Python: execute ping as subprocess with timeout

[erotavlas]

Hi,
I have to measure RTT between several hosts in Internet. In python there are several libraries, however they require root access. For this reason I wrote a simple function that call system ping and parse the output.

for host in tqdm(hosts):
    ping=subprocess.Popen(["ping", "-c", "1", "-w", "0.2", host],stdout=subprocess.PIPE, stderr = subprocess.PIPE)
    [out, err]=ping.communicate()
    if ping.returncode == 0:
        avgRTT=re.search("rtt min/avg/max/mdev = (\d+.\d+)/(\d+.\d+)/(\d+.\d+)/(\d+.\d+)", str(out)).group(1)

I want to ping an host and timeout if it last over 200 ms (200 ms is the minimum value without having root access).
From man ping, I read that the options -w deadline and -W timeout should do the job, but they does not work as aspected if an host is unreachable.
I already read here and the only solution is to use fping that is not portable.
Thank you

[erotavlas]

Hi,
I solved by myself with the following code:

for host in tqdm(hosts):
    ping=subprocess.Popen(["ping", "-c", "1", proxy[0]],stdout=subprocess.PIPE,stderr=subprocess.PIPE)
        try:             
            [out, err]=ping.communicate(timeout=0.1)
            if ping.returncode == 0:
                avgRTT=re.search("rtt min/avg/max/mdev = (\d+.\d+)/(\d+.\d+)/(\d+.\d+)/(\d+.\d+)", str(out)).group(1)
            except subprocess.TimeoutExpired:
                ping.kill()

The only problem is that I have to use python3.3+ since even by installing subprocess32 does not work for me.

[riyawilliams]

Hai,
I tried this one, it worked out for me.
import subprocess

from threading import Timer

kill = lambda process: process.kill()
cmd = ['ping', 'www.google.com']
ping = subprocess.Popen(
cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

my_timer = Timer(5, kill, [ping])

try:
my_timer.start()
stdout, stderr = ping.communicate()
finally:
my_timer.cancel()
I used the python 3.3 it works fine.
Thank you,
Riya

[erotavlas]

Thank you of your answer of course your solution works for python3.3+ as the mine.
I think I will use only python3.3+. Moreover, I modified the script in order to work for different operating system.

for host in tqdm(hosts):
    if platform == "linux" or platform == "darwin":
        command=["ping", "-c", "3", "-i", "0.2", host]
            timeout=0.5
        else:
            command=["ping", "-n", "1", host]
            timeout=0.2
        ping=subprocess.Popen(command,stdout=subprocess.PIPE,stderr=subprocess.PIPE)
        try:             
            [out, err]=proc.communicate(timeout=2.1)
            if proc.returncode == 0:
                if platform == "linux" or platform == "darwin":
                    avgRTT=re.search("rtt min/avg/max/mdev = (\d+.\d+)/(\d+.\d+)/(\d+.\d+)/(\d+.\d+)", str(out)).group(2)
                else:
                    # to do
                    avgRTT=re.search("", str(out))

Unfortunately, windows has different ping version than GNU/linux or mac os X that does not support the option -i and so I have to play with timeout in order to limit the time required.
Moreover, also the parsing is different.