif not status.startswith("2"):
print("ERROR: Server returned undefined status code %s!" % status)
return
# Handle success
assert status.startswith("2")
if len(header_split) < 2:
print("ERROR: Success status requires a meta value in header!")
return
mime = meta
if mime == "":
mime = "text/gemini; charset=utf-8"
msg = EmailMessage()
msg['content-type'] = mime
mime, mime_options = msg.get_content_type(), msg['Content-Type'].params
default_charset = "utf-8"
charset = None
if "charset" in mime_options:
try:
codecs.lookup(mime_options["charset"])
charset = mime_options["charset"]
except LookupError:
print("Header declared unknown encoding %s" % mime_options["charset"])
return
lang = mime_options["lang"] if "lang" in mime_options else None
# Read the response body over the network
try:
body = f.read()
except Exception:
print("Error reading response over network!")
return
if mime.startswith("text/"):
try:
content = codecs.decode(body, charset or default_charset)
except:
# print("ERROR: problem decoding content with %s charset" % charset)
return
else:
content = body
return Response(
content=content,
content_type=mime,
charset=charset,
lang=lang,
num_bytes=len(body),
url=url.geturl(),
status=status,
)
def _send_request(url):
"""Send a selector to a given host and port.
Returns the resolved address and binary file with the reply."""
port = url.port if url.port is not None else 1965
addresses = _get_addresses(url.hostname, port)
# Connect to remote host by any address possible
err = None
for address in addresses:
_debug("Connecting to: " + str(address[4]))
s = socket.socket(address[0], address[1])
s.settimeout(15.0)
context = ssl.SSLContext(protocol=ssl.PROTOCOL_TLS_CLIENT)
context.check_hostname = False
context.verify_mode = ssl.CERT_NONE
# Impose minimum TLS version
if sys.version_info.minor == 7:
context.minimum_version = ssl.TLSVersion.TLSv1_2
else:
context.options | ssl.OP_NO_TLSv1_1
context.options | ssl.OP_NO_SSLv3
context.options | ssl.OP_NO_SSLv2
context.set_ciphers(
"AES256-GCM-SHA384:AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!3DES:!MD5:!PSK"
)
# print(context.get_ciphers())
s = context.wrap_socket(s, server_hostname=url.hostname)
try:
s.connect(address[4])
break
except OSError as e:
err = e
else:
# If we couldn't connect to *any* of the addresses, just
# bubble up the exception from the last attempt and deny
# knowledge of earlier failures.
raise err
_debug("Established {} connection.".format(s.version()))
_debug("Cipher is: {}.".format(s.cipher()))
# Send request and wrap response in a file descriptor
_debug("Sending %s<CRLF>" % url.geturl())
s.sendall((url.geturl() + "\r\n").encode("UTF-8"))
return address, s.makefile(mode="rb")
def _get_addresses(host, port):
# DNS lookup - will get IPv4 and IPv6 records if IPv6 is enabled
if ":" in host:
# This is likely a literal IPv6 address, so we can *only* ask for
# IPv6 addresses or getaddrinfo will complain
family_mask = socket.AF_INET6
elif socket.has_ipv6:
# Accept either IPv4 or IPv6 addresses
family_mask = 0
else:
# IPv4 only
family_mask = socket.AF_INET
addresses = socket.getaddrinfo(
host, port, family=family_mask, type=socket.SOCK_STREAM
)
# Sort addresses so IPv6 ones come first
addresses.sort(key=lambda add: add[0] == socket.AF_INET6, reverse=True)
return addresses
def _parse_url(url):
"""Work around issues with Python's urrlib.parse"""
pass
def _debug(message):
pass