hickory_proto/rr/rdata/

txt.rs

// Copyright 2015-2023 Benjamin Fry <benjaminfry@me.com>
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// https://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.

//! text records for storing arbitrary data
use std::fmt;
use std::slice::Iter;

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

use crate::{
    error::ProtoResult,
    rr::{RData, RecordData, RecordDataDecodable, RecordType},
    serialize::binary::*,
};

/// [RFC 1035, DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION, November 1987](https://tools.ietf.org/html/rfc1035)
///
/// ```text
/// 3.3.14. TXT RDATA format
///
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///     /                   TXT-DATA                    /
///     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
///
///
/// TXT RRs are used to hold descriptive text.  The semantics of the text
/// depends on the domain where it is found.
/// ```
#[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub struct TXT {
    txt_data: Box<[Box<[u8]>]>,
}

impl TXT {
    /// Creates a new TXT record data.
    ///
    /// # Arguments
    ///
    /// * `txt_data` - the set of strings which make up the txt_data.
    ///
    /// # Return value
    ///
    /// The new TXT record data.
    pub fn new(txt_data: Vec<String>) -> Self {
        Self {
            txt_data: txt_data
                .into_iter()
                .map(|s| s.into_bytes().into_boxed_slice())
                .collect::<Vec<_>>()
                .into_boxed_slice(),
        }
    }

    /// Creates a new TXT record data from bytes.
    /// Allows creating binary record data.
    ///
    /// # Arguments
    ///
    /// * `txt_data` - the set of bytes which make up the txt_data.
    ///
    /// # Return value
    ///
    /// The new TXT record data.
    pub fn from_bytes(txt_data: Vec<&[u8]>) -> Self {
        Self {
            txt_data: txt_data
                .into_iter()
                .map(|s| s.to_vec().into_boxed_slice())
                .collect::<Vec<_>>()
                .into_boxed_slice(),
        }
    }

    /// ```text
    /// TXT-DATA        One or more <character-string>s.
    /// ```
    pub fn txt_data(&self) -> &[Box<[u8]>] {
        &self.txt_data
    }

    /// Returns an iterator over the arrays in the txt data
    pub fn iter(&self) -> Iter<'_, Box<[u8]>> {
        self.txt_data.iter()
    }
}

impl BinEncodable for TXT {
    fn emit(&self, encoder: &mut BinEncoder<'_>) -> ProtoResult<()> {
        for s in self.txt_data() {
            encoder.emit_character_data(s)?;
        }

        Ok(())
    }
}

impl RecordDataDecodable<'_> for TXT {
    fn read_data(decoder: &mut BinDecoder<'_>, rdata_length: Restrict<u16>) -> ProtoResult<Self> {
        let data_len = decoder.len();
        let mut strings = Vec::with_capacity(1);

        // no unsafe usage of rdata length after this point
        let rdata_length =
            rdata_length.map(|u| u as usize).unverified(/*used as a higher bound, safely*/);
        while data_len - decoder.len() < rdata_length {
            let string = decoder.read_character_data()?.unverified(/*any data should be validate in TXT usage*/);
            strings.push(string.to_vec().into_boxed_slice());
        }
        Ok(Self {
            txt_data: strings.into_boxed_slice(),
        })
    }
}

impl RecordData for TXT {
    fn try_from_rdata(data: RData) -> Result<Self, RData> {
        match data {
            RData::TXT(data) => Ok(data),
            _ => Err(data),
        }
    }

    fn try_borrow(data: &RData) -> Option<&Self> {
        match data {
            RData::TXT(data) => Some(data),
            _ => None,
        }
    }

    fn record_type(&self) -> RecordType {
        RecordType::TXT
    }

    fn into_rdata(self) -> RData {
        RData::TXT(self)
    }
}

impl fmt::Display for TXT {
    /// Format a [TXT] with lossy conversion of invalid utf8.
    ///
    /// ## Case of invalid utf8
    ///
    /// Invalid utf8 will be converted to:
    /// `U+FFFD REPLACEMENT CHARACTER`, which looks like this: �
    ///
    /// Same behaviour as `alloc::string::String::from_utf8_lossy`.
    /// ```rust
    /// # use hickory_proto::rr::rdata::TXT;
    /// let first_bytes = b"Invalid utf8 <\xF0\x90\x80>.";
    /// let second_bytes = b" Valid utf8 <\xF0\x9F\xA4\xA3>";
    /// let rdata: Vec<&[u8]> = vec![first_bytes, second_bytes];
    /// let txt = TXT::from_bytes(rdata);
    ///
    /// let tested = format!("{}", txt);
    /// assert_eq!(
    ///     tested.as_bytes(),
    ///     b"Invalid utf8 <\xEF\xBF\xBD>. Valid utf8 <\xF0\x9F\xA4\xA3>",
    ///     "Utf8 lossy conversion error! Mismatch between input and expected"
    /// );
    /// ```
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
        for txt in self.txt_data.iter() {
            f.write_str(&String::from_utf8_lossy(txt))?;
        }

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    #![allow(clippy::dbg_macro, clippy::print_stdout)]

    use super::*;

    #[test]
    fn test() {
        let rdata = TXT::new(vec!["Test me some".to_string(), "more please".to_string()]);

        let mut bytes = Vec::new();
        let mut encoder: BinEncoder<'_> = BinEncoder::new(&mut bytes);
        assert!(rdata.emit(&mut encoder).is_ok());
        let bytes = encoder.into_bytes();

        println!("bytes: {bytes:?}");

        let mut decoder: BinDecoder<'_> = BinDecoder::new(bytes);
        let restrict = Restrict::new(bytes.len() as u16);
        let read_rdata = TXT::read_data(&mut decoder, restrict).expect("Decoding error");
        assert_eq!(rdata, read_rdata);
    }

    #[test]
    fn publish_binary_txt_record() {
        let bin_data = vec![0, 1, 2, 3, 4, 5, 6, 7, 8];
        let rdata = TXT::from_bytes(vec![b"Test me some", &bin_data]);

        let mut bytes = Vec::new();
        let mut encoder: BinEncoder<'_> = BinEncoder::new(&mut bytes);
        assert!(rdata.emit(&mut encoder).is_ok());
        let bytes = encoder.into_bytes();

        println!("bytes: {bytes:?}");

        let mut decoder: BinDecoder<'_> = BinDecoder::new(bytes);
        let restrict = Restrict::new(bytes.len() as u16);
        let read_rdata = TXT::read_data(&mut decoder, restrict).expect("Decoding error");
        assert_eq!(rdata, read_rdata);
    }
}