mail_parser/decoders/
encoded_word.rs

/*
 * Copyright Stalwart Labs Ltd. See the COPYING
 * file at the top-level directory of this distribution.
 *
 * Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 * https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 * <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
 * option. This file may not be copied, modified, or distributed
 * except according to those terms.
 */

use crate::{decoders::charsets::map::get_charset_decoder, parsers::message::MessageStream};

use super::{
    base64::decode_base64, quoted_printable::decode_quoted_printable, DecodeFnc, DecodeResult,
};

enum Rfc2047State {
    Init,
    Charset,
    Encoding,
    Data,
}

pub fn decode_rfc2047(stream: &MessageStream, start_pos: usize) -> (usize, Option<String>) {
    let mut read_pos: usize = start_pos;
    let mut state = Rfc2047State::Init;

    let mut charset_start = 0;
    let mut charset_end = 0;
    let mut decode_fnc: Option<DecodeFnc> = None;

    for ch in stream.data[start_pos..].iter() {
        read_pos += 1;

        match state {
            Rfc2047State::Init => {
                if ch != &b'?' {
                    return (0, None);
                }
                state = Rfc2047State::Charset;
                charset_start = read_pos;
                charset_end = read_pos;
            }
            Rfc2047State::Charset => match ch {
                b'?' => {
                    if charset_end == charset_start {
                        charset_end = read_pos - 1;
                    }
                    if (charset_end - charset_start) < 2 {
                        return (0, None);
                    }
                    state = Rfc2047State::Encoding;
                }
                b'*' => {
                    if charset_end == charset_start {
                        charset_end = read_pos - 1;
                    }
                }
                b'\n' => {
                    return (0, None);
                }
                _ => (),
            },
            Rfc2047State::Encoding => {
                match ch {
                    b'q' | b'Q' => decode_fnc = Some(decode_quoted_printable),
                    b'b' | b'B' => decode_fnc = Some(decode_base64),
                    _ => {
                        return (0, None);
                    }
                }
                state = Rfc2047State::Data;
            }
            Rfc2047State::Data => {
                if ch != &b'?' {
                    return (0, None);
                } else {
                    break;
                }
            }
        }
    }

    if let Some(decode_fnc) = decode_fnc {
        if let (bytes_read @ 1..=usize::MAX, DecodeResult::Owned(bytes)) =
            decode_fnc(stream, read_pos, b"?=", true)
        {
            return (
                (read_pos - start_pos) + bytes_read,
                if let Some(decoder) = get_charset_decoder(&stream.data[charset_start..charset_end])
                {
                    decoder(&bytes).into()
                } else {
                    String::from_utf8(bytes)
                        .unwrap_or_else(|e| String::from_utf8_lossy(e.as_bytes()).into_owned())
                        .into()
                },
            );
        } else if let Some(b"?=") = stream.data.get(read_pos..read_pos + 2) {
            return ((read_pos - start_pos) + 2, Some(String::new()));
        }
    }

    (0, None)
}

#[cfg(test)]
mod tests {
    use crate::{decoders::encoded_word::decode_rfc2047, parsers::message::MessageStream};

    #[test]
    fn decode_rfc2047_string() {
        let inputs = [
            (
                "?iso-8859-1?q?this=20is=20some=20text?=".to_string(),
                "this is some text",
                true,
            ),
            (
                "?iso-8859-1?q?this is some text?=".to_string(),
                "this is some text",
                true,
            ),
            (
                "?US-ASCII?Q?Keith_Moore?=".to_string(),
                "Keith Moore",
                false,
            ),
            (
                "?iso_8859-1:1987?Q?Keld_J=F8rn_Simonsen?=".to_string(),
                "Keld Jørn Simonsen",
                true,
            ),
            (
                "?ISO-8859-1?B?SWYgeW91IGNhbiByZWFkIHRoaXMgeW8=?=".to_string(),
                "If you can read this yo",
                true,
            ),
            (
                "?ISO-8859-2?B?dSB1bmRlcnN0YW5kIHRoZSBleGFtcGxlLg==?=".to_string(),
                "u understand the example.",
                true,
            ),
            (
                "?ISO-8859-1?Q?Olle_J=E4rnefors?=".to_string(),
                "Olle Järnefors",
                true,
            ),
            (
                "?ISO-8859-1?Q?Patrik_F=E4ltstr=F6m?=".to_string(),
                "Patrik Fältström",
                true,
            ),
            ("?ISO-8859-1*?Q?a?=".to_string(), "a", true),
            ("?ISO-8859-1**?Q?a_b?=".to_string(), "a b", true),
            (
                "?utf-8?b?VGjDrXMgw61zIHbDoWzDrWQgw5pURjg=?=".to_string(),
                "Thís ís válíd ÚTF8",
                false,
            ),
            (
                "?utf-8*unknown?q?Th=C3=ADs_=C3=ADs_v=C3=A1l=C3=ADd_=C3=9ATF8?=".to_string(),
                "Thís ís válíd ÚTF8",
                false,
            ),
            (
                "?Iso-8859-6?Q?=E5=D1=CD=C8=C7 =C8=C7=E4=D9=C7=E4=E5?=".to_string(),
                "مرحبا بالعالم",
                true,
            ),
            (
                "?Iso-8859-6*arabic?b?5dHNyMcgyMfk2cfk5Q==?=".to_string(),
                "مرحبا بالعالم",
                true,
            ),
            #[cfg(feature = "full_encoding")]
            (
                "?shift_jis?B?g26DjYFbgUWDj4Fbg4uDaA==?=".to_string(),
                "ハロー・ワールド",
                true,
            ),
            #[cfg(feature = "full_encoding")]
            (
                "?iso-2022-jp?q?=1B$B%O%m!<!&%o!<%k%I=1B(B?=".to_string(),
                "ハロー・ワールド",
                true,
            ),
        ];

        for input in inputs {
            let str = input.0.to_string();

            match decode_rfc2047(&MessageStream::new(str.as_bytes()), 0) {
                (_, Some(string)) => {
                    //println!("Decoded '{}'", string);
                    assert_eq!(string, input.1);
                }
                _ => panic!("Failed to decode '{}'", input.0),
            }
        }
    }
}
mail_parser/decoders/encoded_word.rs

mail_parser/decoders/
encoded_word.rs
