服务器代理地图数据

admin_map_source_routes.go

@@ -155,5 +155,9 @@ func mapTileSourceDTO(row mapTileSourceRecord) gin.H {
 }
 
 func publicMapTileSourceDTO(row mapTileSourceRecord) gin.H {
-	return gin.H{"id": row.ID, "name": row.Name, "url_template": row.URLTemplate, "attribution": row.Attribution, "max_zoom": row.MaxZoom}
+	hash := row.URLTemplateHash
+	if hash == "" {
+		hash = mapTileSourceHash(row.URLTemplate)
+	}
+	return gin.H{"id": row.ID, "name": row.Name, "url_template": "/api/map/" + hash + "?x={x}&y={y}&z={z}", "attribution": row.Attribution, "max_zoom": row.MaxZoom}
 }

config.go

@@ -56,6 +56,7 @@ type webConfig struct {
 	Port            int            `yaml:"port"`
 	SocketPath      string         `yaml:"socket_path"`
 	StaticDir       string         `yaml:"static_dir"`
+	MapTileCacheDir string         `yaml:"map_tile_cache_dir"`
 	Admin           webAdminConfig `yaml:"admin"`
 }
 
@@ -109,6 +110,7 @@ type rawWebConfig struct {
 	Port            *int               `yaml:"port"`
 	SocketPath      *string            `yaml:"socket_path"`
 	StaticDir       *string            `yaml:"static_dir"`
+	MapTileCacheDir *string            `yaml:"map_tile_cache_dir"`
 	Admin           *rawWebAdminConfig `yaml:"admin"`
 }
 
@@ -145,6 +147,7 @@ func defaultConfig() *config {
 			Port:            8080,
 			SocketPath:      defaultWebSocketPath(),
 			StaticDir:       "./dist",
+			MapTileCacheDir: defaultMapTileCacheDir(),
 			Admin: webAdminConfig{
 				Username:      "admin",
 				Password:      "admin",
@@ -176,6 +179,17 @@ func defaultWebSocketPath() string {
 	return defaultWebSocketPathForGOOS(runtime.GOOS)
 }
 
+func defaultMapTileCacheDir() string {
+	return defaultMapTileCacheDirForGOOS(runtime.GOOS)
+}
+
+func defaultMapTileCacheDirForGOOS(goos string) string {
+	if goos == "windows" {
+		return filepath.Join(".", "win", "srv", "mesh_mqtt_go")
+	}
+	return filepath.Join(string(filepath.Separator), "srv", "mesh_mqtt_go")
+}
+
 func defaultWebSocketPathForGOOS(goos string) string {
 	if goos == "windows" {
 		return ""
@@ -342,6 +356,11 @@ func normalizeConfig(raw rawConfig) (*config, bool) {
 		} else {
 			cfg.Web.StaticDir = *raw.Web.StaticDir
 		}
+		if raw.Web.MapTileCacheDir == nil {
+			changed = true
+		} else {
+			cfg.Web.MapTileCacheDir = *raw.Web.MapTileCacheDir
+		}
 		if raw.Web.Admin == nil {
 			changed = true
 		} else {
@@ -394,6 +413,9 @@ func validateConfig(cfg *config) error {
 		if cfg.Web.StaticDir == "" {
 			return fmt.Errorf("web.static_dir is required when web is enabled")
 		}
+		if cfg.Web.MapTileCacheDir == "" {
+			return fmt.Errorf("web.map_tile_cache_dir is required when web is enabled")
+		}
 		if cfg.Web.Admin.Username == "" {
 			return fmt.Errorf("web.admin.username is required when web is enabled")
 		}

