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-rwxr-xr-xfiles/client/apt-avahi-discover138
1 files changed, 138 insertions, 0 deletions
diff --git a/files/client/apt-avahi-discover b/files/client/apt-avahi-discover
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--- /dev/null
+++ b/files/client/apt-avahi-discover
@@ -0,0 +1,138 @@
+#!/usr/bin/python
+#
+# use avahi to find a _apt_proxy._tcp provider and return
+# a http proxy string suitable for apt
+
+import asyncore
+import functools
+import os
+import socket
+import sys
+import time
+from subprocess import Popen, PIPE, call
+from syslog import syslog, LOG_INFO, LOG_USER
+
+DEFAULT_CONNECT_TIMEOUT_SEC = 2
+
+def DEBUG(msg):
+ if "--debug" in sys.argv:
+ sys.stderr.write(msg + "\n")
+
+
+def get_avahi_discover_timeout():
+ APT_AVAHI_TIMEOUT_VAR = "APT::Avahi-Discover::Timeout"
+ p = Popen(
+ ["/usr/bin/apt-config", "shell", "TIMEOUT", APT_AVAHI_TIMEOUT_VAR],
+ stdout=PIPE)
+ stdout, stderr = p.communicate()
+ if not stdout:
+ DEBUG(
+ "no timeout set, using default '%s'" % DEFAULT_CONNECT_TIMEOUT_SEC)
+ return DEFAULT_CONNECT_TIMEOUT_SEC
+ if not stdout.startswith("TIMEOUT="):
+ raise ValueError("got unexpected apt-config output: '%s'" % stdout)
+ varname, sep, value = stdout.strip().partition("=")
+ timeout = int(value.strip("'"))
+ DEBUG("using timeout: '%s'" % timeout)
+ return timeout
+
+@functools.total_ordering
+class AptAvahiClient(asyncore.dispatcher):
+ def __init__(self, addr):
+ asyncore.dispatcher.__init__(self)
+ if is_ipv6(addr[0]):
+ self.create_socket(socket.AF_INET6, socket.SOCK_STREAM)
+ self.connect( (addr[0], addr[1], 0, 0) )
+ else:
+ self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
+ self.connect(addr)
+ self._time_init = time.time()
+ self.time_to_connect = sys.maxint
+ self.address = addr
+ def handle_connect(self):
+ self.time_to_connect = time.time() - self._time_init
+ self.close()
+ def __eq__(self, other):
+ return self.time_to_connect == other.time_to_connect
+ def __lt__(self, other):
+ return self.time_to_connect < other.time_to_connect
+ def __repr__(self):
+ return "<%s> %s: %s" % (
+ self.__class__.__name__, self.addr, self.time_to_connect)
+ def log(self, message):
+ syslog((LOG_INFO|LOG_USER), '%s\n' % str(message))
+ def log_info(self, message, type='info'):
+ if type not in self.ignore_log_types:
+ self.log('%s: %s' % (type, message))
+
+
+def is_ipv6(a):
+ return ':' in a
+
+def is_linklocal(addr):
+ # Link-local should start with fe80 and six null bytes
+ return addr.startswith("fe80::")
+
+def get_proxy_host_port_from_avahi():
+ service = '_apt_proxy._tcp'
+
+ # Obtain all of the services addresses from avahi, pulling the IPv6
+ # addresses to the top.
+ addr4 = []
+ addr6 = []
+ p = Popen(['avahi-browse', '-kprtf', service], stdout=PIPE)
+ DEBUG("avahi-browse output:")
+ for line in p.stdout:
+ DEBUG(" '%s'" % line)
+ if line.startswith('='):
+ tokens = line.split(';')
+ addr = tokens[7]
+ port = int(tokens[8])
+ if is_ipv6(addr):
+ # We need to skip ipv6 link-local addresses since
+ # APT can't use them
+ if not is_linklocal(addr):
+ addr6.append((addr, port))
+ else:
+ addr4.append((addr, port))
+
+ # Run through the offered addresses and see if we we have a bound local
+ # address for it.
+ addrs = []
+ for (ip, port) in addr6 + addr4:
+ try:
+ res = socket.getaddrinfo(ip, port, 0, 0, 0, socket.AI_ADDRCONFIG)
+ if res:
+ addrs.append((ip, port))
+ except socket.gaierror:
+ pass
+ if not addrs:
+ return None
+
+ # sort by answering speed
+ hosts = []
+ for addr in addrs:
+ hosts.append(AptAvahiClient(addr))
+ # 2s timeout, arbitray
+ timeout = get_avahi_discover_timeout()
+ asyncore.loop(timeout=timeout)
+ DEBUG("sorted hosts: '%s'" % sorted(hosts))
+
+ # No host wanted to connect
+ if (all(h.time_to_connect == sys.maxint for h in hosts)):
+ return None
+
+ fastest_host = sorted(hosts)[0]
+ fastest_address = fastest_host.address
+ return fastest_address
+
+
+if __name__ == "__main__":
+ # Dump the approved address out in an appropriate format.
+ address = get_proxy_host_port_from_avahi()
+ if address:
+ (ip, port) = address
+ if is_ipv6(ip):
+ print "http://[%s]:%s/" % (ip, port)
+ else:
+ print "http://%s:%s/" % (ip, port)