define HTTP request methods at module level outside of class

This is a refactor to prepare for matching the API of HTTPRequest
definitions in both namespaces http_bitcoin and http_libevent. In
particular, to provide a consistent return type for GetRequestMethod()
in both classes.

src/httprpc.cpp

@@ -198,7 +198,7 @@ UniValue ExecuteHTTPRPC(const UniValue& valRequest, JSONRPCRequest& jreq, HTTPSt
 static void HTTPReq_JSONRPC(const std::any& context, HTTPRequest* req)
 {
     // JSONRPC handles only POST
-    if (req->GetRequestMethod() != HTTPRequest::POST) {
+    if (req->GetRequestMethod() != HTTPRequestMethod::POST) {
         req->WriteReply(HTTP_BAD_METHOD, "JSONRPC server handles only POST requests");
         return;
     }

src/httpserver.cpp

@@ -183,19 +183,15 @@ static bool InitHTTPAllowList()
 }
 
 /** HTTP request method as string - use for logging only */
-std::string RequestMethodString(HTTPRequest::RequestMethod m)
+std::string_view RequestMethodString(HTTPRequestMethod m)
 {
     switch (m) {
-    case HTTPRequest::GET:
-        return "GET";
-    case HTTPRequest::POST:
-        return "POST";
-    case HTTPRequest::HEAD:
-        return "HEAD";
-    case HTTPRequest::PUT:
-        return "PUT";
-    case HTTPRequest::UNKNOWN:
-        return "unknown";
+    using enum HTTPRequestMethod;
+    case GET: return "GET";
+    case POST: return "POST";
+    case HEAD: return "HEAD";
+    case PUT: return "PUT";
+    case UNKNOWN: return "unknown";
     } // no default case, so the compiler can warn about missing cases
     assert(false);
 }
@@ -237,7 +233,7 @@ static void http_request_cb(struct evhttp_request* req, void* arg)
     }
 
     // Early reject unknown HTTP methods
-    if (hreq->GetRequestMethod() == HTTPRequest::UNKNOWN) {
+    if (hreq->GetRequestMethod() == HTTPRequestMethod::UNKNOWN) {
         LogDebug(BCLog::HTTP, "HTTP request from %s rejected: Unknown HTTP request method\n",
                  hreq->GetPeer().ToStringAddrPort());
         hreq->WriteReply(HTTP_BAD_METHOD);
@@ -655,19 +651,19 @@ std::string HTTPRequest::GetURI() const
     return evhttp_request_get_uri(req);
 }
 
-HTTPRequest::RequestMethod HTTPRequest::GetRequestMethod() const
+HTTPRequestMethod HTTPRequest::GetRequestMethod() const
 {
     switch (evhttp_request_get_command(req)) {
     case EVHTTP_REQ_GET:
-        return GET;
+        return HTTPRequestMethod::GET;
     case EVHTTP_REQ_POST:
-        return POST;
+        return HTTPRequestMethod::POST;
     case EVHTTP_REQ_HEAD:
-        return HEAD;
+        return HTTPRequestMethod::HEAD;
     case EVHTTP_REQ_PUT:
-        return PUT;
+        return HTTPRequestMethod::PUT;
     default:
-        return UNKNOWN;
+        return HTTPRequestMethod::UNKNOWN;
     }
 }
 
@@ -849,7 +845,19 @@ bool HTTPRequest::LoadControlData(LineReader& reader)
 
     const std::vector<std::string_view> parts{Split<std::string_view>(request_line, " ")};
     if (parts.size() != 3) throw std::runtime_error("HTTP request line malformed");
-    m_method = parts[0];
+
+    if (parts[0] == "GET") {
+        m_method = HTTPRequestMethod::GET;
+    } else if (parts[0] == "POST") {
+        m_method = HTTPRequestMethod::POST;
+    } else if (parts[0] == "HEAD") {
+        m_method = HTTPRequestMethod::HEAD;
+    } else if (parts[0] == "PUT") {
+        m_method = HTTPRequestMethod::PUT;
+    } else {
+        m_method = HTTPRequestMethod::UNKNOWN;
+    }
+
     m_target = parts[1];
 
     if (parts[2].rfind("HTTP/") != 0) throw std::runtime_error("HTTP request line malformed");
@@ -1411,7 +1419,7 @@ void HTTPServer::MaybeDispatchRequestsFromClient(const std::shared_ptr<HTTPRemot
         LogDebug(
             BCLog::HTTP,
             "Received a %s request for %s from %s (id=%llu)",
-            req->m_method,
+            RequestMethodString(req->m_method),
             req->m_target,
             client->m_origin,
             client->m_id);

src/httpserver.h

@@ -45,6 +45,14 @@ struct evhttp_request;
 struct event_base;
 class CService;
 
