diff --git a/include/socks/util.h b/include/socks/util.h
index e48114c..c94303e 100644
--- a/include/socks/util.h
+++ b/include/socks/util.h
@@ -9,6 +9,7 @@
 extern "C" {
 #endif
 
+extern uint64_t hash_string(const char *s);
 extern void data_size_to_string(size_t value, char *out, size_t outsz);
 static inline bool power_of_2(size_t x) { return (x > 0 && (x & (x - 1)) == 0); }
 static inline unsigned long long div64_pow2(unsigned long long x, unsigned long long y)
diff --git a/util/hash.c b/util/hash.c
new file mode 100644
index 0000000..7f8a2c6
--- /dev/null
+++ b/util/hash.c
@@ -0,0 +1,14 @@
+#include <stdint.h>
+
+uint64_t hash_string(const char *s)
+{
+	uint64_t h = 0xcbf29ce484222325;
+
+	while (*s) {
+		h ^= *(unsigned char *)s;
+		h *= 0x100000001b3;
+		s++;
+	}
+
+	return h;
+}