make inet_ntop format v4-mapped ipv6 addresses properly

based on a patch by orc. POSIX actually fails to specify the format of
the ntop conversion; presumably, any output that will correctly
round-trip back via the (well-specified) pton operation is acceptable.
the new behavior is much more convenient than the old, however.

this patch also affects getnameinfo, which is implemented in terms of
inet_ntop and which is the preferred interface for performing this
conversion.

I've also removed some inexplicable cruft (filling the buffer with 'x'
before doing anything) whose origin I was unable to track down.
This commit is contained in:
Rich Felker 2013-07-25 03:20:02 -04:00
parent 43d2531316
commit 1cd417bdf1

View File

@ -18,14 +18,20 @@ const char *inet_ntop(int af, const void *restrict a0, char *restrict s, socklen
return s;
break;
case AF_INET6:
memset(buf, 'x', sizeof buf);
buf[sizeof buf-1]=0;
snprintf(buf, sizeof buf,
"%x:%x:%x:%x:%x:%x:%x:%x",
256*a[0]+a[1],256*a[2]+a[3],
256*a[4]+a[5],256*a[6]+a[7],
256*a[8]+a[9],256*a[10]+a[11],
256*a[12]+a[13],256*a[14]+a[15]);
if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\377\377", 12))
snprintf(buf, sizeof buf,
"%x:%x:%x:%x:%x:%x:%x:%x",
256*a[0]+a[1],256*a[2]+a[3],
256*a[4]+a[5],256*a[6]+a[7],
256*a[8]+a[9],256*a[10]+a[11],
256*a[12]+a[13],256*a[14]+a[15]);
else
snprintf(buf, sizeof buf,
"%x:%x:%x:%x:%x:%x:%d.%d.%d.%d",
256*a[0]+a[1],256*a[2]+a[3],
256*a[4]+a[5],256*a[6]+a[7],
256*a[8]+a[9],256*a[10]+a[11],
a[12],a[13],a[14],a[15]);
/* Replace longest /(^0|:)[:0]{2,}/ with "::" */
for (i=best=0, max=2; buf[i]; i++) {
if (i && buf[i] != ':') continue;