fix rejection of dns responses with pointers past 512 byte offset

[musl] / src / string / strverscmp.c

diff --git a/src/string/strverscmp.c b/src/string/strverscmp.c
index 7054967..16c1da2 100644 (file)
--- a/src/string/strverscmp.c
+++ b/src/string/strverscmp.c
@@ -1,7 +1,34 @@
+#define _GNU_SOURCE
+#include <ctype.h>
 #include <string.h>
 
-int strverscmp(const char *l, const char *r)
+int strverscmp(const char *l0, const char *r0)
 {
-       /* FIXME */
-       return strcmp(l, r);
+       const unsigned char *l = (const void *)l0;
+       const unsigned char *r = (const void *)r0;
+       size_t i, dp, j;
+       int z = 1;
+
+       /* Find maximal matching prefix and track its maximal digit
+        * suffix and whether those digits are all zeros. */
+       for (dp=i=0; l[i]==r[i]; i++) {
+               int c = l[i];
+               if (!c) return 0;
+               if (!isdigit(c)) dp=i+1, z=1;
+               else if (c!='0') z=0;
+       }
+
+       if (l[dp]-'1'<9U && r[dp]-'1'<9U) {
+               /* If we're looking at non-degenerate digit sequences starting
+                * with nonzero digits, longest digit string is greater. */
+               for (j=i; isdigit(l[j]); j++)
+                       if (!isdigit(r[j])) return 1;
+               if (isdigit(r[j])) return -1;
+       } else if (z && dp<i && (isdigit(l[i]) || isdigit(r[i]))) {
+               /* Otherwise, if common prefix of digit sequence is
+                * all zeros, digits order less than non-digits. */
+               return (unsigned char)(l[i]-'0') - (unsigned char)(r[i]-'0');
+       }
+
+       return l[i] - r[i];
 }