config_test.go

@@ -44,6 +44,9 @@ func TestLoadConfigCreatesDefaultFile(t *testing.T) {
 	if cfg.Web.StaticDir != "./dist" {
 		t.Fatalf("web static dir = %q, want ./dist", cfg.Web.StaticDir)
 	}
+	if cfg.Web.MapTileCacheDir != defaultMapTileCacheDir() {
+		t.Fatalf("web map tile cache dir = %q, want %q", cfg.Web.MapTileCacheDir, defaultMapTileCacheDir())
+	}
 	if _, err := os.Stat(path); err != nil {
 		t.Fatalf("default config was not written: %v", err)
 	}
@@ -80,7 +83,7 @@ func TestLoadConfigFillsMissingFields(t *testing.T) {
 		t.Fatal(err)
 	}
 	text := string(data)
-	for _, want := range []string{"host:", "tls:", "enabled:", "cert_file:", "key_file:", "meshtastic:", "psk:", "database:", "driver:", "sqlite:", "mysql:", "dsn:", "web:", "port:", "socket_path:", "static_dir:"} {
+	for _, want := range []string{"host:", "tls:", "enabled:", "cert_file:", "key_file:", "meshtastic:", "psk:", "database:", "driver:", "sqlite:", "mysql:", "dsn:", "web:", "port:", "socket_path:", "static_dir:", "map_tile_cache_dir:"} {
 		if !strings.Contains(text, want) {
 			t.Fatalf("completed config missing %q in:\n%s", want, text)
 		}
@@ -154,6 +157,20 @@ func TestLoadConfigMalformedYAMLDoesNotOverwrite(t *testing.T) {
 	}
 }
 
+func TestDefaultMapTileCacheDirForGOOS(t *testing.T) {
+	windowsPath := defaultMapTileCacheDirForGOOS("windows")
+	wantWindows := filepath.Join(".", "win", "srv", "mesh_mqtt_go")
+	if windowsPath != wantWindows {
+		t.Fatalf("windows map tile cache dir = %q, want %q", windowsPath, wantWindows)
+	}
+
+	linuxPath := defaultMapTileCacheDirForGOOS("linux")
+	wantLinux := filepath.Join(string(filepath.Separator), "srv", "mesh_mqtt_go")
+	if linuxPath != wantLinux {
+		t.Fatalf("linux map tile cache dir = %q, want %q", linuxPath, wantLinux)
+	}
+}
+
 func TestDefaultWebSocketPathForGOOS(t *testing.T) {
 	if windowsPath := defaultWebSocketPathForGOOS("windows"); windowsPath != "" {
 		t.Fatalf("windows web socket path = %q, want empty", windowsPath)
@@ -228,6 +245,7 @@ func TestValidateConfigWeb(t *testing.T) {
 	}
 
 	cfg = defaultConfig()
+	cfg.Web.SocketPath = filepath.Join(string(filepath.Separator), "tmp", "mesh_mqtt_go.sock")
 	cfg.Web.Port = 0
 	if err := validateConfig(cfg); err != nil {
 		t.Fatalf("web socket with invalid port error = %v, want nil", err)
@@ -246,6 +264,12 @@ func TestValidateConfigWeb(t *testing.T) {
 		t.Fatalf("missing web static dir error = %v, want web.static_dir error", err)
 	}
 
+	cfg = defaultConfig()
+	cfg.Web.MapTileCacheDir = ""
+	if err := validateConfig(cfg); err == nil || !strings.Contains(err.Error(), "web.map_tile_cache_dir") {
+		t.Fatalf("missing map tile cache dir error = %v, want web.map_tile_cache_dir error", err)
+	}
+
 	cfg = defaultConfig()
 	cfg.Web.Enabled = false
 	cfg.Web.Port = 0

db.go

@@ -119,6 +119,7 @@ type mapTileSourceRecord struct {
 	ID              uint64    `gorm:"column:id;primaryKey;autoIncrement"`
 	Name            string    `gorm:"column:name;not null;uniqueIndex"`
 	URLTemplate     string    `gorm:"column:url_template;not null;uniqueIndex"`
+	URLTemplateHash string    `gorm:"column:url_template_hash;size:64;not null;uniqueIndex"`
 	Attribution     string    `gorm:"column:attribution"`
 	MaxZoom         int       `gorm:"column:max_zoom;not null"`
 	Enabled         bool      `gorm:"column:enabled;not null;index"`
@@ -463,10 +464,41 @@ func (s *store) migrate() error {
 				return err
 			}
 		}
+		if err := migrateMapTileSourceHash(tx, migrator, s.driver); err != nil {
+			return err
+		}
 		return (&store{db: tx, driver: s.driver}).EnsureDefaultMapTileSource()
 	})
 }
 
