Pull/97

examples/make_tables.rs

@@ -26,7 +26,7 @@ fn main() {
         .chain(0x30..0x3A)
         // -
         .chain(0x2D..0x2E)
-        // _s
+        // _
         .chain(0x5F..0x60)
         .collect();
     print_encode_table(&url_alphabet, "URL_SAFE_ENCODE", 0);
@@ -41,6 +41,20 @@ fn main() {
         .collect();
     print_encode_table(&crypt_alphabet, "CRYPT_ENCODE", 0);
     print_decode_table(&crypt_alphabet, "CRYPT_DECODE", 0);
+
+    // A-Z
+    let imap_alphabet: Vec<u8> = (0x41..0x5B)
+        // a-z
+        .chain(0x61..0x7B)
+        // 0-9
+        .chain(0x30..0x3A)
+        // +
+        .chain(0x2B..0x2C)
+        // ,
+        .chain(0x2C..0x2D)
+        .collect();
+    print_encode_table(&imap_alphabet, "IMAP_MUTF7_ENCODE", 0);
+    print_decode_table(&imap_alphabet, "IMAP_MUTF7_DECODE", 0);
 }
 
 fn print_encode_table(alphabet: &[u8], const_name: &str, indent_depth: usize) {

src/decode.rs

@@ -856,4 +856,12 @@ mod tests {
             }
         }
     }
+
+    #[test]
+    fn decode_imap() {
+        assert_eq!(
+            decode_config(b"+,,+", crate::IMAP_MUTF7),
+            decode_config(b"+//+", crate::STANDARD_NO_PAD)
+        );
+    }
 }

src/encode.rs

@@ -664,4 +664,12 @@ mod tests {
 
         assert_eq!(encoded_len, encoded.len());
     }
+
+    #[test]
+    fn encode_imap() {
+        assert_eq!(
+            encode_config(b"\xFB\xFF", crate::IMAP_MUTF7),
+            encode_config(b"\xFB\xFF", crate::STANDARD_NO_PAD).replace("/", ",")
+        );
+    }
 }

src/lib.rs

@@ -119,6 +119,10 @@ pub enum CharacterSet {
     ///
     /// Not standardized, but folk wisdom on the net asserts that this alphabet is what crypt uses.
     Crypt,
+    /// The character set used in IMAP-modified UTF-7 (uses `+` and `,`).
+    ///
+    /// See [RFC 3501](https://tools.ietf.org/html/rfc3501#section-5.1.3)
+    ImapMutf7,
 }
 
 impl CharacterSet {
@@ -127,6 +131,7 @@ impl CharacterSet {
             CharacterSet::Standard => tables::STANDARD_ENCODE,
             CharacterSet::UrlSafe => tables::URL_SAFE_ENCODE,
             CharacterSet::Crypt => tables::CRYPT_ENCODE,
+            CharacterSet::ImapMutf7 => tables::IMAP_MUTF7_ENCODE,
         }
     }
 
@@ -135,6 +140,7 @@ impl CharacterSet {
             CharacterSet::Standard => tables::STANDARD_DECODE,
             CharacterSet::UrlSafe => tables::URL_SAFE_DECODE,
             CharacterSet::Crypt => tables::CRYPT_DECODE,
+            CharacterSet::ImapMutf7 => tables::IMAP_MUTF7_DECODE,
         }
     }
 }
@@ -211,3 +217,10 @@ pub const CRYPT: Config = Config {
     pad: false,
     decode_allow_trailing_bits: false,
 };
+
+/// IMAP modified UTF-7 requirements
+pub const IMAP_MUTF7: Config = Config {
+    char_set: CharacterSet::ImapMutf7,
+    pad: false,
+    decode_allow_trailing_bits: false,
+};