1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

//! Extended DNS Error from RFC 8914

use super::super::{
    iana::{
        exterr::{ExtendedErrorCode, EDE_PRIVATE_RANGE_BEGIN},
        OptionCode,
    },
    octets::{OctetsBuilder, OctetsRef, Parse, ParseError},
    opt::CodeOptData,
    Compose, Parser, ShortBuf,
};
use core::{convert::TryFrom, fmt, str};

/// Extended Error data structure
#[derive(Debug, Clone)]
pub struct ExtendedError<Octets> {
    /// Info code provides the additional context for the
    /// RESPONSE-CODE of the DNS message.
    code: ExtendedErrorCode,
    /// Extra UTF-8 encoded text, which may hold additional textual
    /// information(optional).
    text: Option<Octets>,
}

impl<Octets: AsRef<[u8]>> ExtendedError<Octets> {
    /// Get INFO-CODE field.
    pub fn code(&self) -> ExtendedErrorCode {
        self.code
    }

    /// Get EXTRA-TEXT field.
    pub fn text(&self) -> Option<&Octets> {
        self.text.as_ref()
    }

    /// Set EXTRA-TEXT field. `text` must be UTF-8 encoded.
    pub fn set_text(&mut self, text: Octets) -> Result<(), str::Utf8Error> {
        // validate encoding
        let _ = str::from_utf8(text.as_ref())?;
        self.text = Some(text);
        Ok(())
    }

    /// Returns true if the code is in the private range.
    pub fn is_private(&self) -> bool {
        self.code().to_int() >= EDE_PRIVATE_RANGE_BEGIN
    }
}

impl<Octets> From<ExtendedErrorCode> for ExtendedError<Octets> {
    fn from(code: ExtendedErrorCode) -> Self {
        Self { code, text: None }
    }
}

impl<Octets: AsRef<[u8]>> TryFrom<(ExtendedErrorCode, Octets)> for ExtendedError<Octets> {
    type Error = str::Utf8Error;

    fn try_from(v: (ExtendedErrorCode, Octets)) -> Result<Self, Self::Error> {
        let mut ede: Self = v.0.into();
        ede.set_text(v.1)?;
        Ok(ede)
    }
}

impl<Octets> From<u16> for ExtendedError<Octets> {
    fn from(code: u16) -> Self {
        Self {
            code: ExtendedErrorCode::from_int(code),
            text: None,
        }
    }
}

impl<Ref: OctetsRef> Parse<Ref> for ExtendedError<Ref::Range> {
    fn parse(parser: &mut Parser<Ref>) -> Result<Self, ParseError> {
        let mut ede: Self = parser.parse_u16()?.into();
        let n = parser.remaining();
        if n > 0 {
            ede.set_text(parser.parse_octets(n)?)
                .map_err(|_| ParseError::form_error("invalid extended error text encoding"))?;
        }
        Ok(ede)
    }

    fn skip(parser: &mut Parser<Ref>) -> Result<(), ParseError> {
        parser.advance_to_end();
        Ok(())
    }
}

impl<Octets> CodeOptData for ExtendedError<Octets> {
    const CODE: OptionCode = OptionCode::ExtendedError;
}

impl<Octets: AsRef<[u8]>> Compose for ExtendedError<Octets> {
    fn compose<T: OctetsBuilder>(&self, target: &mut T) -> Result<(), ShortBuf> {
        target.append_slice(&self.code.to_int().to_be_bytes())?;
        if let Some(text) = &self.text {
            target.append_slice(text.as_ref())?;
        }
        Ok(())
    }
}

impl<Octets: AsRef<[u8]>> fmt::Display for ExtendedError<Octets> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.code.fmt(f)?;

        if let Some(text) = &self.text {
            let text = str::from_utf8(text.as_ref()).map_err(|_| fmt::Error)?;
            write!(f, " ({})", text)?;
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::{super::super::octets::Octets512, *};
    use core::convert::TryInto;

    #[test]
    fn compose() {
        let ede: ExtendedError<&[u8]> = (ExtendedErrorCode::StaleAnswer, "some text".as_ref())
            .try_into()
            .unwrap();

        let mut buf = Octets512::new();
        ede.compose(&mut buf).unwrap();

        let parsed = ExtendedError::parse(&mut Parser::from_ref(buf.as_ref())).unwrap();
        assert_eq!(ede.code, parsed.code);
        assert_eq!(ede.text, parsed.text);
    }

    #[test]
    fn private() {
        let ede: ExtendedError<&[u8]> = ExtendedErrorCode::DnssecBogus.into();
        assert!(!ede.is_private());

        let ede: ExtendedError<&[u8]> = EDE_PRIVATE_RANGE_BEGIN.into();
        assert!(ede.is_private());
    }

    #[test]
    fn encoding() {
        assert!(ExtendedError::try_from((ExtendedErrorCode::Other, b"\x30".as_ref())).is_ok());
        assert!(ExtendedError::try_from((ExtendedErrorCode::Other, b"\xff".as_ref())).is_err());
    }
}