MINOR: uri_normalizer: Add `fragment-encode` normalizer

This normalizer encodes '#' as '%23'.

See GitHub Issue #714.
diff --git a/src/http_act.c b/src/http_act.c
index f30694e..f613624 100644
--- a/src/http_act.c
+++ b/src/http_act.c
@@ -337,6 +337,23 @@
 
 			break;
 		}
+		case ACT_NORMALIZE_URI_FRAGMENT_ENCODE: {
+			const struct ist path = http_get_path(uri);
+			struct ist newpath = ist2(replace->area, replace->size);
+
+			if (!isttest(path))
+				goto leave;
+
+			err = uri_normalizer_fragment_encode(path, &newpath);
+
+			if (err != URI_NORMALIZER_ERR_NONE)
+				break;
+
+			if (!http_replace_req_path(htx, newpath, 1))
+				goto fail_rewrite;
+
+			break;
+		}
 	}
 
 	switch (err) {
@@ -462,6 +479,11 @@
 
 		rule->action = ACT_NORMALIZE_URI_FRAGMENT_STRIP;
 	}
+	else if (strcmp(args[cur_arg], "fragment-encode") == 0) {
+		cur_arg++;
+
+		rule->action = ACT_NORMALIZE_URI_FRAGMENT_ENCODE;
+	}
 	else {
 		memprintf(err, "unknown normalizer '%s'", args[cur_arg]);
 		return ACT_RET_PRS_ERR;
diff --git a/src/uri_normalizer.c b/src/uri_normalizer.c
index 4fd783d..bc793f2 100644
--- a/src/uri_normalizer.c
+++ b/src/uri_normalizer.c
@@ -18,6 +18,41 @@
 #include <haproxy/tools.h>
 #include <haproxy/uri_normalizer.h>
 
+/* Encodes '#' as '%23'. */
+enum uri_normalizer_err uri_normalizer_fragment_encode(const struct ist input, struct ist *dst)
+{
+	enum uri_normalizer_err err;
+
+	const size_t size = istclear(dst);
+	struct ist output = *dst;
+
+	struct ist scanner = input;
+
+	while (istlen(scanner)) {
+		const struct ist before_hash = istsplit(&scanner, '#');
+
+		if (istcat(&output, before_hash, size) < 0) {
+			err = URI_NORMALIZER_ERR_ALLOC;
+			goto fail;
+		}
+
+		if (istend(before_hash) != istend(scanner)) {
+			if (istcat(&output, ist("%23"), size) < 0) {
+				err = URI_NORMALIZER_ERR_ALLOC;
+				goto fail;
+			}
+		}
+	}
+
+	*dst = output;
+
+	return URI_NORMALIZER_ERR_NONE;
+
+  fail:
+
+	return err;
+}
+
 /* Returns 1 if the given character is part of the 'unreserved' set in the
  * RFC 3986 ABNF.
  * Returns 0 if not.