+func migrateMapTileSourceHash(tx *gorm.DB, migrator gorm.Migrator, driver string) error {
+	if !migrator.HasColumn(&mapTileSourceRecord{}, "URLTemplateHash") {
+		if driver == databaseDriverSQLite {
+			if err := tx.Exec("ALTER TABLE map_tile_sources ADD COLUMN url_template_hash TEXT NOT NULL DEFAULT ''").Error; err != nil {
+				return fmt.Errorf("migrate map_tile_sources url_template_hash column: %w", err)
+			}
+		} else if err := migrator.AddColumn(&mapTileSourceRecord{}, "URLTemplateHash"); err != nil {
+			return fmt.Errorf("migrate map_tile_sources url_template_hash column: %w", err)
+		}
+	}
+
+	var rows []mapTileSourceRecord
+	if err := tx.Model(&mapTileSourceRecord{}).Where("url_template_hash = '' OR url_template_hash IS NULL").Find(&rows).Error; err != nil {
+		return fmt.Errorf("list map_tile_sources missing url_template_hash: %w", err)
+	}
+	for _, row := range rows {
+		if err := tx.Model(&mapTileSourceRecord{}).Where("id = ?", row.ID).Update("url_template_hash", mapTileSourceHash(row.URLTemplate)).Error; err != nil {
+			return fmt.Errorf("backfill map_tile_sources url_template_hash: %w", err)
+		}
+	}
+	if !migrator.HasIndex(&mapTileSourceRecord{}, "idx_map_tile_sources_url_template_hash") {
+		if err := migrator.CreateIndex(&mapTileSourceRecord{}, "idx_map_tile_sources_url_template_hash"); err != nil {
+			return fmt.Errorf("migrate map_tile_sources index idx_map_tile_sources_url_template_hash: %w", err)
+		}
+	}
+	return nil
+}
+
 func createMissingIndexes(migrator gorm.Migrator, model any, label string, indexNames []string) error {
 	for _, indexName := range indexNames {
 		if !migrator.HasIndex(model, indexName) {

main.go

@@ -175,6 +175,7 @@ func parseArgs() (*config, error) {
 	flag.IntVar(&cfg.Web.Port, "web-port", cfg.Web.Port, "Web server listen port")
 	flag.StringVar(&cfg.Web.SocketPath, "web-socket-path", cfg.Web.SocketPath, "Web server Unix socket path; empty uses host and port; unsupported on Windows")
 	flag.StringVar(&cfg.Web.StaticDir, "web-static-dir", cfg.Web.StaticDir, "Web frontend static files directory")
+	flag.StringVar(&cfg.Web.MapTileCacheDir, "web-map-tile-cache-dir", cfg.Web.MapTileCacheDir, "Map tile disk cache root directory")
 	flag.StringVar(&cfg.Web.Admin.Username, "admin-username", cfg.Web.Admin.Username, "Web admin username")
 	flag.Parse()
 

map_source_store.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"net/url"
@@ -81,6 +83,14 @@ func (s *store) GetDefaultMapTileSource() (*mapTileSourceRecord, error) {
 	return &row, nil
 }
 
+func (s *store) GetEnabledMapTileSourceByHash(hash string) (*mapTileSourceRecord, error) {
+	var row mapTileSourceRecord
+	if err := s.db.Where("enabled = ? AND url_template_hash = ?", true, hash).Take(&row).Error; err != nil {
+		return nil, err
+	}
+	return &row, nil
+}
+
 func (s *store) CreateMapTileSource(input mapTileSourceInput) (*mapTileSourceRecord, error) {
 	row, err := mapTileSourceFromInput(input)
 	if err != nil {
@@ -139,6 +149,7 @@ func (s *store) UpdateMapTileSource(id uint64, input mapTileSourceInput) (*mapTi
 		updates := map[string]any{
 			"name":              row.Name,
 			"url_template":      row.URLTemplate,
+			"url_template_hash": row.URLTemplateHash,
 			"attribution":       row.Attribution,
 			"max_zoom":          row.MaxZoom,
 			"enabled":           row.Enabled,
@@ -244,10 +255,16 @@ func (s *store) EnsureDefaultMapTileSource() error {
 	})
 }
 
