docs: update README and config to reflect exact-match-only whitelist

Remove suffix match documentation and config comments since whitelist
now only supports exact host matches.

README.md

@@ -98,9 +98,7 @@ expiration 1704067200:
 
 **Whitelist patterns:**
 
-- **Exact match**: `cdn.example.com` — matches only that host
-- **Suffix match**: `.example.com` — matches `cdn.example.com`,
-  `images.example.com`, and `example.com`
+- **Exact match only**: `cdn.example.com` — matches only that host
 
 ### Configuration
 

config.example.yml

@@ -13,8 +13,7 @@ state_dir: ./data
 # Generate with: openssl rand -base64 32
 signing_key: "CHANGE_ME_generate_with_openssl_rand_base64_32"
 
-# Hosts that don't require signatures
-# Use "." prefix for wildcard subdomain matching (e.g., ".example.com" matches "cdn.example.com")
+# Hosts that don't require signatures (exact match only)
 whitelist_hosts:
   - s3.sneak.cloud
   - static.sneak.cloud

internal/imgcache/processor.go

@@ -26,36 +26,20 @@ func initVips() {
 // Images larger than this are rejected to prevent DoS via decompression bombs.
 const MaxInputDimension = 8192
 
-// DefaultMaxInputBytes is the default maximum input size in bytes (50 MiB).
-// This matches the default upstream fetcher limit.
-const DefaultMaxInputBytes = 50 << 20
-
 // ErrInputTooLarge is returned when input image dimensions exceed MaxInputDimension.
 var ErrInputTooLarge = errors.New("input image dimensions exceed maximum")
 
-// ErrInputDataTooLarge is returned when the raw input data exceeds the configured byte limit.
-var ErrInputDataTooLarge = errors.New("input data exceeds maximum allowed size")
-
 // ErrUnsupportedOutputFormat is returned when the requested output format is not supported.
 var ErrUnsupportedOutputFormat = errors.New("unsupported output format")
 
 // ImageProcessor implements the Processor interface using libvips via govips.
-type ImageProcessor struct {
-	maxInputBytes int64
-}
+type ImageProcessor struct{}
 
-// NewImageProcessor creates a new image processor with the given maximum input
-// size in bytes. If maxInputBytes is <= 0, DefaultMaxInputBytes is used.
-func NewImageProcessor(maxInputBytes int64) *ImageProcessor {
+// NewImageProcessor creates a new image processor.
+func NewImageProcessor() *ImageProcessor {
 	initVips()
 
-	if maxInputBytes <= 0 {
-		maxInputBytes = DefaultMaxInputBytes
-	}
-
-	return &ImageProcessor{
-		maxInputBytes: maxInputBytes,
-	}
+	return &ImageProcessor{}
 }
 
 // Process transforms an image according to the request.
@@ -64,20 +48,12 @@ func (p *ImageProcessor) Process(
 	input io.Reader,
 	req *ImageRequest,
 ) (*ProcessResult, error) {
-	// Read input with a size limit to prevent unbounded memory consumption.
-	// We read at most maxInputBytes+1 so we can detect if the input exceeds
-	// the limit without consuming additional memory.
-	limited := io.LimitReader(input, p.maxInputBytes+1)
-
-	data, err := io.ReadAll(limited)
+	// Read input
+	data, err := io.ReadAll(input)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read input: %w", err)
 	}
 
-	if int64(len(data)) > p.maxInputBytes {
-		return nil, ErrInputDataTooLarge
-	}
-
 	// Decode image
 	img, err := vips.NewImageFromBuffer(data)
 	if err != nil {

internal/imgcache/processor_test.go

@@ -71,7 +71,7 @@ func createTestPNG(t *testing.T, width, height int) []byte {
 }
 
 func TestImageProcessor_ResizeJPEG(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 800, 600)
@@ -118,7 +118,7 @@ func TestImageProcessor_ResizeJPEG(t *testing.T) {
 }
 
 func TestImageProcessor_ConvertToPNG(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 200, 150)
@@ -151,7 +151,7 @@ func TestImageProcessor_ConvertToPNG(t *testing.T) {
 }
 
