import re
import shutil
import signal
+import socket
import subprocess
import string
import sys
pass
def find_available_port():
- """Return a port number that is not in use right now.
+ """Return an IPv4 port number that is not in use right now.
+
+ We assume whoever needs to use the returned port is able to reuse
+ a recently used port without waiting for TIME_WAIT (see
+ SO_REUSEADDR / SO_REUSEPORT).
Some opportunity for races here, but it's better than choosing
something at random and not checking at all. If all of our servers
(hey Passenger) knew that listening on port 0 was a thing, the OS
would take care of the races, and this wouldn't be needed at all.
"""
- port = None
- while port is None:
- port = random.randint(20000, 40000)
- port_hex = ':%04x ' % port
- try:
- with open('/proc/net/tcp', 'r') as f:
- for line in f:
- if 0 <= string.find(line, port_hex):
- port = None
- break
- except OSError:
- # This isn't going so well. Just use the random port.
- pass
- except IOError:
- pass
+
+ sock = socket.socket()
+ sock.bind(('0.0.0.0', 0))
+ port = sock.getsockname()[1]
+ sock.close()
return port
def run(leave_running_atexit=False):