tests(fuzz): Add parse_date fuzzing target (#1127)

Add a fuzzing target for parsing into a Timestamp and comparing the result with crate chrono.

fuzz/Cargo.toml

@@ -12,6 +12,8 @@ cargo-fuzz = true
 libfuzzer-sys = "0.4"
 tests = { path = "../tests" }
 protobuf = { path = "../protobuf" }
+prost-types = { path = "../prost-types" }
+chrono = "0.4"
 
 [[bin]]
 name = "proto3"
@@ -26,3 +28,10 @@ path = "fuzzers/proto2.rs"
 test = false
 doc = false
 bench = false
+
+[[bin]]
+name = "parse_date"
+path = "fuzzers/parse_date.rs"
+test = false
+doc = false
+bench = false

fuzz/fuzzers/parse_date.rs

@@ -0,0 +1,49 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| test_parse_date(data));
+
+fn test_parse_date(data: &[u8]) {
+ use std::str::from_utf8;
+ use std::str::FromStr;
+
+ // input must be text
+ let Ok(original_text) = from_utf8(data) else {
+ return;
+ };
+
+ // parse input as a datetime
+ let Ok(timestamp) = prost_types::Timestamp::from_str(original_text) else {
+ let chrono_parse = chrono::DateTime::parse_from_rfc3339(original_text);
+ assert!(
+ chrono_parse.is_err(),
+ "prost failed to parse time, but chrono does parse this time: {}",
+ original_text
+ );
+ return;
+ };
+
+ // roundtrip to and from string
+ let roundtrip_text = format!("{timestamp}");
+ assert_eq!(Ok(&timestamp), roundtrip_text.parse().as_ref());
+
+ // chrono can only parse year 0000 till 9999
+ if let Ok(chrono_time) = chrono::DateTime::parse_from_rfc3339(original_text) {
+ if chrono_time.timestamp_subsec_nanos() > 999_999_999 {
+ // prost ignores leap seconds, but chrono increases the nanos in that case
+ return;
+ }
+
+ assert_eq!(timestamp.seconds, chrono_time.timestamp());
+ assert_eq!(timestamp.nanos, chrono_time.timestamp_subsec_nanos() as i32);
+
+ // roundtrip using chrono
+ let chrono_text = chrono_time.to_utc().to_rfc3339();
+ assert_eq!(
+ roundtrip_text.strip_suffix("Z").unwrap(),
+ chrono_text.strip_suffix("+00:00").unwrap()
+ );
+ assert_eq!(Ok(&timestamp), chrono_text.parse().as_ref());
+ }
+}