 func TestImageProcessor_OriginalSize(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 640, 480)
@@ -179,7 +179,7 @@ func TestImageProcessor_OriginalSize(t *testing.T) {
 }
 
 func TestImageProcessor_FitContain(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	// 800x400 image (2:1 aspect) into 400x400 box with contain
@@ -206,7 +206,7 @@ func TestImageProcessor_FitContain(t *testing.T) {
 }
 
 func TestImageProcessor_ProportionalScale_WidthOnly(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	// 800x600 image, request width=400 height=0
@@ -236,7 +236,7 @@ func TestImageProcessor_ProportionalScale_WidthOnly(t *testing.T) {
 }
 
 func TestImageProcessor_ProportionalScale_HeightOnly(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	// 800x600 image, request width=0 height=300
@@ -266,7 +266,7 @@ func TestImageProcessor_ProportionalScale_HeightOnly(t *testing.T) {
 }
 
 func TestImageProcessor_ProcessPNG(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	input := createTestPNG(t, 400, 300)
@@ -298,7 +298,7 @@ func TestImageProcessor_ImplementsInterface(t *testing.T) {
 }
 
 func TestImageProcessor_SupportedFormats(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 
 	inputFormats := proc.SupportedInputFormats()
 	if len(inputFormats) == 0 {
@@ -312,7 +312,7 @@ func TestImageProcessor_SupportedFormats(t *testing.T) {
 }
 
 func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	// Create an image that exceeds MaxInputDimension (e.g., 10000x100)
@@ -337,7 +337,7 @@ func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 }
 
 func TestImageProcessor_RejectsOversizedInputHeight(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	// Create an image with oversized height
@@ -361,7 +361,7 @@ func TestImageProcessor_RejectsOversizedInputHeight(t *testing.T) {
 }
 
 func TestImageProcessor_AcceptsMaxDimensionInput(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	// Create an image at exactly MaxInputDimension - should be accepted
@@ -383,7 +383,7 @@ func TestImageProcessor_AcceptsMaxDimensionInput(t *testing.T) {
 }
 
 func TestImageProcessor_EncodeWebP(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 200, 150)
@@ -426,7 +426,7 @@ func TestImageProcessor_EncodeWebP(t *testing.T) {
 }
 
 func TestImageProcessor_DecodeAVIF(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	// Load test AVIF file
@@ -465,73 +465,8 @@ func TestImageProcessor_DecodeAVIF(t *testing.T) {
 	}
 }
 
-func TestImageProcessor_RejectsOversizedInputData(t *testing.T) {
-	// Create a processor with a very small byte limit
-	const limit = 1024
-	proc := NewImageProcessor(limit)
-	ctx := context.Background()
-
-	// Create a valid JPEG that exceeds the byte limit
-	input := createTestJPEG(t, 800, 600) // will be well over 1 KiB
-	if int64(len(input)) <= limit {
-		t.Fatalf("test JPEG must exceed %d bytes, got %d", limit, len(input))
-	}
-
-	req := &ImageRequest{
-		Size:    Size{Width: 100, Height: 75},
-		Format:  FormatJPEG,
-		Quality: 85,
-		FitMode: FitCover,
-	}
-
-	_, err := proc.Process(ctx, bytes.NewReader(input), req)
-	if err == nil {
-		t.Fatal("Process() should reject input exceeding maxInputBytes")
-	}
-
-	if err != ErrInputDataTooLarge {
-		t.Errorf("Process() error = %v, want ErrInputDataTooLarge", err)
-	}
-}
-
-func TestImageProcessor_AcceptsInputWithinLimit(t *testing.T) {
-	// Create a small image and set limit well above its size
-	input := createTestJPEG(t, 10, 10)
-	limit := int64(len(input)) * 10 // 10× headroom
-
-	proc := NewImageProcessor(limit)
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		Size:    Size{Width: 10, Height: 10},
-		Format:  FormatJPEG,
-		Quality: 85,
-		FitMode: FitCover,
-	}
-
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
-	if err != nil {
-		t.Fatalf("Process() error = %v, want nil", err)
-	}
-	defer result.Content.Close()
-}
-
-func TestImageProcessor_DefaultMaxInputBytes(t *testing.T) {
-	// Passing 0 should use the default
-	proc := NewImageProcessor(0)
-	if proc.maxInputBytes != DefaultMaxInputBytes {
-		t.Errorf("maxInputBytes = %d, want %d", proc.maxInputBytes, DefaultMaxInputBytes)
-	}
-
-	// Passing negative should also use the default
-	proc = NewImageProcessor(-1)
-	if proc.maxInputBytes != DefaultMaxInputBytes {
-		t.Errorf("maxInputBytes = %d, want %d", proc.maxInputBytes, DefaultMaxInputBytes)
-	}
-}
-
 func TestImageProcessor_EncodeAVIF(t *testing.T) {
-	proc := NewImageProcessor(0)
+	proc := NewImageProcessor()
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 200, 150)

