From 734bfdeaf290a64f4170f79770dfac7151951942 Mon Sep 17 00:00:00 2001
From: Smitty <me@smitop.com>
Date: Thu, 8 Jul 2021 14:13:42 -0400
Subject: [PATCH] Disallow octal zeros in IPv4 addresses

---
 library/std/src/net/ip/tests.rs |  8 ++++++++
 library/std/src/net/parser.rs   | 26 +++++++++++++++++---------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/library/std/src/net/ip/tests.rs b/library/std/src/net/ip/tests.rs
index 2109980ad05..5ff0bd697b1 100644
--- a/library/std/src/net/ip/tests.rs
+++ b/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]
diff --git a/library/std/src/net/parser.rs b/library/std/src/net/parser.rs
index 88a8cb76bef..d43d40400ab 100644
--- a/library/std/src/net/parser.rs
+++ b/library/std/src/net/parser.rs
@@ -12,7 +12,7 @@
 use crate::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
 use crate::str::FromStr;
 
-trait ReadNumberHelper: crate::marker::Sized {
+trait ReadNumberHelper: crate::marker::Sized + crate::cmp::PartialEq {
     const ZERO: Self;
     fn checked_mul(&self, other: u32) -> Option<Self>;
     fn checked_add(&self, other: u32) -> Option<Self>;
@@ -111,10 +111,12 @@ fn read_number<T: ReadNumberHelper>(
         &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 +129,16 @@ fn read_number<T: ReadNumberHelper>(
                 }
             }
 
-            if digit_count == 0 { None } else { Some(result) }
+            if digit_count == 0 {
+                None
+            } else if !allow_zero_prefix
+                && has_leading_zero
+                && (result != T::ZERO || result == T::ZERO && digit_count > 1)
+            {
+                None
+            } else {
+                Some(result)
+            }
         })
     }
 
@@ -140,10 +151,7 @@ fn read_ipv4_addr(&mut self) -> Option<Ipv4Addr> {
                 *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, None, false)
                 })?;
             }
 
@@ -175,7 +183,7 @@ fn read_groups(p: &mut Parser<'_>, groups: &mut [u16]) -> (usize, bool) {
                     }
                 }
 
-                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,
@@ -227,7 +235,7 @@ fn read_ip_addr(&mut self) -> Option<IpAddr> {
     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)
         })
     }
 
@@ -235,7 +243,7 @@ fn read_port(&mut self) -> Option<u16> {
     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)
         })
     }
 
-- 
2.44.0