proxywatchd: preliminary support for ip caching

whenever we make a socks4 check, the ip of the destination server
needs to be resolved because socks4 does not support server-side
dns resolution. in order to prevent doing the same lookups over
and over, we know manually resolve the ip before first usage, and
store it in a cache.

proxywatchd.py

@@ -13,6 +13,7 @@ import rocksock
 config = Config()
 
 _run_standalone = False
+cached_dns = dict()
 
 class WorkerJob():
 	def __init__(self, proxy, proto, failcount, success_count, total_duration):
@@ -24,7 +25,7 @@ class WorkerJob():
 		self.total_duration = total_duration
 
 	def connect_socket(self):
-		srv = random.choice(config.servers).strip()
+		srvname = random.choice(config.servers).strip()
 		protos = ['http', 'socks5', 'socks4'] if self.proto is None else [self.proto]
 		server_port = 6697 if config.watchd.use_ssl else 6667
 
@@ -32,6 +33,31 @@ class WorkerJob():
 
 		for proto in protos:
 			torhost = random.choice(config.torhosts)
+			srv = srvname
+			if proto == 'socks4':
+				# socks4 (without 4a) requires a raw ip address
+				# rocksock automatically resolves if needed, but it's more
+				# efficient to cache the result.
+				if srv in cached_dns:
+					srv = cached_dns[srvname]
+					if config.watchd.debug:
+						_log("using cached ip (%s) for %s (proxy: %s)"%(srv, srvname, self.proxy), "debug")
+				else:
+					dns_fail = False
+					try:
+						af, sa = rocksock.resolve(rocksock.RocksockHostinfo(srvname, server_port), want_v4=True)
+						if sa is not None:
+							cached_dns[srvname] = sa[0]
+							srv = sa[0]
+						else: dns_fail = True
+					except rocksock.RocksockException as e:
+						assert(e.get_errortype() == rocksock.RS_ET_GAI)
+						dns_fail = True
+					if dns_fail:
+						fail_inc = 0
+						_log("could not resolve connection target %s"%srvname, "ERROR")
+						break
+
 			duration = time.time()
 			proxies = [
 				rocksock.RocksockProxyFromURL('socks4://%s' % torhost),
@@ -42,7 +68,7 @@ class WorkerJob():
 				sock = rocksock.Rocksock(host=srv, port=server_port, ssl=config.watchd.use_ssl, proxies=proxies, timeout=config.watchd.timeout)
 				sock.connect()
 				sock.send('%s\n' % random.choice(['NICK', 'USER', 'JOIN', 'MODE', 'PART', 'INVITE', 'KNOCK', 'WHOIS', 'WHO', 'NOTICE', 'PRIVMSG', 'PING', 'QUIT']))
-				return sock, proto, duration, torhost, srv, 0
+				return sock, proto, duration, torhost, srvname, 0
 			except rocksock.RocksockException as e:
 				if config.watchd.debug:
 					_log("proxy failed: %s://%s: %s"%(proto, self.proxy, e.get_errormessage()), 'debug')
@@ -66,8 +92,9 @@ class WorkerJob():
 							_log("could not connect to proxy 0, sleep 5s", "ERROR")
 						time.sleep(5)
 				elif et == rocksock.RS_ET_GAI:
+					assert(0)
 					fail_inc = 0
-					_log("could not resolve connection target %s"%srv, "ERROR")
+					_log("could not resolve connection target %s"%srvname, "ERROR")
 					break
 
 			except KeyboardInterrupt as e: