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check-http/yunodiagnoser.py
Laurent Peuch 69d6d54911 [fix] never do catch all exceptions
2021-01-08 02:33:56 +01:00

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Python
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import re
import time
import asyncio
import aiohttp
import validators
import socket
from sanic import Sanic
from sanic.log import logger
from sanic.response import html, json as json_response
from sanic.exceptions import InvalidUsage
app = Sanic()
# ########################################################################### #
# Rate limit #
# ########################################################################### #
# keep that in memory
RATE_LIMIT_DB = {}
# to prevent DDoS or bounce attack attempt or something like that
# Can't do more than 10 requests in a 300-seconds window
RATE_LIMIT_SECONDS = 300
RATE_LIMIT_NB_REQUESTS = 10
def clear_rate_limit_db(now):
to_delete = []
"Remove too old rate limit values"
for key, times in RATE_LIMIT_DB.items():
# Remove values older RATE_LIMIT_SECONDS
RATE_LIMIT_DB[key] = [t for t in times if now - t < RATE_LIMIT_SECONDS]
# If list is empty, remove the key
if RATE_LIMIT_DB[key] == []:
# a dictionnary can't be modified during iteration so delegate this
# operation
to_delete.append(key)
for key in to_delete:
del RATE_LIMIT_DB[key]
def check_rate_limit(key, now):
# If there are more recent attempts than allowed
if key in RATE_LIMIT_DB and len(RATE_LIMIT_DB[key]) > RATE_LIMIT_NB_REQUESTS:
oldest_attempt = RATE_LIMIT_DB[key][0]
logger.info(f"Rate limit reached for {key}, can retry in {int(RATE_LIMIT_SECONDS - now + oldest_attempt)} seconds")
return json_response({
"error": {
"code": "error_rate_limit",
"content": f"Rate limit reached for this domain or ip, retry in {int(RATE_LIMIT_SECONDS - now + oldest_attempt)} seconds"
}
}, status=400)
# In any case, add this attempt to the DB
if key not in RATE_LIMIT_DB:
RATE_LIMIT_DB[key] = [now]
else:
RATE_LIMIT_DB[key].append(now)
# ########################################################################### #
# HTTP check #
# ########################################################################### #
@app.route("/check-http", methods=["POST"])
async def check_http(request):
"""
This function received an HTTP request from a YunoHost instance while this
server is hosted on our infrastructure. The request is expected to be a
POST request with a body like {"domains": ["domain1.tld", "domain2.tld"],
"nonce": "1234567890abcdef" }
The nonce value is a single-use ID, and we will try to reach
http://domain.tld/.well-known/ynh-{nonce} which should return 200 if we
are indeed reaching the right server.
The general workflow is the following:
- grab the ip from the request
- check for ip based rate limit (see RATE_LIMIT_SECONDS value)
- get json from body and domain from it
- check for domain-based rate limit (see RATE_LIMIT_SECONDS value)
- check domains are in valid format
- for each domain:
- try to do an http request on the ip (using the domain as target host) for the page /.well-known/ynh-diagnosis/{nonce}
- answer saying if the domain can be reached
"""
# this is supposed to be a fast operation if run often enough
now = time.time()
clear_rate_limit_db(now)
# ############################################# #
# Validate request and extract the parameters #
# ############################################# #
ip = request.headers["x-forwarded-for"].split(",")[0]
check_rate_limit_ip = check_rate_limit(ip, now)
if check_rate_limit_ip:
return check_rate_limit_ip
try:
data = request.json
except InvalidUsage:
logger.info(f"Invalid json in request, body is: {request.body}")
return json_response({
"error": {
"code": "error_bad_json",
"content": "Invalid usage, body isn't proper json"
}
}, status=400)
try:
assert data, "Empty request body"
assert isinstance(data, dict), "Request body ain't a proper dict"
assert "domains" in data, "No 'domains' provided"
assert "nonce" in data, "No 'nonce' provided"
# Check domain list format
assert isinstance(data["domains"], list), "'domains' ain't a list"
assert len(data["domains"]) > 0, "'domains' list is empty"
assert len(data["domains"]) < 30, "You cannot test that many domains"
for domain in data["domains"]:
assert isinstance(domain, str), "domain names must be strings"
assert len(domain) < 100, "Domain %s name seems pretty long, that's suspicious...?" % domain
assert len(data["domains"]) == len(set(data["domains"])), "'domains' list should contain unique elements"
# Check domain rate limit
for domain in data["domains"]:
check_rate_limit_domain = check_rate_limit(domain, now)
if check_rate_limit_domain:
return check_rate_limit_domain
# Check domains are valid domain names
for domain in data["domains"]:
assert validators.domain(domain), f"{domain} is not a valid domain"
# Check nonce format
assert isinstance(data["nonce"], str), "'nonce' ain't a string"
assert re.match(r"^[a-f0-9]{16}$", data["nonce"]), "'nonce' is not in the right forwat (it should be a 16-digit hexadecimal string)"
except AssertionError as e:
logger.info(f"Invalid request: {e} ... Original request body was: {request.body}")
return json_response({
"error": {
"code": "error_bad_json_data",
"content": f"Invalid request: {e} ... Original request body was: {request.body}"
}
}, status=400)
domains = data["domains"]
nonce = data["nonce"]
return json_response({
"http": {domain: await check_http_domain(ip, domain, nonce) for domain in domains}
})
async def check_http_domain(ip, domain, nonce):
if ":" in ip:
ip = "[%s]" % ip
async with aiohttp.ClientSession() as session:
try:
url = "http://" + ip + "/.well-known/ynh-diagnosis/" + nonce
async with session.get(url,
headers={"Host": domain},
allow_redirects=False,
timeout=aiohttp.ClientTimeout(total=5)) as response:
# XXX in the futur try to do a double check with the server to
# see if the correct content is get
await response.text()
# TODO various kind of errors
except (aiohttp.client_exceptions.ServerTimeoutError, asyncio.TimeoutError):
return {
"status": "error_http_check_timeout",
