MINOR: uri_normalizer: Add a `percent-decode-unreserved` normalizer
This normalizer decodes percent encoded characters within the RFC 3986
unreserved set.
See GitHub Issue #714.
diff --git a/src/http_act.c b/src/http_act.c
index df2bbe4..58e1bb8 100644
--- a/src/http_act.c
+++ b/src/http_act.c
@@ -302,6 +302,24 @@
break;
}
+ case ACT_NORMALIZE_URI_PERCENT_DECODE_UNRESERVED:
+ case ACT_NORMALIZE_URI_PERCENT_DECODE_UNRESERVED_STRICT: {
+ const struct ist path = http_get_path(uri);
+ struct ist newpath = ist2(replace->area, replace->size);
+
+ if (!isttest(path))
+ goto leave;
+
+ err = uri_normalizer_percent_decode_unreserved(path, rule->action == ACT_NORMALIZE_URI_PERCENT_DECODE_UNRESERVED_STRICT, &newpath);
+
+ if (err != URI_NORMALIZER_ERR_NONE)
+ break;
+
+ if (!http_replace_req_path(htx, newpath, 1))
+ goto fail_rewrite;
+
+ break;
+ }
}
switch (err) {
@@ -407,6 +425,21 @@
return ACT_RET_PRS_ERR;
}
}
+ else if (strcmp(args[cur_arg], "percent-decode-unreserved") == 0) {
+ cur_arg++;
+
+ if (strcmp(args[cur_arg], "strict") == 0) {
+ cur_arg++;
+ rule->action = ACT_NORMALIZE_URI_PERCENT_DECODE_UNRESERVED_STRICT;
+ }
+ else if (!*args[cur_arg]) {
+ rule->action = ACT_NORMALIZE_URI_PERCENT_DECODE_UNRESERVED;
+ }
+ else if (strcmp(args[cur_arg], "if") != 0 && strcmp(args[cur_arg], "unless") != 0) {
+ memprintf(err, "unknown argument '%s' for 'percent-decode-unreserved' normalizer", args[cur_arg]);
+ return ACT_RET_PRS_ERR;
+ }
+ }
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 8d95936..4fd783d 100644
--- a/src/uri_normalizer.c
+++ b/src/uri_normalizer.c
@@ -18,6 +18,101 @@
#include <haproxy/tools.h>
#include <haproxy/uri_normalizer.h>
+/* Returns 1 if the given character is part of the 'unreserved' set in the
+ * RFC 3986 ABNF.
+ * Returns 0 if not.
+ */
+static int is_unreserved_character(unsigned char c)
+{
+ switch (c) {
+ case 'A'...'Z': /* ALPHA */
+ case 'a'...'z': /* ALPHA */
+ case '0'...'9': /* DIGIT */
+ case '-':
+ case '.':
+ case '_':
+ case '~':
+ return 1;
+ default:
+ return 0;
+ }
+}
+
+/* Decodes percent encoded characters that are part of the 'unreserved' set.
+ *
+ * RFC 3986, section 2.3:
+ * > URIs that differ in the replacement of an unreserved character with
+ * > its corresponding percent-encoded US-ASCII octet are equivalent [...]
+ * > when found in a URI, should be decoded to their corresponding unreserved
+ * > characters by URI normalizers.
+ *
+ * If `strict` is set to 0 then percent characters that are not followed by a
+ * hexadecimal digit are returned as-is without performing any decoding.
+ * If `strict` is set to 1 then `URI_NORMALIZER_ERR_INVALID_INPUT` is returned
+ * for invalid sequences.
+ */
+enum uri_normalizer_err uri_normalizer_percent_decode_unreserved(const struct ist input, int strict, struct ist *dst)
+{
+ enum uri_normalizer_err err;
+
+ const size_t size = istclear(dst);
+ struct ist output = *dst;
+
+ struct ist scanner = input;
+
+ /* The output will either be shortened or have the same length. */
+ if (size < istlen(input)) {
+ err = URI_NORMALIZER_ERR_ALLOC;
+ goto fail;
+ }
+
+ while (istlen(scanner)) {
+ const char current = istshift(&scanner);
+
+ if (current == '%') {
+ if (istlen(scanner) >= 2) {
+ if (ishex(istptr(scanner)[0]) && ishex(istptr(scanner)[1])) {
+ char hex1, hex2, c;
+
+ hex1 = istshift(&scanner);
+ hex2 = istshift(&scanner);
+ c = (hex2i(hex1) << 4) + hex2i(hex2);
+
+ if (is_unreserved_character(c)) {
+ output = __istappend(output, c);
+ }
+ else {
+ output = __istappend(output, current);
+ output = __istappend(output, hex1);
+ output = __istappend(output, hex2);
+ }
+
+ continue;
+ }
+ }
+
+ if (strict) {
+ err = URI_NORMALIZER_ERR_INVALID_INPUT;
+ goto fail;
+ }
+ else {
+ output = __istappend(output, current);
+ }
+ }
+ else {
+ output = __istappend(output, current);
+ }
+ }
+
+ *dst = output;
+
+ return URI_NORMALIZER_ERR_NONE;
+
+ fail:
+
+ return err;
+}
+
/* Uppercases letters used in percent encoding.
*
* If `strict` is set to 0 then percent characters that are not followed by a