346 lines
11 KiB
Rust
346 lines
11 KiB
Rust
//! A private parser implementation of IPv4 and IPv6 network addresses.
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//!
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//! The existing `std::net::parser` module cannot be extended because it
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//! is private. It is copied and extended here with methods for parsing
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//! IP network addresses.
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use std::error::Error;
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use std::fmt;
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use std::net::{Ipv4Addr, Ipv6Addr};
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use std::str::FromStr;
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use crate::ipnet::{IpNet, Ipv4Net, Ipv6Net};
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pub struct Parser<'a> {
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// parsing as ASCII, so can use byte array
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s: &'a [u8],
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pos: usize,
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}
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impl<'a> Parser<'a> {
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fn new(s: &'a str) -> Parser<'a> {
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Parser {
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s: s.as_bytes(),
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pos: 0,
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}
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}
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fn is_eof(&self) -> bool {
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self.pos == self.s.len()
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}
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// Commit only if parser returns Some
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fn read_atomically<T, F>(&mut self, cb: F) -> Option<T> where
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F: FnOnce(&mut Parser) -> Option<T>,
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{
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let pos = self.pos;
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let r = cb(self);
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if r.is_none() {
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self.pos = pos;
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}
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r
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}
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// Commit only if parser read till EOF
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fn read_till_eof<T, F>(&mut self, cb: F) -> Option<T> where
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F: FnOnce(&mut Parser) -> Option<T>,
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{
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self.read_atomically(move |p| {
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match cb(p) {
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Some(x) => if p.is_eof() {Some(x)} else {None},
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None => None,
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}
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})
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}
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// Return result of first successful parser
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fn read_or<T>(&mut self, parsers: &mut [Box<dyn FnMut(&mut Parser) -> Option<T> + 'static>])
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-> Option<T> {
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for pf in parsers {
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if let Some(r) = self.read_atomically(|p: &mut Parser| pf(p)) {
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return Some(r);
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}
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}
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None
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}
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// Apply 3 parsers sequentially
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fn read_seq_3<A, B, C, PA, PB, PC>(&mut self,
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pa: PA,
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pb: PB,
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pc: PC)
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-> Option<(A, B, C)> where
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PA: FnOnce(&mut Parser) -> Option<A>,
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PB: FnOnce(&mut Parser) -> Option<B>,
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PC: FnOnce(&mut Parser) -> Option<C>,
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{
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self.read_atomically(move |p| {
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let a = pa(p);
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let b = if a.is_some() { pb(p) } else { None };
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let c = if b.is_some() { pc(p) } else { None };
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match (a, b, c) {
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(Some(a), Some(b), Some(c)) => Some((a, b, c)),
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_ => None
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}
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})
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}
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// Read next char
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fn read_char(&mut self) -> Option<char> {
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if self.is_eof() {
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None
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} else {
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let r = self.s[self.pos] as char;
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self.pos += 1;
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Some(r)
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}
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}
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// Return char and advance iff next char is equal to requested
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fn read_given_char(&mut self, c: char) -> Option<char> {
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self.read_atomically(|p| {
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match p.read_char() {
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Some(next) if next == c => Some(next),
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_ => None,
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}
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})
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}
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// Read digit
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fn read_digit(&mut self, radix: u8) -> Option<u8> {
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fn parse_digit(c: char, radix: u8) -> Option<u8> {
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let c = c as u8;
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// assuming radix is either 10 or 16
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if c >= b'0' && c <= b'9' {
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Some(c - b'0')
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} else if radix > 10 && c >= b'a' && c < b'a' + (radix - 10) {
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Some(c - b'a' + 10)
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} else if radix > 10 && c >= b'A' && c < b'A' + (radix - 10) {
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Some(c - b'A' + 10)
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} else {
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None
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}
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}
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self.read_atomically(|p| {
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p.read_char().and_then(|c| parse_digit(c, radix))
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})
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}
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fn read_number_impl(&mut self, radix: u8, max_digits: u32, upto: u32) -> Option<u32> {
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let mut r = 0;
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let mut digit_count = 0;
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loop {
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match self.read_digit(radix) {
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Some(d) => {
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r = r * (radix as u32) + (d as u32);
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digit_count += 1;
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if digit_count > max_digits || r >= upto {
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return None
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}
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}
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None => {
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if digit_count == 0 {
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return None
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} else {
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return Some(r)
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}
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}
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};
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}
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}
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// Read number, failing if max_digits of number value exceeded
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fn read_number(&mut self, radix: u8, max_digits: u32, upto: u32) -> Option<u32> {
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self.read_atomically(|p| p.read_number_impl(radix, max_digits, upto))
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}
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fn read_ipv4_addr_impl(&mut self) -> Option<Ipv4Addr> {
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let mut bs = [0; 4];
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let mut i = 0;
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while i < 4 {
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if i != 0 && self.read_given_char('.').is_none() {
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return None;
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}
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let octet = self.read_number(10, 3, 0x100).map(|n| n as u8);
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match octet {
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Some(d) => bs[i] = d,
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None => return None,
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};
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i += 1;
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}
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Some(Ipv4Addr::new(bs[0], bs[1], bs[2], bs[3]))
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}
