X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fnetwork%2Fdn_expand.c;h=d9b33936522988756ecf6176383b1ab989bf9319;hb=91d34c4533e6bf6eacad7a9f001f28f9e5ebc656;hp=f817d059ae9c43bdaecb7fdddbbedd740af613b3;hpb=56b57f37a46dab432247bf29d96fcb11fbd02a6d;p=musl

diff --git a/src/network/dn_expand.c b/src/network/dn_expand.c
index f817d059..d9b33936 100644
--- a/src/network/dn_expand.c
+++ b/src/network/dn_expand.c
@@ -4,26 +4,31 @@
 int __dn_expand(const unsigned char *base, const unsigned char *end, const unsigned char *src, char *dest, int space)
 {
 	const unsigned char *p = src;
-	int len = -1, j;
-	if (space > 256) space = 256;
-	if (p==end || !*p) return -1;
-	for (;;) {
+	char *dend, *dbegin = dest;
+	int len = -1, i, j;
+	if (p==end || space <= 0) return -1;
+	dend = dest + (space > 254 ? 254 : space);
+	/* detect reference loop using an iteration counter */
+	for (i=0; i < end-base; i+=2) {
+		/* loop invariants: p<end, dest<dend */
 		if (*p & 0xc0) {
 			if (p+1==end) return -1;
-			j = (p[0]&1) | p[1];
+			j = ((p[0] & 0x3f) << 8) | p[1];
 			if (len < 0) len = p+2-src;
 			if (j >= end-base) return -1;
 			p = base+j;
 		} else if (*p) {
-			j = *p+1;
-			if (j>=end-p || j>space) return -1;
-			while (--j) *dest++ = *p++;
-			*dest++ = *++p ? '.' : 0;
+			if (dest != dbegin) *dest++ = '.';
+			j = *p++;
+			if (j >= end-p || j >= dend-dest) return -1;
+			while (j--) *dest++ = *p++;
 		} else {
+			*dest = 0;
 			if (len < 0) len = p+1-src;
 			return len;
 		}
 	}
+	return -1;
 }
 
 weak_alias(__dn_expand, dn_expand);