+func mapTileSourceHash(urlTemplate string) string {
+	h := sha256.Sum256([]byte(urlTemplate))
+	return hex.EncodeToString(h[:])
+}
+
 func defaultMapTileSourceRecord() mapTileSourceRecord {
 	return mapTileSourceRecord{
 		Name:            defaultMapTileSourceName,
 		URLTemplate:     defaultMapTileSourceURLTemplate,
+		URLTemplateHash: mapTileSourceHash(defaultMapTileSourceURLTemplate),
 		Attribution:     defaultMapTileSourceAttribution,
 		MaxZoom:         defaultMapTileSourceMaxZoom,
 		Enabled:         true,
@@ -274,6 +291,7 @@ func mapTileSourceFromInput(input mapTileSourceInput) (*mapTileSourceRecord, err
 	return &mapTileSourceRecord{
 		Name:            name,
 		URLTemplate:     urlTemplate,
+		URLTemplateHash: mapTileSourceHash(urlTemplate),
 		Attribution:     strings.TrimSpace(input.Attribution),
 		MaxZoom:         maxZoom,
 		Enabled:         input.Enabled,

map_source_store_test.go

@@ -2,7 +2,10 @@ package main
 
 import (
 	"errors"
+	"strings"
 	"testing"
+
+	"gorm.io/gorm"
 )
 
 func TestMapTileSourceDefaultSeeded(t *testing.T) {
@@ -106,3 +109,113 @@ func TestMapTileSourceDuplicateAndDefaultRules(t *testing.T) {
 		t.Fatalf("delete default error = %v, want errMapTileSourceCannotDeleteDefault", err)
 	}
 }
+
+func TestMapTileSourceHashIsSetOnCreate(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	row, err := st.CreateMapTileSource(mapTileSourceInput{Name: "Hashed", URLTemplate: "https://test.example.com/{z}/{x}/{y}.png", MaxZoom: 18, Enabled: true})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource() error = %v", err)
+	}
+	want := mapTileSourceHash("https://test.example.com/{z}/{x}/{y}.png")
+	if row.URLTemplateHash != want {
+		t.Fatalf("URLTemplateHash = %q, want %q", row.URLTemplateHash, want)
+	}
+}
+
+func TestMapTileSourceDefaultHasHash(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	row, err := st.GetDefaultMapTileSource()
+	if err != nil {
+		t.Fatalf("GetDefaultMapTileSource() error = %v", err)
+	}
+	want := mapTileSourceHash(defaultMapTileSourceURLTemplate)
+	if row.URLTemplateHash != want {
+		t.Fatalf("default URLTemplateHash = %q, want %q", row.URLTemplateHash, want)
+	}
+}
+
+func TestGetEnabledMapTileSourceByHash(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	row, err := st.CreateMapTileSource(mapTileSourceInput{Name: "HashLookup", URLTemplate: "https://lookup.example.com/{z}/{x}/{y}.png", MaxZoom: 18, Enabled: true})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource() error = %v", err)
+	}
+
+	found, err := st.GetEnabledMapTileSourceByHash(row.URLTemplateHash)
+	if err != nil {
+		t.Fatalf("GetEnabledMapTileSourceByHash() error = %v", err)
+	}
+	if found.ID != row.ID {
+		t.Fatalf("found ID = %d, want %d", found.ID, row.ID)
+	}
+}
+
+func TestGetEnabledMapTileSourceByHashDisabled(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	row, err := st.CreateMapTileSource(mapTileSourceInput{Name: "DisabledHash", URLTemplate: "https://disabled-hash.example.com/{z}/{x}/{y}.png", MaxZoom: 18, Enabled: false})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource() error = %v", err)
+	}
+
+	_, err = st.GetEnabledMapTileSourceByHash(row.URLTemplateHash)
+	if !errors.Is(err, gorm.ErrRecordNotFound) {
+		t.Fatalf("GetEnabledMapTileSourceByHash(disabled) = %v, want gorm.ErrRecordNotFound", err)
+	}
+}
+
+func TestGetEnabledMapTileSourceByHashUnknown(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	_, err := st.GetEnabledMapTileSourceByHash("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+	if !errors.Is(err, gorm.ErrRecordNotFound) {
+		t.Fatalf("GetEnabledMapTileSourceByHash(unknown) = %v, want gorm.ErrRecordNotFound", err)
+	}
+}
+
+func TestPublicMapTileSourceDTOProxyURL(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	row, err := st.CreateMapTileSource(mapTileSourceInput{Name: "ProxyTest", URLTemplate: "https://proxy.example.com/{z}/{x}/{y}.png", MaxZoom: 18, Enabled: true})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource() error = %v", err)
+	}
+
+	dto := publicMapTileSourceDTO(*row)
+	urlTemplate, ok := dto["url_template"].(string)
+	if !ok {
+		t.Fatal("url_template is not a string")
+	}
+	wantPrefix := "/api/map/" + row.URLTemplateHash + "?x={x}&y={y}&z={z}"
+	if urlTemplate != wantPrefix {
+		t.Fatalf("url_template = %q, want %q", urlTemplate, wantPrefix)
+	}
+	if strings.Contains(urlTemplate, "proxy.example.com") {
+		t.Fatal("url_template should not contain upstream hostname")
+	}
+}
+
+func TestMapTileSourceHashFunction(t *testing.T) {
+	hash1 := mapTileSourceHash("https://tile.openstreetmap.jp/{z}/{x}/{y}.png")
+	hash2 := mapTileSourceHash("https://tile.openstreetmap.jp/{z}/{x}/{y}.png")
+	hash3 := mapTileSourceHash("https://other.example.com/{z}/{x}/{y}.png")
+
+	if hash1 != hash2 {
+		t.Fatal("hash should be deterministic")
+	}
+	if len(hash1) != 64 {
+		t.Fatalf("hash length = %d, want 64", len(hash1))
+	}
+	if hash1 == hash3 {
+		t.Fatal("different URLs should produce different hashes")
+	}
+}

