diff --git a/doc/go1.16.html b/doc/go1.16.html
index 0beb62d..fc6b668 100644
--- a/doc/go1.16.html
+++ b/doc/go1.16.html
@@ -891,6 +891,14 @@ func TestFoo(t *testing.T) {
is missing; this is common on musl-based systems and makes
Go programs match the behavior of C programs on those systems.
+
+ The ParseIP and ParseCIDR
+ functions now reject IPv4 addresses which contain decimal components with leading zeros.
+ These components were always interpreted as decimal, but some operating systems treat them as octal.
+ This mismatch could hypothetically lead to security issues if a Go application was used to validate IP addresses
+ which were then used in their original form with non-Go applications which interpreted components as octal. Generally,
+ it is advisable to always re-encoded values after validation, which avoids this class of parser misalignment issues.
+
diff --git a/src/net/hosts_test.go b/src/net/hosts_test.go
index f850e2f..19c4399 100644
--- a/src/net/hosts_test.go
+++ b/src/net/hosts_test.go
@@ -36,7 +36,7 @@ var lookupStaticHostTests = []struct {
},
},
{
- "testdata/ipv4-hosts", // see golang.org/issue/8996
+ "testdata/ipv4-hosts",
[]staticHostEntry{
{"localhost", []string{"127.0.0.1", "127.0.0.2", "127.0.0.3"}},
{"localhost.localdomain", []string{"127.0.0.3"}},
@@ -102,7 +102,7 @@ var lookupStaticAddrTests = []struct {
},
},
{
- "testdata/ipv4-hosts", // see golang.org/issue/8996
+ "testdata/ipv4-hosts",
[]staticHostEntry{
{"127.0.0.1", []string{"localhost"}},
{"127.0.0.2", []string{"localhost"}},
diff --git a/src/net/ip.go b/src/net/ip.go
index c00fe8e..007f3f7 100644
--- a/src/net/ip.go
+++ b/src/net/ip.go
@@ -552,6 +552,10 @@ func parseIPv4(s string) IP {
if !ok || n > 0xFF {
return nil
}
+ if c > 1 && s[0] == '0' {
+ // Reject non-zero components with leading zeroes.
+ return nil
+ }
s = s[c:]
p[i] = byte(n)
}
diff --git a/src/net/ip_test.go b/src/net/ip_test.go
index a5fc5e6..585381d 100644
--- a/src/net/ip_test.go
+++ b/src/net/ip_test.go
@@ -20,9 +20,7 @@ var parseIPTests = []struct {
}{
{"127.0.1.2", IPv4(127, 0, 1, 2)},
{"127.0.0.1", IPv4(127, 0, 0, 1)},
- {"127.001.002.003", IPv4(127, 1, 2, 3)},
{"::ffff:127.1.2.3", IPv4(127, 1, 2, 3)},
- {"::ffff:127.001.002.003", IPv4(127, 1, 2, 3)},
{"::ffff:7f01:0203", IPv4(127, 1, 2, 3)},
{"0:0:0:0:0000:ffff:127.1.2.3", IPv4(127, 1, 2, 3)},
{"0:0:0:0:000000:ffff:127.1.2.3", IPv4(127, 1, 2, 3)},
@@ -42,6 +40,11 @@ var parseIPTests = []struct {
{"fe80::1%911", nil},
{"", nil},
{"a1:a2:a3:a4::b1:b2:b3:b4", nil}, // Issue 6628
+ {"127.001.002.003", nil},
+ {"::ffff:127.001.002.003", nil},
+ {"123.000.000.000", nil},
+ {"1.2..4", nil},
+ {"0123.0.0.1", nil},
}
func TestParseIP(t *testing.T) {
@@ -357,6 +360,7 @@ var parseCIDRTests = []struct {
{"0.0.-2.0/32", nil, nil, &ParseError{Type: "CIDR address", Text: "0.0.-2.0/32"}},
{"0.0.0.-3/32", nil, nil, &ParseError{Type: "CIDR address", Text: "0.0.0.-3/32"}},
{"0.0.0.0/-0", nil, nil, &ParseError{Type: "CIDR address", Text: "0.0.0.0/-0"}},
+ {"127.000.000.001/32", nil, nil, &ParseError{Type: "CIDR address", Text: "127.000.000.001/32"}},
{"", nil, nil, &ParseError{Type: "CIDR address", Text: ""}},
}
diff --git a/src/net/testdata/ipv4-hosts b/src/net/testdata/ipv4-hosts
index 5208bb4..6b99675 100644
--- a/src/net/testdata/ipv4-hosts
+++ b/src/net/testdata/ipv4-hosts
@@ -1,12 +1,8 @@
# See https://tools.ietf.org/html/rfc1123.
-#
-# The literal IPv4 address parser in the net package is a relaxed
-# one. It may accept a literal IPv4 address in dotted-decimal notation
-# with leading zeros such as "001.2.003.4".
# internet address and host name
127.0.0.1 localhost # inline comment separated by tab
-127.000.000.002 localhost # inline comment separated by space
+127.0.0.2 localhost # inline comment separated by space
# internet address, host name and aliases
-127.000.000.003 localhost localhost.localdomain
+127.0.0.3 localhost localhost.localdomain