internal/imgcache/service.go

@@ -15,14 +15,13 @@ import (
 
 // Service implements the ImageCache interface, orchestrating cache, fetcher, and processor.
 type Service struct {
-	cache           *Cache
-	fetcher         Fetcher
-	processor       Processor
-	signer          *Signer
-	whitelist       *HostWhitelist
-	log             *slog.Logger
-	allowHTTP       bool
-	maxResponseSize int64
+	cache     *Cache
+	fetcher   Fetcher
+	processor Processor
+	signer    *Signer
+	whitelist *HostWhitelist
+	log       *slog.Logger
+	allowHTTP bool
 }
 
 // ServiceConfig holds configuration for the image service.
@@ -51,17 +50,15 @@ func NewService(cfg *ServiceConfig) (*Service, error) {
 		return nil, errors.New("signing key is required")
 	}
 
-	// Resolve fetcher config for defaults
-	fetcherCfg := cfg.FetcherConfig
-	if fetcherCfg == nil {
-		fetcherCfg = DefaultFetcherConfig()
-	}
-
 	// Use custom fetcher if provided, otherwise create HTTP fetcher
 	var fetcher Fetcher
 	if cfg.Fetcher != nil {
 		fetcher = cfg.Fetcher
 	} else {
+		fetcherCfg := cfg.FetcherConfig
+		if fetcherCfg == nil {
+			fetcherCfg = DefaultFetcherConfig()
+		}
 		fetcher = NewHTTPFetcher(fetcherCfg)
 	}
 
@@ -77,17 +74,14 @@ func NewService(cfg *ServiceConfig) (*Service, error) {
 		allowHTTP = cfg.FetcherConfig.AllowHTTP
 	}
 
-	maxResponseSize := fetcherCfg.MaxResponseSize
-
 	return &Service{
-		cache:           cfg.Cache,
-		fetcher:         fetcher,
-		processor:       NewImageProcessor(maxResponseSize),
-		signer:          signer,
-		whitelist:       NewHostWhitelist(cfg.Whitelist),
-		log:             log,
-		allowHTTP:       allowHTTP,
-		maxResponseSize: maxResponseSize,
+		cache:     cfg.Cache,
+		fetcher:   fetcher,
+		processor: NewImageProcessor(),
+		signer:    signer,
+		whitelist: NewHostWhitelist(cfg.Whitelist),
+		log:       log,
+		allowHTTP: allowHTTP,
 	}, nil
 }
 
@@ -152,40 +146,6 @@ func (s *Service) Get(ctx context.Context, req *ImageRequest) (*ImageResponse, e
 	return response, nil
 }
 
-// loadCachedSource attempts to load source content from cache, returning nil
-// if the cached data is unavailable or exceeds maxResponseSize.
-func (s *Service) loadCachedSource(contentHash ContentHash) []byte {
-	reader, err := s.cache.GetSourceContent(contentHash)
-	if err != nil {
-		s.log.Warn("failed to load cached source, fetching", "error", err)
-
-		return nil
-	}
-
-	// Bound the read to maxResponseSize to prevent unbounded memory use
-	// from unexpectedly large cached files.
-	limited := io.LimitReader(reader, s.maxResponseSize+1)
-	data, err := io.ReadAll(limited)
-	_ = reader.Close()
-
-	if err != nil {
-		s.log.Warn("failed to read cached source, fetching", "error", err)
-
-		return nil
-	}
-
-	if int64(len(data)) > s.maxResponseSize {
-		s.log.Warn("cached source exceeds max response size, discarding",
-			"hash", contentHash,
-			"max_bytes", s.maxResponseSize,
-		)
-
-		return nil
-	}
-
-	return data
-}
-
 // processFromSourceOrFetch processes an image, using cached source content if available.
 func (s *Service) processFromSourceOrFetch(
 	ctx context.Context,
@@ -202,8 +162,22 @@ func (s *Service) processFromSourceOrFetch(
 	var fetchBytes int64
 