map_tile_proxy_routes.go

@@ -0,0 +1,200 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+)
+
+const (
+	mapTileCacheControl = "public, max-age=86400"
+	maxMapTileBytes     = 10 << 20
+)
+
+type mapTileProxy struct {
+	store    *store
+	cacheDir string
+	client   *http.Client
+}
+
+func registerMapTileProxyRoutes(r gin.IRouter, store *store, cacheDir string) {
+	proxy := &mapTileProxy{
+		store:    store,
+		cacheDir: cacheDir,
+		client:   &http.Client{Timeout: 15 * time.Second},
+	}
+	r.GET("/map/:sourceHash", proxy.handle)
+}
+
+func (p *mapTileProxy) handle(c *gin.Context) {
+	sourceHash := strings.ToLower(c.Param("sourceHash"))
+	if !isMapTileSourceHash(sourceHash) {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid map source hash"})
+		return
+	}
+
+	row, err := p.store.GetEnabledMapTileSourceByHash(sourceHash)
+	if errors.Is(err, gorm.ErrRecordNotFound) {
+		c.JSON(http.StatusNotFound, gin.H{"error": "map source not found"})
+		return
+	}
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	tile, ok := parseMapTileCoordinates(c, row.MaxZoom)
+	if !ok {
+		return
+	}
+
+	cachePath := mapTileCachePath(p.cacheDir, sourceHash, tile)
+	if data, err := os.ReadFile(cachePath); err == nil {
+		writeMapTile(c, data)
+		return
+	} else if !os.IsNotExist(err) {
+		// Fall through to upstream fetch. A broken cache file should not prevent map rendering.
+	}
+
+	data, status, err := p.fetchRemoteTile(c.Request, row.URLTemplate, tile)
+	if err != nil {
+		c.JSON(status, gin.H{"error": err.Error()})
+		return
+	}
+	_ = writeMapTileCacheFile(cachePath, data)
+	writeMapTile(c, data)
+}
+
+func (p *mapTileProxy) fetchRemoteTile(req *http.Request, template string, tile mapTileCoordinates) ([]byte, int, error) {
+	remoteURL := expandMapTileURLTemplate(template, tile)
+	upstreamReq, err := http.NewRequestWithContext(req.Context(), http.MethodGet, remoteURL, nil)
+	if err != nil {
+		return nil, http.StatusBadGateway, fmt.Errorf("build upstream map tile request: %w", err)
+	}
+	upstreamReq.Header.Set("User-Agent", "mesh_mqtt_go map tile cache")
+
+	resp, err := p.client.Do(upstreamReq)
+	if err != nil {
+		return nil, http.StatusBadGateway, fmt.Errorf("fetch upstream map tile: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusNotFound {
+		return nil, http.StatusNotFound, fmt.Errorf("upstream map tile not found")
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, http.StatusBadGateway, fmt.Errorf("upstream map tile returned status %d", resp.StatusCode)
+	}
+
+	data, err := io.ReadAll(io.LimitReader(resp.Body, maxMapTileBytes+1))
+	if err != nil {
+		return nil, http.StatusBadGateway, fmt.Errorf("read upstream map tile: %w", err)
+	}
+	if len(data) > maxMapTileBytes {
+		return nil, http.StatusBadGateway, fmt.Errorf("upstream map tile is too large")
