Detect content types when browsing files

go.mod

@@ -5,9 +5,10 @@ go 1.25.6
 require (
 	github.com/BurntSushi/toml v1.6.0
 	github.com/CycloneDX/cyclonedx-go v0.11.0
-	github.com/git-pkgs/archives v0.3.1
+	github.com/git-pkgs/archives v0.4.0
 	github.com/git-pkgs/cooldown v0.1.1
 	github.com/git-pkgs/enrichment v0.6.4
+	github.com/git-pkgs/magic v0.1.0
 	github.com/git-pkgs/purl v0.1.15
 	github.com/git-pkgs/registries v0.6.4
 	github.com/git-pkgs/spdx v0.1.4

go.sum

@@ -244,12 +244,14 @@ github.com/fzipp/gocyclo v0.6.0 h1:lsblElZG7d3ALtGMx9fmxeTKZaLLpU8mET09yN4BBLo=
 github.com/fzipp/gocyclo v0.6.0/go.mod h1:rXPyn8fnlpa0R2csP/31uerbiVBugk5whMdlyaLkLoA=
 github.com/ghostiam/protogetter v0.3.20 h1:oW7OPFit2FxZOpmMRPP9FffU4uUpfeE/rEdE1f+MzD0=
 github.com/ghostiam/protogetter v0.3.20/go.mod h1:FjIu5Yfs6FT391m+Fjp3fbAYJ6rkL/J6ySpZBfnODuI=
-github.com/git-pkgs/archives v0.3.1 h1:GKUuw++0YXAAElxweVHiR4AaSShKKYoVQmyxlF5blG4=
-github.com/git-pkgs/archives v0.3.1/go.mod h1:408oQv3FxLCtePa33zp3sg3njXnwH74vnHZFxkRqoPo=
+github.com/git-pkgs/archives v0.4.0 h1:KNmmIsLiSH27lUdT27EfUkQXFaLgXV5KezE81iyOIgo=
+github.com/git-pkgs/archives v0.4.0/go.mod h1:tfio0OIuPKEBKHs/UCL5XBUvYmKpnvtnba2iDlfSd6g=
 github.com/git-pkgs/cooldown v0.1.1 h1:9OqqzCB8gANz/y44SmqGD0Jp8Qtu81D1sCbKl6Ehg7w=
 github.com/git-pkgs/cooldown v0.1.1/go.mod h1:v7APuK/UouTiu8mWQZbdDmj7DfxxkGUeuhjaRB5gv9E=
 github.com/git-pkgs/enrichment v0.6.4 h1:mGrfenttwmcUfPXRkWpB0wBJiiGj55ltniUh66Pq4bU=
 github.com/git-pkgs/enrichment v0.6.4/go.mod h1:zz1vPUak/w8Jhajll0KDRN2MjKaEYeCzQTxumWnVhqY=
+github.com/git-pkgs/magic v0.1.0 h1:xLrqq7CMXB9g5bJnmJyKw17Rvlh0GFiEmO6e5RFsoeY=
+github.com/git-pkgs/magic v0.1.0/go.mod h1:3ndidt+yvFaI1M0aEkkzkOlFnLPkeVQASIUojazcxCI=
 github.com/git-pkgs/packageurl-go v0.3.1 h1:WM3RBABQZLaRBxgKyYughc3cVBE8KyQxbSC6Jt5ak7M=
 github.com/git-pkgs/packageurl-go v0.3.1/go.mod h1:rcIxiG37BlQLB6FZfgdj9Fm7yjhRQd3l+5o7J0QPAk4=
 github.com/git-pkgs/pom v0.1.5 h1:TGT8Az2OMxGWsXnSagtUMGzZm7Oax8HrSCteA+mi0qY=

internal/server/browse.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"bufio"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -10,29 +11,22 @@ import (
 
 	"github.com/git-pkgs/archives"
 	"github.com/git-pkgs/archives/diff"
+	"github.com/git-pkgs/magic"
 	"github.com/git-pkgs/proxy/internal/database"
 	"github.com/git-pkgs/purl"
 	"github.com/go-chi/chi/v5"
 )
 
-const contentTypePlainText = "text/plain; charset=utf-8"
+const (
+	contentTypePlainText = "text/plain; charset=utf-8"
+	browseSniffSize      = 512
+)
 
 // maxBrowseArchiveSize caps how much data openArchive will buffer for
 // prefix detection. Artifacts larger than this are rejected to prevent
 // memory exhaustion from a single request.
 const maxBrowseArchiveSize = 512 << 20 // 512 MB
 
