fix: URL-escape placeholder values in BuildLookasideURL and dist-git URL construction

internal/providers/sourceproviders/fedorasource/fedorasource.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"net/url"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -406,18 +407,41 @@ const (
 	PlaceholderHash = "$hash"
 )
 
+// validateAbsoluteURL parses uri and verifies it is an absolute URL with a
+// non-empty scheme and host. The label parameter is used in error messages to
+// identify the URL's purpose (e.g. "lookaside", "dist-git").
+func validateAbsoluteURL(uri, label string) error {
+	u, err := url.Parse(uri)
+	if err != nil {
+		return fmt.Errorf("resulting %s URL is not valid:\n%w", label, err)
+	}
+
+	if u.Scheme == "" || u.Host == "" {
+		return fmt.Errorf("resulting %s URL %#q is missing scheme or host", label, uri)
+	}
+
+	return nil
+}
+
 // BuildLookasideURL constructs a lookaside cache URL by substituting placeholders in the
 // URI template with the provided values. Supported placeholders are [PlaceholderPkg],
 // [PlaceholderFilename], [PlaceholderHashType], and [PlaceholderHash].
 // Placeholders not present in the template are simply ignored.
 //
+// Substituted values are URL path-escaped via [url.PathEscape] so that reserved
+// characters such as /, ?, #, and % do not alter the URL structure.
+//
 // Returns an error if any of the provided values contain a placeholder string, as this
-// would cause ambiguous substitution results depending on replacement order.
+// would cause ambiguous substitution results depending on replacement order, or if the
+// resulting URL is not valid.
 func BuildLookasideURL(template, packageName, fileName, hashType, hash string) (string, error) {
 	// allPlaceholders lists all supported lookaside URI template placeholders.
 	allPlaceholders := []string{PlaceholderPkg, PlaceholderFilename, PlaceholderHashType, PlaceholderHash}
 	hashType = strings.ToLower(hashType)
 
+	// Normalize hashType to lowercase since that is the form actually substituted.
+	hashType = strings.ToLower(hashType)
+
 	for _, v := range []string{packageName, fileName, hashType, hash} {
 		for _, p := range allPlaceholders {
 			if strings.Contains(v, p) {
@@ -427,10 +451,37 @@ func BuildLookasideURL(template, packageName, fileName, hashType, hash string) (
 	}
 
 	uri := template
-	uri = strings.ReplaceAll(uri, PlaceholderPkg, packageName)
-	uri = strings.ReplaceAll(uri, PlaceholderFilename, fileName)
-	uri = strings.ReplaceAll(uri, PlaceholderHashType, hashType)
-	uri = strings.ReplaceAll(uri, PlaceholderHash, hash)
+	uri = strings.ReplaceAll(uri, PlaceholderPkg, url.PathEscape(packageName))
+	uri = strings.ReplaceAll(uri, PlaceholderFilename, url.PathEscape(fileName))
+	uri = strings.ReplaceAll(uri, PlaceholderHashType, url.PathEscape(hashType))
+	uri = strings.ReplaceAll(uri, PlaceholderHash, url.PathEscape(hash))
+
+	if err := validateAbsoluteURL(uri, "lookaside"); err != nil {
+		return "", err
+	}
+
+	return uri, nil
+}
+
+// BuildDistGitURL constructs a dist-git repository URL by substituting the
+// [PlaceholderPkg] placeholder in the URI template with the provided package name.
+//
+// The package name is URL path-escaped via [url.PathEscape] so that reserved
+// characters such as /, ?, #, and % do not alter the URL structure.
+//
+// Returns an error if the package name contains a placeholder string, or if the
+// resulting URL is not valid.
+func BuildDistGitURL(template, packageName string) (string, error) {
+	if strings.Contains(packageName, PlaceholderPkg) {
+		return "", fmt.Errorf("package name %#q contains placeholder %#q, which would cause ambiguous substitution",
+			packageName, PlaceholderPkg)
+	}
+
+	uri := strings.ReplaceAll(template, PlaceholderPkg, url.PathEscape(packageName))
+
+	if err := validateAbsoluteURL(uri, "dist-git"); err != nil {
+		return "", err
+	}
 