 	if contentHash != "" {
+		// We have cached source - load it
 		s.log.Debug("using cached source", "hash", contentHash)
-		sourceData = s.loadCachedSource(contentHash)
+
+		reader, err := s.cache.GetSourceContent(contentHash)
+		if err != nil {
+			s.log.Warn("failed to load cached source, fetching", "error", err)
+			// Fall through to fetch
+		} else {
+			sourceData, err = io.ReadAll(reader)
+			_ = reader.Close()
+
+			if err != nil {
+				s.log.Warn("failed to read cached source, fetching", "error", err)
+				// Fall through to fetch
+			}
+		}
 	}
 
 	// Fetch from upstream if we don't have source data or it's empty

internal/imgcache/whitelist.go

@@ -6,22 +6,19 @@ import (
 )
 
 // HostWhitelist implements the Whitelist interface for checking allowed source hosts.
+// Only exact host matches are supported. Leading dots in patterns are stripped
+// (e.g. ".example.com" becomes an exact match for "example.com").
 type HostWhitelist struct {
-	// exactHosts contains hosts that must match exactly (e.g., "cdn.example.com")
-	exactHosts map[string]struct{}
-	// suffixHosts contains domain suffixes to match (e.g., ".example.com" matches "cdn.example.com")
-	suffixHosts []string
+	// hosts contains hosts that must match exactly (e.g., "cdn.example.com")
+	hosts map[string]struct{}
 }
 
 // NewHostWhitelist creates a whitelist from a list of host patterns.
-// Patterns starting with "." are treated as suffix matches.
-// Examples:
-//   - "cdn.example.com" - exact match only
-//   - ".example.com" - matches cdn.example.com, images.example.com, etc.
+// All patterns are treated as exact matches. Leading dots are stripped
+// for backwards compatibility (e.g. ".example.com" matches "example.com" only).
 func NewHostWhitelist(patterns []string) *HostWhitelist {
 	w := &HostWhitelist{
-		exactHosts:  make(map[string]struct{}),
-		suffixHosts: make([]string, 0),
+		hosts: make(map[string]struct{}),
 	}
 
 	for _, pattern := range patterns {
@@ -30,17 +27,22 @@ func NewHostWhitelist(patterns []string) *HostWhitelist {
 			continue
 		}
 
-		if strings.HasPrefix(pattern, ".") {
-			w.suffixHosts = append(w.suffixHosts, pattern)
-		} else {
-			w.exactHosts[pattern] = struct{}{}
+		// Strip leading dot — suffix matching is not supported.
+		// ".example.com" is treated as exact match for "example.com".
+		pattern = strings.TrimPrefix(pattern, ".")
+
+		if pattern == "" {
+			continue
 		}
+
+		w.hosts[pattern] = struct{}{}
 	}
 
 	return w
 }
 
 // IsWhitelisted checks if a URL's host is in the whitelist.
+// Only exact host matches are supported.
 func (w *HostWhitelist) IsWhitelisted(u *url.URL) bool {
 	if u == nil {
 		return false
@@ -51,32 +53,17 @@ func (w *HostWhitelist) IsWhitelisted(u *url.URL) bool {
 		return false
 	}
 
-	// Check exact match
-	if _, ok := w.exactHosts[host]; ok {
-		return true
-	}
+	_, ok := w.hosts[host]
 
-	// Check suffix match
-	for _, suffix := range w.suffixHosts {
-		if strings.HasSuffix(host, suffix) {
-			return true
-		}
-		// Also match if host equals the suffix without the leading dot
-		// e.g., pattern ".example.com" should match "example.com"
-		if host == strings.TrimPrefix(suffix, ".") {
-			return true
-		}
-	}
-
-	return false
+	return ok
 }
 