-// archiveFilename returns a filename suitable for archive format detection.
-// Some ecosystems (e.g. composer) store artifacts with bare hash filenames
-// that have no extension. This adds .zip when the original has no extension
-// and the content is likely a zip archive.
-func archiveFilename(filename string) string {
-	if path.Ext(filename) == "" {
-		return filename + ".zip"
-	}
-	return filename
-}
-
 // detectSingleRootDir returns the single top-level directory name if all files
 // in the archive live under one common directory (e.g. GitHub zipballs use
 // "repo-hash/"). Returns "" if there's no single root or the archive is flat.
@@ -66,8 +60,6 @@ func detectSingleRootDir(reader archives.Reader) string {
 // and stripping a single top-level directory prefix (like GitHub zipballs).
 // For npm, the hardcoded "package/" prefix takes precedence.
 func openArchive(filename string, content io.Reader, ecosystem string) (archives.Reader, error) { //nolint:ireturn // wraps multiple archive implementations
-	fname := archiveFilename(filename)
-
 	limited := io.LimitReader(content, maxBrowseArchiveSize+1)
 	data, err := io.ReadAll(limited)
 	if err != nil {
@@ -78,17 +70,17 @@ func openArchive(filename string, content io.Reader, ecosystem string) (archives
 	}
 
 	if ecosystem == "npm" {
-		return archives.OpenBytesWithPrefix(fname, data, "package/")
+		return archives.OpenBytesWithPrefix(filename, data, "package/")
 	}
 
-	probe, err := archives.OpenBytes(fname, data)
+	probe, err := archives.OpenBytes(filename, data)
 	if err != nil {
 		return nil, err
 	}
 	prefix := detectSingleRootDir(probe)
 	_ = probe.Close()
 
-	return archives.OpenBytesWithPrefix(fname, data, prefix)
+	return archives.OpenBytesWithPrefix(filename, data, prefix)
 }
 
 // BrowseListResponse contains the file listing for a directory in an archives.
@@ -361,7 +353,14 @@ func (s *Server) browseFile(w http.ResponseWriter, r *http.Request, ecosystem, n
 	}
 	defer func() { _ = fileReader.Close() }()
 
-	contentType := detectContentType(filePath)
+	contentType, knownPath := detectContentTypeFromPath(filePath)
+	var content io.Reader = fileReader
+	if !knownPath {
+		bufferedFile := bufio.NewReaderSize(fileReader, browseSniffSize)
+		prefix, _ := bufferedFile.Peek(browseSniffSize)
+		contentType = detectContentType(filePath, prefix)
+		content = bufferedFile
+	}
 	w.Header().Set("Content-Type", contentType)
 	w.Header().Set("Content-Security-Policy", "sandbox")
 	w.Header().Set("X-Content-Type-Options", "nosniff")
@@ -370,85 +369,112 @@ func (s *Server) browseFile(w http.ResponseWriter, r *http.Request, ecosystem, n
 	w.Header().Set("Content-Disposition", fmt.Sprintf("inline; filename=%q", filename))
 
 	// Stream the file
-	_, _ = io.Copy(w, fileReader)
+	_, _ = io.Copy(w, content)
 }
 
-// detectContentType returns an appropriate content type based on file extension.
-func detectContentType(filename string) string {
+// detectContentType returns an appropriate content type. Known filenames and
+// extensions take precedence; content detection handles the remaining files.
+func detectContentType(filename string, prefix []byte) string {
+	if contentType, ok := detectContentTypeFromPath(filename); ok {
+		return contentType
+	}
+	return detectContentTypeFromPrefix(prefix)
+}
+
+func detectContentTypeFromPath(filename string) (string, bool) {
 	ext := strings.ToLower(path.Ext(filename))
 
 	switch ext {
 	// Text formats
 	case ".txt", ".md", ".markdown":
-		return contentTypePlainText
+		return contentTypePlainText, true
 	case ".html", ".htm", ".xhtml":
-		return contentTypePlainText
+		return contentTypePlainText, true
 	case ".css":
-		return "text/css; charset=utf-8"
+		return "text/css; charset=utf-8", true
 	case ".js", ".mjs":
-		return "application/javascript; charset=utf-8"
+		return "application/javascript; charset=utf-8", true
 	case ".json":
-		return "application/json; charset=utf-8"
+		return "application/json; charset=utf-8", true
 	case ".xml":
-		return "application/xml; charset=utf-8"
+		return "application/xml; charset=utf-8", true
 	case ".yaml", ".yml":
-		return "text/yaml; charset=utf-8"
+		return "text/yaml; charset=utf-8", true
 	case ".toml":
-		return "text/toml; charset=utf-8"
+		return "text/toml; charset=utf-8", true
 
