When trying to resolve a hostname by getaddrinfo() using some specific
settings, it will always return -EAI_NONAME (Name or service not known).
To reproduce this behavior, you need to request an IPv6 address with the
additional AF_V4MAPPED flag set from an non IPv6 capable hostname. If
you choose a IPv4/IPv6 capable hostname like google.com, everything
works fine.
This patch is more or less a port [1][2] from the glibc and their behavior
for the AF_V4MAPPED flag. To test the bug you can use the following snippet.
---- 8< ----
int ret;
struct addrinfo* result;
struct addrinfo hints;
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_INET6;
hints.ai_flags = AI_V4MAPPED;
ret = getaddrinfo("test.com", NULL, &hints, &result);
printf("getaddrinfo(): %i", ret);
---- 8< ----
[1]
https://sourceware.org/git/?p=glibc.git;a=commit;f=sysdeps/posix/getaddrinfo.c;h=925c3c5c71596c02f7e58a0ffcdcaae44eb065c1
[2]
https://sourceware.org/git/?p=glibc.git;a=commit;f=sysdeps/posix/getaddrinfo.c;h=28977c2c1acb789660ad47e0d88e42486059c916
Signed-off-by: Alexander Wenzel <[email protected]>
---
libc/inet/getaddrinfo.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/libc/inet/getaddrinfo.c b/libc/inet/getaddrinfo.c
index 7ae32be..a9000ae 100644
--- a/libc/inet/getaddrinfo.c
+++ b/libc/inet/getaddrinfo.c
@@ -391,6 +391,9 @@ static uint8_t __gai_precedence = 0; /* =1 - IPv6,
IPv4
memcpy((*pat)->addr, h->h_addr_list[i], sizeof(_type));
\
pat = &((*pat)->next);
\
}
\
+ if (_family == AF_INET6 && i > 0) {
\
+ got_ipv6 = true;
\
+ }
\
}
\
}
@@ -404,6 +407,7 @@ gaih_inet(const char *name, const struct gaih_service
*service,
struct gaih_servtuple *st;
struct gaih_addrtuple *at;
int rc;
+ bool got_ipv6 = false;
int v4mapped = req->ai_family == PF_INET6 && (req->ai_flags &
AI_V4MAPPED);
unsigned seen = 0;
if (req->ai_flags & AI_ADDRCONFIG) {
@@ -586,7 +590,7 @@ gaih_inet(const char *name, const struct gaih_service
*service,
#endif
if (req->ai_family == AF_INET
|| (!v4mapped && req->ai_family == AF_UNSPEC)
- || (v4mapped && (no_inet6_data != 0 || (req->ai_flags
& AI_ALL)))
+ || (v4mapped && (!got_ipv6 || (req->ai_flags &
AI_ALL)))
) {
if (!(req->ai_flags & AI_ADDRCONFIG) || (seen &
SEEN_IPV4))
gethosts(AF_INET, struct in_addr);
@@ -705,6 +709,14 @@ gaih_inet(const char *name, const struct gaih_service
*service,
if (at2->family == AF_INET6 || v4mapped) {
family = AF_INET6;
socklen = sizeof(struct sockaddr_in6);
+
+ /* If we looked up IPv4 mapped address discard
them here if
+ the caller isn't interested in all address
and we have
+ found at least one IPv6 address. */
+ if (got_ipv6
+ && (req->ai_flags & (AI_V4MAPPED|AI_ALL)) ==
AI_V4MAPPED
+ && IN6_IS_ADDR_V4MAPPED (at2->addr))
+ goto ignore;
}
#endif
#if defined __UCLIBC_HAS_IPV4__ && defined __UCLIBC_HAS_IPV6__
@@ -781,7 +793,7 @@ gaih_inet(const char *name, const struct gaih_service
*service,
(*pai)->ai_next = NULL;
pai = &((*pai)->ai_next);
}
-
+ignore:
at2 = at2->next;
}
}
--
2.1.4
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