Take the signature, the expiry and the URL scheme off the image request (closes #314)

The image request now holds only its source and its transform, exactly what
the variant key covers. The /v1/image/ handler checks the allowlist and
verifies the signature itself with Signer.Verify(req, sig, expires). Both
image handlers keep the URL's expiry as a local value for Cache-Control. The
image service holds no signer, allowlist or AllowHTTP, and ValidateRequest is
gone. The fetcher takes the source and builds its URL with Source.URL from its
own AllowHTTP, so no URL string is built and parsed again. chooseAutoFormat
returns the format it chooses instead of writing into the request. The signed
URL format and every route's answers are unchanged.

Model: opus-5-5

internal/httpfetcher/httpfetcher_internal_test.go

@@ -5,9 +5,12 @@ import (
 	"errors"
 	"io"
 	"net"
+	"net/url"
 	"testing"
 	"testing/fstest"
 	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // testHost is the hostname used by mock fetch tests.
@@ -49,33 +52,6 @@ func TestIsAllowedContentType(t *testing.T) {
 	}
 }
 
-func TestExtractHost(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		url  string
-		want string
-	}{
-		{"https://example.com/path", testHost},
-		{"http://example.com:8080/path", "example.com:8080"},
-		{"https://example.com", testHost},
-		{"https://example.com?q=1", testHost},
-		{"example.com/path", testHost},
-		{"", ""},
-	}
-
-	for _, tc := range tests {
-		t.Run(tc.url, func(t *testing.T) {
-			t.Parallel()
-
-			got := extractHost(tc.url)
-			if got != tc.want {
-				t.Errorf("extractHost(%q) = %q, want %q", tc.url, got, tc.want)
-			}
-		})
-	}
-}
-
 func TestIsLocalhost(t *testing.T) {
 	t.Parallel()
 
@@ -188,7 +164,7 @@ func TestIsPrivateIPJudgesEmbeddedIPv4Address(t *testing.T) {
 func TestValidateURL_RejectsNonHTTPS(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), "http://example.com/path", false)
+	err := validateURL(t.Context(), &url.URL{Scheme: "http", Host: testHost}, false)
 	if !errors.Is(err, ErrUnsupportedScheme) {
 		t.Errorf("validateURL http = %v, want ErrUnsupportedScheme", err)
 	}
@@ -198,7 +174,8 @@ func TestValidateURL_AllowsHTTPWhenConfigured(t *testing.T) {
 	t.Parallel()
 
 	// Use a host that won't resolve (explicit .invalid TLD) so we don't hit DNS.
-	err := validateURL(t.Context(), "http://nonexistent.invalid/path", true)
+	err := validateURL(t.Context(),
+		&url.URL{Scheme: "http", Host: "nonexistent.invalid"}, true)
 	// We expect a host resolution error, not ErrUnsupportedScheme.
 	if errors.Is(err, ErrUnsupportedScheme) {
 		t.Error("validateURL with AllowHTTP should not return ErrUnsupportedScheme")
@@ -208,7 +185,7 @@ func TestValidateURL_AllowsHTTPWhenConfigured(t *testing.T) {
 func TestValidateURL_RejectsLocalhost(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), "https://localhost/path", false)
+	err := validateURL(t.Context(), &url.URL{Scheme: "https", Host: "localhost"}, false)
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Errorf("validateURL localhost = %v, want ErrSSRFBlocked", err)
 	}
@@ -217,7 +194,7 @@ func TestValidateURL_RejectsLocalhost(t *testing.T) {
 func TestValidateURL_EmptyHost(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), "https:///path", false)
+	err := validateURL(t.Context(), &url.URL{Scheme: "https"}, false)
 	if !errors.Is(err, ErrInvalidHost) {
 		t.Errorf("validateURL empty host = %v, want ErrInvalidHost", err)
 	}
@@ -232,7 +209,8 @@ func TestMockFetcher_FetchesFile(t *testing.T) {
 
 	m := NewMock(mockFS)
 
-	result, err := m.Fetch(context.Background(), "https://example.com/images/photo.jpg")
+	result, err := m.Fetch(context.Background(),
+		imagerequest.Source{Host: testHost, Path: "/images/photo.jpg"})
 	if err != nil {
 		t.Fatalf("Fetch() error = %v", err)
 	}
@@ -263,7 +241,8 @@ func TestMockFetcher_MissingFileReturnsUpstreamError(t *testing.T) {
 	mockFS := fstest.MapFS{}
 	m := NewMock(mockFS)
 
-	_, err := m.Fetch(context.Background(), "https://example.com/missing.jpg")
+	_, err := m.Fetch(context.Background(),
+		imagerequest.Source{Host: testHost, Path: "/missing.jpg"})
 	if !errors.Is(err, ErrUpstreamError) {
 		t.Errorf("Fetch() error = %v, want ErrUpstreamError", err)
 	}
@@ -280,7 +259,7 @@ func TestMockFetcher_RespectsContextCancellation(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	_, err := m.Fetch(ctx, "https://example.com/photo.jpg")
+	_, err := m.Fetch(ctx, imagerequest.Source{Host: testHost, Path: "/photo.jpg"})
 	if !errors.Is(err, context.Canceled) {
 		t.Errorf("Fetch() error = %v, want context.Canceled", err)
 	}