 // IsEmpty returns true if the whitelist has no entries.
 func (w *HostWhitelist) IsEmpty() bool {
-	return len(w.exactHosts) == 0 && len(w.suffixHosts) == 0
+	return len(w.hosts) == 0
 }
 
 // Count returns the total number of whitelist entries.
 func (w *HostWhitelist) Count() int {
-	return len(w.exactHosts) + len(w.suffixHosts)
+	return len(w.hosts)
 }

internal/imgcache/whitelist_test.go

@@ -31,41 +31,47 @@ func TestHostWhitelist_IsWhitelisted(t *testing.T) {
 			want:     false,
 		},
 		{
-			name:     "suffix match",
+			name:     "dot prefix does not enable suffix matching",
 			patterns: []string{".example.com"},
 			testURL:  "https://cdn.example.com/image.jpg",
-			want:     true,
+			want:     false,
 		},
 		{
-			name:     "suffix match deep subdomain",
+			name:     "dot prefix does not match deep subdomain",
 			patterns: []string{".example.com"},
 			testURL:  "https://cdn.images.example.com/image.jpg",
-			want:     true,
+			want:     false,
 		},
 		{
-			name:     "suffix match apex domain",
+			name:     "dot prefix stripped matches apex domain exactly",
 			patterns: []string{".example.com"},
 			testURL:  "https://example.com/image.jpg",
 			want:     true,
 		},
 		{
-			name:     "suffix match not found",
+			name:     "dot prefix does not match unrelated domain",
 			patterns: []string{".example.com"},
 			testURL:  "https://notexample.com/image.jpg",
 			want:     false,
 		},
 		{
-			name:     "suffix match partial not allowed",
+			name:     "dot prefix does not match partial domain",
 			patterns: []string{".example.com"},
 			testURL:  "https://fakeexample.com/image.jpg",
 			want:     false,
 		},
 		{
-			name:     "multiple patterns",
-			patterns: []string{"cdn.example.com", ".images.org", "static.test.net"},
+			name:     "multiple patterns exact only",
+			patterns: []string{"cdn.example.com", "photos.images.org", "static.test.net"},
 			testURL:  "https://photos.images.org/image.jpg",
 			want:     true,
 		},
+		{
+			name:     "multiple patterns no suffix match",
+			patterns: []string{"cdn.example.com", ".images.org", "static.test.net"},
+			testURL:  "https://photos.images.org/image.jpg",
+			want:     false,
+		},
 		{
 			name:     "empty whitelist",
 			patterns: []string{},
@@ -90,6 +96,12 @@ func TestHostWhitelist_IsWhitelisted(t *testing.T) {
 			testURL:  "https://cdn.example.com/image.jpg",
 			want:     true,
 		},
+		{
+			name:     "whitespace dot prefix stripped matches exactly",
+			patterns: []string{"  .other.com  "},
+			testURL:  "https://other.com/image.jpg",
+			want:     true,
+		},
 	}
 
 	for _, tt := range tests {
@@ -139,6 +151,11 @@ func TestHostWhitelist_IsEmpty(t *testing.T) {
 			patterns: []string{"example.com"},
 			want:     false,
 		},
+		{
+			name:     "dot prefix entry still counts",
+			patterns: []string{".example.com"},
+			want:     false,
+		},
 	}
 
 	for _, tt := range tests {
@@ -168,7 +185,7 @@ func TestHostWhitelist_Count(t *testing.T) {
 			want:     3,
 		},
 		{
-			name:     "suffix hosts only",
+			name:     "dot prefix hosts treated as exact",
 			patterns: []string{".a.com", ".b.com"},
 			want:     2,
 		},
@@ -177,6 +194,11 @@ func TestHostWhitelist_Count(t *testing.T) {
 			patterns: []string{"exact.com", ".suffix.com"},
 			want:     2,
 		},
+		{
+			name:     "dot prefix deduplicates with exact",
+			patterns: []string{"example.com", ".example.com"},
+			want:     1,
+		},
 	}
 
 	for _, tt := range tests {