 	return uri, nil
 }

internal/providers/sourceproviders/fedorasource/fedorasource_test.go

@@ -344,6 +344,78 @@ func TestBuildLookasideURL(t *testing.T) {
 			hash:          "abc123",
 			expectedError: "ambiguous substitution",
 		},
+		{
+			name:     "filename with slash is path-escaped",
+			template: "https://example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:      "my-pkg",
+			filename: "foo/bar",
+			hashType: "SHA512",
+			hash:     "abc123",
+			expected: "https://example.com/my-pkg/foo%2Fbar/sha512/abc123",
+		},
+		{
+			name:     "filename with question mark is path-escaped",
+			template: "https://example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:      "my-pkg",
+			filename: "file?x=1",
+			hashType: "SHA512",
+			hash:     "abc123",
+			expected: "https://example.com/my-pkg/file%3Fx=1/sha512/abc123",
+		},
+		{
+			name:     "filename with hash is path-escaped",
+			template: "https://example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:      "my-pkg",
+			filename: "file#frag",
+			hashType: "SHA512",
+			hash:     "abc123",
+			expected: "https://example.com/my-pkg/file%23frag/sha512/abc123",
+		},
+		{
+			name:     "filename with malformed percent is path-escaped",
+			template: "https://example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:      "my-pkg",
+			filename: "file%zz",
+			hashType: "SHA512",
+			hash:     "abc123",
+			expected: "https://example.com/my-pkg/file%25zz/sha512/abc123",
+		},
+		{
+			name:     "packageName with slash is path-escaped",
+			template: "https://example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:      "foo/bar",
+			filename: "source.tar.gz",
+			hashType: "SHA512",
+			hash:     "abc123",
+			expected: "https://example.com/foo%2Fbar/source.tar.gz/sha512/abc123",
+		},
+		{
+			name:     "packageName with hash is path-escaped",
+			template: "https://example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:      "foo#bar",
+			filename: "source.tar.gz",
+			hashType: "SHA512",
+			hash:     "abc123",
+			expected: "https://example.com/foo%23bar/source.tar.gz/sha512/abc123",
+		},
+		{
+			name:          "hashType containing uppercase placeholder is caught after lowercasing",
+			template:      "https://example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:           "my-pkg",
+			filename:      "source.tar.gz",
+			hashType:      "$PKG",
+			hash:          "abc123",
+			expectedError: "ambiguous substitution",
+		},
+		{
+			name:          "template without scheme is rejected",
+			template:      "example.com/$pkg/$filename/$hashtype/$hash",
+			pkg:           "my-pkg",
+			filename:      "source.tar.gz",
+			hashType:      "SHA512",
+			hash:          "abc123",
+			expectedError: "missing scheme or host",
+		},
 	}
 
 	for _, testCase := range tests {
@@ -361,6 +433,71 @@ func TestBuildLookasideURL(t *testing.T) {
 	}
 }
 
+func TestBuildDistGitURL(t *testing.T) {
+	tests := []struct {
+		name          string
+		template      string
+		pkg           string
+		expected      string
+		expectedError string
+	}{
+		{
+			name:     "standard template",
+			template: "https://src.example.com/rpms/$pkg.git",
+			pkg:      "curl",
+			expected: "https://src.example.com/rpms/curl.git",
+		},
+		{
+			name:          "packageName containing $pkg placeholder",
+			template:      "https://src.example.com/rpms/$pkg.git",
+			pkg:           "evil-$pkg-name",
+			expectedError: "ambiguous substitution",
+		},
+		{
+			name:     "packageName with slash is path-escaped",
+			template: "https://src.example.com/rpms/$pkg.git",
+			pkg:      "foo/bar",
+			expected: "https://src.example.com/rpms/foo%2Fbar.git",
+		},
+		{
+			name:     "packageName with hash is path-escaped",
+			template: "https://src.example.com/rpms/$pkg.git",
+			pkg:      "foo#bar",
+			expected: "https://src.example.com/rpms/foo%23bar.git",
+		},
+		{
+			name:     "packageName with question mark is path-escaped",
+			template: "https://src.example.com/rpms/$pkg.git",
+			pkg:      "foo?bar",
+			expected: "https://src.example.com/rpms/foo%3Fbar.git",
+		},
+		{
+			name:     "packageName with malformed percent is path-escaped",
+			template: "https://src.example.com/rpms/$pkg.git",
+			pkg:      "foo%zz",
+			expected: "https://src.example.com/rpms/foo%25zz.git",
+		},
+		{
+			name:          "template without scheme is rejected",
+			template:      "example.com/rpms/$pkg.git",
+			pkg:           "curl",
+			expectedError: "missing scheme or host",
+		},
+	}
+
+	for _, testCase := range tests {
+		t.Run(testCase.name, func(t *testing.T) {
+			result, err := BuildDistGitURL(testCase.template, testCase.pkg)
+			if testCase.expectedError != "" {
+				assert.ErrorContains(t, err, testCase.expectedError)
+			} else {
+				require.NoError(t, err)
+				assert.Equal(t, testCase.expected, result)
+			}
+		})
+	}
+}
+
 func TestFormatSourcesEntry(t *testing.T) {
 	tests := []struct {
 		name     string

internal/providers/sourceproviders/fedorasourceprovider.go

@@ -9,7 +9,6 @@ import (
 	"fmt"
 	"log/slog"
 	"path/filepath"
-	"strings"
 	"time"
 
 	"github.com/microsoft/azure-linux-dev-tools/internal/app/azldev/core/components"
@@ -106,7 +105,10 @@ func (g *FedoraSourcesProviderImpl) GetComponent(
 		return errors.New("destination path cannot be empty")
 	}
 
-	gitRepoURL := strings.ReplaceAll(g.distroGitBaseURI, "$pkg", upstreamNameToUse)
+	gitRepoURL, err := fedorasource.BuildDistGitURL(g.distroGitBaseURI, upstreamNameToUse)
+	if err != nil {
+		return fmt.Errorf("failed to build dist-git URL for %#q:\n%w", upstreamNameToUse, err)
+	}
 
 	slog.Info("Getting component from git repo",
 		"component", componentName,
@@ -259,7 +261,10 @@ func (g *FedoraSourcesProviderImpl) ResolveIdentity(
 		upstreamName = component.GetName()
 	}
 
-	gitRepoURL := strings.ReplaceAll(g.distroGitBaseURI, "$pkg", upstreamName)
+	gitRepoURL, err := fedorasource.BuildDistGitURL(g.distroGitBaseURI, upstreamName)
+	if err != nil {
+		return "", fmt.Errorf("failed to build dist-git URL for %#q:\n%w", upstreamName, err)
+	}
 
 	return g.resolveCommit(ctx, gitRepoURL, upstreamName, component.GetConfig().Spec.UpstreamCommit)
 }