 	// Programming languages
 	case ".go":
-		return "text/x-go; charset=utf-8"
+		return "text/x-go; charset=utf-8", true
 	case ".rs":
-		return "text/x-rust; charset=utf-8"
+		return "text/x-rust; charset=utf-8", true
 	case ".py":
-		return "text/x-python; charset=utf-8"
+		return "text/x-python; charset=utf-8", true
 	case ".rb":
-		return "text/x-ruby; charset=utf-8"
+		return "text/x-ruby; charset=utf-8", true
 	case ".java":
-		return "text/x-java; charset=utf-8"
+		return "text/x-java; charset=utf-8", true
 	case ".c", ".h":
-		return "text/x-c; charset=utf-8"
+		return "text/x-c; charset=utf-8", true
 	case ".cpp", ".cc", ".cxx", ".hpp":
-		return "text/x-c++; charset=utf-8"
+		return "text/x-c++; charset=utf-8", true
 	case ".ts":
-		return "text/typescript; charset=utf-8"
+		return "text/typescript; charset=utf-8", true
 	case ".tsx":
-		return "text/tsx; charset=utf-8"
+		return "text/tsx; charset=utf-8", true
 	case ".jsx":
-		return "text/jsx; charset=utf-8"
+		return "text/jsx; charset=utf-8", true
 	case ".php":
-		return "text/x-php; charset=utf-8"
+		return "text/x-php; charset=utf-8", true
 
 	// Config files
 	case ".conf", ".config", ".ini":
-		return contentTypePlainText
+		return contentTypePlainText, true
 	case ".sh", ".bash":
-		return "text/x-shellscript; charset=utf-8"
+		return "text/x-shellscript; charset=utf-8", true
 	case ".dockerfile":
-		return "text/x-dockerfile; charset=utf-8"
+		return "text/x-dockerfile; charset=utf-8", true
 
 	// Images
 	case ".png":
-		return "image/png"
+		return "image/png", true
 	case ".jpg", ".jpeg":
-		return "image/jpeg"
+		return "image/jpeg", true
 	case ".gif":
-		return "image/gif"
+		return "image/gif", true
 	case ".svg":
-		return contentTypePlainText
+		return contentTypePlainText, true
 	case ".ico":
-		return "image/x-icon"
+		return "image/x-icon", true
 
 	// Archives
 	case ".zip", ".tar", ".gz", ".bz2", ".xz":
-		return "application/octet-stream"
+		return "application/octet-stream", true
 
 	default:
-		// Try to detect if it looks like text
 		if isLikelyText(filename) {
-			return contentTypePlainText
+			return contentTypePlainText, true
 		}
+		return "", false
+	}
+}
+
+func detectContentTypeFromPrefix(prefix []byte) string {
+	result := magic.DetectPrefix(prefix)
+	if result.Kind == magic.KindText {
+		return contentTypePlainText
+	}
+
+	switch result.Format {
+	case "png":
+		return "image/png"
+	case "jpeg":
+		return "image/jpeg"
+	case "gif":
+		return "image/gif"
+	case "pdf":
+		return "application/pdf"
+	default:
 		return "application/octet-stream"
 	}
 }

internal/server/browse_bench_test.go

@@ -55,3 +55,28 @@ func BenchmarkOpenArchive(b *testing.B) {
 		})
 	}
 }
+
+func BenchmarkDetectContentType(b *testing.B) {
+	cases := []struct {
+		name     string
+		filename string
+		prefix   []byte
+	}{
+		{"known-path", "README.md", nil},
+		{"text-prefix", "artifact", bytes.Repeat([]byte("a"), browseSniffSize)},
+		{"png-prefix", "artifact", append([]byte("\x89PNG\r\n\x1a\n"), make([]byte, browseSniffSize-8)...)},
+	}
+
+	for _, tc := range cases {
+		b.Run(tc.name, func(b *testing.B) {
+			b.ReportAllocs()
+			var contentType string
+			for b.Loop() {
+				contentType = detectContentType(tc.filename, tc.prefix)
+			}
+			if contentType == "" {
+				b.Fatal("empty content type")
+			}
+		})
+	}
+}

internal/server/browse_test.go

@@ -137,29 +137,44 @@ func TestHandleBrowseFile(t *testing.T) {
 		t.Fatalf("failed to upsert artifact: %v", err)
 	}
 
