rename handler files

This commit renames a bunch of files to try to make it a bit less confusing;

protocol_ is now auth as they contained registration, auth and login/out flow
protocol_.*_poll is now poll.go
api.go and other generic handlers are now handlers.go

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/auth_legacy.go

@@ -0,0 +1,61 @@
+//go:build ts2019
+
+package hscontrol
+
+import (
+	"io"
+	"net/http"
+
+	"github.com/gorilla/mux"
+	"github.com/juanfont/headscale/hscontrol/util"
+	"github.com/rs/zerolog/log"
+	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
+)
+
+// RegistrationHandler handles the actual registration process of a machine
+// Endpoint /machine/:mkey.
+func (h *Headscale) RegistrationHandler(
+	writer http.ResponseWriter,
+	req *http.Request,
+) {
+	vars := mux.Vars(req)
+	machineKeyStr, ok := vars["mkey"]
+	if !ok || machineKeyStr == "" {
+		log.Error().
+			Str("handler", "RegistrationHandler").
+			Msg("No machine ID in request")
+		http.Error(writer, "No machine ID in request", http.StatusBadRequest)
+
+		return
+	}
+
+	body, _ := io.ReadAll(req.Body)
+
+	var machineKey key.MachinePublic
+	err := machineKey.UnmarshalText([]byte(util.MachinePublicKeyEnsurePrefix(machineKeyStr)))
+	if err != nil {
+		log.Error().
+			Caller().
+			Err(err).
+			Msg("Cannot parse machine key")
+		machineRegistrations.WithLabelValues("unknown", "web", "error", "unknown").Inc()
+		http.Error(writer, "Cannot parse machine key", http.StatusBadRequest)
+
+		return
+	}
+	registerRequest := tailcfg.RegisterRequest{}
+	err = util.DecodeAndUnmarshalNaCl(body, &registerRequest, &machineKey, h.privateKey2019)
+	if err != nil {
+		log.Error().
+			Caller().
+			Err(err).
+			Msg("Cannot decode message")
+		machineRegistrations.WithLabelValues("unknown", "web", "error", "unknown").Inc()
+		http.Error(writer, "Cannot decode message", http.StatusBadRequest)
+
+		return
+	}
+
+	h.handleRegister(writer, req, registerRequest, machineKey, false)
+}