fix: prevent local absolute paths from being treated as remote URLs (#2397)

Add filepath.IsAbs guard to IsRemote and Parse to prevent Windows drive
letter paths (e.g., C:\path) from being misinterpreted as remote URLs
by go-getter's url.Parse, which prepends file:// to drive letter paths.

Fixes #2384

Signed-off-by: Aditya Menon <amenon@canarytechnologies.com>

pkg/remote/remote.go

@@ -102,6 +102,9 @@ type Source struct {
 }
 
 func IsRemote(goGetterSrc string) bool {
+	if filepath.IsAbs(goGetterSrc) {
+		return false
+	}
 	if _, err := Parse(goGetterSrc); err != nil {
 		return false
 	}
@@ -122,6 +125,13 @@ func Parse(goGetterSrc string) (*Source, error) {
 		}
 	}
 
+	// Local absolute paths (e.g., C:\path on Windows, /path on Unix)
+	// are not remote URLs. Reject them before go-getter's url.Parse
+	// can misinterpret Windows drive letters as URL schemes.
+	if filepath.IsAbs(goGetterSrc) {
+		return nil, InvalidURLError{err: fmt.Sprintf("parse url: local absolute path is not a remote URL: %s", goGetterSrc)}
+	}
+
 	u, err := url.Parse(goGetterSrc)
 	if err != nil {
 		return nil, InvalidURLError{err: fmt.Sprintf("parse url: %v", err)}

pkg/remote/remote_test.go

@@ -356,6 +356,54 @@ func TestRemote_S3(t *testing.T) {
 	}
 }
 
+func TestIsRemote(t *testing.T) {
+	testcases := []struct {
+		name     string
+		input    string
+		expected bool
+	}{
+		{
+			name:     "git remote URL",
+			input:    "git::https://github.com/cloudposse/helmfiles.git@releases/kiam.yaml?ref=0.40.0",
+			expected: true,
+		},
+		{
+			name:     "s3 remote URL",
+			input:    "s3://helm-s3-values-example/values.yaml",
+			expected: true,
+		},
+		{
+			name:     "https remote URL",
+			input:    "https://example.com/values.yaml",
+			expected: true,
+		},
+		{
+			name:     "relative path",
+			input:    "relative/path/to/file.yaml",
+			expected: false,
+		},
+		{
+			name:     "parent-relative path",
+			input:    "../services/values.yaml",
+			expected: false,
+		},
+		{
+			name:     "unix absolute path",
+			input:    "/absolute/path/to/file.yaml",
+			expected: false,
+		},
+	}
+
+	for _, tt := range testcases {
+		t.Run(tt.name, func(t *testing.T) {
+			result := IsRemote(tt.input)
+			if result != tt.expected {
+				t.Errorf("IsRemote(%q) = %v, want %v", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
 func TestParse(t *testing.T) {
 	testcases := []struct {
 		name   string
@@ -372,6 +420,11 @@ func TestParse(t *testing.T) {
 			input: "raw/incubator",
 			err:   "parse url: missing scheme - probably this is a local file path? raw/incubator",
 		},
+		{
+			name:  "unix absolute path",
+			input: "/absolute/path/to/file.yaml",
+			err:   "parse url: local absolute path is not a remote URL: /absolute/path/to/file.yaml",
+		},
 		{
 			name:   "git scheme",
 			input:  "git::https://github.com/stakater/Forecastle.git@deployments/kubernetes/chart/forecastle?ref=v1.0.54",

pkg/remote/remote_windows_test.go

@@ -0,0 +1,69 @@
+//go:build windows
+
+package remote
+
+import (
+	"testing"
+)
+
+func TestIsRemote_Windows(t *testing.T) {
+	testcases := []struct {
+		name     string
+		input    string
+		expected bool
+	}{
+		{
+			name:     "windows drive letter path",
+			input:    `C:\project\services\values.yaml`,
+			expected: false,
+		},
+		{
+			name:     "windows UNC path",
+			input:    `\\server\share\path\values.yaml`,
+			expected: false,
+		},
+	}
+
+	for _, tt := range testcases {
+		t.Run(tt.name, func(t *testing.T) {
+			result := IsRemote(tt.input)
+			if result != tt.expected {
+				t.Errorf("IsRemote(%q) = %v, want %v", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestParse_Windows(t *testing.T) {
+	testcases := []struct {
+		name  string
+		input string
+		err   string
+	}{
+		{
+			name:  "windows drive letter path",
+			input: `C:\project\services\values.yaml`,
+			err:   `parse url: local absolute path is not a remote URL: C:\project\services\values.yaml`,
+		},
+		{
+			name:  "windows UNC path",
+			input: `\\server\share\path\values.yaml`,
+			err:   `parse url: local absolute path is not a remote URL: \\server\share\path\values.yaml`,
+		},
+	}
+
+	for _, tt := range testcases {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := Parse(tt.input)
+			if err == nil {
+				t.Fatalf("Parse(%q) expected error, got nil", tt.input)
+			}
+			if _, ok := err.(InvalidURLError); !ok {
+				t.Fatalf("Parse(%q) expected InvalidURLError, got %T: %v", tt.input, err, err)
+			}
+			if err.Error() != tt.err {
+				t.Errorf("Parse(%q) error = %q, want %q", tt.input, err.Error(), tt.err)
+			}
+		})
+	}
+}