--- ucspi-tcp-0.88.orig/ip6_fmt.c	2008-03-08 17:53:53.000000000 +0900
+++ ucspi-tcp-0.88/ip6_fmt.c	2008-03-08 18:00:37.000000000 +0900
@@ -6,39 +6,43 @@
 unsigned int ip6_fmt(char *s,char ip[16])
 {
   unsigned int len;
-  unsigned int i;
-  unsigned int temp;
-  unsigned int compressing;
-  int j;
+  unsigned int i, j, k;
+  unsigned long u[16];
+  unsigned int compressed;
+  unsigned int z;
 
-  len = 0; compressing = 0;
-  for (j=0; j<16; j+=2) {
-    if (j==12 && ip6_isv4mapped(ip)) {
-      temp=ip4_fmt(s,ip+12);
-      len+=temp;
-      s+=temp;
+  len = 0; compressed = 0;
+
+  for (j = 0; j < 16;) {
+    if (j == 12 && ip6_isv4mapped(ip)) {
+      *s++ = ':'; ++len;
+      i = ip4_fmt(s,ip + 12); len += i; if (s) s += i;
       break;
     }
-    temp = ((unsigned long) (unsigned char) ip[j] << 8) +
-            (unsigned long) (unsigned char) ip[j+1];
-    if (temp == 0) {
-      if (!compressing) {
-	compressing=1;
-	if (j==0) {
-	  *s=':'; s+=1; ++len;
-	}
+    k = 0; z = -1;
+    do {
+      u[++z] = ((unsigned long) (unsigned char) ip[j] << 8) +
+                (unsigned long) (unsigned char) ip[j+1];
+      j += 2;
+    } while (!u[z] && j < 16);
+
+    if (!compressed && z > 1) {
+      if (!u[z]) {
+        *s++ = ':'; ++len;
+        *s++ = ':'; ++len;
+        break;
       }
-    } else {
-      if (compressing) {
-	compressing=0;
-	*s=':'; s+=1; ++len;
+      *s++ = ':'; ++len;
+      compressed = 1; k = z;
+    }
+      
+    for (; k <= z; k++) {
+      if (len) {
+        *s++ = ':'; ++len;
       }
-      i = fmt_xlong(s,temp); len += i; if (s) s += i;
-      if (s && j<14) *s++ = ':'; ++len;
+      i = fmt_xlong(s, u[k]); len += i; if (s) s += i;
     }
   }
-
-  if (s) *s=0;
   return len;
 }