caddyhttp: Refactor and export SanitizedPathJoin for use in fastcgi (#4207)

1 files changed, 94 insertions, 0 deletions

diff --git a/modules/caddyhttp/caddyhttp_test.go b/modules/caddyhttp/caddyhttp_test.go
new file mode 100644
index 0000000..09011fe
--- /dev/null
+++ b/modules/caddyhttp/caddyhttp_test.go
@@ -0,0 +1,94 @@
+package caddyhttp
+
+import (
+	"net/url"
+	"path/filepath"
+	"testing"
+)
+
+func TestSanitizedPathJoin(t *testing.T) {
+	// For reference:
+	// %2e = .
+	// %2f = /
+	// %5c = \
+	for i, tc := range []struct {
+		inputRoot string
+		inputPath string
+		expect    string
+	}{
+		{
+			inputPath: "",
+			expect:    ".",
+		},
+		{
+			inputPath: "/",
+			expect:    ".",
+		},
+		{
+			inputPath: "/foo",
+			expect:    "foo",
+		},
+		{
+			inputPath: "/foo/",
+			expect:    "foo" + separator,
+		},
+		{
+			inputPath: "/foo/bar",
+			expect:    filepath.Join("foo", "bar"),
+		},
+		{
+			inputRoot: "/a",
+			inputPath: "/foo/bar",
+			expect:    filepath.Join("/", "a", "foo", "bar"),
+		},
+		{
+			inputPath: "/foo/../bar",
+			expect:    "bar",
+		},
+		{
+			inputRoot: "/a/b",
+			inputPath: "/foo/../bar",
+			expect:    filepath.Join("/", "a", "b", "bar"),
+		},
+		{
+			inputRoot: "/a/b",
+			inputPath: "/..%2fbar",
+			expect:    filepath.Join("/", "a", "b", "bar"),
+		},
+		{
+			inputRoot: "/a/b",
+			inputPath: "/%2e%2e%2fbar",
+			expect:    filepath.Join("/", "a", "b", "bar"),
+		},
+		{
+			inputRoot: "/a/b",
+			inputPath: "/%2e%2e%2f%2e%2e%2f",
+			expect:    filepath.Join("/", "a", "b") + separator,
+		},
+		{
+			inputRoot: "C:\\www",
+			inputPath: "/foo/bar",
+			expect:    filepath.Join("C:\\www", "foo", "bar"),
+		},
+		{
+			inputRoot: "C:\\www",
+			inputPath: "/D:\\foo\\bar",
+			expect:    filepath.Join("C:\\www", "D:\\foo\\bar"),
+		},
+	} {
+		// we don't *need* to use an actual parsed URL, but it
+		// adds some authenticity to the tests since real-world
+		// values will be coming in from URLs; thus, the test
+		// corpus can contain paths as encoded by clients, which
+		// more closely emulates the actual attack vector
+		u, err := url.Parse("http://test:9999" + tc.inputPath)
+		if err != nil {
+			t.Fatalf("Test %d: invalid URL: %v", i, err)
+		}
+		actual := SanitizedPathJoin(tc.inputRoot, u.Path)
+		if actual != tc.expect {
+			t.Errorf("Test %d: SanitizedPathJoin('%s', '%s') =>  %s (expected '%s')",
+				i, tc.inputRoot, tc.inputPath, actual, tc.expect)
+		}
+	}
+}