inet_ntop: do not compress single zeros in IPv6

maintainer's note: this change is for conformance with RFC 5952,
4.2.2, which explicitly forbids use of :: to shorten a single 16-bit 0
field when producing the canonical text representation for an IPv6
address. fixes a test failure reported by Philip Homburg, who also
submitted a patch, but this fix is simpler and should produce smaller
code.

diff --git a/src/network/inet_ntop.c b/src/network/inet_ntop.c
index 14f9f4c4018ed5dc0a3a4c9db1839c411135bfad..4bfef2c557ab4478afeb5c22f5d548fd69e51d3c 100644 (file)
--- a/src/network/inet_ntop.c
+++ b/src/network/inet_ntop.c
@@ -36,7 +36,7 @@ const char *inet_ntop(int af, const void *restrict a0, char *restrict s, socklen
                        j = strspn(buf+i, ":0");
                        if (j>max) best=i, max=j;
                }
-               if (max>2) {
+               if (max>3) {
                        buf[best] = buf[best+1] = ':';
                        memmove(buf+best+2, buf+best+max, i-best-max+1);
                }