Fix apply-remap-rule directive.

Fix use of when directive in remap hook.

plugin/include/txn_box/common.h

@@ -376,18 +376,20 @@ BufferWriter &bwformat(BufferWriter &w, bwf::Spec const &spec, ValueMask const &
 }
 
 /// Supported hooks.
+/// @internal These must be in order because that is used to check if the value for the _when_
+/// directive is valid from the current hook.
 enum class Hook {
   INVALID, ///< Invalid hook (default initialization value).
   POST_LOAD, ///< After configuration loading.
   TXN_START, ///< Transaction start.
   CREQ, ///< Read Request from user agent.
   PRE_REMAP, ///< Before remap.
+  REMAP, ///< Remap (implicit).
   POST_REMAP, ///< After remap.
   PREQ, ///< Send request from proxy to upstream.
   URSP, ///< Read response from upstream.
   PRSP, ///< Send response to user agent from proxy.
   TXN_CLOSE, ///< Transaction close.
-  REMAP, ///< Remap (implicit).
   MSG ///< During plugin message handling (implicit).
 };
 

plugin/src/Features.cc

@@ -491,6 +491,28 @@ void HttpFieldTuple::advance() {
 
 Feature HttpFieldTuple::extract() const { return _current.value(); }
 
+/* ------------------------------------------------------------------------------------ */
+/** The entire URL.
+ * Because of the nature of the C API, this can only be a transient external string and
+ * therefore must be copied in to context storage.
+ */
+class Ex_preq_url : public StringExtractor {
+public:
+  static constexpr TextView NAME { "preq-url" };
+
+  BufferWriter& format(BufferWriter& w, Spec const& spec, Context& ctx) override;
+};
+
+BufferWriter& Ex_preq_url::format(BufferWriter &w, Spec const &spec, Context &ctx) {
+  FeatureView zret;
+  if ( auto hdr { ctx.preq_hdr() } ; hdr.is_valid()) {
+    if ( ts::URL url { hdr.url() } ; url.is_valid()) {
+      bwformat(w, spec, url.view());
+    }
+  }
+  return w;
+}
+
 /* ------------------------------------------------------------------------------------ */
 class Ex_preq_host : public Extractor {
 public:
@@ -758,6 +780,7 @@ Ex_creq_field creq_field;
 
 Ex_preq_host preq_host;
 
+Ex_preq_url preq_url;
 Ex_prsp_field prsp_field;
 Ex_ursp_field ursp_field;
 
@@ -788,6 +811,7 @@ Ex_remainder_feature ex_remainder_feature;
 
   Extractor::define(Ex_preq_host::NAME, &preq_host);
 
+  Extractor::define(Ex_preq_url::NAME, &preq_url);
   Extractor::define(Ex_prsp_field::NAME, &prsp_field);
   Extractor::define(Ex_ursp_field::NAME, &ursp_field);
 

plugin/src/Machinery.cc

@@ -312,13 +312,15 @@ Errata Do_apply_remap_rule::invoke(Context &ctx) {
     // Need to do better - see if Context can provide an ArenaWriter?
     swoc::LocalBufferWriter<(1<<16) - 1> url_w;
     url_w.write(replacement_path);
-    if (request_path.size() > replacement_path.size()) {
-      if (replacement_path.size() > 0 && url_w.view()[replacement_path.size()-1] != '/') {
+    if (request_path.size() > target_path.size()) {
+      // Always slash separate the replacement from the remnant of the incoming request path.
+      if (url_w.size() && url_w.view()[url_w.size()-1] != '/') {
         url_w.write('/');
       }
-      url_w.write(request_path.substr(replacement_path.size()).ltrim('/'));
+      // Already have the separating slash, trim it from the target path.
+      url_w.write(request_path.substr(target_path.size()).ltrim('/'));
     }
-    request_url.path_set(url_w.view());
+    request_url.path_set(TextView{url_w.view()}.ltrim('/'));
   };
 
 //  TSUrlCopy(ctx._remap_info->requestBufp, ctx._remap_info->requestUrl, ctx._remap_info->requestBufp, ctx._remap_info->mapToUrl);
@@ -1541,7 +1543,7 @@ Errata With::load_case(Config & cfg, YAML::Node node) {
 
 /* ------------------------------------------------------------------------------------ */
 const std::string When::KEY { "when" };
-const HookMask When::HOOKS  { MaskFor({Hook::CREQ, Hook::PREQ, Hook::URSP, Hook::PRSP, Hook::PRE_REMAP, Hook::POST_REMAP }) };
+const HookMask When::HOOKS  { MaskFor({Hook::CREQ, Hook::PREQ, Hook::URSP, Hook::PRSP, Hook::PRE_REMAP, Hook::REMAP, Hook::POST_REMAP }) };
 
 When::When(Hook hook_idx, Directive::Handle &&directive) : _hook(hook_idx), _directive(std::move
 (directive)) {}