MINOR: uri_normalizer: Add a `dotdot` normalizer to http-request normalize-uri
This normalizer merges `../` path segments with the predecing segment, removing
both the preceding segment and the `../`.
Empty segments do not receive special treatment. The `merge-slashes` normalizer
should be executed first.
See GitHub Issue #714.
diff --git a/src/uri_normalizer.c b/src/uri_normalizer.c
index abc029b..05e8cd5 100644
--- a/src/uri_normalizer.c
+++ b/src/uri_normalizer.c
@@ -15,6 +15,88 @@
#include <haproxy/api.h>
#include <haproxy/uri_normalizer.h>
+/* Merges `/../` with preceding path segments. */
+enum uri_normalizer_err uri_normalizer_path_dotdot(const struct ist path, struct ist *dst)
+{
+ enum uri_normalizer_err err;
+
+ const size_t size = istclear(dst);
+ char * const tail = istptr(*dst) + size;
+ char *head = tail;
+
+ ssize_t offset = istlen(path) - 1;
+
+ int up = 0;
+
+ /* The path will either be shortened or have the same length. */
+ if (size < istlen(path)) {
+ err = URI_NORMALIZER_ERR_ALLOC;
+ goto fail;
+ }
+
+ /* Handle `/..` at the end of the path without a trailing slash. */
+ if (offset >= 2 && istmatch(istadv(path, offset - 2), ist("/.."))) {
+ up++;
+ offset -= 2;
+ }
+
+ while (offset >= 0) {
+ if (offset >= 3 && istmatch(istadv(path, offset - 3), ist("/../"))) {
+ up++;
+ offset -= 3;
+ continue;
+ }
+
+ if (up > 0) {
+ /* Skip the slash. */
+ offset--;
+
+ /* First check whether we already reached the start of the path,
+ * before popping the current `/../`.
+ */
+ if (offset >= 0) {
+ up--;
+
+ /* Skip the current path segment. */
+ while (offset >= 0 && istptr(path)[offset] != '/')
+ offset--;
+ }
+ }
+ else {
+ /* Prepend the slash. */
+ *(--head) = istptr(path)[offset];
+ offset--;
+
+ /* Prepend the current path segment. */
+ while (offset >= 0 && istptr(path)[offset] != '/') {
+ *(--head) = istptr(path)[offset];
+ offset--;
+ }
+ }
+ }
+
+ if (up > 0) {
+ /* Prepend a trailing slash. */
+ *(--head) = '/';
+
+ /* Prepend unconsumed `/..`. */
+ do {
+ *(--head) = '.';
+ *(--head) = '.';
+ *(--head) = '/';
+ up--;
+ } while (up > 0);
+ }
+
+ *dst = ist2(head, tail - head);
+
+ return URI_NORMALIZER_ERR_NONE;
+
+ fail:
+
+ return err;
+}
+
/* Merges adjacent slashes in the given path. */
enum uri_normalizer_err uri_normalizer_path_merge_slashes(const struct ist path, struct ist *dst)
{