lua-resty-dns: Getting error while sending data to sock: attempt to call a number value. Network capture shows data sent/received successfully

rohit.c.joshi · 2016-03-08T21:24:06+00:00

This recent discussion on the nginx mailing list is relevant: http://mailman.nginx.org/pipermail/nginx/2016-February/049872.htmlOn Sun, Mar 6, 2016 at 3...

lua-resty-dns: Getting error while sending data to sock: attempt to call a number value. Network capture shows data sent/received successfully

rohit.c.joshi

Thanks for making it possible to DNS query using lua. I am sending below query request and getting an error : " attempt to call a number value" while making call to : sock:send(query)

query: "êT\u0001\u0000\u0000\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u0004maps\ngoogleapis\u0003com\u0000\u0000\u0001\u0000\u0001"

send: fd:24 37 of 37

Error:failed to send request to UDP server 8.8.8.8:53: attempt to call a number value

Here is network capture:

Request:

Frame 1063: 79 bytes on wire (632 bits), 79 bytes captured (632 bits) on interface 0

Ethernet II, Src: Apple_c1:50:1a (78:31:c1:c1:50:1a), Dst: VerizonB_90:78:42 (c8:a7:0a:90:78:42)

Internet Protocol Version 4, Src: 192.168.1.155, Dst: 8.8.8.8

User Datagram Protocol, Src Port: 54677 (54677), Dst Port: 53 (53)

Domain Name System (query)

[Response In: 1074]

Transaction ID: 0xea54

Flags: 0x0100 Standard query

0... .... .... .... = Response: Message is a query

.000 0... .... .... = Opcode: Standard query (0)

.... ..0. .... .... = Truncated: Message is not truncated

.... ...1 .... .... = Recursion desired: Do query recursively

.... .... .0.. .... = Z: reserved (0)

.... .... ...0 .... = Non-authenticated data: Unacceptable

Questions: 1

Answer RRs: 0

Authority RRs: 0

Additional RRs: 0

Queries

maps.googleapis.com: type A, class IN

Name: maps.googleapis.com

[Name Length: 19]

[Label Count: 3]

Type: A (Host Address) (1)

Class: IN (0x0001)

Response:

Frame 1074: 129 bytes on wire (1032 bits), 129 bytes captured (1032 bits) on interface 0

Ethernet II, Src: VerizonB_90:78:42 (c8:a7:0a:90:78:42), Dst: Apple_c1:50:1a (78:31:c1:c1:50:1a)

Internet Protocol Version 4, Src: 8.8.8.8, Dst: 192.168.1.155

User Datagram Protocol, Src Port: 53 (53), Dst Port: 54677 (54677)

Domain Name System (response)

[Request In: 1063]

[Time: 0.031131000 seconds]

Transaction ID: 0xea54

Flags: 0x8180 Standard query response, No error

1... .... .... .... = Response: Message is a response

.000 0... .... .... = Opcode: Standard query (0)

.... .0.. .... .... = Authoritative: Server is not an authority for domain

.... ..0. .... .... = Truncated: Message is not truncated

.... ...1 .... .... = Recursion desired: Do query recursively

.... .... 1... .... = Recursion available: Server can do recursive queries

.... .... .0.. .... = Z: reserved (0)

.... .... ..0. .... = Answer authenticated: Answer/authority portion was not authenticated by the server

.... .... ...0 .... = Non-authenticated data: Unacceptable

.... .... .... 0000 = Reply code: No error (0)

Questions: 1

Answer RRs: 2

Authority RRs: 0

Additional RRs: 0

Queries

maps.googleapis.com: type A, class IN

Name: maps.googleapis.com

[Name Length: 19]

[Label Count: 3]

Type: A (Host Address) (1)

Class: IN (0x0001)

Answers

maps.googleapis.com: type CNAME, class IN, cname googleapis.l.google.com

Name: maps.googleapis.com

Type: CNAME (Canonical NAME for an alias) (5)

Class: IN (0x0001)

Time to live: 3599

Data length: 22

CNAME: googleapis.l.google.com

googleapis.l.google.com: type A, class IN, addr 173.194.204.95

Name: googleapis.l.google.com

Type: A (Host Address) (1)

Class: IN (0x0001)

Time to live: 299

Data length: 4

Address: 173.194.204.95

rpaprocki

Is this error from a stack trace? If so can you send the full trace. Can you also please provide a full snippet of code so we can reproduce the problem? (I have a sneaking suspicion about your syntax but obvs there's no way to tell ;) )

On Mar 8, 2016, at 05:24, RJoshi <rohit....@gmail.com> wrote:

Thanks for making it possible to DNS query using lua. I am sending below query request and getting an error : " attempt to call a number value" while making call to : sock:send(query)

query: "êT\u0001\u0000\u0000\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u0004maps\ngoogleapis\u0003com\u0000\u0000\u0001\u0000\u0001"
send: fd:24 37 of 37

