[ruby/ipaddr] ntop: Measure address size in bytes

`IPAddr.ntop` takes the binary representation of an IP address, whose length should be 4 or 16 *bytes* (not characters/codepoints). The current implementation accepts strings in any encoding, but for some values in non-BINARY encoding, it fails proper length check and raises an `AddressFamilyError`. Since passing strings in a multibyte encoding has never worked correctly for years, this patch makes it an explicit error with an `InvalidAddressError`. Fixes: ruby/ipaddr#56 ruby/ipaddr@a33fd14d4a
ruby · Dec 25, 2023 · eb53131 · eb53131
1 parent ea5776e
commit eb53131
Show file tree

Hide file tree

Showing 2 changed files with 30 additions and 6 deletions.
diff --git a/lib/ipaddr.rb b/lib/ipaddr.rb
@@ -110,8 +110,13 @@ def self.new_ntoh(addr)
 
   # Convert a network byte ordered string form of an IP address into
   # human readable form.
+  # It expects the string to be encoded in Encoding::ASCII_8BIT (BINARY).
   def self.ntop(addr)
-    case addr.size
+    if addr.is_a?(String) && addr.encoding != Encoding::BINARY
+      raise InvalidAddressError, "invalid encoding (given #{addr.encoding}, expected BINARY)"
+    end
+
+    case addr.bytesize
     when 4
       addr.unpack('C4').join('.')
     when 16

diff --git a/test/test_ipaddr.rb b/test/test_ipaddr.rb
@@ -133,18 +133,37 @@ def test_s_new_ntoh
 
   def test_ntop
     # IPv4
-    assert_equal("192.168.1.1", IPAddr.ntop("\xC0\xA8\x01\x01"))
+    assert_equal("192.168.1.1", IPAddr.ntop("\xC0\xA8\x01\x01".b))
+    assert_equal("10.231.140.171", IPAddr.ntop("\x0A\xE7\x8C\xAB".b))
     # IPv6
     assert_equal("0000:0000:0000:0000:0000:0000:0000:0001",
-                 IPAddr.ntop("\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"))
+                 IPAddr.ntop("\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01".b))
+    assert_equal("fe80:0000:0000:0000:f09f:9985:f09f:9986",
+                 IPAddr.ntop("\xFE\x80\x00\x00\x00\x00\x00\x00\xF0\x9F\x99\x85\xF0\x9F\x99\x86".b))
 
     # Invalid parameters
+    ## wrong length
     assert_raise(IPAddr::AddressFamilyError) {
-      IPAddr.ntop("192.168.1.1")
+      IPAddr.ntop("192.168.1.1".b)
     }
-
     assert_raise(IPAddr::AddressFamilyError) {
-      IPAddr.ntop("\xC0\xA8\x01\xFF1")
+      IPAddr.ntop("\xC0\xA8\x01\xFF1".b)
+    }
+    ## UTF-8
+    assert_raise(IPAddr::InvalidAddressError) {
+      IPAddr.ntop("192.168.1.1")
+    }
+    assert_raise(IPAddr::InvalidAddressError) {
+      IPAddr.ntop("\x0A\x0A\x0A\x0A")
+    }
+    assert_raise(IPAddr::InvalidAddressError) {
+      IPAddr.ntop("\x0A\xE7\x8C\xAB")
+    }
+    assert_raise(IPAddr::InvalidAddressError) {
+      IPAddr.ntop("\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
+    }
+    assert_raise(IPAddr::InvalidAddressError) {
+      IPAddr.ntop("\xFE\x80\x00\x00\x00\x00\x00\x00\xF0\x9F\x99\x85\xF0\x9F\x99\x86")
     }
   end