version 4.1: add bad seed checkers

wyhash.h

@@ -10,6 +10,7 @@
 
 #ifndef wyhash_final_version_4
 #define wyhash_final_version_4
+// Version 4.1
 
 #ifndef WYHASH_CONDOM
 //protections that produce different results:
@@ -113,6 +114,72 @@ static inline uint64_t _wyr4(const uint8_t *p) {
   return (((v >> 24) & 0xff)| ((v >>  8) & 0xff00)| ((v <<  8) & 0xff0000)| ((v << 24) & 0xff000000));
 }
 #endif
+#if WYHASH_CONDOM
+// must be sorted
+static const uint32_t wyhash32low_badseeds[]
+= { 0x138d5f9f, 0x1e4f8661, 0x29362732, 0x49a7ee03,
+    0x4d29ced1, 0x5ee3628c, 0x833f0eb6, 0x928fce63,
+    0x99be0ae5, 0xac470842, 0xcaf21e71, 0xfc1c4878 };
+//static const uint32_t wyhash_badseeds[] = { };
+
+# if defined __cplusplus
+// fixup bad seeds with WYHASH_CONDOM
+static inline void wyhash_seed_init(uint32_t &seed) {
+  return;
+  /*for (auto s : wyhash_badseeds) {
+    if (s == seed) {
+        seed++;
+        return;
+    }
+    if (s > seed)
+      return;
+  }*/
+}
+static inline void wyhash_seed_init(uint64_t &seed) {
+  return;
+  /*for (auto s : wyhash_badseeds) {
+    if (s & seed) {
+        seed++;
+        return;
+    }
+  }*/
+}
+static void wyhash32low_seed_init(uint32_t &seed) {
+  // just linear search for now
+  for (auto s : wyhash32low_badseeds) {
+    if (s == seed) {
+        seed++;
+        return;
+    }
+    if (s > seed)
+      return;
+  }
+}
+# else
+// check bad seeds with WYHASH_CONDOM
+static inline bool wyhash_badseed(const uint64_t seed) {
+  /*for (auto s : wyhash_badseeds) {
+    if (s & seed) {
+        return true;
+    }
+  }*/
+  return false;
+}
+static bool wyhash32low_badseed(const uint32_t seed) {
+  // just linear search for now
+  for (auto s : wyhash32low_badseeds) {
+    if (s == seed) {
+        return true;
+    }
+    if (s > seed)
+      return false;
+  }
+  return false;
+}
+# endif
+#endif // WYHASH_CONDOM
+
+
 static inline uint64_t _wyr3(const uint8_t *p, size_t k) { return (((uint64_t)p[0])<<16)|(((uint64_t)p[k>>1])<<8)|p[k-1];}
 //wyhash main function
 static inline uint64_t wyhash(const void *key, size_t len, uint64_t seed, const uint64_t *secret){

wyhash32.h

@@ -1,4 +1,5 @@
 // Author: Wang Yi <godspeed_china@yeah.net>
+// Version 4.1
 #include <stdint.h>
 #include <string.h>
 #ifndef WYHASH32_BIG_ENDIAN
@@ -14,8 +15,21 @@ static inline void _wymix32(unsigned  *A,  unsigned  *B){
   *A=(unsigned)c;
   *B=(unsigned)(c>>32);
 }
-// This version is vulnerable when used with a few bad seeds, which should be skipped beforehand:
-// 0x429dacdd, 0xd637dbf3
+// This version is vulnerable when used with a few bad seeds, which should be
+// skipped or changed beforehand: 0x51a43a0f, 0x522235ae, 0x99ac2b20
+#ifdef __cplusplus
+static void wyhash32_seed_init(uint32_t &seed) {
+  if ((seed == 0x51a43a0f) || (seed == 0x522235ae) || (seed == 0x99ac2b20))
+    seed++;
+}
+#else
+static bool wyhash32_badseed(const uint32_t seed) {
+  if ((seed == 0x51a43a0f) || (seed == 0x522235ae) || (seed == 0x99ac2b20))
+    return true;
+  return false;
+}
+#endif
+
 static inline unsigned wyhash32(const void *key, uint64_t len, unsigned seed) {
   const uint8_t *p=(const uint8_t *)key; uint64_t i=len;
   unsigned see1=(unsigned)len; seed^=(unsigned)(len>>32); _wymix32(&seed, &see1);