return al;
}
+#define IS_IPV4(addr) (((const ip_address *) addr)->type == IPV4_ADDRESS)
+
+/* Compare two IP addresses by type, giving preference to the IPv4
+ address (sorting it first). In other words, return -1 if ADDR1 is
+ IPv4 and ADDR2 is IPv6, +1 if ADDR1 is IPv6 and ADDR2 is IPv4, and
+ 0 otherwise.
+
+ This is intended to be used as the comparator arg to a qsort-like
+ sorting function, which is why it accepts generic pointers. */
+
+static int
+cmp_prefer_ipv4 (const void *addr1, const void *addr2)
+{
+ return !IS_IPV4 (addr1) - !IS_IPV4 (addr2);
+}
+
+#define IS_IPV6(addr) (((const ip_address *) addr)->type == IPV6_ADDRESS)
+
+/* Like the above, but give preference to the IPv6 address. */
+
+static int
+cmp_prefer_ipv6 (const void *addr1, const void *addr2)
+{
+ return !IS_IPV6 (addr1) - !IS_IPV6 (addr2);
+}
+
#else /* not ENABLE_IPV6 */
/* Create an address_list from a NULL-terminated vector of IPv4
int
is_valid_ipv6_address (const char *str, const char *end)
{
+ /* Use lower-case for these to avoid clash with system headers. */
enum {
- NS_INADDRSZ = 4,
- NS_IN6ADDRSZ = 16,
- NS_INT16SZ = 2
+ ns_inaddrsz = 4,
+ ns_in6addrsz = 16,
+ ns_int16sz = 2
};
const char *curtok;
}
else if (str == end)
return 0;
- if (tp > NS_IN6ADDRSZ - NS_INT16SZ)
+ if (tp > ns_in6addrsz - ns_int16sz)
return 0;
- tp += NS_INT16SZ;
+ tp += ns_int16sz;
saw_xdigit = 0;
val = 0;
continue;
}
/* if ch is a dot ... */
- if (ch == '.' && (tp <= NS_IN6ADDRSZ - NS_INADDRSZ)
+ if (ch == '.' && (tp <= ns_in6addrsz - ns_inaddrsz)
&& is_valid_ipv4_address (curtok, end) == 1)
{
- tp += NS_INADDRSZ;
+ tp += ns_inaddrsz;
saw_xdigit = 0;
break;
}
if (saw_xdigit == 1)
{
- if (tp > NS_IN6ADDRSZ - NS_INT16SZ)
+ if (tp > ns_in6addrsz - ns_int16sz)
return 0;
- tp += NS_INT16SZ;
+ tp += ns_int16sz;
}
if (colonp != NULL)
{
- if (tp == NS_IN6ADDRSZ)
+ if (tp == ns_in6addrsz)
return 0;
- tp = NS_IN6ADDRSZ;
+ tp = ns_in6addrsz;
}
- if (tp != NS_IN6ADDRSZ)
+ if (tp != ns_in6addrsz)
return 0;
return 1;
}
}
\f
-/* Look up HOST in DNS and return a list of IP addresses. The
- addresses in the list are in the same order in which
- gethostbyname/getaddrinfo returned them.
+/* Look up HOST in DNS and return a list of IP addresses.
This function caches its result so that, if the same host is passed
the second time, the addresses are returned without DNS lookup.
(Use LH_REFRESH to force lookup, or set opt.dns_cache to 0 to
globally disable caching.)
+ The order of the returned addresses is affected by the setting of
+ opt.prefer_family: if it is set to prefer_ipv4, IPv4 addresses are
+ placed at the beginning; if it is prefer_ipv6, IPv6 ones are placed
+ at the beginning; otherwise, the order is left intact. The
+ relative order of addresses with the same family is left
+ undisturbed in either case.
+
FLAGS can be a combination of:
LH_SILENT - don't print the "resolving ... done" messages.
LH_BIND - resolve addresses for use with bind, which under
_("failed: No IPv4/IPv6 addresses for host.\n"));
return NULL;
}
+
+ /* Reorder addresses so that IPv4 ones (or IPv6 ones, as per
+ --prefer-family) come first. Sorting is stable so the order of
+ the addresses with the same family is undisturbed. */
+ if (al->count > 1 && opt.prefer_family != prefer_none)
+ stable_sort (al->addresses, al->count, sizeof (ip_address),
+ opt.prefer_family == prefer_ipv4
+ ? cmp_prefer_ipv4 : cmp_prefer_ipv6);
}
#else /* not ENABLE_IPV6 */
{