Some proxy DNS servers might not resolve IPv6 names to addresses.
Instead they reply with NOERROR while passing no real data.
That combination of NOERROR and EAI_NODATA happen because the DNS
server has a recored for requested name (example.net in our case)
but that record is not of AAAA type which was requested.
That's what Wireshark sees in that case:
---------------------------------->8-----------------------------
Domain Name System (response)
Transaction ID: 0x6e2e
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: 0
Authority RRs: 0
Additional RRs: 0
Queries
example.net: type AAAA, class IN
Name: example.net
[Name Length: 11]
[Label Count: 2]
Type: AAAA (IPv6 Address) (28)
Class: IN (0x0001)
---------------------------------->8-----------------------------
And that's what we see if Google DNS server (8.8.8.8) is used instead:
---------------------------------->8-----------------------------
Domain Name System (response)
Transaction ID: 0x3cd4
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: 1
Authority RRs: 0
Additional RRs: 0
Queries
example.net: type AAAA, class IN
Name: example.net
[Name Length: 11]
[Label Count: 2]
Type: AAAA (IPv6 Address) (28)
Class: IN (0x0001)
Answers
example.net: type AAAA, class IN, addr 2606:2800:220:1:248:1893:25c8:1946
---------------------------------->8-----------------------------
---
posix/tst-getaddrinfo4.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/posix/tst-getaddrinfo4.c b/posix/tst-getaddrinfo4.c
index dc9e423448af..0139dee777a1 100644
--- a/posix/tst-getaddrinfo4.c
+++ b/posix/tst-getaddrinfo4.c
@@ -39,6 +39,7 @@ try (const char *service, int family, int flags)
case 0:
case EAI_AGAIN:
case EAI_NONAME:
+ case EAI_NODATA:
printf ("SUCCESS getaddrinfo(service=%s, family=%d, flags=%d): %s: %m\n",
service ?: "NULL", family, flags, gai_strerror (res));
return 0;
--
2.17.1
