Make router take up less space for verbs

As is, the router designates routes for every possible boost verb, of
which there are 31.  In bmcweb, we only make use of 6 of those verbs, so
that ends up being quite a bit of wasted space and cache non-locality.

This commit invents a new enum class for declaring a subset of boost
verbs that we support, and a mapping between bmcweb verbs and boost
verbs.

Then it walks through and updates the router to support converting one
to another.

Tested:
Unit Tested
Redfish Service Validator performed on future commit

Signed-off-by: Ed Tanous <edtanous@google.com>
Signed-off-by: Edward Lee <edwarddl@google.com>
Change-Id: I3c89e896c632a5d4134dbd08a30b313c12a60de6
diff --git a/http/routing.hpp b/http/routing.hpp
index 870a62c..6c393ab 100644
--- a/http/routing.hpp
+++ b/http/routing.hpp
@@ -9,6 +9,7 @@
 #include "privileges.hpp"
 #include "sessions.hpp"
 #include "utility.hpp"
+#include "verb.hpp"
 #include "websocket.hpp"
 
 #include <async_resp.hpp>
@@ -20,6 +21,7 @@
 #include <cstdlib>
 #include <limits>
 #include <memory>
+#include <optional>
 #include <tuple>
 #include <utility>
 #include <vector>
@@ -27,13 +29,7 @@
 namespace crow
 {
 
-// Note, this is an imperfect abstraction.  There are a lot of verbs that we
-// use memory for, but are basically unused by most implementations.
-// Ideally we would have a list of verbs that we do use, and only index in
-// to a smaller array of those, but that would require a translation from
-// boost::beast::http::verb, to the bmcweb index.
-static constexpr size_t maxVerbIndex =
-    static_cast<size_t>(boost::beast::http::verb::patch);
+static constexpr size_t maxVerbIndex = static_cast<size_t>(HttpVerb::Max) - 1U;
 
 // MaxVerb + 1 is designated as the "not found" verb.  It is done this way
 // to keep the BaseRule as a single bitfield (thus keeping the struct small)
@@ -107,8 +103,7 @@
         return false;
     }
 
-    size_t methodsBitfield{
-        1 << static_cast<size_t>(boost::beast::http::verb::get)};
+    size_t methodsBitfield{1 << static_cast<size_t>(HttpVerb::Get)};
     static_assert(std::numeric_limits<decltype(methodsBitfield)>::digits >
                       methodNotAllowedIndex,
                   "Not enough bits to store bitfield");
@@ -445,7 +440,11 @@
     self_t& methods(boost::beast::http::verb method)
     {
         self_t* self = static_cast<self_t*>(this);
-        self->methodsBitfield = 1U << static_cast<size_t>(method);
+        std::optional<HttpVerb> verb = httpVerbFromBoost(method);
+        if (verb)
+        {
+            self->methodsBitfield = 1U << static_cast<size_t>(*verb);
+        }
         return *self;
     }
 
@@ -454,7 +453,11 @@
     {
         self_t* self = static_cast<self_t*>(this);
         methods(argsMethod...);
-        self->methodsBitfield |= 1U << static_cast<size_t>(method);
+        std::optional<HttpVerb> verb = httpVerbFromBoost(method);
+        if (verb)
+        {
+            self->methodsBitfield |= 1U << static_cast<size_t>(*verb);
+        }
         return *self;
     }
 
@@ -1210,7 +1213,12 @@
     {
         FindRouteResponse findRoute;
 
-        size_t reqMethodIndex = static_cast<size_t>(req.method());
+        std::optional<HttpVerb> verb = httpVerbFromBoost(req.method());
+        if (!verb)
+        {
+            return findRoute;
+        }
+        size_t reqMethodIndex = static_cast<size_t>(*verb);
         // Check to see if this url exists at any verb
         for (size_t perMethodIndex = 0; perMethodIndex <= maxVerbIndex;
              perMethodIndex++)
@@ -1227,8 +1235,8 @@
             {
                 findRoute.allowHeader += ", ";
             }
-            findRoute.allowHeader += boost::beast::http::to_string(
-                static_cast<boost::beast::http::verb>(perMethodIndex));
+            HttpVerb thisVerb = static_cast<HttpVerb>(perMethodIndex);
+            findRoute.allowHeader += httpVerbToString(thisVerb);
             if (perMethodIndex == reqMethodIndex)
             {
                 findRoute.route = route;
@@ -1240,14 +1248,14 @@
     template <typename Adaptor>
     void handleUpgrade(const Request& req, Response& res, Adaptor&& adaptor)
     {
-        if (static_cast<size_t>(req.method()) >= perMethods.size())
+        std::optional<HttpVerb> verb = httpVerbFromBoost(req.method());
+        if (!verb || static_cast<size_t>(*verb) >= perMethods.size())
         {
             res.result(boost::beast::http::status::not_found);
             res.end();
             return;
         }
-
-        PerMethod& perMethod = perMethods[static_cast<size_t>(req.method())];
+        PerMethod& perMethod = perMethods[static_cast<size_t>(*verb)];
         Trie& trie = perMethod.trie;
         std::vector<BaseRule*>& rules = perMethod.rules;
 
@@ -1309,7 +1317,8 @@
     void handle(Request& req,
                 const std::shared_ptr<bmcweb::AsyncResp>& asyncResp)
     {
-        if (static_cast<size_t>(req.method()) >= perMethods.size())
+        std::optional<HttpVerb> verb = httpVerbFromBoost(req.method());
+        if (!verb || static_cast<size_t>(*verb) >= perMethods.size())
         {
             asyncResp->res.result(boost::beast::http::status::not_found);
             return;