+	}
+	return data, http.StatusOK, nil
+}
+
+type mapTileCoordinates struct {
+	x int64
+	y int64
+	z int64
+}
+
+func parseMapTileCoordinates(c *gin.Context, maxZoom int) (mapTileCoordinates, bool) {
+	x, ok := parseMapTileCoordinate(c, "x")
+	if !ok {
+		return mapTileCoordinates{}, false
+	}
+	y, ok := parseMapTileCoordinate(c, "y")
+	if !ok {
+		return mapTileCoordinates{}, false
+	}
+	z, ok := parseMapTileCoordinate(c, "z")
+	if !ok {
+		return mapTileCoordinates{}, false
+	}
+	if z > int64(maxZoom) {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "map tile z exceeds max zoom"})
+		return mapTileCoordinates{}, false
+	}
+	limit := int64(1) << z
+	if x >= limit || y >= limit {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "map tile coordinates out of range"})
+		return mapTileCoordinates{}, false
+	}
+	return mapTileCoordinates{x: x, y: y, z: z}, true
+}
+
+func parseMapTileCoordinate(c *gin.Context, name string) (int64, bool) {
+	value := c.Query(name)
+	if value == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "missing map tile " + name})
+		return 0, false
+	}
+	parsed, err := strconv.ParseInt(value, 10, 64)
+	if err != nil || parsed < 0 || parsed > 30_000_000_000 {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid map tile " + name})
+		return 0, false
+	}
+	return parsed, true
+}
+
+func isMapTileSourceHash(value string) bool {
+	if len(value) != 64 {
+		return false
+	}
+	for _, r := range value {
+		if (r < '0' || r > '9') && (r < 'a' || r > 'f') {
+			return false
+		}
+	}
+	return true
+}
+
+func expandMapTileURLTemplate(template string, tile mapTileCoordinates) string {
+	result := strings.ReplaceAll(template, "{x}", strconv.FormatInt(tile.x, 10))
+	result = strings.ReplaceAll(result, "{y}", strconv.FormatInt(tile.y, 10))
+	result = strings.ReplaceAll(result, "{z}", strconv.FormatInt(tile.z, 10))
+	return result
+}
+
+func mapTileCachePath(cacheDir, sourceHash string, tile mapTileCoordinates) string {
+	return filepath.Join(cacheDir, sourceHash, strconv.FormatInt(tile.z, 10), strconv.FormatInt(tile.x, 10), strconv.FormatInt(tile.y, 10)+".tile")
+}
+
+func writeMapTileCacheFile(path string, data []byte) error {
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return err
+	}
+	tmp, err := os.CreateTemp(filepath.Dir(path), filepath.Base(path)+".*.tmp")
+	if err != nil {
+		return err
+	}
+	tmpPath := tmp.Name()
+	defer os.Remove(tmpPath)
+	if _, err := tmp.Write(data); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	return os.Rename(tmpPath, path)
+}
+
+func writeMapTile(c *gin.Context, data []byte) {
+	contentType := http.DetectContentType(data)
+	c.Header("Cache-Control", mapTileCacheControl)
+	c.Data(http.StatusOK, contentType, data)
+}