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// Read IPv4 address
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fn read_ipv4_addr(&mut self) -> Option<Ipv4Addr> {
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self.read_atomically(|p| p.read_ipv4_addr_impl())
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}
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fn read_ipv6_addr_impl(&mut self) -> Option<Ipv6Addr> {
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fn ipv6_addr_from_head_tail(head: &[u16], tail: &[u16]) -> Ipv6Addr {
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assert!(head.len() + tail.len() <= 8);
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let mut gs = [0; 8];
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gs[..head.len()].copy_from_slice(head);
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gs[(8 - tail.len()) .. 8].copy_from_slice(tail);
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Ipv6Addr::new(gs[0], gs[1], gs[2], gs[3], gs[4], gs[5], gs[6], gs[7])
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}
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fn read_groups(p: &mut Parser, groups: &mut [u16; 8], limit: usize)
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-> (usize, bool) {
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let mut i = 0;
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while i < limit {
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if i < limit - 1 {
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let ipv4 = p.read_atomically(|p| {
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if i == 0 || p.read_given_char(':').is_some() {
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p.read_ipv4_addr()
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} else {
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None
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}
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});
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if let Some(v4_addr) = ipv4 {
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let octets = v4_addr.octets();
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groups[i + 0] = ((octets[0] as u16) << 8) | (octets[1] as u16);
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groups[i + 1] = ((octets[2] as u16) << 8) | (octets[3] as u16);
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return (i + 2, true);
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}
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}
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let group = p.read_atomically(|p| {
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if i == 0 || p.read_given_char(':').is_some() {
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p.read_number(16, 4, 0x10000).map(|n| n as u16)
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} else {
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None
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}
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});
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match group {
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Some(g) => groups[i] = g,
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None => return (i, false)
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}
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i += 1;
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}
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(i, false)
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}
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let mut head = [0; 8];
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let (head_size, head_ipv4) = read_groups(self, &mut head, 8);
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if head_size == 8 {
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return Some(Ipv6Addr::new(
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head[0], head[1], head[2], head[3],
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head[4], head[5], head[6], head[7]))
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}
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// IPv4 part is not allowed before `::`
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if head_ipv4 {
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return None
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}
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// read `::` if previous code parsed less than 8 groups
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if !self.read_given_char(':').is_some() || !self.read_given_char(':').is_some() {
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return None;
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}
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let mut tail = [0; 8];
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let (tail_size, _) = read_groups(self, &mut tail, 8 - head_size);
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Some(ipv6_addr_from_head_tail(&head[..head_size], &tail[..tail_size]))
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}
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fn read_ipv6_addr(&mut self) -> Option<Ipv6Addr> {
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self.read_atomically(|p| p.read_ipv6_addr_impl())
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}
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/* Additions for IpNet below. */
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// Read IPv4 network
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fn read_ipv4_net(&mut self) -> Option<Ipv4Net> {
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let ip_addr = |p: &mut Parser| p.read_ipv4_addr();
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let slash = |p: &mut Parser| p.read_given_char('/');
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let prefix_len = |p: &mut Parser| {
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p.read_number(10, 2, 33).map(|n| n as u8)
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};
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self.read_seq_3(ip_addr, slash, prefix_len).map(|t| {
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let (ip, _, prefix_len): (Ipv4Addr, char, u8) = t;
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Ipv4Net::new(ip, prefix_len).unwrap()
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})
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}
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// Read Ipv6 network
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fn read_ipv6_net(&mut self) -> Option<Ipv6Net> {
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let ip_addr = |p: &mut Parser| p.read_ipv6_addr();
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let slash = |p: &mut Parser| p.read_given_char('/');
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let prefix_len = |p: &mut Parser| {
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p.read_number(10, 3, 129).map(|n| n as u8)
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};
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self.read_seq_3(ip_addr, slash, prefix_len).map(|t| {
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let (ip, _, prefix_len): (Ipv6Addr, char, u8) = t;
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Ipv6Net::new(ip, prefix_len).unwrap()
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})
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}
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fn read_ip_net(&mut self) -> Option<IpNet> {
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let ipv4_net = |p: &mut Parser| p.read_ipv4_net().map(IpNet::V4);
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let ipv6_net = |p: &mut Parser| p.read_ipv6_net().map(IpNet::V6);
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self.read_or(&mut [Box::new(ipv4_net), Box::new(ipv6_net)])
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}
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/* Additions for IpNet above. */
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}
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/* Additions for IpNet below. */
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impl FromStr for IpNet {
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type Err = AddrParseError;
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fn from_str(s: &str) -> Result<IpNet, AddrParseError> {
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match Parser::new(s).read_till_eof(|p| p.read_ip_net()) {
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Some(s) => Ok(s),
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None => Err(AddrParseError(()))
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}
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}
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}
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impl FromStr for Ipv4Net {
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type Err = AddrParseError;
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fn from_str(s: &str) -> Result<Ipv4Net, AddrParseError> {
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match Parser::new(s).read_till_eof(|p| p.read_ipv4_net()) {
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Some(s) => Ok(s),
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None => Err(AddrParseError(()))
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}
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}
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}
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impl FromStr for Ipv6Net {
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type Err = AddrParseError;
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fn from_str(s: &str) -> Result<Ipv6Net, AddrParseError> {
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match Parser::new(s).read_till_eof(|p| p.read_ipv6_net()) {
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Some(s) => Ok(s),
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None => Err(AddrParseError(()))
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}
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}
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}
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/* Additions for IpNet above. */
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/// An error which can be returned when parsing an IP network address.
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///
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/// This error is used as the error type for the [`FromStr`] implementation for
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/// [`IpNet`], [`Ipv4Net`], and [`Ipv6Net`].
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///
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/// [`FromStr`]: https://doc.rust-lang.org/std/str/trait.FromStr.html
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/// [`IpNet`]: enum.IpNet.html
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/// [`Ipv4Net`]: struct.Ipv4Net.html
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/// [`Ipv6Net`]: struct.Ipv6Net.html
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct AddrParseError(());
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impl fmt::Display for AddrParseError {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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fmt.write_str("invalid IP address syntax")
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}
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}
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impl Error for AddrParseError {}
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