I have the following code sample
import socket
try:
sock=socket
sock.setdefaulttimeout(1)
for result in sock.gethostbyaddr("165.139.149.169"):
if result and "[" not in str(result):
print str(result)
except socket.herror:
print("Host Not Found")
which works as part of a network discovery type POC that I'm building (mostly to learn Python). As I said, the code works, but when an address has no DNS record it takes forever. Is there a way to change the timeout of the sock.gethostbyaddr() method so that it will throw host not found sooner?
Related
Good day. I apologize for asking for obvious things because I'm writing in PHP and I know Python at the level "I started learning this yesterday". I've already spent a few days on this - but to no avail.
I downloaded twisted example of the SSH server for version 20.3 from here https://docs.twistedmatrix.com/en/twisted-20.3.0/conch/examples/. Line 162 has an execCommand method that I need to implement to make it work. Then I noticed a comment in this method "We don't support command execution sessions". Therefore, the question: Is this comment apply only to the example, or twisted library entirely. Ie, is it possible to implement this method to make the example server will work as I need?
More information. I don't think that this info is required to answer my questions above.
Why do I need it? I'm trying to compile an environment for writing functional (!) tests (there would be no such problems with the unit tests, I guess). Our API uses the SSH client (phpseclib / SSH2) by 30%+ of endpoints. Whatever I do, I had only 3 options of the results depending on how did I implement this method: (result: success, response: "" - empty; result: success, response: "1"; result: failed, response: "Unable to fulfill channel request at… SSH2.php:3853"). Those were for an SSH2 Client. If the error occurs (3rd case), the server shows logs in the terminal:
[SSHServerTransport, 0,127.0.0.1] Got remote error, code 11 reason: ""
[SSHServerTransport, 0,127.0.0.1] connection lost
I just found this works:
def execCommand(self, protocol, cmd):
protocol.write('Some text to return')
protocol.session.conn.sendEOF(protocol.session)
If I don't send EOF the client throws a timeout error.
Working with Python 2.7 on Raspberry pi, I created a Pushbullet account and installed it on my iPhone 7 (iOS 12.4). In this instance, I'm using a github library from https://github.com/rbrcsk/pushbullet.py but I've noticed this lag using other methods as well.
Here's the code:
#!/usr/bin/env python
from pushbullet import Pushbullet
PB_API_KEY = 'o.00000000000000000000000000000000'
print("creating pb object with key:")
try:
pb = Pushbullet(PB_API_KEY)
except Exception as e:
print (str(e))
exit()
print("pushing note:")
try:
push = pb.push_note('important subject','this is a test')
except Exception as e:
print (str(e))
exit()
print ("done")
What happens is, when I run this script, it prints "creating pb object with key:" and then it appears to hang. 30 minutes (or so) later the notification appeared on my phone, and I saw that the next two print lines had appeared and the script had completed.
I'm anxious to begin using Pushbullet to push alarm notifications from my PI-GPIO home alarms. It appears to work, but why the big lag?
This issue was related to an incorrect ipV6 setting in my router (as in, it was enabled for some reason). This was giving me a stack of gateway and DNS addresses that had to time out before I could get a request out. So - this problem is NOT related to pushbullet.
Sorry about this false alarm.
===SIMPLE & SHORT===
Does anybody have working application that talks with Poloniex through WAMP in these days (January, 2018)?
===MORE SPECIFIC===
I used several info sources to make it work using combo: autobahn-cpp & C++. Windows 10 OS.
I was able to connect to wss://api.poloniex.com, realm1. Plus I was able to subscribe and get subscription ID. But I never got any events even when everything established.
===RESEARCH===
During research in the web I saw a lot of controversial information:
1. Claims, that wss://api2.poloniex.com should be used, and channels names are actually numbers - How to connect to poloniex.com websocket api using a python library
2. This answer gave me base code, but I am getting anything more than just connections, also by following this answer - wss://api.poloniex.com is correct address - Connecting to Poloniex Push-API
3. I saw post (sorry, lost the link), there were comments made that websockets implementation are basically broken on poloniex. They were posted 6 months ago.
===SPECS===
1. Windows 10
2. Autobahn-Cpp
3. wss://api.poloniex.com:443 ; realm1
4. Different subscriptions: ticker, BTC_ETH, 148, 1002, etc..
5. Source code I got from here
===WILL HELP AS WELL===
Is there any way to get all valid subscriptions or, probably, those, that have more than 0 subscribers? I mean, does WAMP have a way to do that?
Is there any known issues with Autobahn-Cpp and poloniex combo?
Is there any simpler way to test WAMP elsewhere to make sure Autobahn isn't a problem? Like any other well documented & supported online projects that accept WAMP websocket communication?
I can receive the correct tick order book data from wss://api2.poloniex.com use python3
but sometime The channel 1002 may stop sending the new tick info.
wss://api.poloniex.com:443 ; realm1
This may be the issue as I've been using api2 and here is the code that works, and has been working for the past 2 quarters non-stop. Its in python, but should be easy enough to port to C++.
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import websocket
import json
def on_error(ws, error):
print(error)
def on_close(ws):
print("### closed ###")
connection.close()
def on_open(ws):
print("ONOPEN")
ws.send(json.dumps({'command':'subscribe','channel':'BTC_ETH'}))
def on_message(ws, message):
message = json.loads(message)
print(message)
websocket.enableTrace(True)
ws = websocket.WebSocketApp("wss://api2.poloniex.com/",
on_message = on_message,
on_error = on_error,
on_close = on_close)
ws.on_open = on_open
ws.run_forever()
the code is pretty much self-explanatory (You can check all channels/pairs on Poloniex API website), just save it and run in terminal
python3 fileName.py
should provide You with BTCETH raw stream of orders and trades on console output.
