Fixed IpAddress port printing for ports higher than 9999:
snprintf includes zero-terminator in its size limit, so 7 
rather than 6 bytes are needed to snprintf a colon followed
by 5 port digits.

Whether the bug has any runtime effects in the current code,
I do not know, but I did waste a few hours following
misleading debugging output.

=== modified file 'src/ip/IpAddress.cc'
--- src/ip/IpAddress.cc	2010-03-01 01:13:17 +0000
+++ src/ip/IpAddress.cc	2010-05-01 03:43:09 +0000
@@ -1041,9 +1041,9 @@
 
     p += ToHostname(p, blen);
 
-    if (m_SocketAddr.sin6_port > 0 && p < (buf+blen-6) ) {
-        /* 6 is max length of expected ':port' (short int) */
-        snprintf(p, 6,":%d", GetPort() );
+    if (m_SocketAddr.sin6_port > 0 && p <= (buf+blen-7) ) {
+        // ':port' (short int) needs at most 6 bytes plus 1 for 0-terminator
+        snprintf(p, 7, ":%d", GetPort() );
     }
 
     // force a null-terminated string