+enum class HTTPRequestMethod {
+    UNKNOWN,
+    GET,
+    POST,
+    HEAD,
+    PUT
+};
+
 namespace http_libevent {
 class HTTPRequest;
 
@@ -96,14 +104,6 @@ public:
     explicit HTTPRequest(struct evhttp_request* req, const util::SignalInterrupt& interrupt, bool replySent = false);
     ~HTTPRequest();
 
-    enum RequestMethod {
-        UNKNOWN,
-        GET,
-        POST,
-        HEAD,
-        PUT
-    };
-
     /** Get requested URI.
      */
     std::string GetURI() const;
@@ -114,7 +114,7 @@ public:
 
     /** Get request method.
      */
-    RequestMethod GetRequestMethod() const;
+    HTTPRequestMethod GetRequestMethod() const;
 
     /** Get the query parameter value from request uri for a specified key, or std::nullopt if the
      * key is not found.
@@ -287,7 +287,7 @@ class HTTPRemoteClient;
 class HTTPRequest
 {
 public:
-    std::string m_method;
+    HTTPRequestMethod m_method;
     std::string m_target;
     HTTPVersion m_version;
     HTTPHeaders m_headers;

src/test/fuzz/http_request.cpp

@@ -22,12 +22,13 @@
 
 extern "C" int evhttp_parse_firstline_(struct evhttp_request*, struct evbuffer*);
 extern "C" int evhttp_parse_headers_(struct evhttp_request*, struct evbuffer*);
+
+std::string_view RequestMethodString(HTTPRequestMethod m);
+
 FUZZ_TARGET(http_request)
 {
     using http_libevent::HTTPRequest;
 
-    std::string RequestMethodString(HTTPRequest::RequestMethod m);
-
     FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
     evhttp_request* evreq = evhttp_request_new(nullptr, nullptr);
     assert(evreq != nullptr);
@@ -51,7 +52,7 @@ FUZZ_TARGET(http_request)
 
     util::SignalInterrupt interrupt;
     HTTPRequest http_request{evreq, interrupt, true};
-    const HTTPRequest::RequestMethod request_method = http_request.GetRequestMethod();
+    const HTTPRequestMethod request_method = http_request.GetRequestMethod();
     (void)RequestMethodString(request_method);
     (void)http_request.GetURI();
     (void)http_request.GetHeader("Host");

src/test/httpserver_tests.cpp

@@ -189,7 +189,7 @@ BOOST_AUTO_TEST_CASE(http_request_tests)
         BOOST_CHECK(req.LoadControlData(reader));
         BOOST_CHECK(req.LoadHeaders(reader));
         BOOST_CHECK(req.LoadBody(reader));
-        BOOST_CHECK_EQUAL(req.m_method, "POST");
+        BOOST_CHECK_EQUAL(req.m_method, HTTPRequestMethod::POST);
         BOOST_CHECK_EQUAL(req.m_target, "/");
         BOOST_CHECK_EQUAL(req.m_version.major, 1);
         BOOST_CHECK_EQUAL(req.m_version.minor, 1);
@@ -294,7 +294,7 @@ BOOST_AUTO_TEST_CASE(http_request_tests)
         BOOST_CHECK(req.LoadControlData(reader));
         BOOST_CHECK(req.LoadHeaders(reader));
         BOOST_CHECK(req.LoadBody(reader));
-        BOOST_CHECK_EQUAL(req.m_method, "GET");
+        BOOST_CHECK_EQUAL(req.m_method, HTTPRequestMethod::GET);
         BOOST_CHECK_EQUAL(req.m_target, "/");
         BOOST_CHECK_EQUAL(req.m_version.major, 1);
         BOOST_CHECK_EQUAL(req.m_version.minor, 0);