Parse invalid single-letter timezones as -00:00

chronotope · Jun 30, 2023 · 7582a3f · 7582a3f
1 parent 3d38361
commit 7582a3f
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Showing 2 changed files with 34 additions and 15 deletions.
diff --git a/src/format/parse.rs b/src/format/parse.rs
@@ -1316,8 +1316,9 @@ mod tests {
             ("Tue, 20 Jan 2015 17:35:20 PDT", Ok(ymd_hmsn(2015, 1, 20, 17, 35, 20, 0, -7))),
             ("Tue, 20 Jan 2015 17:35:20 PST", Ok(ymd_hmsn(2015, 1, 20, 17, 35, 20, 0, -8))),
             ("Tue, 20 Jan 2015 17:35:20 pst", Ok(ymd_hmsn(2015, 1, 20, 17, 35, 20, 0, -8))),
-            // named single-letter military timezones must fallback to +0000
+            // Z is the only single-letter military timezones that maps to +0000
             ("Tue, 20 Jan 2015 17:35:20 Z", Ok(ymd_hmsn(2015, 1, 20, 17, 35, 20, 0, 0))),
+            // named single-letter military timezones must fallback to +0000
             ("Tue, 20 Jan 2015 17:35:20 A", Ok(ymd_hmsn(2015, 1, 20, 17, 35, 20, 0, 0))),
             ("Tue, 20 Jan 2015 17:35:20 a", Ok(ymd_hmsn(2015, 1, 20, 17, 35, 20, 0, 0))),
             ("Tue, 20 Jan 2015 17:35:20 K", Ok(ymd_hmsn(2015, 1, 20, 17, 35, 20, 0, 0))),
@@ -1354,6 +1355,22 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_rfc2822_no_offset_info() {
+        fn rfc2822_to_offset(date: &str) -> FixedOffset {
+            let mut parsed = Parsed::new();
+            parse(&mut parsed, date, [Item::Fixed(Fixed::RFC2822)].iter()).unwrap();
+            parsed.to_fixed_offset().unwrap()
+        }
+        assert_eq!(
+            rfc2822_to_offset("Tue, 20 Jan 2015 17:35:20 -0000"),
+            FixedOffset::OFFSET_UNKNOWN
+        );
+        assert_eq!(rfc2822_to_offset("Tue, 20 Jan 2015 17:35:20 A"), FixedOffset::OFFSET_UNKNOWN);
+        assert_eq!(rfc2822_to_offset("Tue, 20 Jan 2015 17:35:20 a"), FixedOffset::OFFSET_UNKNOWN);
+        assert_eq!(rfc2822_to_offset("Tue, 20 Jan 2015 17:35:20 K"), FixedOffset::OFFSET_UNKNOWN);
+    }
+
     #[test]
     fn parse_rfc850() {
         static RFC850_FMT: &str = "%A, %d-%b-%y %T GMT";

diff --git a/src/format/scan.rs b/src/format/scan.rs
@@ -313,30 +313,32 @@ pub(super) fn timezone_offset_2822(s: &str) -> ParseResult<(&str, Option<i32>)>
         let name = &s.as_bytes()[..upto];
         let s = &s[upto..];
         let offset_hours = |o| Ok((s, Some(o * 3600)));
-        if name.eq_ignore_ascii_case(b"gmt") || name.eq_ignore_ascii_case(b"ut") {
-            offset_hours(0)
+        // RFC 2822 requires support for some named North America timezones, a small subset of all
+        // named timezones.
+        if name.eq_ignore_ascii_case(b"gmt")
+            || name.eq_ignore_ascii_case(b"ut")
+            || name.eq_ignore_ascii_case(b"z")
+        {
+            return offset_hours(0);
         } else if name.eq_ignore_ascii_case(b"edt") {
-            offset_hours(-4)
+            return offset_hours(-4);
         } else if name.eq_ignore_ascii_case(b"est") || name.eq_ignore_ascii_case(b"cdt") {
-            offset_hours(-5)
+            return offset_hours(-5);
         } else if name.eq_ignore_ascii_case(b"cst") || name.eq_ignore_ascii_case(b"mdt") {
-            offset_hours(-6)
+            return offset_hours(-6);
         } else if name.eq_ignore_ascii_case(b"mst") || name.eq_ignore_ascii_case(b"pdt") {
-            offset_hours(-7)
+            return offset_hours(-7);
         } else if name.eq_ignore_ascii_case(b"pst") {
-            offset_hours(-8)
+            return offset_hours(-8);
         } else if name.len() == 1 {
-            match name[0] {
+            if let b'a'..=b'i' | b'k'..=b'y' | b'A'..=b'I' | b'K'..=b'Y' = name[0] {
                 // recommended by RFC 2822: consume but treat it as -0000
-                b'a'..=b'i' | b'k'..=b'z' | b'A'..=b'I' | b'K'..=b'Z' => offset_hours(0),
-                _ => Err(INVALID),
+                return Ok((s, None));
             }
-        } else {
-            Err(INVALID)
         }
+        Err(INVALID)
     } else {
-        let (s_, offset) = timezone_offset(s, |s| Ok(s), false, false, false)?;
-        Ok((s_, offset))
+        timezone_offset(s, |s| Ok(s), false, false, false)
     }
 }