map_tile_proxy_routes_test.go

@@ -0,0 +1,154 @@
+package main
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestMapTileProxyFetchesAndCaches(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	requests := 0
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		requests++
+		if r.URL.Path != "/3/1/2.png" {
+			t.Fatalf("upstream path = %q, want /3/1/2.png", r.URL.Path)
+		}
+		w.Header().Set("Content-Type", "image/png")
+		_, _ = w.Write([]byte("tile-data"))
+	}))
+	defer upstream.Close()
+
+	row, err := st.CreateMapTileSource(mapTileSourceInput{Name: "Tiles", URLTemplate: upstream.URL + "/{z}/{x}/{y}.png", MaxZoom: 18, Enabled: true})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource() error = %v", err)
+	}
+
+	cacheDir := t.TempDir()
+	router := newRouter(webConfig{StaticDir: t.TempDir(), MapTileCacheDir: cacheDir}, st, nil, nil, nil, nil, nil)
+
+	url := "/api/map/" + row.URLTemplateHash + "?x=1&y=2&z=3"
+	for i := 0; i < 2; i++ {
+		recorder := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, url, nil)
+		router.ServeHTTP(recorder, req)
+		if recorder.Code != http.StatusOK {
+			t.Fatalf("request %d status = %d, body = %s", i+1, recorder.Code, recorder.Body.String())
+		}
+		if recorder.Body.String() != "tile-data" {
+			t.Fatalf("request %d body = %q, want tile-data", i+1, recorder.Body.String())
+		}
+	}
+	if requests != 1 {
+		t.Fatalf("upstream requests = %d, want 1", requests)
+	}
+
+	cachePath := filepath.Join(cacheDir, row.URLTemplateHash, "3", "1", "2.tile")
+	data, err := os.ReadFile(cachePath)
+	if err != nil {
+		t.Fatalf("read cache file %s: %v", cachePath, err)
+	}
+	if string(data) != "tile-data" {
+		t.Fatalf("cache file = %q, want tile-data", string(data))
+	}
+}
+
+func TestMapTileProxyRejectsInvalidCoordinates(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	row, err := st.CreateMapTileSource(mapTileSourceInput{Name: "Tiles", URLTemplate: "https://tiles.example.com/{z}/{x}/{y}.png", MaxZoom: 3, Enabled: true})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource() error = %v", err)
+	}
+
+	router := newRouter(webConfig{StaticDir: t.TempDir(), MapTileCacheDir: t.TempDir()}, st, nil, nil, nil, nil, nil)
+
+	cases := []string{
+		"/api/map/" + row.URLTemplateHash + "?y=0&z=0",
+		"/api/map/" + row.URLTemplateHash + "?x=-1&y=0&z=0",
+		"/api/map/" + row.URLTemplateHash + "?x=0&y=0&z=4",
+		"/api/map/" + row.URLTemplateHash + "?x=2&y=0&z=1",
+	}
+	for _, url := range cases {
+		recorder := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, url, nil)
+		router.ServeHTTP(recorder, req)
+		if recorder.Code != http.StatusBadRequest {
+			t.Fatalf("%s status = %d, want 400; body = %s", url, recorder.Code, recorder.Body.String())
+		}
+	}
+}
+
+func TestMapTileProxyUnknownAndDisabledSource(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	disabled, err := st.CreateMapTileSource(mapTileSourceInput{Name: "Disabled", URLTemplate: "https://disabled.example.com/{z}/{x}/{y}.png", MaxZoom: 3, Enabled: false})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource() error = %v", err)
+	}
+
+	router := newRouter(webConfig{StaticDir: t.TempDir(), MapTileCacheDir: t.TempDir()}, st, nil, nil, nil, nil, nil)
+
+	cases := []string{
+		"/api/map/not-a-hash?x=0&y=0&z=0",
+		"/api/map/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa?x=0&y=0&z=0",
+		"/api/map/" + disabled.URLTemplateHash + "?x=0&y=0&z=0",
+	}
+	wantStatus := []int{http.StatusBadRequest, http.StatusNotFound, http.StatusNotFound}
+	for i, url := range cases {
+		recorder := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, url, nil)
+		router.ServeHTTP(recorder, req)
+		if recorder.Code != wantStatus[i] {
+			t.Fatalf("%s status = %d, want %d; body = %s", url, recorder.Code, wantStatus[i], recorder.Body.String())
+		}
+	}
+}
+
+func TestMapTileProxyUpstreamStatus(t *testing.T) {
+	st := openTestStore(t)
+	defer st.Close()
+
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if strings.Contains(r.URL.Path, "/404/") {
+			http.NotFound(w, r)
+			return
+		}
+		http.Error(w, "upstream error", http.StatusInternalServerError)
+	}))
+	defer upstream.Close()
+
+	row404, err := st.CreateMapTileSource(mapTileSourceInput{Name: "NotFoundTiles", URLTemplate: upstream.URL + "/404/{z}/{x}/{y}.png", MaxZoom: 18, Enabled: true})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource(404) error = %v", err)
+	}
+	row500, err := st.CreateMapTileSource(mapTileSourceInput{Name: "StatusTiles", URLTemplate: upstream.URL + "/{z}/{x}/{y}.png", MaxZoom: 18, Enabled: true})
+	if err != nil {
+		t.Fatalf("CreateMapTileSource(500) error = %v", err)
+	}
+
+	router := newRouter(webConfig{StaticDir: t.TempDir(), MapTileCacheDir: t.TempDir()}, st, nil, nil, nil, nil, nil)
+
+	cases := []struct {
+		url  string
+		want int
+	}{
+		{url: "/api/map/" + row404.URLTemplateHash + "?x=0&y=0&z=0", want: http.StatusNotFound},
+		{url: "/api/map/" + row500.URLTemplateHash + "?x=0&y=0&z=0", want: http.StatusBadGateway},
+	}
+	for _, tc := range cases {
+		recorder := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, tc.url, nil)
+		router.ServeHTTP(recorder, req)
+		if recorder.Code != tc.want {
+			t.Fatalf("%s status = %d, want %d; body = %s", tc.url, recorder.Code, tc.want, recorder.Body.String())
+		}
+	}
+}

