rust-url/src/idna.rs

//! International domain names
//!
//! https://url.spec.whatwg.org/#idna

use idna_mapping::*;
use punycode;
use std::ascii::AsciiExt;
use unicode_normalization::UnicodeNormalization;

fn idna_mapped(mapping: &'static [char]) -> Result<String, Error> {
    let mut ret = "".to_string();
    for &c in mapping {
        ret.push(c)
    }
    return Ok(ret);
}

fn idna_deviation(codepoint: char, mapping: &'static [char], transitional: bool) -> Result<String, Error> {
    if transitional {
       return idna_mapped(mapping);
    }
    return Ok(codepoint.to_string());
}

fn idna_disallowed_std3_valid(codepoint: char, use_std3_asciirules: bool) -> Result<String, Error> {
    if use_std3_asciirules {
        return Err(Error::DissallowedByStd3AsciiRules);
    }
    return Ok(codepoint.to_string());
}

fn idna_disallowed_std3_mapped(mapping: &'static [char], use_std3_asciirules: bool) -> Result<String, Error> {
    if use_std3_asciirules {
        return Err(Error::DissallowedMappedInStd3);
    }
    return idna_mapped(mapping);
}

fn map_char(codepoint: char, flags: Uts46Flags) -> Result<String, Error> {
    let mut min = 0;
    let mut max = TABLE.len() - 1;
    while max > min {
        let mid = (min + max) >> 1;
        if codepoint > TABLE[mid].to {
           min = mid;
        } else if codepoint < TABLE[mid].from {
            max = mid;
        } else {
            min = mid;
            max = mid;
        }
    }

    let mapping = TABLE[min].mapping;

    match TABLE[min].status {
        MappingStatus::valid => Ok(codepoint.to_string()),
        MappingStatus::ignored => Ok("".to_string()),
        MappingStatus::mapped => idna_mapped(mapping),
        MappingStatus::deviation => {
            idna_deviation(codepoint, mapping, flags.transitional_processing)
        }
        MappingStatus::disallowed => Err(Error::DissallowedCharacter),
        MappingStatus::disallowed_STD3_valid => {
            idna_disallowed_std3_valid(codepoint, flags.use_std3_ascii_rules)
        }
        MappingStatus::disallowed_STD3_mapped => {
            idna_disallowed_std3_mapped(mapping, flags.use_std3_ascii_rules)
        }
    }
}

#[derive(Copy, Clone)]
pub struct Uts46Flags {
   pub use_std3_ascii_rules: bool,
   pub transitional_processing: bool,
}

pub enum Error {
    PunycodeEncodingError,
    DissallowedByStd3AsciiRules,
    DissallowedMappedInStd3,
    DissallowedCharacter,
}

/// http://www.unicode.org/reports/tr46/#ToASCII
pub fn uts46_to_ascii(domain: &str, flags: Uts46Flags) -> Result<String, Error> {
    let mut ret = String::new();
    for c in domain.chars() {
        match map_char(c, flags) {
            Ok(mystr) => ret.push_str(&mystr),
            Err(x) => return Err(x)
        }
    }

    // normalize NFC
    let ret = ret.nfc().collect::<String>();

    let vec: Vec<&str> = ret.split(".").collect();
    let mut result = String::new();

    for label in vec {
        if label.is_ascii() {
            if result.len() > 0 {
                result.push('.');
            }
            result.push_str(label);
        } else {
            match punycode::encode_str(label) {
                Some(x) => {
                    if result.len() > 0 {
                        result.push('.');
                    }
                    result.push_str("xn--");
                    result.push_str(&x);
                },
                None => return Err(Error::PunycodeEncodingError)
            }
        }
    }

    return Ok(result);
}

/// https://url.spec.whatwg.org/#concept-domain-to-ascii
pub fn domain_to_ascii(domain: &str) -> Result<String, Error> {
    uts46_to_ascii(domain, Uts46Flags {
        use_std3_ascii_rules: false,
        transitional_processing: true,
    })
}