create DB struct

This is step one in detaching the Database layer from Headscale (h). The
ultimate goal is to have all function that does database operations in
its own package, and keep the business logic and writing separate.

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

hscontrol/api.go

@@ -3,25 +3,28 @@ package hscontrol
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"html/template"
 	"net/http"
 	"time"
 
 	"github.com/gorilla/mux"
+	"github.com/juanfont/headscale/hscontrol/util"
 	"github.com/rs/zerolog/log"
 	"tailscale.com/types/key"
 )
 
 const (
 	// TODO(juan): remove this once https://github.com/juanfont/headscale/issues/727 is fixed.
-	registrationHoldoff                      = time.Second * 5
-	reservedResponseHeaderSize               = 4
-	RegisterMethodAuthKey                    = "authkey"
-	RegisterMethodOIDC                       = "oidc"
-	RegisterMethodCLI                        = "cli"
-	ErrRegisterMethodCLIDoesNotSupportExpire = Error(
-		"machines registered with CLI does not support expire",
-	)
+	registrationHoldoff        = time.Second * 5
+	reservedResponseHeaderSize = 4
+	RegisterMethodAuthKey      = "authkey"
+	RegisterMethodOIDC         = "oidc"
+	RegisterMethodCLI          = "cli"
+)
+
+var ErrRegisterMethodCLIDoesNotSupportExpire = errors.New(
+	"machines registered with CLI does not support expire",
 )
 
 func (h *Headscale) HealthHandler(
@@ -53,7 +56,7 @@ func (h *Headscale) HealthHandler(
 		}
 	}
 
-	if err := h.pingDB(req.Context()); err != nil {
+	if err := h.db.pingDB(req.Context()); err != nil {
 		respond(err)
 
 		return
@@ -95,7 +98,7 @@ func (h *Headscale) RegisterWebAPI(
 	vars := mux.Vars(req)
 	nodeKeyStr, ok := vars["nkey"]
 
-	if !NodePublicKeyRegex.Match([]byte(nodeKeyStr)) {
+	if !util.NodePublicKeyRegex.Match([]byte(nodeKeyStr)) {
 		log.Warn().Str("node_key", nodeKeyStr).Msg("Invalid node key passed to registration url")
 
 		writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
@@ -116,7 +119,7 @@ func (h *Headscale) RegisterWebAPI(
 	// the template and log an error.
 	var nodeKey key.NodePublic
 	err := nodeKey.UnmarshalText(
-		[]byte(NodePublicKeyEnsurePrefix(nodeKeyStr)),
+		[]byte(util.NodePublicKeyEnsurePrefix(nodeKeyStr)),
 	)
 
 	if !ok || nodeKeyStr == "" || err != nil {