use rs/cors library to handle multiple CORS origins [#191]

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/dustin/go-humanize v1.0.1
 	github.com/paulmach/orb v0.10.0
 	github.com/prometheus/client_golang v1.19.1
+	github.com/rs/cors v1.11.1
 	github.com/schollz/progressbar/v3 v3.13.1
 	github.com/stretchr/testify v1.9.0
 	go.uber.org/zap v1.27.0

go.sum

@@ -435,6 +435,8 @@ github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJ
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.12.0 h1:exVL4IDcn6na9z1rAb56Vxr+CgyK3nn3O+epU5NdKM8=
 github.com/rogpeppe/go-internal v1.12.0/go.mod h1:E+RYuTGaKKdloAfM02xzb0FW3Paa99yedzYV+kq4uf4=
+github.com/rs/cors v1.11.1 h1:eU3gRzXLRK57F5rKMGMZURNdIG4EoAmX8k94r9wXWHA=
+github.com/rs/cors v1.11.1/go.mod h1:XyqrcTp5zjWr1wsJ8PIRZssZ8b/WMcMf71DJnit4EMU=
 github.com/rs/xid v1.2.1/go.mod h1:+uKXf+4Djp6Md1KODXJxgGQPKngRmWyn10oCKFzNHOQ=
 github.com/rs/xid v1.5.0 h1:mKX4bl4iPYJtEIxp6CYiUuLQ/8DYMoz0PUdtGgMFRVc=
 github.com/rs/xid v1.5.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=

main.go

@@ -8,10 +8,12 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/alecthomas/kong"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/rs/cors"
 
 	"github.com/protomaps/go-pmtiles/pmtiles"
 	_ "gocloud.dev/blob/azureblob"
@@ -93,7 +95,7 @@ var cli struct {
 		Interface string `default:"0.0.0.0"`
 		Port      int    `default:"8080"`
 		AdminPort int    `default:"-1"`
-		Cors      string `help:"Value of HTTP CORS header."`
+		Cors      string `help:"Comma-separated list of of allowed HTTP CORS origins."`
 		CacheSize int    `default:"64" help:"Size of cache in Megabytes."`
 		Bucket    string `help:"Remote bucket"`
 		PublicURL string `help:"Public base URL of tile endpoint for TileJSON e.g. https://example.com/tiles/"`
@@ -139,7 +141,7 @@ func main() {
 			logger.Fatalf("Failed to show tile, %v", err)
 		}
 	case "serve <path>":
-		server, err := pmtiles.NewServer(cli.Serve.Bucket, cli.Serve.Path, logger, cli.Serve.CacheSize, cli.Serve.Cors, cli.Serve.PublicURL)
+		server, err := pmtiles.NewServer(cli.Serve.Bucket, cli.Serve.Path, logger, cli.Serve.CacheSize, cli.Serve.PublicURL)
 
 		if err != nil {
 			logger.Fatalf("Failed to create new server, %v", err)
@@ -148,7 +150,9 @@ func main() {
 		pmtiles.SetBuildInfo(version, commit, date)
 		server.Start()
 
-		http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		mux := http.NewServeMux()
+
+		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 			start := time.Now()
 			statusCode := server.ServeHTTP(w, r)
 			logger.Printf("served %d %s in %s", statusCode, url.PathEscape(r.URL.Path), time.Since(start))
@@ -164,7 +168,16 @@ func main() {
 				logger.Fatal(startHTTPServer(cli.Serve.Interface+":"+adminPort, adminMux))
 			}()
 		}
-		logger.Fatal(startHTTPServer(cli.Serve.Interface+":"+strconv.Itoa(cli.Serve.Port), nil))
+
+		if cli.Serve.Cors != "" {
+			c := cors.New(cors.Options{
+				AllowedOrigins: strings.Split(cli.Serve.Cors, ","),
+			})
+			muxWithCors := c.Handler(mux)
+			logger.Fatal(startHTTPServer(cli.Serve.Interface+":"+strconv.Itoa(cli.Serve.Port), muxWithCors))
+		} else {
+			logger.Fatal(startHTTPServer(cli.Serve.Interface+":"+strconv.Itoa(cli.Serve.Port), mux))
+		}
 	case "extract <input> <output>":
 		err := pmtiles.Extract(logger, cli.Extract.Bucket, cli.Extract.Input, cli.Extract.Minzoom, cli.Extract.Maxzoom, cli.Extract.Region, cli.Extract.Bbox, cli.Extract.Output, cli.Extract.DownloadThreads, cli.Extract.Overfetch, cli.Extract.DryRun)
 		if err != nil {

pmtiles/server.go

@@ -49,13 +49,12 @@ type Server struct {
 	bucket    Bucket
 	logger    *log.Logger
 	cacheSize int
-	cors      string
 	publicURL string
 	metrics   *metrics
 }
 
 // NewServer creates a new pmtiles HTTP server.
-func NewServer(bucketURL string, prefix string, logger *log.Logger, cacheSize int, cors string, publicURL string) (*Server, error) {
+func NewServer(bucketURL string, prefix string, logger *log.Logger, cacheSize int, publicURL string) (*Server, error) {
 
 	ctx := context.Background()
 
@@ -71,11 +70,11 @@ func NewServer(bucketURL string, prefix string, logger *log.Logger, cacheSize in
 		return nil, err
 	}
 
-	return NewServerWithBucket(bucket, prefix, logger, cacheSize, cors, publicURL)
+	return NewServerWithBucket(bucket, prefix, logger, cacheSize, publicURL)
 }
 
 // NewServerWithBucket creates a new HTTP server for a gocloud Bucket.
-func NewServerWithBucket(bucket Bucket, _ string, logger *log.Logger, cacheSize int, cors string, publicURL string) (*Server, error) {
+func NewServerWithBucket(bucket Bucket, _ string, logger *log.Logger, cacheSize int, publicURL string) (*Server, error) {
 
 	reqs := make(chan request, 8)
 
@@ -84,7 +83,6 @@ func NewServerWithBucket(bucket Bucket, _ string, logger *log.Logger, cacheSize
 		bucket:    bucket,
 		logger:    logger,
 		cacheSize: cacheSize,
-		cors:      cors,
 		publicURL: publicURL,
 		metrics:   createMetrics("", logger), // change scope string if there are multiple servers running in one process
 	}
@@ -474,9 +472,6 @@ func (server *Server) get(ctx context.Context, unsanitizedPath string) (archive,
 	handler = ""
 	archive = ""
 	headers = make(map[string]string)
-	if len(server.cors) > 0 {
-		headers["Access-Control-Allow-Origin"] = server.cors
-	}
 
 	if ok, key, z, x, y, ext := parseTilePath(unsanitizedPath); ok {
 		archive, handler = key, "tile"
@@ -518,18 +513,7 @@ func (lrw *loggingResponseWriter) WriteHeader(code int) {
 // Serve an HTTP response from the archive
 func (server *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) int {
 	tracker := server.metrics.startRequest()
-	if r.Method == http.MethodOptions {
-		if len(server.cors) > 0 {
-			w.Header().Set("Access-Control-Allow-Origin", server.cors)
-		}
-		w.WriteHeader(204)
-		tracker.finish(r.Context(), "", r.Method, 204, 0, false)
-		return 204
-	} else if r.Method != http.MethodGet && r.Method != http.MethodHead {
-		w.WriteHeader(405)
-		tracker.finish(r.Context(), "", r.Method, 405, 0, false)
-		return 405
-	}
+
 	archive, handler, statusCode, headers, body := server.get(r.Context(), r.URL.Path)
 	for k, v := range headers {
 		w.Header().Set(k, v)