Support zone identifiers in IPv6 addresses

These are supported by Ruby's socket library if the operating system
supports zone indentifiers, so they should be supported by ipaddr.
See RFCs 4007 and 6874 for additional information.

Implements Ruby Feature #10911

Author: jeremyevans

lib/ipaddr.rb

@@ -213,7 +213,13 @@ def to_s
   # Returns a string containing the IP address representation in
   # canonical form.
   def to_string
-    return _to_string(@addr)
+    str = _to_string(@addr)
+
+    if @family == Socket::AF_INET6
+      str << zone_id.to_s
+    end
+
+    return str
   end
 
   # Returns a network byte ordered string form of the IP address.
@@ -385,7 +391,7 @@ def eql?(other)
 
   # Returns a hash value used by Hash, Set, and Array classes
   def hash
-    return ([@addr, @mask_addr].hash << 1) | (ipv4? ? 0 : 1)
+    return ([@addr, @mask_addr, @zone_id].hash << 1) | (ipv4? ? 0 : 1)
   end
 
   # Creates a Range object for the network address.
@@ -441,18 +447,44 @@ def inspect
       af = "IPv4"
     when Socket::AF_INET6
       af = "IPv6"
+      zone_id = @zone_id.to_s
     else
       raise AddressFamilyError, "unsupported address family"
     end
-    return sprintf("#<%s: %s:%s/%s>", self.class.name,
-                   af, _to_string(@addr), _to_string(@mask_addr))
+    return sprintf("#<%s: %s:%s%s/%s>", self.class.name,
+                   af, _to_string(@addr), zone_id, _to_string(@mask_addr))
   end
 
   # Returns the netmask in string format e.g. 255.255.0.0
   def netmask
     _to_string(@mask_addr)
   end
 
+  # Returns the IPv6 zone identifier, if present.
+  # Raises InvalidAddressError if not an IPv6 address.
+  def zone_id
+    if @family == Socket::AF_INET6
+      @zone_id
+    else
+      raise InvalidAddressError, "not an IPv6 address"
+    end
+  end
+
+  # Returns the IPv6 zone identifier, if present.
+  # Raises InvalidAddressError if not an IPv6 address.
+  def zone_id=(zid)
+    if @family == Socket::AF_INET6
+      case zid
+      when nil, /\A%(\w+)\z/
+        @zone_id = zid
+      else
+        raise InvalidAddressError, "invalid zone identifier for address"
+      end
+    else
+      raise InvalidAddressError, "not an IPv6 address"
+    end
+  end
+
   protected
 
   # Set +@addr+, the internal stored ip address, to given +addr+. The
@@ -561,6 +593,11 @@ def initialize(addr = '::', family = Socket::AF_UNSPEC)
       prefix = $1
       family = Socket::AF_INET6
     end
+    if prefix =~ /\A(.*)(%\w+)\z/
+      prefix = $1
+      zone_id = $2
+      family = Socket::AF_INET6
+    end
     # It seems AI_NUMERICHOST doesn't do the job.
     #Socket.getaddrinfo(left, nil, Socket::AF_INET6, Socket::SOCK_STREAM, nil,
     #                  Socket::AI_NUMERICHOST)
@@ -575,6 +612,7 @@ def initialize(addr = '::', family = Socket::AF_UNSPEC)
       @addr = in6_addr(prefix)
       @family = Socket::AF_INET6
     end
+    @zone_id = zone_id
     if family != Socket::AF_UNSPEC && @family != family
       raise AddressFamilyError, "address family mismatch"
     end

test/test_ipaddr.rb

@@ -43,6 +43,17 @@ def test_s_new
     assert_equal("3ffe:0505:0002:0000:0000:0000:0000:0000", a.to_string)
     assert_equal(Socket::AF_INET6, a.family)
     assert_equal(48, a.prefix)
+    assert_nil(a.zone_id)
+
+    a = IPAddr.new("fe80::1%ab0")
+    assert_equal("fe80::1%ab0", a.to_s)
+    assert_equal("fe80:0000:0000:0000:0000:0000:0000:0001%ab0", a.to_string)
+    assert_equal(Socket::AF_INET6, a.family)
+    assert_equal(false, a.ipv4?)
+    assert_equal(true, a.ipv6?)
+    assert_equal("#<IPAddr: IPv6:fe80:0000:0000:0000:0000:0000:0000:0001%ab0/ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff>", a.inspect)
+    assert_equal(128, a.prefix)
+    assert_equal('%ab0', a.zone_id)
 
     a = IPAddr.new("0.0.0.0")
     assert_equal("0.0.0.0", a.to_s)
@@ -87,7 +98,8 @@ def test_s_new
 
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.256") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.011") }
-    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("fe80::1%fxp0") }
+    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("fe80::1%") }
+    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("fe80::1%]") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("[192.168.1.2]/120") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("[2001:200:300::]\nINVALID") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.1/32\nINVALID") }
@@ -208,6 +220,18 @@ def test_netmask
     a = IPAddr.new("192.168.1.2/24")
     assert_equal(a.netmask, "255.255.255.0")
   end
+
+  def test_zone_id
+    a = IPAddr.new("192.168.1.2")
+    assert_raise(IPAddr::InvalidAddressError) { a.zone_id = '%ab0' }
+    assert_raise(IPAddr::InvalidAddressError) { a.zone_id }
+
+    a = IPAddr.new("1:2:3:4:5:6:7:8")
+    a.zone_id = '%ab0'
+    assert_equal('%ab0', a.zone_id)
+    assert_equal("1:2:3:4:5:6:7:8%ab0", a.to_s)
+    assert_raise(IPAddr::InvalidAddressError) { a.zone_id = '%' }
+  end
 end
 
 class TC_Operator < Test::Unit::TestCase