[Pdns-users] Need help with PowerDNS Remote HTTP Backend
Aki Tuomi
cmouse at youzen.ext.b2.fi
Sat Jan 9 15:23:28 UTC 2016
It works if you use HTTP/1.1 compatible responses. RFC says that you either
need to send your response chunked or set content-length. YaHTTP will check
and enforce this.
Aki
On Sat, Jan 09, 2016 at 11:10:19AM +0200, Aleksey Chudov wrote:
> Finally I found the cause of the problem. PowerDNS Remote HTTP Backend
> works only with 'Content-Length' header.
>
> So, the following code works until 'Content-Length' header exists.
>
>
> import BaseHTTPServer
>
> class HTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
> def do_GET(self):
> if self.path == '/dns/lookup/example.com/SOA':
> self.wfile.write('HTTP/1.1 200 OK\r\nContent-Length:
> 145\r\n\r\n{"result":[{"qtype":"SOA","qname":"example.com","content":"
> dns1.icann.org. hostmaster.icann.org. 2012080849 7200 3600 1209600
> 3600","ttl":3600}]}')
>
> if __name__ == '__main__':
> server = BaseHTTPServer.HTTPServer(('127.0.0.1', 8080),
> HTTPRequestHandler)
> server.serve_forever()
>
>
> I don't know whether this is bug in YaHTTP client used by PowerDNS or expected
> behavior. But please add a note to the documentation.
>
>
> On Fri, Jan 8, 2016 at 11:25 PM, Aleksey Chudov <aleksey.chudov at gmail.com>
> wrote:
>
> > Some more information.
> >
> > I have tested pdns-static_3.4.7-1_amd64.deb on Debian and
> > pdns-3.4.7-1.el7.x86_64 + pdns-backend-remote-3.4.7-1.el7.x86_64 on CentOS
> > 7.2 with no success.
> >
> > Also I have tried manually reply to pdns request using netcat utility. As
> > can be seen pdns sends next request just after headers + newline without
> > waiting for the body.
> >
> >
> > # grep -Ev '^$|^#' /etc/powerdns/pdns.conf
> > launch=remote
> > remote-connection-string=http:url=http://127.0.0.1:8080/dns,timeout=60000
> > cache-ttl=0
> > negquery-cache-ttl=0
> > query-cache-ttl=0
> >
> >
> > # dig @127.0.0.1 example.com. SOA
> >
> > ; <<>> DiG 9.7.3 <<>> @127.0.0.1 example.com. SOA
> > ; (1 server found)
> > ;; global options: +cmd
> > ;; Got answer:
> > ;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 59226
> > ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
> > ;; WARNING: recursion requested but not available
> >
> > ;; QUESTION SECTION:
> > ;example.com. IN SOA
> >
> > ;; Query time: 0 msec
> > ;; SERVER: 127.0.0.1#53(127.0.0.1)
> > ;; WHEN: Fri Jan 8 23:22:47 2016
> > ;; MSG SIZE rcvd: 29
> >
> >
> > # netcat -l 127.0.0.1 -p 8080
> > GET /dns/lookup/example.com/SOA HTTP/1.1
> > Accept: application/json
> > Connection: Keep-Alive
> > Host: 127.0.0.1
> > User-Agent: YaHTTP v1.0
> > X-Remotebackend-Local: 0.0.0.0
> > X-Remotebackend-Real-Remote: 127.0.0.1/32
> > X-Remotebackend-Remote: 127.0.0.1
> > X-Remotebackend-Zone-Id: -1
> >
> > HTTP/1.1 200 OK
> > Content-Type: text/javascript; charset=utf-8
> >
> > GET /dns/lookup/com/SOA HTTP/1.1
> > Accept: application/json
> > Connection: Keep-Alive
> > Host: 127.0.0.1
> > User-Agent: YaHTTP v1.0
> > X-Remotebackend-Local: 0.0.0.0
> > X-Remotebackend-Real-Remote: 127.0.0.1/32
> > X-Remotebackend-Remote: 127.0.0.1
> > X-Remotebackend-Zone-Id: -1
> >
> >
> > Is this a bug or am I missing something?
> >
> >
> > On Fri, Jan 8, 2016 at 11:42 AM, Aleksey Chudov <aleksey.chudov at gmail.com>
> > wrote:
> >
> >> Hi,
> >>
> >> I'm trying to implement simple PowerDNS Remote HTTP Backend in Python.
> >> Below is test code just like
> >> https://doc.powerdns.com/md/authoritative/backend-remote/#scenario-soa-lookup-with-http-connector
> >>
> >>
> >> import BaseHTTPServer
> >>
> >> REPLY = """{
> >> "result":
> >> [
> >> { "qtype": "SOA",
> >> "qname": "example.com",
> >> "content": "dns1.icann.org. hostmaster.icann.org. 2012080849 7200
> >> 3600 1209600 3600",
> >> "ttl": 3600,
> >> "domain_id": -1
> >> }
> >> ]
> >> }"""
> >>
> >> class HTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
> >> def do_GET(self):
> >> if self.path == '/dns/lookup/example.com/SOA':
> >> self.send_response(200)
> >> self.send_header('Content-Type', 'text/javascript;
> >> charset=utf-8')
> >> self.end_headers()
> >> self.wfile.write(REPLY + '\r\n')
> >> else:
> >> self.send_error(501)
> >>
> >> if __name__ == '__main__':
> >> server = BaseHTTPServer.HTTPServer(('127.0.0.1', 8080),
> >> HTTPRequestHandler)
> >> server.serve_forever()
> >>
> >>
> >> Looks pretty simple. And curl shows the result.
