dns: implement tcp fallback in __res_msend query core

[musl] / src / network / dn_expand.c

diff --git a/src/network/dn_expand.c b/src/network/dn_expand.c
index 01b449b..eac343a 100644 (file)
--- a/src/network/dn_expand.c
+++ b/src/network/dn_expand.c
@@ -1,28 +1,33 @@
 #include <resolv.h>
-#include <string.h>
 
-#define BITOP(a,b,op) \
- ((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a))))
-
-int dn_expand(unsigned char *b, unsigned char *pz, unsigned char *p, unsigned char *s, int outlen)
+int __dn_expand(const unsigned char *base, const unsigned char *end, const unsigned char *src, char *dest, int space)
 {
-       /* Remember jump destinations to detect loops and abort */
-       size_t seen[512/8/sizeof(size_t)] = { 0 };
-       unsigned char *sz = s + outlen;
-       if (pz-b > 512) return -1;
-       for (;;) {
-               if (p>=pz) return -1;
-               else if (*p&0xc0) {
-                       int j = (p[0]&1) | p[1];
-                       if (BITOP(seen, j, &)) return -1;
-                       BITOP(seen, j, |=);
-                       p = b + j;
+       const unsigned char *p = src;
+       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] & 0x3f) << 8) | p[1];
+                       if (len < 0) len = p+2-src;
+                       if (j >= end-base) return -1;
+                       p = base+j;
                } else if (*p) {
-                       if (p+*p+1>=pz || s+*p>=sz) return -1;
-                       memcpy(s, p+1, *p);
-                       s += *p+1;
-                       p += *p+1;
-                       s[-1] = *p ? '.' : 0;
-               } else return 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);