web.go

@@ -51,13 +51,13 @@ func newRouter(cfg webConfig, store *store, sessions *sessionManager, mqttStatus
 	r := gin.New()
 	r.Use(gin.Logger(), gin.Recovery())
 	api := r.Group("/api")
-	registerAPIRoutes(api, store)
+	registerAPIRoutes(api, store, cfg.MapTileCacheDir)
 	registerAdminRoutes(api.Group("/admin"), store, sessions, mqttStatus, blocking, forwarder, settings)
 	registerStaticRoutes(r, cfg.StaticDir)
 	return r
 }
 
-func registerAPIRoutes(r gin.IRouter, store *store) {
+func registerAPIRoutes(r gin.IRouter, store *store, mapTileCacheDir string) {
 	r.GET("/health", func(c *gin.Context) {
 		status := gin.H{"status": "ok", "database": "ok"}
 		if err := store.Ping(); err != nil {
@@ -73,6 +73,7 @@ func registerAPIRoutes(r gin.IRouter, store *store) {
 	registerNodeInfoRoutes(r, store, "/nodes")
 	registerMapReportRoutes(r, store)
 	registerMapSourceRoutes(r, store)
+	registerMapTileProxyRoutes(r, store, mapTileCacheDir)
 	registerHelpRoutes(r, store)
 	r.GET("/text-messages", func(c *gin.Context) {
 		opts, ok := parseListOptions(c)