Playing with the message/subscriptions You can then do as You please with it.
It seems that websockets in Poloniex are unstable. Therefore I can stop my attempts make Autobahn-Cpp work with it at least by now and move on.
I tried creating a simple libtorrent python client (for magnet uri), and I failed, the program never continues past the "downloading metadata".
If you may help me write a simple client it would be amazing.
P.S. When I choose a save path, is the save path the folder which I want my data to be saved in? or the path for the data itself.
(I used a code someone posted here)
import libtorrent as lt
import time
ses = lt.session()
ses.listen_on(6881, 6891)
params = {
'save_path': '/home/downloads/',
'storage_mode': lt.storage_mode_t(2),
'paused': False,
'auto_managed': True,
'duplicate_is_error': True}
link = "magnet:?xt=urn:btih:4MR6HU7SIHXAXQQFXFJTNLTYSREDR5EI&tr=http://tracker.vodo.net:6970/announce"
handle = lt.add_magnet_uri(ses, link, params)
ses.start_dht()
print 'downloading metadata...'
while (not handle.has_metadata()):
time.sleep(1)
print 'got metadata, starting torrent download...'
while (handle.status().state != lt.torrent_status.seeding):
s = handle.status()
state_str = ['queued', 'checking', 'downloading metadata', \
'downloading', 'finished', 'seeding', 'allocating']
print '%.2f%% complete (down: %.1f kb/s up: %.1f kB/s peers: %d) %s %.3' % \
(s.progress * 100, s.download_rate / 1000, s.upload_rate / 1000, \
s.num_peers, state_str[s.state], s.total_download/1000000)
time.sleep(5)
What happens it is that the first while loop becomes infinite because the state does not change.
You have to add a s = handle.status (); for having the metadata the status changes and the loop stops. Alternatively add the first while inside the other while so that the same will happen.
Yes, the save path you specify is the one that the torrents will be downloaded to.
As for the metadata downloading part, I would add the following extensions first:
ses.add_extension(lt.create_metadata_plugin)
ses.add_extension(lt.create_ut_metadata_plugin)
Second, I would add a DHT bootstrap node:
ses.add_dht_router("router.bittorrent.com", 6881)
Finally, I would begin debugging the application by seeing if my network interface is binding or if any other errors come up (my experience with BitTorrent download problems, in general, is that they are network related). To get an idea of what's happening I would use libtorrent-rasterbar's alert system:
ses.set_alert_mask(lt.alert.category_t.all_categories)
And make a thread (with the following code) to collect the alerts and display them:
while True:
ses.wait_for_alert(500)
alert = lt_session.pop_alert()
if not alert:
continue
print "[%s] %s" % (type(alert), alert.__str__())
Even with all this working correctly, make sure that torrent you are trying to download actually has peers. Even if there are a few peers, none may be configured correctly or support metadata exchange (exchanging metadata is not a standard BitTorrent feature). Try to load a torrent file (which doesn't require downloading metadata) and see if you can download successfully (to rule out some network issues).
I'm running a django-celery application on Ubuntu-12.04.
When I run a celery task from my web interface, I get the following error, taken form postgresql-9.3 logfile (maximum level of log):
2013-11-12 13:57:01 GMT tss_usr 8113 LOG: could not receive data from client: Connection reset by peer
tss_usr is the postgresql user of the django application database and (in this example) 8113 is the pid of the process who killed the connection, I guess.
Have you got any idea on why this happens or at least how to debug this issue?
To make things work again I need to restart postgresql which is extremely uncomfortable.
I know this is an older post, but I just found it because I had the same error today in my postgres logs. I narrowed it down to a PDO select statement. I'm using Zend Framework 1.10.3 on Ubuntu Precise.
The following pdo statement generated an error if $opinion is a long text string. The column opinion is type Text in my postgres table. The query succeeds if $opinion is under a certain number of characters. 1000 characters works fine. 2000 characters fails with "could not receive data from client: Connection reset by peer".
$select = $this->db->select()
->from( 'datauserstopics' )
->where("opinion = ?",trim($opinion))
->where("datatopicsid = ?",trim($tid))
->where("datausersid= ?",$datausersid);
$stmt = $this->db->query($select);
I circumvented the problem by using:
->where("substr(opinion,1,100) = ?",trim(substr($opinion,1,100)))
This is not a perfect solution, but for my purposes, the select statement using substr() suffices.
Note that I have no problem inserting long strings into the same table/column. The disconnect problem only appears for me on the PDO select with relatively long text strings.
I'm getting it in 2017 with 9.4, I have no text fields, don't know what a PDO is. My select statement is about 50 bytes long, I'm trying to fetch an int4 and a double precision. I suspect the error message can mean multiple things.
I've since found https://dba.stackexchange.com/questions/142350/postgres-could-not-receive-data-from-client-connection-reset-by-peer which indicates it could be a problem with the client configuration. My client is libpg and PQconnectdb() is giving me a CONNECTION_OK return. It works at least partly.
For me, restarting the hypervisor where both the Postgres and the application using it helped. I've seen stack traces in dmesg before, though.