[Dnsmasq-discuss] Dnsmasq doesn't reply to queries made over (link-local) IPv6

[Kevin Darbyshire-Bryant]

On 04/09/16 12:14, Toke Høiland-Jørgensen wrote:
> Simon Kelley <simon at thekelleys.org.uk> writes:
>
>> OK, naive attempts to reproduce this have failed entirely, it just works
>> for me :-)
>>
>>
>> I see something similar:
>>
>> recvmsg(10, {msg_name={sa_family=AF_INET6, sin6_port=htons(50214), inet_pton(AF_INET6, "fe80::c23f:d5ff:fe62:22ac", &sin6_addr), sin6_flowinfo=htonl(0), sin6_scope_id=if_nametoindex("eth1.1")}, msg_namelen=28, msg_iov=[{iov_base="\243\307\1\0\0\1\0\0\0\0\0\0\6google\3com\0\0\1\0\1", iov_len=4096}], msg_iovlen=1, msg_control=[{cmsg_len=32, cmsg_level=SOL_IPV6, cmsg_type=0x32}], msg_controllen=32, msg_flags=0}, 0) = 28
>> dnsmasq: query[A] google.com from fe80::c23f:d5ff:fe62:22ac
>>

So I've LEDE r1504 (+8 special sauce local tweaks) + bleeding edge 
dnsmasq commit 16800ea072dd0cdf14d951c4bb8d2808b3dfe53d on an Archer C7 
router.  Using linux mint 18 client: kevin at Animal ~/git/github/lede 
(exp) $ dig -6 @fe80::62e3:27ff:feaf:9e50%wlan0 google.com AAAA

; <<>> DiG 9.10.3-P4-Ubuntu <<>> -6 @fe80::62e3:27ff:feaf:9e50%wlan0 
google.com AAAA
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54808
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;google.com.            IN    AAAA

;; ANSWER SECTION:
google.com.        33    IN    AAAA 2a00:1450:4009:80a::200e

;; Query time: 10 msec
;; SERVER: fe80::62e3:27ff:feaf:9e50%3#53(fe80::62e3:27ff:feaf:9e50%3)
;; WHEN: Sun Sep 04 16:01:01 BST 2016
;; MSG SIZE  rcvd: 67


strace running on the router:

clock_gettime(CLOCK_REALTIME, {1473001369, 678036759}) = 0
recvmsg(10, {msg_name={sa_family=AF_INET6, sin6_port=htons(43191), 
inet_pton(AF_INET6, "fe80::2677:3ff:fe47:8fec", &sin6_addr), 
sin6_flowinfo=htonl(0), sin6_scope_id=if_nametoindex("br-lan")}, 
msg_namelen=28, msg_iov=[{iov_base="\356;\1 
\0\1\0\0\0\0\0\1\6google\3com\0\0\34\0\1\0\0)\20"..., iov_len=4096}], 
msg_iovlen=1, msg_control=[{cmsg_len=32, cmsg_level=SOL_IPV6, 
cmsg_type=0x32}], msg_controllen=32, msg_flags=0}, 0) = 39
ioctl(10, SIOCGIFNAME, {ifr_index=17, ifr_name="br-lan"}) = 0
sendmsg(10, {msg_name={sa_family=AF_INET6, sin6_port=htons(43191), 
inet_pton(AF_INET6, "fe80::2677:3ff:fe47:8fec", &sin6_addr), 
sin6_flowinfo=htonl(0), sin6_scope_id=if_nametoindex("br-lan")}, 
msg_namelen=28, 
msg_iov=[{iov_base="\356;\201\200\0\1\0\1\0\0\0\1\6google\3com\0\0\34\0\1\300\f\0\34"..., 
iov_len=67}], msg_iovlen=1, msg_control=[{cmsg_len=32, 
cmsg_level=SOL_IPV6, cmsg_type=0x32}], msg_controllen=32, msg_flags=0}, 
0) = 67
poll([{fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=6, 
events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}, {fd=9, 
events=POLLIN}, {fd=10, events=POLLIN}, {fd=11, events=POLLIN}, {fd=12, 
events=POLLIN}, {fd=13, events=POLLIN}], 10, -1

I can confirm client box has linklocal inet6 addr: 
fe80::2677:3ff:fe47:8fec/64 Scope:Link.  I think it 'just works' for me too.

However I'm sure recently I saw some discussion on ipv6 link local 
'unresponsive' type issues in the lede chat room.   Maybe worth asking 
in there.

Kevin