[Pdns-users] Need help with PowerDNS Remote HTTP Backend

Aleksey Chudov aleksey.chudov at gmail.com
Fri Jan 8 21:25:27 UTC 2016


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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