Error:failed to send request to UDP server 8.8.8.8:53: attempt to call a number value

Here is network capture:

Request:
Frame 1063: 79 bytes on wire (632 bits), 79 bytes captured (632 bits) on interface 0
Ethernet II, Src: Apple_c1:50:1a (78:31:c1:c1:50:1a), Dst: VerizonB_90:78:42 (c8:a7:0a:90:78:42)
Internet Protocol Version 4, Src: 192.168.1.155, Dst: 8.8.8.8
User Datagram Protocol, Src Port: 54677 (54677), Dst Port: 53 (53)
Domain Name System (query)
[Response In: 1074]
Transaction ID: 0xea54
Flags: 0x0100 Standard query
0... .... .... .... = Response: Message is a query
.000 0... .... .... = Opcode: Standard query (0)
.... ..0. .... .... = Truncated: Message is not truncated
.... ...1 .... .... = Recursion desired: Do query recursively
.... .... .0.. .... = Z: reserved (0)
.... .... ...0 .... = Non-authenticated data: Unacceptable
Questions: 1
Answer RRs: 0
Authority RRs: 0
Additional RRs: 0
Queries
maps.googleapis.com: type A, class IN
Name: maps.googleapis.com
[Name Length: 19]
[Label Count: 3]
Type: A (Host Address) (1)
Class: IN (0x0001)

Response:
Frame 1074: 129 bytes on wire (1032 bits), 129 bytes captured (1032 bits) on interface 0
Ethernet II, Src: VerizonB_90:78:42 (c8:a7:0a:90:78:42), Dst: Apple_c1:50:1a (78:31:c1:c1:50:1a)
Internet Protocol Version 4, Src: 8.8.8.8, Dst: 192.168.1.155
User Datagram Protocol, Src Port: 53 (53), Dst Port: 54677 (54677)
Domain Name System (response)
[Request In: 1063]
[Time: 0.031131000 seconds]
Transaction ID: 0xea54
Flags: 0x8180 Standard query response, No error
1... .... .... .... = Response: Message is a response
.000 0... .... .... = Opcode: Standard query (0)
.... .0.. .... .... = Authoritative: Server is not an authority for domain
.... ..0. .... .... = Truncated: Message is not truncated
.... ...1 .... .... = Recursion desired: Do query recursively
.... .... 1... .... = Recursion available: Server can do recursive queries
.... .... .0.. .... = Z: reserved (0)
.... .... ..0. .... = Answer authenticated: Answer/authority portion was not authenticated by the server
.... .... ...0 .... = Non-authenticated data: Unacceptable
.... .... .... 0000 = Reply code: No error (0)
Questions: 1
Answer RRs: 2
Authority RRs: 0
Additional RRs: 0
Queries
maps.googleapis.com: type A, class IN
Name: maps.googleapis.com
[Name Length: 19]
[Label Count: 3]
Type: A (Host Address) (1)
Class: IN (0x0001)
Answers
maps.googleapis.com: type CNAME, class IN, cname googleapis.l.google.com
Name: maps.googleapis.com
Type: CNAME (Canonical NAME for an alias) (5)
Class: IN (0x0001)
Time to live: 3599
Data length: 22
CNAME: googleapis.l.google.com
googleapis.l.google.com: type A, class IN, addr 173.194.204.95
Name: googleapis.l.google.com
Type: A (Host Address) (1)
Class: IN (0x0001)
Time to live: 299
Data length: 4
Address: 173.194.204.95

.

rohit.c.joshi

It seems problem was due to my work VPN. Now it works fine.

Question: If I have 3 DNS name server, does it retry automatically to all three before returning?

On Tuesday, 8 March 2016 11:15:44 UTC-5, rpaprocki wrote:

Is this error from a stack trace? If so can you send the full trace. Can you also please provide a full snippet of code so we can reproduce the problem? (I have a sneaking suspicion about your syntax but obvs there's no way to tell ;) )

On Mar 8, 2016, at 05:24, RJoshi <rohit....@gmail.com> wrote:

Thanks for making it possible to DNS query using lua. I am sending below query request and getting an error : " attempt to call a number value" while making call to : sock:send(query)

query: "êT\u0001\u0000\u0000\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u0004maps\ngoogleapis\u0003com\u0000\u0000\u0001\u0000\u0001"
send: fd:24 37 of 37

Error:failed to send request to UDP server 8.8.8.8:53: attempt to call a number value

Here is network capture:

