Add simple check script:

- check dns forward lookups
- check reachability via icmpv4/icmpv6 echo request

scripts/check

@@ -0,0 +1,131 @@
+#!/usr/bin/env python
+
+import sys
+import os
+import socket
+import subprocess
+from optparse import OptionParser
+
+
+def error(*arg):
+    print(*arg, file=sys.stderr)
+
+
+def check_host_lookup(hostname, port):
+    try:
+        return socket.getaddrinfo(hostname, port)
+    except Exception as e:
+        error("DNS Lookup for {hostname} failed".format(hostname=hostname))
+        return []
+
+
+def check_reachability(host, family):
+    if family is socket.AddressFamily.AF_INET:
+        process_name = 'ping'
+    else:
+        process_name = 'ping6'
+    child = subprocess.Popen([process_name, host, '-c', '1', '-W', '5'],
+                             stdout=subprocess.PIPE)
+    child.communicate()
+    if child.returncode:
+        error("Host {host} is unreachable".format(host=host))
+    return 0 if child.returncode == 0 else 1
+
+
+def get_hosts_data(srcdir):
+    for fname in sorted(list(set(os.listdir(srcdir)))):
+        if fname.startswith("."):
+            continue
+
+        fpath = os.path.join(srcdir, fname)
+        if os.path.isfile(fpath):
+            with open(fpath) as f:
+                ignore_key = False
+                addresses = []
+                port = 655  # tinc default port
+
+                for line in f.readlines():
+
+                    if '-----BEGIN RSA PUBLIC KEY-----' in line:
+                        ignore_key = True
+                    elif '-----END RSA PUBLIC KEY-----' in line:
+                        ignore_key = False
+
+                    if line.startswith("#") or ignore_key:
+                        continue
+
+                    chunks = line.split("=")
+                    if len(chunks) == 2:
+                        import pdb
+                        # pdb.set_trace()
+                        (k, v) = (x.strip().lower() for x in chunks)
+
+                        if k == "port":
+                            try:
+                                port = int(v)
+                            except ValueError:
+                                error("non-integer default port given")
+                        elif k == "address":
+                            if " " in v:
+                                parts = v.split(' ')
+                                if len(parts) != 2:
+                                    error("unknown address format")
+                                try:
+                                    int(parts[1])
+                                    addresses.append(parts)
+                                except ValueError:
+                                    error("non-integer port given")
+                            else:
+                                addresses.append((v, None))
+                        elif k in ('ecdsapublickey'):
+                            continue
+                        else:
+                            error("unknown key {key} with value {val}"
+                                  .format(key=k, val=v))
+
+                # set explicit port for address/port pairs
+                for i, addr in enumerate(addresses):
+                    if addr[1] is None:
+                        item = (addr[0], port)
+                        addresses[i] = item
+
+                yield(dict(community=fname, addresses=addresses))
+
+
+def do_checks(srcdir):
+    errcnt = 0
+    for host in get_hosts_data(srcdir):
+        print("Checking {community}".format(community=host['community']))
+        for address in host['addresses']:
+            host, port = address
+
+            # dns lookup
+            records = check_host_lookup(host, port)
+            if not records:
+                errcnt += 1
+            else:
+                for record in records:
+                    if record[1] is not socket.SocketType.SOCK_DGRAM:
+                        # we get SOCK_STREAM, SOCK_DGRAM and SOCK_RAW
+                        # for every IP/Port pair, lets just pick one
+                        # to have unique ip addresses
+                        continue
+                    errcnt += check_reachability(record[4][0], record[0])
+
+    print("{errcnt} errors".format(errcnt=errcnt))
+
+    return 0 if errcnt == 0 else 1
+
+
+if __name__ == "__main__":
+    parser = OptionParser()
+    parser.add_option("-s", "--sourcedir", dest="src",
+                      help="Location of tinc host files. Default: ../hosts",
+                      metavar="DIR",
+                      default="../hosts/")
+
+    (options, args) = parser.parse_args()
+
+    ret = do_checks(options.src)
+
+    sys.exit(ret)