feat: add hexDecode transformation (#1275)

* with commented code * go sum update * simple implementation * add comment * add unit tests * change names in tests, remove redundant * grammar fix * updated hex method and tests --------- Co-authored-by: Roman Suvorov <[email protected]> Co-authored-by: José Carlos Chávez <[email protected]> Co-authored-by: Felipe Zipitría <[email protected]>
corazawaf · Jan 24, 2025 · 761cd64 · 761cd64
1 parent 077bde8
commit 761cd64
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Showing 4 changed files with 150 additions and 42 deletions.
diff --git a/internal/transformations/hex_decode.go b/internal/transformations/hex_decode.go
@@ -0,0 +1,16 @@
+package transformations
+
+import (
+	"encoding/hex"
+
+	"github.com/corazawaf/coraza/v3/internal/strings"
+)
+
+func hexDecode(data string) (string, bool, error) {
+	dst, err := hex.DecodeString(data)
+	if err != nil {
+		return "", false, err
+	}
+
+	return strings.WrapUnsafe(dst), true, nil
+}
diff --git a/internal/transformations/hex_decode_test.go b/internal/transformations/hex_decode_test.go
@@ -0,0 +1,98 @@
+package transformations
+
+import (
+	"testing"
+)
+
+func TestHexDecode(t *testing.T) {
+	tests := []struct {
+		name           string
+		input          string
+		expectedOutput string
+		expectedValid  bool
+		expectError    bool
+	}{
+		{
+			name:           "valid hexadecimal string",
+			input:          "48656c6c6f",
+			expectedOutput: "Hello",
+			expectedValid:  true,
+			expectError:    false,
+		},
+		{
+			name:           "odd length",
+			input:          "48656c6c6f7",
+			expectedOutput: "",
+			expectedValid:  false,
+			expectError:    true,
+		},
+		{
+			name:           "invalid with non hex characters",
+			input:          "YyYy",
+			expectedOutput: "",
+			expectedValid:  false,
+			expectError:    true,
+		},
+		{
+			name:           "invalid with extra characters",
+			input:          "123G",
+			expectedOutput: "",
+			expectedValid:  false,
+			expectError:    true,
+		},
+		{
+			name:           "empty input",
+			input:          "",
+			expectedOutput: "",
+			expectedValid:  true,
+			expectError:    false,
+		},
+		{
+			name:           "uppercase hex string",
+			input:          "48454C4C4F",
+			expectedOutput: "HELLO",
+			expectedValid:  true,
+			expectError:    false,
+		},
+		{
+			name:           "mixed case",
+			input:          "48454c4C4f",
+			expectedOutput: "HELLO",
+			expectedValid:  true,
+			expectError:    false,
+		},
+		{
+			name:           "special characters",
+			input:          "21402324255E262A28",
+			expectedOutput: "!@#$%^&*(",
+			expectedValid:  true,
+			expectError:    false,
+		},
+		{
+			name:           "odd length with invalid character",
+			input:          "48656c6c6fZ",
+			expectedOutput: "",
+			expectedValid:  false,
+			expectError:    true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			output, valid, err := hexDecode(tt.input)
+
+			if (err != nil) != tt.expectError {
+				t.Errorf("hexDecode(%q): expected error=%v, got error=%v", tt.input, tt.expectError, err)
+			}
+
+			if output != tt.expectedOutput {
+				t.Errorf("hexDecode(%q): expected output=%q, got output=%q", tt.input, tt.expectedOutput, output)
+			}
+
+			if valid != tt.expectedValid {
+				t.Errorf("hexDecode(%q): expected valid=%v, got valid=%v", tt.input, tt.expectedValid, valid)
+			}
+		})
+	}
+}
diff --git a/internal/transformations/testdata/hexDecode.json b/internal/transformations/testdata/hexDecode.json
@@ -1,44 +1,37 @@
 [
-   {
-      "ret" : 1,
-      "input" : "",
-      "type" : "tfn",
-      "name" : "hexDecode",
-      "output" : ""
-   },
-   {
-      "output" : "TestCase",
-      "ret" : 1,
-      "name" : "hexDecode",
-      "input" : "5465737443617365",
-      "type" : "tfn"
-   },
-   {
-      "type" : "tfn",
-      "input" : "546573740043617365",
-      "name" : "hexDecode",
-      "ret" : 1,
-      "output" : "Test\\u0000Case"
-   },
-   {
-      "output" : "\\x01#Eg\\x89\\x0a#\\x01#Eg\\x89\\x0a",
-      "type" : "tfn",
-      "input" : "01234567890a0z01234567890a",
-      "name" : "hexDecode",
-      "ret" : 1
-   },
-   {
-       "type" : "tfn",
-       "name" : "hexDecode",
-       "input" : "01234567890az",
-       "output" : "\\x01#Eg\\x89\\x0a",
-       "ret" : 1
-   },
-   {
-       "type" : "tfn",
-       "name" : "hexDecode",
-       "input" : "01234567890a0",
-       "output" : "\\x01#Eg\\x89\\x0a",
-       "ret" : 1
-   }
+  {
+    "ret": 1,
+    "input": "",
+    "type": "tfn",
+    "name": "hexDecode",
+    "output": ""
+  },
+  {
+    "output": "TestCase",
+    "ret": 1,
+    "name": "hexDecode",
+    "input": "5465737443617365",
+    "type": "tfn"
+  },
+  {
+    "type": "tfn",
+    "input": "546573740043617365",
+    "name": "hexDecode",
+    "ret": 1,
+    "output": "Test\\u0000Case"
+  },
+  {
+    "type": "tfn",
+    "name": "invalidCharacter",
+    "input": "01234567890z",
+    "output": "",
+    "ret": 0
+  },
+  {
+    "type": "tfn",
+    "name": "invalidLen",
+    "input": "54657374004",
+    "output": "",
+    "ret": 0
+  }
 ]
diff --git a/internal/transformations/transformations.go b/internal/transformations/transformations.go
@@ -35,6 +35,7 @@ func init() {
 	Register("compressWhitespace", compressWhitespace)
 	Register("cssDecode", cssDecode)
 	Register("escapeSeqDecode", escapeSeqDecode)
+	Register("hexDecode", hexDecode)
 	Register("hexEncode", hexEncode)
 	Register("htmlEntityDecode", htmlEntityDecode)
 	Register("jsDecode", jsDecode)