我写了一些查询adns的代码。这段代码的问题是它被卡住了，怎么办？让我解释一下：
假设我的dnslist为[“ 8.8.4.4”，“ 8.8.8.8”，“ 208.67.220.220”，“ 208.67.222.222”，“ 192.168.50.1”]
它将从列表中弹出一个dns并再次查询它，这意味着将以相反的顺序查询DNS。
不管我做什么，它都不会显示它首先选择的dns的结果（在我们的情况下为192.168.50.1）
我不确定该DNS是否回复过
首先，我将DNS列表更改为仅包含最后一个DNS服务器，并且代码执行正常
其次，我将旧列表与5个DNS服务器一起使用，除了最后一个由我管理，因此我可以跟踪代码是否查询它，令我惊讶的是查询确实发生了。
这样就进行了查询，我们得到了结果，但是由于某种原因该结果从未插入到resolve_hosts中，并且由于未插入该结果，因此其长度将保持小于dnslist的长度，从而导致无限循环。
您认为可能是什么原因导致了此问题，以及如何解决？
代码执行结果
Inside class's init'
Data
host www.yahoo.com
dnslist length 5
intensity 1
Inside resolve()
inside finished_resolving()
Resolved : 0/5
Inside 'while not finished_resolving'
Queue: 0/1
Launching Querying for www.yahoo.com/1 on 192.168.50.1
Queue: 1/1
Launching Querying for www.yahoo.com/1 on 208.67.222.222
inside collect_results()
inside finished_resolving()
Resolved : 0/5
Inside 'while not finished_resolving'
------------------------ CLIPPED ----------------
Inside 'while not finished_resolving'
inside collect_results()
Inside collect_results's for query in self.adns.completed()
DNS used was208.67.222.222
Answered : (0, 'any-fp.wa1.b.yahoo.com', 1286169807, ('69.147.125.65', '67.195.160.76'))
Resolved www.yahoo.com to 69.147.125.65 using 208.67.222.222
Resolved hosts count1
And they are:
{'208.67.222.222': '69.147.125.65'}
inside finished_resolving()
Resolved : 1/5
Inside 'while not finished_resolving'
Queue: 1/1
Launching Querying for www.yahoo.com/1 on 208.67.220.220
inside collect_results()
inside finished_resolving()
Resolved : 1/5
Inside 'while not finished_resolving'
-------------------------- CLIPPED --------------------
inside collect_results()
Inside collect_results's for query in self.adns.completed()
DNS used was208.67.220.220
Answered : (0, 'any-fp.wa1.b.yahoo.com', 1286169790, ('67.195.160.76', '69.147.125.65'))
Resolved www.yahoo.com to 67.195.160.76 using 208.67.220.220
Resolved hosts count2
And they are:
{'208.67.222.222': '69.147.125.65', '208.67.220.220': '67.195.160.76'}
inside finished_resolving()
Resolved : 2/5
Inside 'while not finished_resolving'
Queue: 1/1
Launching Querying for www.yahoo.com/1 on 8.8.8.8
inside collect_results()
inside finished_resolving()
Resolved : 2/5
Inside 'while not finished_resolving'
-------------------------- CLIPPED --------------------
inside collect_results()
Inside collect_results's for query in self.adns.completed()
DNS used was8.8.8.8
Answered : (0, 'eu-fp.wa1.b.yahoo.com', 1286169758, ('87.248.122.122',))
Resolved www.yahoo.com to 87.248.122.122 using 8.8.8.8
Resolved hosts count3
And they are:
{'208.67.222.222': '69.147.125.65', '208.67.220.220': '67.195.160.76', '8.8.8.8': '87.248.122.122'}
inside finished_resolving()
Resolved : 3/5
Inside 'while not finished_resolving'
Queue: 1/1
Launching Querying for www.yahoo.com/1 on 8.8.4.4
inside collect_results()
inside finished_resolving()
Resolved : 3/5
Inside 'while not finished_resolving'
-------------------- CLIPPED -------------------------------------
inside collect_results()
Inside collect_results's for query in self.adns.completed()
DNS used was8.8.4.4
Answered : (0, 'eu-fp.wa1.b.yahoo.com', 1286169757, ('87.248.122.122',))
Resolved www.yahoo.com to 87.248.122.122 using 8.8.4.4
Resolved hosts count4
And they are:
{'208.67.222.222': '69.147.125.65', '208.67.220.220': '67.195.160.76', '8.8.8.8': '87.248.122.122', '8.8.4.4': '87.248.122.122'}
inside finished_resolving()
Resolved : 4/5
Inside 'while not finished_resolving'
inside collect_results()
