Fix a bug in match().

The search may have matched a string that is actually a prefix of
the subject string, if a longer string with the same prefix is also
in the set.

This "happens" to give correct results for match(), but which()
would return the wrong value.

The fix uses strcmp() instead of memcmp(), but that is also
vectorized, where the C library uses vector instructions.

configure.ac

@@ -69,6 +69,7 @@ AC_CHECK_FUNCS([strdup])
 AC_CHECK_FUNCS([memset])
 AC_CHECK_FUNCS([select])
 AC_CHECK_FUNCS([strerror])
+AC_CHECK_FUNCS([getline])
 AC_CHECK_HEADERS([limits.h])
 AC_C_INLINE
 AC_C_RESTRICT
@@ -111,5 +112,6 @@ fi
 AC_CONFIG_FILES([
 	Makefile
 	src/Makefile
+	src/tests/bench/Makefile
 ])
 AC_OUTPUT

src/patricia.c

@@ -250,7 +250,7 @@ PT_Lookup(const struct pt_y * const restrict root,
 		l = y->off + y->len;
 		if (l > len)
 			return UINT_MAX;
-		if (l == len && memcmp(subject, strings[y->idx], len) == 0)
+		if (l == len && strcmp(subject, strings[y->idx]) == 0)
 			return y->idx;
 		b = (y->bitmask & subject[l]) != 0;
 		assert(b < 2);

src/tests/match.vtc

@@ -50,6 +50,40 @@ client c1 {
 	expect resp.http.Match-Raboof == "false"
 } -run
 
+varnish v1 -vcl {
+	import ${vmod_selector};
+	backend b { .host = "${bad_ip}"; }
+
+	sub vcl_init {
+		new t = selector.set();
+		t.add("études");
+		t.add("étude's");
+		t.add("étude");
+	}
+
+	sub vcl_recv {
+		return (synth(200));
+	}
+
+	sub vcl_synth {
+		set resp.http.Match-Etude = t.match("étude");
+		set resp.http.Which-Etude = t.which();
+		set resp.http.Match-Etudes = t.match("études");
+		set resp.http.Which-Etudes = t.which();
+		set resp.body = t.debug();
+		return (deliver);
+	}
+}
+
+client c1 {
+	txreq
+	rxresp
+	expect resp.http.Match-Etude == "true"
+	expect resp.http.Which-Etude == 3
+	expect resp.http.Match-Etudes == "true"
+	expect resp.http.Which-Etudes == 1
+} -run
+
 varnish v1 -vcl {
 	import ${vmod_selector};
 	import std;