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-rw-r--r--src/network/dn_expand.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/src/network/dn_expand.c b/src/network/dn_expand.c
new file mode 100644
index 00000000..01b449bb
--- /dev/null
+++ b/src/network/dn_expand.c
@@ -0,0 +1,28 @@
+#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)
+{
+ /* 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;
+ } 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;
+ }
+}