-	// Test fetching a file
-	req := httptest.NewRequest("GET", "/ui/api/browse/npm/test-browse/1.0.0/file/README.md", nil)
-	w := httptest.NewRecorder()
-	ts.handler.ServeHTTP(w, req)
-
-	if w.Code != http.StatusOK {
-		t.Fatalf("expected status 200, got %d: %s", w.Code, w.Body.String())
+	files := []struct {
+		path        string
+		content     string
+		contentType string
+	}{
+		{"README.md", "# Test Package\n", contentTypePlainText},
+		{"notes.data", "short text\n", contentTypePlainText},
+		{"logo", "\x89PNG\r\n\x1a\nimage data", "image/png"},
+		{"page", "<!DOCTYPE html><html></html>", contentTypePlainText},
+		{"misleading.txt", "\x89PNG\r\n\x1a\nimage data", contentTypePlainText},
 	}
+	for _, file := range files {
+		t.Run(file.path, func(t *testing.T) {
+			req := httptest.NewRequest("GET", "/ui/api/browse/npm/test-browse/1.0.0/file/"+file.path, nil)
+			w := httptest.NewRecorder()
+			ts.handler.ServeHTTP(w, req)
 
-	body := w.Body.String()
-	if body != "# Test Package\n" {
-		t.Errorf("unexpected file content: %q", body)
-	}
-
-	// Check content type
-	contentType := w.Header().Get("Content-Type")
-	if contentType != contentTypePlainText {
-		t.Errorf("expected text/plain content type, got %q", contentType)
+			if w.Code != http.StatusOK {
+				t.Fatalf("expected status 200, got %d: %s", w.Code, w.Body.String())
+			}
+			if w.Body.String() != file.content {
+				t.Errorf("unexpected file content: %q", w.Body.String())
+			}
+			if got := w.Header().Get("Content-Type"); got != file.contentType {
+				t.Errorf("Content-Type = %q, want %q", got, file.contentType)
+			}
+			if got := w.Header().Get("Content-Security-Policy"); got != "sandbox" {
+				t.Errorf("Content-Security-Policy = %q, want sandbox", got)
+			}
+			if got := w.Header().Get("X-Content-Type-Options"); got != "nosniff" {
+				t.Errorf("X-Content-Type-Options = %q, want nosniff", got)
+			}
+		})
 	}
 
 	// Test fetching non-existent file
-	req = httptest.NewRequest("GET", "/ui/api/browse/npm/test-browse/1.0.0/file/nonexistent.txt", nil)
-	w = httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/ui/api/browse/npm/test-browse/1.0.0/file/nonexistent.txt", nil)
+	w := httptest.NewRecorder()
 	ts.handler.ServeHTTP(w, req)
 
 	if w.Code != http.StatusNotFound {
@@ -169,34 +184,47 @@ func TestHandleBrowseFile(t *testing.T) {
 
