add literal validations

Author: jialinli98

src/json.nr

@@ -759,6 +759,32 @@ impl<let NumBytes: u32, let NumPackedFields: u32, let MaxNumTokens: u32, let Max
             let index_valid: Field = range_valid[i] as Field;
             // 1 gate
             let entry = TranscriptEntry::to_field(TranscriptEntry { token, index, length });
+
+            if token == LITERAL_TOKEN as Field {
+                let index_as_u32 = index as u32;
+                index.assert_max_bit_size::<8>();
+                if length == 5 {
+                    let is_false = (self.json[index_as_u32] == 102) &      // 'f'
+                    (self.json[index_as_u32 + 1] == 97) &    // 'a'
+                    (self.json[index_as_u32 + 2] == 108) &   // 'l'
+                    (self.json[index_as_u32 + 3] == 115) &   // 's'
+                    (self.json[index_as_u32 + 4] == 101);    // 'e'
+                    assert(is_false, "invalid literal");
+                } else if length == 4 {
+                    let is_true = (self.json[index_as_u32] == 116) &      // 't'
+                    (self.json[index_as_u32 + 1] == 114) &    // 'r'
+                    (self.json[index_as_u32 + 2] == 117) &   // 'u'
+                    (self.json[index_as_u32 + 3] == 101);    // 'e'
+
+                    let is_null = (self.json[index_as_u32] == 110) &      // 'n'
+                    (self.json[index_as_u32 + 1] == 117) &    // 'u'
+                    (self.json[index_as_u32 + 2] == 108) &   // 'l'
+                    (self.json[index_as_u32 + 3] == 108);    // 'l'
+                    assert(is_null | is_true, "invalid literal");
+                } else {
+                    assert(false, "invalid literal");
+                }
+            }
             // 2 gates
             let diff = updated_transcript[cast_num_to_u32(transcript_ptr)] - entry;
             std::as_witness(diff);
@@ -1133,3 +1159,21 @@ fn key_is_not_a_key() {
     let json_string = "{1\n:0}";
     let _: JSON<26, 10, 20, 20, 2> = JSON::parse_json_from_string(json_string);
 }
+
+#[test(should_fail_with = "invalid literal")]
+fn test_incorrect_json_parsing() {
+    let text = "{ \"name\":fal }";
+    let _: JSON<153, 10, 60, 60, 2> = JSON::parse_json_from_string(text);
+}
+
+#[test(should_fail_with = "invalid literal")]
+fn test_incorrect_json_parsing_2() {
+    let text = "{ \"name\":treu}";
+    let _: JSON<153, 10, 60, 60, 2> = JSON::parse_json_from_string(text);
+}
+
+#[test(should_fail_with = "invalid literal")]
+fn test_incorrect_json_parsing_3() {
+    let text = "{ \"name\":truea }";
+    let _: JSON<153, 10, 60, 60, 2> = JSON::parse_json_from_string(text);
+}