hrw: Supports indexed query parameters as conds

doc/admin-guide/plugins/header_rewrite.en.rst

@@ -1529,6 +1529,15 @@ The URL part names which may be used for these conditions and actions are:
               parameters, until the end of the URL. Empty string if there were no
               query parameters. ``Value`` = `p=hrw&v=1`
 
+              A specific query parameter value can be extracted using the sub-key
+              syntax ``QUERY:<param_name>``. For example, ``%{CLIENT-URL:QUERY:p}``
+              would return ``hrw`` for the URL above.
+
+              .. note::
+                 Query parameter names and values are matched as-is without URL
+                 decoding. For example, ``%{CLIENT-URL:QUERY:my%20param}`` matches
+                 the literal parameter name ``my%20param``, not ``my param``.
+
    URL        The complete URL.  ``Value`` = `https://docs.trafficserver.apache.org/...`
    ========== ======================================================================
 
@@ -2000,3 +2009,17 @@ Those will pick the address provided by PROXY protocol, instead of the peer's ad
 
    cond %{SEND_RESPONSE_HDR_HOOK}
       set-header real-ip %{INBOUND:REMOTE-ADDR}
+
+Route Based on Query Parameter Value
+------------------------------------
+
+This rule extracts a specific query parameter value and uses it to set a custom
+header or make routing decisions. The ``QUERY:<param_name>`` sub-key syntax
+allows extracting individual query parameter values::
+
+   cond %{REMAP_PSEUDO_HOOK} [AND]
+   cond %{CLIENT-URL:QUERY:version} ="v2"
+      set-destination HOST api-v2.example.com
+
+   cond %{SEND_RESPONSE_HDR_HOOK}
+      set-header X-API-Version %{CLIENT-URL:QUERY:version}

plugins/header_rewrite/conditions.cc

@@ -30,6 +30,8 @@
 #include <array>
 #include <atomic>
 
+#include "swoc/TextView.h"
+
 #include "ts/ts.h"
 
 #include "conditions.h"
@@ -280,7 +282,27 @@ ConditionUrl::set_qualifier(const std::string &q)
   Condition::set_qualifier(q);
 
   Dbg(pi_dbg_ctl, "\tParsing %%{URL:%s}", q.c_str());
-  _url_qual = parse_url_qualifier(q);
+
+  std::string::size_type pos = q.find(':');
+
+  if (pos != std::string::npos) {
+    std::string qual_part = q.substr(0, pos);
+    std::string sub_qual  = q.substr(pos + 1);
+
+    _url_qual = parse_url_qualifier(qual_part);
+
+    if (_url_qual == URL_QUAL_QUERY) {
+      if (!sub_qual.empty()) {
+        _query_param = sub_qual;
+        Dbg(pi_dbg_ctl, "\tQuery parameter sub-key: %s", _query_param.c_str());
+      }
+    } else {
+      TSError("[%s] Sub-qualifier syntax (component:subkey) is only supported for QUERY component, got: %s", PLUGIN_NAME,
+              qual_part.c_str());
+    }
+  } else {
+    _url_qual = parse_url_qualifier(q);
+  }
 }
 
 void
@@ -347,8 +369,19 @@ ConditionUrl::append_value(std::string &s, const Resources &res)
     break;
   case URL_QUAL_QUERY:
     q_str = TSUrlHttpQueryGet(bufp, url, &i);
-    s.append(q_str, i);
-    Dbg(pi_dbg_ctl, "   Query parameters to match is: %.*s", i, q_str);
+    if (_query_param.empty()) {
+      s.append(q_str, i);
+      Dbg(pi_dbg_ctl, "   Query parameters to match is: %.*s", i, q_str);
+    } else {
+      swoc::TextView value = res.get_query_param(_query_param, q_str, i);
+
+      if (value.data() != nullptr && value.size() > 0) {
+        s.append(value.data(), value.size());
+        Dbg(pi_dbg_ctl, "   Query parameter %s value is: %.*s", _query_param.c_str(), static_cast<int>(value.size()), value.data());
+      } else {
+        Dbg(pi_dbg_ctl, "   Query parameter %s is empty or not present", _query_param.c_str());
+      }
+    }
     break;
   case URL_QUAL_SCHEME:
     q_str = TSUrlSchemeGet(bufp, url, &i);

plugins/header_rewrite/conditions.h

@@ -300,6 +300,7 @@ class ConditionUrl : public Condition
 private:
   UrlQualifiers _url_qual = URL_QUAL_NONE;
   UrlType       _type;
+  std::string   _query_param; // Optional: specific query parameter name for QUERY sub-key
 };
 
 // DBM lookups

plugins/header_rewrite/operators.cc

@@ -324,6 +324,7 @@ OperatorSetDestination::exec(const Resources &res) const
 
         const_cast<Resources &>(res).changed_url = true;
         TSUrlHttpQuerySet(bufp, url_m_loc, value.c_str(), value.size());
+        res.reset_query_cache();
         Dbg(pi_dbg_ctl, "OperatorSetDestination::exec() invoked with QUERY: %s", value.c_str());
       }
       break;
@@ -348,6 +349,7 @@ OperatorSetDestination::exec(const Resources &res) const
         if (TSUrlCreate(bufp, &new_url_loc) == TS_SUCCESS && TSUrlParse(bufp, new_url_loc, &start, end) == TS_PARSE_DONE &&
             TSHttpHdrUrlSet(bufp, res.hdr_loc, new_url_loc) == TS_SUCCESS) {
           const_cast<Resources &>(res).changed_url = true;
+          res.reset_query_cache();
           Dbg(pi_dbg_ctl, "Set destination URL to %s", value.c_str());
         } else {
           Dbg(pi_dbg_ctl, "Failed to set URL %s", value.c_str());
@@ -461,6 +463,7 @@ OperatorRMDestination::exec(const Resources &res) const
       }
       const_cast<Resources &>(res).changed_url = true;
       TSUrlHttpQuerySet(bufp, url_m_loc, value.c_str(), value.size());
+      res.reset_query_cache();
       break;
     case URL_QUAL_PORT:
       const_cast<Resources &>(res).changed_url = true;

plugins/header_rewrite/resources.cc

@@ -181,3 +181,35 @@ Resources::destroy()
 
