Allow plugins to use WKS header strings

doc/developer-guide/api/functions/TSMimeHdrFieldFind.en.rst

@@ -29,6 +29,8 @@ Synopsis
     #include <ts/ts.h>
 
 .. function:: TSMLoc TSMimeHdrFieldFind(TSMBuffer bufp, TSMLoc hdr, const char * name, int length)
+.. function:: const char *TSMimeHdrStringToWKS(const char *str, int length)
+
 
 Description
 ===========
@@ -42,3 +44,8 @@ comparison is done between the field name and :arg:`name`. If
 :c:func:`TSMimeHdrFieldFind` cannot find the requested field, it
 returns :c:data:`TS_NULL_MLOC`.  Release the returned :c:type:`TSMLoc`
 handle with a call to :c:func:`TSHandleMLocRelease`.
+
+The :arg:`name` argument is best specified using the pre-defined Well-Known strings, such as e.g.
+``TS_MIME_FIELD_CACHE_CONTROL`` and ``TS_MIME_LEN_CACHE_CONTROL``. These WK constants
+can also be looked up using :c:func:`TSMimeHdrStringToWKS`. If a header does
+not have a WKS, this function will return a :code:`nullptr`.

doc/developer-guide/api/functions/TSMimeHdrFieldValueStringGet.en.rst

@@ -65,6 +65,10 @@ preferred.
 value, and populated :arg:`value_len_ptr` with the length of the
 value in bytes. The returned header value is not NUL-terminated.
 
+In addition to all the predefined constants for Well-Known header strings, you can
+also do a lookup for a header string using :func:`TSMimeHdrStringToWKS`. If a lookup
+fails, this function returns a :code:`nullptr`
+
 Return Values
 =============
 

doc/developer-guide/plugins/http-headers/mime-headers.en.rst

@@ -437,3 +437,4 @@ The MIME header functions are listed below:
 -  :c:func:`TSMimeParserCreate`
 -  :c:func:`TSMimeParserDestroy`
 -  :c:func:`TSMimeHdrPrint`
+-  :c:func:`TSMimeHdrStringToWKS`

include/ts/ts.h

@@ -1061,6 +1061,7 @@ tsapi TSReturnCode TSMimeHdrFieldValueUintInsert(TSMBuffer bufp, TSMLoc hdr, TSM
 tsapi TSReturnCode TSMimeHdrFieldValueDateInsert(TSMBuffer bufp, TSMLoc hdr, TSMLoc field, time_t value);
 
 tsapi TSReturnCode TSMimeHdrFieldValueDelete(TSMBuffer bufp, TSMLoc hdr, TSMLoc field, int idx);
+tsapi const char *TSMimeHdrStringToWKS(const char *str, int length);
 
 /* --------------------------------------------------------------------------
    HTTP headers */

plugins/header_rewrite/condition.h

@@ -97,7 +97,8 @@ class Condition : public Statement
   virtual void
   set_qualifier(const std::string &q)
   {
-    _qualifier = q;
+    _qualifier_wks = TSMimeHdrStringToWKS(q.c_str(), q.length());
+    _qualifier     = q;
   }
 
   // Some getters
@@ -128,8 +129,9 @@ class Condition : public Statement
   virtual bool eval(const Resources &res) = 0;
 
   std::string _qualifier;
-  MatcherOps _cond_op = MATCH_EQUAL;
-  Matcher *_matcher   = nullptr;
+  const char *_qualifier_wks = nullptr;
+  MatcherOps _cond_op        = MATCH_EQUAL;
+  Matcher *_matcher          = nullptr;
 
 private:
   CondModifiers _mods = COND_NONE;

plugins/header_rewrite/conditions.cc

@@ -231,7 +231,7 @@ ConditionHeader::append_value(std::string &s, const Resources &res)
   if (bufp && hdr_loc) {
     TSMLoc field_loc;
 
-    field_loc = TSMimeHdrFieldFind(bufp, hdr_loc, _qualifier.c_str(), _qualifier.size());
+    field_loc = TSMimeHdrFieldFind(bufp, hdr_loc, _qualifier_wks ? _qualifier_wks : _qualifier.c_str(), _qualifier.size());
     TSDebug(PLUGIN_NAME, "Getting Header: %s, field_loc: %p", _qualifier.c_str(), field_loc);
 
     while (field_loc) {

plugins/header_rewrite/operator.cc

@@ -52,7 +52,8 @@ OperatorHeaders::initialize(Parser &p)
 {
   Operator::initialize(p);
 
-  _header = p.get_arg();
+  _header     = p.get_arg();
+  _header_wks = TSMimeHdrStringToWKS(_header.c_str(), _header.length());
 
   require_resources(RSRC_SERVER_RESPONSE_HEADERS);
   require_resources(RSRC_SERVER_REQUEST_HEADERS);

plugins/header_rewrite/operator.h

@@ -85,6 +85,7 @@ class OperatorHeaders : public Operator
 
 protected:
   std::string _header;
+  const char *_header_wks;
 };
 
 ///////////////////////////////////////////////////////////////////////////////

plugins/header_rewrite/operators.cc

@@ -645,7 +645,7 @@ OperatorSetHeader::exec(const Resources &res) const
   }
 
   if (res.bufp && res.hdr_loc) {
-    TSMLoc field_loc = TSMimeHdrFieldFind(res.bufp, res.hdr_loc, _header.c_str(), _header.size());
+    TSMLoc field_loc = TSMimeHdrFieldFind(res.bufp, res.hdr_loc, _header_wks ? _header_wks : _header.c_str(), _header.size());
 
     TSDebug(PLUGIN_NAME, "OperatorSetHeader::exec() invoked on %s: %s", _header.c_str(), value.c_str());
 

src/traffic_server/InkAPI.cc

@@ -3773,6 +3773,16 @@ TSMimeHdrFieldValueDelete(TSMBuffer bufp, TSMLoc hdr, TSMLoc field, int idx)
   return TS_SUCCESS;
 }
 
+const char *
+TSMimeHdrStringToWKS(const char *str, int length)
+{
+  if (length < 0) {
+    return hdrtoken_string_to_wks(str);
+  } else {
+    return hdrtoken_string_to_wks(str, length);
+  }
+}
+
 /**************/
 /* HttpParser */
 /**************/