> >>
> >>
> >> # curl -i http://127.0.0.1:8080/dns/lookup/example.com/SOA
> >> HTTP/1.0 200 OK
> >> Server: BaseHTTP/0.3 Python/2.7.5
> >> Date: Fri, 08 Jan 2016 09:24:54 GMT
> >> Content-Type: text/javascript; charset=utf-8
> >>
> >> {
> >> "result":
> >> [
> >> { "qtype": "SOA",
> >> "qname": "example.com",
> >> "content": "dns1.icann.org. hostmaster.icann.org. 2012080849 7200
> >> 3600 1209600 3600",
> >> "ttl": 3600,
> >> "domain_id": -1
> >> }
> >> ]
> >> }
> >>
> >> And Python script prints
> >>
> >> 127.0.0.1 - - [08/Jan/2016 11:36:31] "GET /dns/lookup/example.com/SOA
> >> HTTP/1.1" 200 -
> >>
> >>
> >> So, I've installed PoweDNS from CentOS 7 Epel repository
> >>
> >> # rpm -qa pdns\*
> >> pdns-3.4.7-1.el7.x86_64
> >> pdns-backend-remote-3.4.7-1.el7.x86_64
> >>
> >>
> >> And my configuration file contains only the following settings
> >>
> >> # grep -Ev '^#|^$' /etc/pdns/pdns.conf
> >> setuid=pdns
> >> setgid=pdns
> >> launch=remote
> >> remote-connection-string=http:url=http://127.0.0.1:8080/dns
> >> cache-ttl=0
> >> negquery-cache-ttl=0
> >> query-cache-ttl=0
> >>
> >>
> >> But my remote backend does not work!
> >>
> >>
> >> # dig @127.0.0.1 example.com. SOA
> >>
> >> ; <<>> DiG 9.9.4-RedHat-9.9.4-29.el7_2.1 <<>> @127.0.0.1 example.com. SOA
> >> ; (1 server found)
> >> ;; global options: +cmd
> >> ;; Got answer:
> >> ;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 5375
> >> ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
> >> ;; WARNING: recursion requested but not available
> >>
> >> ;; OPT PSEUDOSECTION:
> >> ; EDNS: version: 0, flags:; udp: 1680
> >> ;; QUESTION SECTION:
> >> ;example.com. IN SOA
> >>
> >> ;; Query time: 2 msec
> >> ;; SERVER: 127.0.0.1#53(127.0.0.1)
> >> ;; WHEN: Fri Jan 08 11:38:05 EET 2016
> >> ;; MSG SIZE rcvd: 40
> >>
> >>
> >> There is no new messages from pdns_server
> >>
> >> # systemctl status pdns.service
> >> ● pdns.service - PowerDNS Authoritative Server
> >> Loaded: loaded (/usr/lib/systemd/system/pdns.service; enabled; vendor
> >> preset: disabled)
> >> Active: active (running) since Fri 2016-01-08 11:37:50 EET; 18s ago
> >> Process: 1581 ExecStop=/usr/bin/pdns_control quit (code=exited,
> >> status=0/SUCCESS)
> >> Process: 1586 ExecStart=/usr/sbin/pdns_server --daemon (code=exited,
> >> status=0/SUCCESS)
> >> Main PID: 1587 (pdns_server)
> >> CGroup: /system.slice/pdns.service
> >> └─1587 /usr/sbin/pdns_server --daemon
> >>
> >> Jan 08 11:37:50 localhost pdns[1587]: Listening on controlsocket in
> >> '/var/run/pdns.controlsocket'
> >> Jan 08 11:37:50 localhost systemd[1]: Started PowerDNS Authoritative
> >> Server.
> >> Jan 08 11:37:50 localhost pdns[1587]: UDP server bound to 0.0.0.0:53
> >> Jan 08 11:37:50 localhost pdns[1587]: TCP server bound to 0.0.0.0:53
> >> Jan 08 11:37:51 localhost pdns[1587]: PowerDNS Authoritative Server 3.4.7
> >> (jenkins at autotest.powerdns.com) (C) 2001-2015 PowerDNS.COM BV
> >> Jan 08 11:37:51 localhost pdns[1587]: Using 64-bits mode. Built on
> >> 20151108152440 by mockbuild at buildvm-19.phx2.fedoraproject.org, gcc 4.8.3
> >> 20140911 (Red Hat 4.8.3-9).
> >> Jan 08 11:37:51 localhost pdns[1587]: PowerDNS comes with ABSOLUTELY NO
> >> WARRANTY. This is free software, and you are welcome to redistribute it
> >> according to the terms of the GPL version 2.
> >> Jan 08 11:37:51 localhost pdns[1587]: Creating backend connection for TCP
> >> Jan 08 11:37:51 localhost pdns[1587]: About to create 3 backend threads
> >> for UDP
> >> Jan 08 11:37:51 localhost pdns[1587]: Done launching threads, ready to
> >> distribute questions
> >>
> >>
> >> But Python prints
> >>
> >> 127.0.0.1 - - [08/Jan/2016 11:38:05] "GET /dns/lookup/example.com/SOA
> >> HTTP/1.1" 200 -
> >> 127.0.0.1 - - [08/Jan/2016 11:38:05] code 501, message Not Implemented
> >> 127.0.0.1 - - [08/Jan/2016 11:38:05] "GET /dns/lookup/com/SOA HTTP/1.1"
> >> 501 -
> >> 127.0.0.1 - - [08/Jan/2016 11:38:05] code 501, message Not Implemented
> >> 127.0.0.1 - - [08/Jan/2016 11:38:05] "GET /dns/lookup//SOA HTTP/1.1" 501 -
> >>
> >>
> >> Where am I wrong?
> >>
> >>
> >> Regards,
> >> Aleksey
> >>
> >
> >
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