Request:
Frame 1063: 79 bytes on wire (632 bits), 79 bytes captured (632 bits) on interface 0
Ethernet II, Src: Apple_c1:50:1a (78:31:c1:c1:50:1a), Dst: VerizonB_90:78:42 (c8:a7:0a:90:78:42)
Internet Protocol Version 4, Src: 192.168.1.155, Dst: 8.8.8.8
User Datagram Protocol, Src Port: 54677 (54677), Dst Port: 53 (53)
Domain Name System (query)
[Response In: 1074]
Transaction ID: 0xea54
Flags: 0x0100 Standard query
0... .... .... .... = Response: Message is a query
.000 0... .... .... = Opcode: Standard query (0)
.... ..0. .... .... = Truncated: Message is not truncated
.... ...1 .... .... = Recursion desired: Do query recursively
.... .... .0.. .... = Z: reserved (0)
.... .... ...0 .... = Non-authenticated data: Unacceptable
Questions: 1
Answer RRs: 0
Authority RRs: 0
Additional RRs: 0
Queries
maps.googleapis.com: type A, class IN
Name: maps.googleapis.com
[Name Length: 19]
[Label Count: 3]
Type: A (Host Address) (1)
Class: IN (0x0001)

Response:
Frame 1074: 129 bytes on wire (1032 bits), 129 bytes captured (1032 bits) on interface 0
Ethernet II, Src: VerizonB_90:78:42 (c8:a7:0a:90:78:42), Dst: Apple_c1:50:1a (78:31:c1:c1:50:1a)
Internet Protocol Version 4, Src: 8.8.8.8, Dst: 192.168.1.155
User Datagram Protocol, Src Port: 53 (53), Dst Port: 54677 (54677)
Domain Name System (response)
[Request In: 1063]
[Time: 0.031131000 seconds]
Transaction ID: 0xea54
Flags: 0x8180 Standard query response, No error
1... .... .... .... = Response: Message is a response
.000 0... .... .... = Opcode: Standard query (0)
.... .0.. .... .... = Authoritative: Server is not an authority for domain
.... ..0. .... .... = Truncated: Message is not truncated
.... ...1 .... .... = Recursion desired: Do query recursively
.... .... 1... .... = Recursion available: Server can do recursive queries
.... .... .0.. .... = Z: reserved (0)
.... .... ..0. .... = Answer authenticated: Answer/authority portion was not authenticated by the server
.... .... ...0 .... = Non-authenticated data: Unacceptable
.... .... .... 0000 = Reply code: No error (0)
Questions: 1
Answer RRs: 2
Authority RRs: 0
Additional RRs: 0
Queries
maps.googleapis.com: type A, class IN
Name: maps.googleapis.com
[Name Length: 19]
[Label Count: 3]
Type: A (Host Address) (1)
Class: IN (0x0001)
Answers
maps.googleapis.com: type CNAME, class IN, cname googleapis.l.google.com
Name: maps.googleapis.com
Type: CNAME (Canonical NAME for an alias) (5)
Class: IN (0x0001)
Time to live: 3599
Data length: 22
CNAME: googleapis.l.google.com
googleapis.l.google.com: type A, class IN, addr 173.194.204.95
Name: googleapis.l.google.com
Type: A (Host Address) (1)
Class: IN (0x0001)
Time to live: 299
Data length: 4
Address: 173.194.204.95

.

agentzh

Hello!

On Tue, Mar 8, 2016 at 2:43 PM, RJoshi wrote:
> It seems problem was due to my work VPN.  Now it works fine.
>
> Question:  If I have 3 DNS name server, does it retry automatically to all
> three before returning?
>

Yes when your `retrans` setting is larger or equal to 3.

Regards,
-agentzh

rohit.c.joshi

It did not work. My retrans is set to 5. If it times out or fails to send request to one server, it returns from that function.

It was coming out in below return.

local ok, err = sock:send(query)

if not ok then

local server = _get_cur_server(self)

return nil, "failed to send request to UDP server "

.. concat(server, ":") .. ": " .. err

end

if err ~= "timeout" or i == retrans then

local server = _get_cur_server(self)

return nil, "failed to receive reply from UDP server "

.. concat(server, ":") .. ": " .. err

end

On Wednesday, 16 March 2016 15:46:35 UTC-4, agentzh wrote:

Hello!

On Tue, Mar 8, 2016 at 2:43 PM, RJoshi wrote:
> It seems problem was due to my work VPN. Now it works fine.
>
> Question: If I have 3 DNS name server, does it retry automatically to all
> three before returning?
>

Yes when your `retrans` setting is larger or equal to 3.

Regards,
-agentzh

agentzh

Hello!

On Wed, Mar 16, 2016 at 1:01 PM, RJoshi wrote:
>  It was coming out in below return.
>
>  local ok, err = sock:send(query)
>         if not ok then
>             local server = _get_cur_server(self)
>             return nil, "failed to send request to UDP server "
>                 .. concat(server, ":") .. ": " .. err
>         end
>
> if err ~= "timeout" or i == retrans then
>             local server = _get_cur_server(self)
>             return nil, "failed to receive reply from UDP server "
>                 .. concat(server, ":") .. ": " .. err
>         end
>

Okay. This looks like a bug to me. Patches welcome :)

Best regards,
-agentzh

rohit.c.joshi

Sure, will submit PR.