Rollup merge of rust-lang#86984 - Smittyvb:ipv4-octal-zero, r=m-ou-se

Reject octal zeros in IPv4 addresses

This fixes rust-lang#86964 by rejecting octal zeros in IP addresses, such that `192.168.00.00000000` is rejected with a parse error, since having leading zeros in front of another zero indicates it is a zero written in octal notation, which is not allowed in the strict mode specified by RFC 6943 3.1.1. Octal rejection was implemented in rust-lang#83652, but due to the way it was implemented octal zeros were still allowed.

Author: JohnTitor

library/std/src/net/ip.rs

@@ -59,7 +59,8 @@ pub enum IpAddr {
 ///
 /// `Ipv4Addr` provides a [`FromStr`] implementation. The four octets are in decimal
 /// notation, divided by `.` (this is called "dot-decimal notation").
-/// Notably, octal numbers and hexadecimal numbers are not allowed per [IETF RFC 6943].
+/// Notably, octal numbers (which are indicated with a leading `0`) and hexadecimal numbers (which
+/// are indicated with a leading `0x`) are not allowed per [IETF RFC 6943].
 ///
 /// [IETF RFC 6943]: https://tools.ietf.org/html/rfc6943#section-3.1.1
 /// [`FromStr`]: crate::str::FromStr
@@ -72,6 +73,9 @@ pub enum IpAddr {
 /// let localhost = Ipv4Addr::new(127, 0, 0, 1);
 /// assert_eq!("127.0.0.1".parse(), Ok(localhost));
 /// assert_eq!(localhost.is_loopback(), true);
+/// assert!("012.004.002.000".parse::<Ipv4Addr>().is_err()); // all octets are in octal
+/// assert!("0000000.0.0.0".parse::<Ipv4Addr>().is_err()); // first octet is a zero in octal
+/// assert!("0xcb.0x0.0x71.0x00".parse::<Ipv4Addr>().is_err()); // all octets are in hex
 /// ```
 #[derive(Copy)]
 #[stable(feature = "rust1", since = "1.0.0")]

library/std/src/net/ip/tests.rs

@@ -20,6 +20,14 @@ fn test_from_str_ipv4() {
     // no number between dots
     let none: Option<Ipv4Addr> = "255.0..1".parse().ok();
     assert_eq!(None, none);
+    // octal
+    let none: Option<Ipv4Addr> = "255.0.0.01".parse().ok();
+    assert_eq!(None, none);
+    // octal zero
+    let none: Option<Ipv4Addr> = "255.0.0.00".parse().ok();
+    assert_eq!(None, none);
+    let none: Option<Ipv4Addr> = "255.0.00.0".parse().ok();
+    assert_eq!(None, none);
 }
 
 #[test]

library/std/src/net/parser.rs

@@ -111,10 +111,12 @@ impl<'a> Parser<'a> {
         &mut self,
         radix: u32,
         max_digits: Option<usize>,
+        allow_zero_prefix: bool,
     ) -> Option<T> {
         self.read_atomically(move |p| {
             let mut result = T::ZERO;
             let mut digit_count = 0;
+            let has_leading_zero = p.peek_char() == Some('0');
 
             while let Some(digit) = p.read_atomically(|p| p.read_char()?.to_digit(radix)) {
                 result = result.checked_mul(radix)?;
@@ -127,7 +129,13 @@ impl<'a> Parser<'a> {
                 }
             }
 
-            if digit_count == 0 { None } else { Some(result) }
+            if digit_count == 0 {
+                None
+            } else if !allow_zero_prefix && has_leading_zero && digit_count > 1 {
+                None
+            } else {
+                Some(result)
+            }
         })
     }
 
@@ -140,10 +148,7 @@ impl<'a> Parser<'a> {
                 *slot = p.read_separator('.', i, |p| {
                     // Disallow octal number in IP string.
                     // https://tools.ietf.org/html/rfc6943#section-3.1.1
-                    match (p.peek_char(), p.read_number(10, None)) {
-                        (Some('0'), Some(number)) if number != 0 => None,
-                        (_, number) => number,
-                    }
+                    p.read_number(10, Some(3), false)
                 })?;
             }
 
@@ -175,7 +180,7 @@ impl<'a> Parser<'a> {
                     }
                 }
 
-                let group = p.read_separator(':', i, |p| p.read_number(16, Some(4)));
+                let group = p.read_separator(':', i, |p| p.read_number(16, Some(4), true));
 
                 match group {
                     Some(g) => *slot = g,
@@ -227,15 +232,15 @@ impl<'a> Parser<'a> {
     fn read_port(&mut self) -> Option<u16> {
         self.read_atomically(|p| {
             p.read_given_char(':')?;
-            p.read_number(10, None)
+            p.read_number(10, None, true)
         })
     }
 
     /// Read a `%` followed by a scope ID in base 10.
     fn read_scope_id(&mut self) -> Option<u32> {
         self.read_atomically(|p| {
             p.read_given_char('%')?;
-            p.read_number(10, None)
+            p.read_number(10, None, true)
         })
     }
 
@@ -281,7 +286,12 @@ impl FromStr for IpAddr {
 impl FromStr for Ipv4Addr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<Ipv4Addr, AddrParseError> {
-        Parser::new(s).parse_with(|p| p.read_ipv4_addr())
+        // don't try to parse if too long
+        if s.len() > 15 {
+            Err(AddrParseError(()))
+        } else {
+            Parser::new(s).parse_with(|p| p.read_ipv4_addr())
+        }
     }
 }