diff -r a38e6916504c -r e135ccae6783 ext/ezmlm/hash/hash.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ext/ezmlm/hash/hash.c	Fri May 12 16:17:41 2017 -0700
@@ -0,0 +1,193 @@
+
+#include "hash.h"
+
+/*
+ * I originally attemped to just convert surf.c to pure Ruby, but I
+ * confess a lack of understanding surrounding the char casts from
+ * unsigned ints, etc, and screwing up a hash algo doesn't do anyone
+ * any good, least of all, me.  In other words, I don't have to fully
+ * understand DJB code to trust in it. :-)
+ *
+ * The following is copied verbatim from the ezmlm-idx source, version
+ * 7.2.2.  See: subhash.c, surf.c, and surfpcs.c.
+ *
+*/
+
+void surf(unsigned int out[8],const unsigned int in[12],const unsigned int seed[32])
+{
+  unsigned int t[12]; unsigned int x; unsigned int sum = 0;
+  int r; int i; int loop;
+
+  for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i];
+  for (i = 0;i < 8;++i) out[i] = seed[24 + i];
+  x = t[11];
+  for (loop = 0;loop < 2;++loop) {
+    for (r = 0;r < 16;++r) {
+      sum += 0x9e3779b9;
+      MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)
+      MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)
+      MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)
+    }
+    for (i = 0;i < 8;++i) out[i] ^= t[i + 4];
+  }
+}
+
+void surfpcs_init(surfpcs *s,const unsigned int k[32])
+{
+  int i;
+  for (i = 0;i < 32;++i) s->seed[i] = k[i];
+  for (i = 0;i < 8;++i) s->sum[i] = 0;
+  for (i = 0;i < 12;++i) s->in[i] = 0;
+  s->todo = 0;
+}
+
+void surfpcs_add(surfpcs *s,const char *x,unsigned int n)
+{
+  int i;
+  while (n--) {
+    data[end[s->todo++]] = *x++;
+    if (s->todo == 32) {
+      s->todo = 0;
+      if (!++s->in[8])
+        if (!++s->in[9])
+          if (!++s->in[10])
+            ++s->in[11];
+      surf(s->out,s->in,s->seed);
+      for (i = 0;i < 8;++i)
+	s->sum[i] += s->out[i];
+    }
+  }
+}
+
+void surfpcs_addlc(surfpcs *s,const char *x,unsigned int n)
+/* modified from surfpcs_add by case-independence and skipping ' ' & '\t' */
+{
+  unsigned char ch;
+  int i;
+  while (n--) {
+    ch = *x++;
+    if (ch == ' ' || ch == '\t') continue;
+    if (ch >= 'A' && ch <= 'Z')
+      ch -= 'a' - 'A';
+
+    data[end[s->todo++]] = ch;
+    if (s->todo == 32) {
+      s->todo = 0;
+      if (!++s->in[8])
+        if (!++s->in[9])
+          if (!++s->in[10])
+            ++s->in[11];
+      surf(s->out,s->in,s->seed);
+      for (i = 0;i < 8;++i)
+	  s->sum[i] += s->out[i];
+    }
+  }
+}
+
+void surfpcs_out(surfpcs *s,unsigned char h[32])
+{
+  int i;
+  surfpcs_add(s,".",1);
+  while (s->todo) surfpcs_add(s,"",1);
+  for (i = 0;i < 8;++i) s->in[i] = s->sum[i];
+  for (;i < 12;++i) s->in[i] = 0;
+  surf(s->out,s->in,s->seed);
+  for (i = 0;i < 32;++i) h[i] = outdata[end[i]];
+}
+
+void makehash(const char *indata,unsigned int inlen,char *hash)
+	/* makes hash[COOKIE=20] from stralloc *indata, ignoring case and */
+	/* SPACE/TAB */
+{
+  unsigned char h[32];
+  surfpcs s;
+  unsigned int seed[32];
+  int i;
+
+  for (i = 0;i < 32;++i) seed[i] = 0;
+  surfpcs_init(&s,seed);
+  surfpcs_addlc(&s,indata,inlen);
+  surfpcs_out(&s,h);
+  for (i = 0;i < 20;++i)
+    hash[i] = 'a' + (h[i] & 15);
+}
+
+unsigned int subhashb(const char *s,long len)
+{
+  unsigned long h;
+  h = 5381;
+  while (len-- > 0)
+    h = (h + (h << 5)) ^ (unsigned int)*s++;
+  return h % 53;
+}
+
+unsigned int subhashs(const char *s)
+{
+  return subhashb(s,strlen(s));
+}
+
+/* end copy of ezmlm-idx source */
+
+
+
+
+/*
+ * call­seq:
+ *   Ezmlm::Hash.address( email ) -> String
+ *
+ * Call the Surf hashing function on an +email+ address, returning
+ * the hashed string.  This is specific to how ezmlm is seeding
+ * the hash, and parsing email addresses from messages (prefixed with
+ * the '<' character.)
+ *
+ */
+VALUE
+address( VALUE klass, VALUE email ) {
+	char hash[20];
+	char *input;
+
+	Check_Type( email, T_STRING );
+
+	email = rb_str_plus( rb_str_new2("<"), email);
+	input = StringValueCStr( email );
+
+	makehash( input, strlen(input), hash );
+
+	return rb_str_new2( hash );
+}
+
+
+/*
+ * call­seq:
+ *   Ezmlm::Hash.subscriber( address ) -> String
+ *
+ * Call the subscriber hashing function on an email +address+, returning
+ * the index character referring to the file containing subscriber presence.
+ *
+ */
+VALUE
+subscriber( VALUE klass, VALUE email ) {
+	unsigned int prefix;
+
+	Check_Type( email, T_STRING );
+
+	email  = rb_str_plus( rb_str_new2("T"), email);
+	prefix = subhashs( StringValueCStr(email) ) + 64;
+
+	return rb_sprintf( "%c", (char)prefix );
+}
+
+
+
+void
+Init_hash()
+{
+	rb_mEzmlm  = rb_define_module( "Ezmlm" );
+	rb_cEZHash = rb_define_class_under( rb_mEzmlm, "Hash", rb_cObject );
+
+	rb_define_module_function( rb_cEZHash, "address", address, 1 );
+	rb_define_module_function( rb_cEZHash, "subscriber", subscriber, 1 );
+
+	return;
+}
+