   _ready = false;
 }
+
+swoc::TextView
+Resources::get_query_param(const std::string &name, const char *query_str, int query_len) const
+{
+  // Note: Query parameter names and values are matched as-is without URL decoding.
+  // For example, searching for "my%20param" matches the literal string, not "my param".
+  if (!_extended_info.query_parsed) {
+    if (query_str && query_len > 0) {
+      swoc::TextView query_view(query_str, query_len);
+
+      while (!query_view.empty()) {
+        swoc::TextView param       = query_view.take_prefix_at('&');
+        swoc::TextView param_name  = param.take_prefix_at('=');
+        swoc::TextView param_value = param;
+
+        if (!param_name.empty()) {
+          // We only allow caching / using the first instance of a query param
+          _extended_info.query_params[param_name] = param_value;
+        }
+      }
+    }
+    _extended_info.query_parsed = true;
+  }
+
+  auto it = _extended_info.query_params.find(swoc::TextView(name));
+
+  if (it != _extended_info.query_params.end()) {
+    return it->second;
+  }
+
+  return swoc::TextView();
+}

plugins/header_rewrite/resources.h

@@ -22,6 +22,9 @@
 #pragma once
 
 #include <string>
+#include <unordered_map>
+
+#include "swoc/TextView.h"
 
 #include "regex_helper.h"
 #include "ts/ts.h"
@@ -96,6 +99,16 @@ class Resources
     return _extended_info.matches;
   }
 
+  // Get a query parameter value by name, with caching
+  swoc::TextView get_query_param(const std::string &name, const char *query_str, int query_len) const;
+
+  void
+  reset_query_cache() const
+  {
+    _extended_info.query_params.clear();
+    _extended_info.query_parsed = false;
+  }
+
   TSCont              contp          = nullptr;
   TSRemapRequestInfo *_rri           = nullptr;
   TSMBuffer           bufp           = nullptr;
@@ -114,8 +127,10 @@ class Resources
   TSHttpStatus resp_status = TS_HTTP_STATUS_NONE;
 
   struct LifetimeExtension {
-    std::string  subject_storage;
-    RegexMatches matches;
+    std::string                                        subject_storage;
+    RegexMatches                                       matches;
+    std::unordered_map<swoc::TextView, swoc::TextView> query_params;
+    bool                                               query_parsed = false;
   };
   bool                      changed_url = false;
   mutable LifetimeExtension _extended_info;

tests/gold_tests/pluginTest/header_rewrite/header_rewrite_bundle.replay.yaml

@@ -138,6 +138,13 @@ autest:
             args:
               - "rules/nested_ifs.conf"
 
+      - from: "http://www.example.com/from_13/"
+        to: "http://backend.ex:{SERVER_HTTP_PORT}/to_13/"
+        plugins:
+          - name: "header_rewrite.so"
+            args:
+              - "rules/query_sub_key.conf"
+
 
 
 # Proxy verifier sessions
@@ -1019,3 +1026,51 @@ sessions:
         - [ X-Foo-And-Fie, { as: absent } ]
         - [ X-Fie-Anywhere, { value: "Yes", as: equal } ]
         - [ X-When-200-After, { value: "Yes", as: equal } ]
+
+# Test 28: Query parameter sub-key extraction
+- transactions:
+  - client-request:
+      method: "GET"
+      version: "1.1"
+      url: /from_13/?sub=Hello
+      headers:
+        fields:
+        - [ Host, www.example.com ]
+        - [ uuid, 34 ]
+
+    server-response:
+      status: 200
+      reason: OK
+      headers:
+        fields:
+        - [ Connection, close ]
+
+    proxy-response:
+      status: 200
+      headers:
+        fields:
+        - [ X-Query-Sub, { value: "Hello", as: equal } ]
+
+# Test 29: Query parameter sub-key - parameter not present
+- transactions:
+  - client-request:
+      method: "GET"
+      version: "1.1"
+      url: /from_13/?other=value
+      headers:
+        fields:
+        - [ Host, www.example.com ]
+        - [ uuid, 35 ]
+
+    server-response:
+      status: 200
+      reason: OK
+      headers:
+        fields:
+        - [ Connection, close ]
+
+    proxy-response:
+      status: 200
+      headers:
+        fields:
+        - [ X-Query-Sub, { as: absent } ]

tests/gold_tests/pluginTest/header_rewrite/rules/query_sub_key.conf

@@ -0,0 +1,21 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Test query parameter sub-key extraction
+cond %{SEND_RESPONSE_HDR_HOOK} [AND]
+cond %{CLIENT-URL:QUERY:sub} ="" [NOT]
+  set-header X-Query-Sub "%{CLIENT-URL:QUERY:sub}"