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* getaddrinfo/AI_ADDRCONFIG with ipv6 disabled
@ 2019-12-05  2:44 Bob Richmond
  2021-04-30  0:13 ` [musl] " Rich Felker
  0 siblings, 1 reply; 9+ messages in thread
From: Bob Richmond @ 2019-12-05  2:44 UTC (permalink / raw)
  To: musl

[-- Attachment #1: Type: text/plain, Size: 1054 bytes --]

connect() to the IPv6 loopback address can fail with EACCES on Linux if 
IPv6 is disabled on the lo interface, and causes getaddrinfo to fail 
without returning IPv4 addresses. It should be treated as if IPv6 is 
disabled.

echo 1 >/proc/sys/net/ipv6/conf/lo/disable_ipv6

struct addrinfo hints, *res = NULL;
hints.ai_family = PF_UNSPEC;
hints.ai_flags = AI_ADDRCONFIG;
getaddrinfo("192.168.1.1", "80", &hints, &res);

strace:
======start=======
socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, IPPROTO_UDP) = 14
connect(14, {sa_family=AF_INET, sin_port=htons(65535), 
sin_addr=inet_addr("127.0.0.1")}, 16) = 0
close(14)                         = 0 

socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC, IPPROTO_UDP) = 14 

connect(14, {sa_family=AF_INET6, sin6_port=htons(65535), 
inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=htonl(0), 
sin6_scope_id=0}, 28) = -1 EACCES (Permission denied)
close(14)                         = 0
writev(2, [{iov_base="[warn] getaddrinfo: Permission denied\n", 
iov_len=38}, {iov_base=NULL, iov_len=0}], 2) = 38
======end=========

[-- Attachment #2: musl-getaddrinfo-ipv6-eacces.patch --]
[-- Type: text/x-patch, Size: 304 bytes --]

--- musl-1.1.24/src/network/getaddrinfo.c	2019-10-13 14:58:27.000000000 -0700
+++ musl-1.1.24/src/network/getaddrinfo.c	2019-12-04 14:52:11.003784091 -0800
@@ -76,6 +76,7 @@
 			case EHOSTUNREACH:
 			case ENETDOWN:
 			case ENETUNREACH:
+			case EACCES:
 				break;
 			default:
 				return EAI_SYSTEM;

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2021-04-30 19:50 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-12-05  2:44 getaddrinfo/AI_ADDRCONFIG with ipv6 disabled Bob Richmond
2021-04-30  0:13 ` [musl] " Rich Felker
2021-04-30 12:38   ` Rich Felker
2021-04-30 16:40     ` Bastian Bittorf
2021-04-30 16:52       ` Rich Felker
2021-04-30 17:59         ` Julian Squires
2021-04-30 16:59     ` Jeffrey Walton
2021-04-30 18:49       ` Markus Wichmann
2021-04-30 19:50         ` Rich Felker

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