perf(proxy): optimize hot request paths

- Cache route handlers, simplify NoRoute path normalization, and reduce matcher/header allocations

- Honor configured transport pool limits in auto mode and add hotpath regression benchmarks/tests

proxy/hotpath_test.go

@@ -0,0 +1,167 @@
+package proxy
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"reflect"
+	"testing"
+
+	"ghproxy/config"
+
+	"github.com/infinite-iroha/touka"
+)
+
+func TestNormalizeProxyPath(t *testing.T) {
+	testCases := []struct {
+		name        string
+		rawPath     string
+		expected    string
+		expectValid bool
+	}{
+		{name: "Plain host path", rawPath: "/github.com/owner/repo", expected: "github.com/owner/repo", expectValid: true},
+		{name: "HTTPS URL", rawPath: "/https://github.com/owner/repo", expected: "github.com/owner/repo", expectValid: true},
+		{name: "HTTP URL", rawPath: "http://github.com/owner/repo", expected: "github.com/owner/repo", expectValid: true},
+		{name: "Scheme with single slash", rawPath: "https:/github.com/owner/repo", expected: "github.com/owner/repo", expectValid: true},
+		{name: "Extra leading slashes", rawPath: "////github.com/owner/repo", expected: "github.com/owner/repo", expectValid: true},
+		{name: "Empty path", rawPath: "", expectValid: false},
+		{name: "Slash only", rawPath: "////", expectValid: false},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, ok := normalizeProxyPath(tc.rawPath)
+			if ok != tc.expectValid {
+				t.Fatalf("valid = %v, want %v", ok, tc.expectValid)
+			}
+			if got != tc.expected {
+				t.Fatalf("path = %q, want %q", got, tc.expected)
+			}
+		})
+	}
+}
+
+func TestCopyHeaderFiltered(t *testing.T) {
+	src := http.Header{
+		"Accept":          {"text/plain"},
+		"Connection":      {"keep-alive"},
+		"X-Test":          {"one", "two"},
+		"Accept-Encoding": {"gzip"},
+	}
+	dst := make(http.Header)
+
+	copyHeaderFiltered(dst, src, reqHeadersToRemove)
+
+	if got := dst.Values("Accept"); !reflect.DeepEqual(got, []string{"text/plain"}) {
+		t.Fatalf("Accept = %v, want [text/plain]", got)
+	}
+	if got := dst.Values("X-Test"); !reflect.DeepEqual(got, []string{"one", "two"}) {
+		t.Fatalf("X-Test = %v, want [one two]", got)
+	}
+	if got := dst.Values("Connection"); len(got) != 0 {
+		t.Fatalf("Connection should be filtered, got %v", got)
+	}
+	if got := dst.Values("Accept-Encoding"); len(got) != 0 {
+		t.Fatalf("Accept-Encoding should be filtered, got %v", got)
+	}
+}
+
+func TestCopyHeaderFiltered_AllowsAllWhenDenylistEmpty(t *testing.T) {
+	src := http.Header{
+		"X-Test": {"one", "two"},
+	}
+	dst := make(http.Header)
+
+	copyHeaderFiltered(dst, src, nil)
+
+	if got := dst.Values("X-Test"); !reflect.DeepEqual(got, []string{"one", "two"}) {
+		t.Fatalf("X-Test = %v, want [one two]", got)
+	}
+}
+
+func TestBuildProxyPath(t *testing.T) {
+	testCases := []struct {
+		name     string
+		path     string
+		matcher  string
+		expected string
+	}{
+		{
+			name:     "Blob path rewrites to raw host",
+			path:     "github.com/owner/repo/blob/main/file.go",
+			matcher:  "blob",
+			expected: "https://raw.githubusercontent.com/owner/repo/main/file.go",
+		},
+		{
+			name:     "Non blob path keeps host",
+			path:     "raw.githubusercontent.com/owner/repo/main/file.go",
+			matcher:  "raw",
+			expected: "https://raw.githubusercontent.com/owner/repo/main/file.go",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := buildProxyPath(tc.path, tc.matcher); got != tc.expected {
+				t.Fatalf("buildProxyPath() = %q, want %q", got, tc.expected)
+			}
+		})
+	}
+}
+
+func TestNoRouteHandler_InvalidURI_ReturnsBadRequest(t *testing.T) {
+	recorder := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "http://client.example/", nil)
+	req.RequestURI = "/"
+
+	ctx, _ := touka.CreateTestContextWithRequest(recorder, req)
+	NoRouteHandler(&config.Config{})(ctx)
+
+	if recorder.Code != http.StatusBadRequest {
+		t.Fatalf("status = %d, want %d", recorder.Code, http.StatusBadRequest)
+	}
+	if body := recorder.Body.String(); body == "" {
+		t.Fatal("expected error response body to be written")
+	}
+}
+
+func TestNoRouteHandler_NormalizesAbsoluteRequestURIForAPI(t *testing.T) {
+	recorder := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "http://client.example/placeholder", nil)
+	req.RequestURI = "/https://api.github.com/repos/WJQSERVER-STUDIO/ghproxy/releases?per_page=1"
+
+	ctx, _ := touka.CreateTestContextWithRequest(recorder, req)
+	cfg := &config.Config{}
+	NoRouteHandler(cfg)(ctx)
+
+	if recorder.Code != http.StatusForbidden {
+		t.Fatalf("status = %d, want %d", recorder.Code, http.StatusForbidden)
+	}
+	if body := recorder.Body.String(); body == "" {
+		t.Fatal("expected error response body to be written")
+	}
+}
+
+func BenchmarkNormalizeProxyPath(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = normalizeProxyPath("/https://github.com/WJQSERVER-STUDIO/ghproxy/releases/download/v1.0.0/asset.tar.gz")
+	}
+}
+
+func BenchmarkCopyHeaderFiltered(b *testing.B) {
+	src := http.Header{
+		"Accept":            {"text/plain"},
+		"Accept-Encoding":   {"gzip"},
+		"Connection":        {"keep-alive"},
+		"User-Agent":        {"curl/8.0.1"},
+		"X-Test":            {"one", "two"},
+		"CF-Connecting-IP":  {"127.0.0.1"},
+		"X-Forwarded-For":   {"127.0.0.1"},
+		"Transfer-Encoding": {"chunked"},
+	}
+
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		dst := make(http.Header)
+		copyHeaderFiltered(dst, src, reqHeadersToRemove)
+	}
+}