 func TestDetectContentType(t *testing.T) {
 	tests := []struct {
+		name       string
 		filename   string
+		prefix     []byte
 		expectedCT string
 	}{
-		{"file.txt", contentTypePlainText},
-		{"file.md", contentTypePlainText},
-		{"file.json", "application/json; charset=utf-8"},
-		{"file.js", "application/javascript; charset=utf-8"},
-		{"file.go", "text/x-go; charset=utf-8"},
-		{"file.py", "text/x-python; charset=utf-8"},
-		{"file.rs", "text/x-rust; charset=utf-8"},
-		{"file.html", contentTypePlainText},
-		{"file.htm", contentTypePlainText},
-		{"file.xhtml", contentTypePlainText},
-		{"file.svg", contentTypePlainText},
-		{"file.png", "image/png"},
-		{"file.jpg", "image/jpeg"},
-		{"README", contentTypePlainText},
-		{"LICENSE", contentTypePlainText},
-		{"Makefile", contentTypePlainText},
-		{".gitignore", contentTypePlainText},
-		{"file.bin", "application/octet-stream"},
+		{"text extension", "file.txt", nil, contentTypePlainText},
+		{"markdown extension", "file.md", nil, contentTypePlainText},
+		{"JSON extension", "file.json", nil, "application/json; charset=utf-8"},
+		{"JavaScript extension", "file.js", nil, "application/javascript; charset=utf-8"},
+		{"Go extension", "file.go", nil, "text/x-go; charset=utf-8"},
+		{"Python extension", "file.py", nil, "text/x-python; charset=utf-8"},
+		{"Rust extension", "file.rs", nil, "text/x-rust; charset=utf-8"},
+		{"HTML extension", "file.html", nil, contentTypePlainText},
+		{"HTM extension", "file.htm", nil, contentTypePlainText},
+		{"XHTML extension", "file.xhtml", nil, contentTypePlainText},
+		{"SVG extension", "file.svg", nil, contentTypePlainText},
+		{"PNG extension", "file.png", nil, "image/png"},
+		{"JPEG extension", "file.jpg", nil, "image/jpeg"},
+		{"README", "README", nil, contentTypePlainText},
+		{"LICENSE", "LICENSE", nil, contentTypePlainText},
+		{"Makefile", "Makefile", nil, contentTypePlainText},
+		{"gitignore", ".gitignore", nil, contentTypePlainText},
+		{"unknown empty", "file.bin", nil, "application/octet-stream"},
+		{"extensionless PNG", "asset", []byte("\x89PNG\r\n\x1a\n"), "image/png"},
+		{"extensionless JPEG", "asset", []byte("\xff\xd8\xff"), "image/jpeg"},
+		{"extensionless GIF", "asset", []byte("GIF89a"), "image/gif"},
+		{"extensionless PDF", "asset", []byte("%PDF-1.7"), "application/pdf"},
+		{"extensionless text", "asset", []byte("plain text\n"), contentTypePlainText},
+		{"extensionless HTML", "asset", []byte("<!DOCTYPE html><html></html>"), contentTypePlainText},
+		{"extensionless XML", "asset", []byte("<?xml version=\"1.0\"?><root/>"), contentTypePlainText},
+		{"extensionless SVG", "asset", []byte("<svg xmlns=\"http://www.w3.org/2000/svg\"></svg>"), contentTypePlainText},
+		{"extensionless ZIP", "asset", []byte("PK\x03\x04"), "application/octet-stream"},
+		{"extensionless binary", "asset", []byte{0, 1, 2}, "application/octet-stream"},
+		{"known path wins", "file.txt", []byte("\x89PNG\r\n\x1a\n"), contentTypePlainText},
 	}
 
 	for _, tt := range tests {
-		t.Run(tt.filename, func(t *testing.T) {
-			got := detectContentType(tt.filename)
+		t.Run(tt.name, func(t *testing.T) {
+			got := detectContentType(tt.filename, tt.prefix)
 			if got != tt.expectedCT {
-				t.Errorf("detectContentType(%q) = %q, want %q", tt.filename, got, tt.expectedCT)
+				t.Errorf("detectContentType(%q, %q) = %q, want %q", tt.filename, tt.prefix, got, tt.expectedCT)
 			}
 		})
 	}
@@ -255,6 +283,10 @@ func createTestArchive(t *testing.T) []byte {
 		"package/lib/index.js":       "module.exports = {};",
 		"package/lib/helper.js":      "module.exports.help = () => {};",
 		"package/test/index.test.js": "// tests",
+		"package/notes.data":         "short text\n",
+		"package/logo":               "\x89PNG\r\n\x1a\nimage data",
+		"package/page":               "<!DOCTYPE html><html></html>",
+		"package/misleading.txt":     "\x89PNG\r\n\x1a\nimage data",
 	}
 
 	for path, content := range files {
@@ -609,25 +641,19 @@ func TestHandleComparePage(t *testing.T) {
 	}
 }
 
-func TestArchiveFilename(t *testing.T) {
-	tests := []struct {
-		input string
-		want  string
-	}{
-		{"package.tar.gz", "package.tar.gz"},
-		{"d2e2f014ccd6ec9fae8dbe6336a4164346a2a856", "d2e2f014ccd6ec9fae8dbe6336a4164346a2a856.zip"},
-		{"file.zip", "file.zip"},
-		{"archive.tgz", "archive.tgz"},
-		{"noext", "noext.zip"},
+func TestOpenArchiveDetectsExtensionlessTarGz(t *testing.T) {
+	reader, err := openArchive("artifact", bytes.NewReader(createTestArchive(t)), "npm")
+	if err != nil {
+		t.Fatalf("openArchive failed: %v", err)
 	}
+	defer func() { _ = reader.Close() }()
 
-	for _, tt := range tests {
-		t.Run(tt.input, func(t *testing.T) {
-			got := archiveFilename(tt.input)
-			if got != tt.want {
-				t.Errorf("archiveFilename(%q) = %q, want %q", tt.input, got, tt.want)
-			}
-		})
+	files, err := reader.List()
+	if err != nil {
+		t.Fatalf("List failed: %v", err)
+	}
+	if len(files) == 0 {
+		t.Fatal("expected files in extensionless archive")
 	}
 }