"content": "Timed-out while trying to contact your server from outside. It appears to be unreachable. You should check that you're correctly forwarding port 80, that nginx is running, and that a firewall is not interfering.",
}
except aiohttp.client_exceptions.ClientConnectorError as e:
return {
"status": "error_http_check_connection_error",
"content": "Connection error: could not connect to the requested domain, it's very likely unreachable. Raw error: " + str(e),
}
except Exception as e:
import traceback
traceback.print_exc()
return {
"status": "error_http_check_unknown_error",
"content": "An error happened while trying to reach your domain, it's very likely unreachable. Raw error: %s" % e,
}
if response.status != 200:
return {
"status": "error_http_check_bad_status_code",
"content": "Could not reach your server as expected, it returned code %s. It might be that another machine answered instead of your server. You should check that you're correctly forwarding port 80, that your nginx configuration is up to date, and that a reverse-proxy is not interfering." % response.status,
}
else:
return {
"status": "ok"
}
# ########################################################################### #
# Ports check #
# ########################################################################### #
@app.route("/check-ports/", methods=["POST"])
async def check_ports(request):
"""
This function received an HTTP request from a YunoHost instance while this
server is hosted on our infrastructure. The request is expected to be a
POST request with a body like {"ports": [80,443,22,25]}
The general workflow is the following:
- grab the ip from the request
- check for ip based rate limit (see RATE_LIMIT_SECONDS value)
- get json from body and ports list from it
- check ports are opened or closed
- answer the list of opened / closed ports
"""
# this is supposed to be a fast operation if run often enough
now = time.time()
clear_rate_limit_db(now)
# ############################################# #
# Validate request and extract the parameters #
# ############################################# #
ip = request.headers["x-forwarded-for"].split(",")[0]
check_rate_limit_ip = check_rate_limit(ip, now)
if check_rate_limit_ip:
return check_rate_limit_ip
try:
data = request.json
except InvalidUsage:
logger.info(f"Invalid json in request, body is: {request.body}")
return json_response({
"error": {
"code": "error_bad_json",
"content": "Invalid usage, body isn't proper json"
}
}, status=400)
try:
assert data, "Empty request body"
assert isinstance(data, dict), "Request body ain't a proper dict"
assert "ports" in data, "No 'ports' provided"
assert isinstance(data["ports"], list), "'ports' ain't a list"
assert len(data["ports"]) > 0, "'ports' list is empty"
assert len(data["ports"]) < 30, "That's too many ports to check"
assert len(data["ports"]) == len(set(data["ports"])), "'ports' list should contain unique elements"
def is_port_number(p):
return isinstance(p, int) and p > 0 and p < 65535
assert all(is_port_number(p) for p in data["ports"]), "'ports' should a list of valid port numbers"
except AssertionError as e:
logger.info(f"Invalid request: {e} ... Original request body was: {request.body}")
return json_response({
"error": {
"code": "error_bad_json_data",
"content": f"Invalid request: {e} ... Original request body was: {request.body}"
}
}, status=400)
# ############################################# #
# Run the actual check #
# ############################################# #
result = {}
for port in data["ports"]:
result[int(port)] = await check_port_is_open(ip, port)
return json_response({"ports": result})
async def check_port_is_open(ip, port):
if ":" in ip:
sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
else:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(2)
result = sock.connect_ex((ip, port))
sock.close()
return result == 0
# ########################################################################### #
# SMTP check #
# ########################################################################### #
@app.route("/check-smtp/", methods=["POST"])
async def check_smtp(request):
"""
This function received an HTTP request from a YunoHost instance while this
server is hosted on our infrastructure. The request is expected to be a
POST request with an empty body
The general workflow is the following:
- grab the ip from the request
- check for ip based rate limit (see RATE_LIMIT_SECONDS value)
- open a socket on port 25
- the server is supposed to say '200 domain.tld Service ready'
- we return the domain.tld found
"""
# this is supposed to be a fast operation if run often enough
now = time.time()
clear_rate_limit_db(now)
# ############################################# #
# Validate request and extract the parameters #
# ############################################# #
ip = request.headers["x-forwarded-for"].split(",")[0]
check_rate_limit_ip = check_rate_limit(ip, now)
if check_rate_limit_ip:
return check_rate_limit_ip
if ":" in ip:
sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
else:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(2)
result = sock.connect_ex((ip, 25))
if result != 0:
return json_response({
'status': "error_smtp_unreachable",
'content': "Could not open a connection on port 25, probably because of a firewall or port forwarding issue"
})
try:
recv = sock.recv(1024).decode('utf-8')
assert recv[:3] == "220"
helo_domain = recv.split()[1].strip()
except Exception as e:
import traceback
traceback.print_exc()
print(f"Error when trying to get smtp answer: {e}")
return json_response({
'status': "error_smtp_bad_answer",
'content': "SMTP server did not reply with '220 domain.tld' after opening socket ... Maybe another machine answered."
})
finally:
sock.close()
return json_response({'status': 'ok', 'helo': helo_domain})
@app.route("/")
async def main(request):
return html("You aren't really supposed to use this website using your browser.<br><br>It's a small server with an API to check if a services running on YunoHost instance can be reached from 'the global internet'.")
if __name__ == "__main__":
app.run(host="0.0.0.0", port=7000)
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