Parse invalid single-letter timezones as -00:00

chronotope · Jun 1, 2023 · af9a12e · af9a12e
1 parent e3f8fb3
commit af9a12e
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Showing 2 changed files with 19 additions and 19 deletions.
diff --git a/src/format/parse.rs b/src/format/parse.rs
@@ -915,12 +915,13 @@ fn test_rfc2822() {
         ("Tue, 20 Jan 2015 17:35:20 PDT", Ok("Tue, 20 Jan 2015 17:35:20 -0700")),
         ("Tue, 20 Jan 2015 17:35:20 PST", Ok("Tue, 20 Jan 2015 17:35:20 -0800")),
         ("Tue, 20 Jan 2015 17:35:20 pst", Ok("Tue, 20 Jan 2015 17:35:20 -0800")),
-        // 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("Tue, 20 Jan 2015 17:35:20 +0000")),
-        ("Tue, 20 Jan 2015 17:35:20 A", Ok("Tue, 20 Jan 2015 17:35:20 +0000")),
-        ("Tue, 20 Jan 2015 17:35:20 a", Ok("Tue, 20 Jan 2015 17:35:20 +0000")),
-        ("Tue, 20 Jan 2015 17:35:20 K", Ok("Tue, 20 Jan 2015 17:35:20 +0000")),
-        ("Tue, 20 Jan 2015 17:35:20 k", Ok("Tue, 20 Jan 2015 17:35:20 +0000")),
+        // other named single-letter military timezones must fallback to -0000
+        ("Tue, 20 Jan 2015 17:35:20 A", Ok("Tue, 20 Jan 2015 17:35:20 -0000")),
+        ("Tue, 20 Jan 2015 17:35:20 a", Ok("Tue, 20 Jan 2015 17:35:20 -0000")),
+        ("Tue, 20 Jan 2015 17:35:20 K", Ok("Tue, 20 Jan 2015 17:35:20 -0000")),
+        ("Tue, 20 Jan 2015 17:35:20 k", Ok("Tue, 20 Jan 2015 17:35:20 -0000")),
         // named single-letter timezone "J" is specifically not valid
         ("Tue, 20 Jan 2015 17:35:20 J", Err(INVALID)),
         ("Tue, 20 Jan 2015😈17:35:20 -0800", Err(INVALID)), // bad character!

diff --git a/src/format/scan.rs b/src/format/scan.rs
@@ -325,30 +325,29 @@ 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 equals(name, "gmt") || equals(name, "ut") {
-            offset_hours(0)
+        // RFC 2822 requires support for some named North America timezones, a small subset of all
+        // named timezones.
+        if equals(name, "gmt") || equals(name, "ut") || equals(name, "z") || equals(name, "Z") {
+            return offset_hours(0);
         } else if equals(name, "edt") {
-            offset_hours(-4)
+            return offset_hours(-4);
         } else if equals(name, "est") || equals(name, "cdt") {
-            offset_hours(-5)
+            return offset_hours(-5);
         } else if equals(name, "cst") || equals(name, "mdt") {
-            offset_hours(-6)
+            return offset_hours(-6);
         } else if equals(name, "mst") || equals(name, "pdt") {
-            offset_hours(-7)
+            return offset_hours(-7);
         } else if equals(name, "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))?;
-        Ok((s_, offset))
+        timezone_offset(s, |s| Ok(s))
     }
 }