inside finished_resolving()
Resolved : 4/5
---------------- CLIPPED -------------------------------
（最后一个块不断重复，直到系统开始挂断，负载上升到24）
码
test.py
import adns
from time import time
from async_dns import AsyncResolver
dnslist2 = ["8.8.4.4", "8.8.8.8", "208.67.220.220", "208.67.222.222", "192.168.50.1"] #192.168.50.1 is a dns server i manage
host = "www.yahoo.com"
record = adns.rr.A
intensity = len(dnslist2)/5+1
ar = AsyncResolver(dnslist2, host, record, intensity)
start = time()
resolved = ar.resolve()
end = time()
print "\n\n"
for dns, ip in resolved.items():
if ip is None:
print "%s could not resolv %s." % (dns, host)
else:
print "%s resolved it to %s : %s" % (dns, host, ip)
print "\n\n----------------------------------------------------"
print "It took %.2f seconds to query %d dns." % (end-start, len(dnslist))
print "----------------------------------------------------"
async_dns.py
#!/usr/bin/python
#
import sys
import adns
from time import time
class AsyncResolver(object):
def __init__(self, dnslist, host, record, intensity=10):
"""
dnslist: a list of dns used to resolve
host : hostname to resolve
record: recordtype to resolve
intensity: how many hosts to resolve at once
"""
print "Inside class's init'"
self.dnslist = dnslist
self.host = host
self.record = record
if intensity >= len(dnslist) :
self.intensity = len(dnslist)/5+1
else:
self.intensity = intensity
print "Data"
print "host " + host
print "dnslist length " + str(len(dnslist))
print "intensity " + str(intensity)
def resolve(self):
""" Resolves hosts and returns a dictionary of { 'dns': 'ip' }. """
print "Inside resolve()"
host = self.host
record = self.record
resolved_hosts = {}
active_queries = {}
dns_queue = self.dnslist[:]
def collect_results():
print "inside collect_results()"
for query in self.adns.completed():
print "Inside collect_results's for query in self.adns.completed()"
answer = query.check()
dns = active_queries[query]
print "DNS used was" + dns
print "Answered : " + str(answer)
del active_queries[query]
if answer[0] == 0:
#print "Inside answer[0] == 0 , ip:" + answer[3][0]
ip = answer[3][0]
resolved_hosts[dns] = ip
print "Resolved %s to %s using %s" % (host, ip, dns)
print "Resolved hosts count" + str(len(resolved_hosts))
print "And they are: "
print str(resolved_hosts)
print "\n"
elif answer[0] == 101 and not record == adns.rr.CNAME: # CNAME if CNAME wasn't required'
print "ooopppps, i got a CNAME, gotta find its A"
print "\n"
query = self.adns.submit(answer[1], adns.rr.A)
active_queries[query] = dns
else:
resolved_hosts[dns] = None
print "THIS COULD NOT BE RESOLVED"
def finished_resolving():
print "inside finished_resolving()"
print "Resolved : " + str(len(resolved_hosts)) + "/" + str(len(self.dnslist))
return len(resolved_hosts) == len(self.dnslist)
while not finished_resolving():
print "Inside 'while not finished_resolving'"
while dns_queue and len(active_queries) <= self.intensity:
print "Queue: " + str(len(active_queries)) + "/" + str(self.intensity)
dns = dns_queue.pop()
self.adns = adns.init(adns.iflags.noautosys,sys.stderr,"nameserver "+dns)
query = self.adns.submit(host, record)
print "Launching Querying for " + host + "/" + str(record) + " on " + dns
active_queries[query] = dns
collect_results()
return resolved_hosts
最佳答案
我刚刚尝试使用adns python绑定，并且遇到了类似的问题-完成的查询数组永远不会被完全填充，从而导致check循环永远运行。就我而言，似乎无法解析的域（由于NXDOMAIN等）从未添加到完整的查询数组中（具有空/空值）
我看了看C绑定，但是看不到用于保存失败结果的单独数据结构，因此看来确实应该以某种方式将它们添加到“完成”查询中。我怀疑绑定或adns库中存在一个错误，阻止了这种情况的发生。