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Don't request IPv6 addresses if AI_ADDRCONFIG is specified and the system has no IPv6 connectivity.

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This commit is contained in:
Lorenzo Colitti 2009-08-03 22:36:31 -07:00
parent 8b09aa39c3
commit 3d8f4ada56
1 changed files with 42 additions and 8 deletions
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50
libc/netbsd/net/getaddrinfo.c
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@ -335,6 +335,36 @@ str2number(const char *p)
return -1;
}
/* Determine whether IPv6 connectivity is available. */
static int
_have_ipv6() {
/*
* Connect a UDP socket to an global unicast IPv6 address. This will
* cause no network traffic, but will fail fast if the system has no or
* limited IPv6 connectivity (e.g., only a link-local address).
*/
static const struct sockaddr_in6 sin6_test = {
/* family, port, flow label */
AF_INET6, 0, 0,
/* 2000:: */
{{{ 0x20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }}},
/* scope ID */
0};
static const struct sockaddr *sa_test = (struct sockaddr *) &sin6_test;
int s = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
if (s < 0)
return 0;
int ret;
do {
ret = connect(s, sa_test, sizeof(sin6_test));
} while (ret < 0 && errno == EINTR);
int have_ipv6 = (ret == 0);
do {
ret = close(s);
} while (ret < 0 && errno == EINTR);
return have_ipv6;
}
int
getaddrinfo(const char *hostname, const char *servname,
const struct addrinfo *hints, struct addrinfo **res)
@ -1274,7 +1304,6 @@ _dns_getaddrinfo(void *rv, void *cb_data, va_list ap)
name = va_arg(ap, char *);
pai = va_arg(ap, const struct addrinfo *);
//fprintf(stderr, "_dns_getaddrinfo() name = '%s'\n", name);
memset(&q, 0, sizeof(q));
@ -1299,15 +1328,20 @@ _dns_getaddrinfo(void *rv, void *cb_data, va_list ap)
/* prefer IPv6 */
q.name = name;
q.qclass = C_IN;
q.qtype = T_AAAA;
q.answer = buf->buf;
q.anslen = sizeof(buf->buf);
q.next = &q2;
q2.name = name;
q2.qclass = C_IN;
q2.qtype = T_A;
q2.answer = buf2->buf;
q2.anslen = sizeof(buf2->buf);
/* If AI_ADDRCONFIG, lookup IPv6 only if we have connectivity */
if (!(pai->ai_flags & AI_ADDRCONFIG) || _have_ipv6()) {
q.qtype = T_AAAA;
q.next = &q2;
q2.name = name;
q2.qclass = C_IN;
q2.qtype = T_A;
q2.answer = buf2->buf;
q2.anslen = sizeof(buf2->buf);
} else {
q.qtype = T_A;
}
break;
case AF_INET:
q.name = name;