Add IDNA support and integrate with DNS lookup

spec/std/uri/punycode_spec.cr

@@ -0,0 +1,29 @@
+require "spec"
+require "uri/punycode"
+
+describe URI::Punycode do
+  [
+    {"3年B組金八先生", "3B-ww4c5e180e575a65lsy2b"},
+    {"安室奈美恵-with-SUPER-MONKEYS", "-with-SUPER-MONKEYS-pc58ag80a8qai00g7n9n"},
+    {"Hello-Another-Way-それぞれの場所", "Hello-Another-Way--fc4qua05auwb3674vfr0b"},
+    {"ひとつ屋根の下2", "2-u9tlzr9756bt3uc0v"},
+    {"MajiでKoiする5秒前", "MajiKoi5-783gue6qz075azm5e"},
+    {"パフィーdeルンバ", "de-jg4avhby1noc0d"},
+    {"そのスピードで", "d9juau41awczczp"},
+    {"Hello-Another-Way-それぞれ", "Hello-Another-Way--fc4qua97gba"},
+  ].each do |example|
+    dec, enc = example
+
+    it "encodes #{dec} to #{enc}" do
+      URI::Punycode.encode(dec).should eq enc
+    end
+
+    it "decodes #{enc} to #{dec}" do
+      URI::Punycode.decode(enc).should eq dec
+    end
+  end
+
+  it "translate to ascii only host name" do
+    URI::Punycode.to_ascii("test.テスト.テスト").should eq "test.xn--zckzah.xn--zckzah"
+  end
+end

src/socket/addrinfo.cr

@@ -1,3 +1,5 @@
+require "uri/punycode"
+
 class Socket
   # Domain name resolver.
   struct Addrinfo
@@ -76,6 +78,12 @@ class Socket
     end
 
     private def self.getaddrinfo(domain, service, family, type, protocol, timeout)
+      # RFC 3986 says:
+      # > When a non-ASCII registered name represents an internationalized domain name
+      # > intended for resolution via the DNS, the name must be transformed to the IDNA
+      # > encoding [RFC3490] prior to name lookup.
+      domain = URI::Punycode.to_ascii domain
+
       hints = LibC::Addrinfo.new
       hints.ai_family = (family || Family::UNSPEC).to_i32
       hints.ai_socktype = type

src/uri/punycode.cr

@@ -0,0 +1,173 @@
+# `Punycode` provides an interface for IDNA encoding (RFC 5980),
+# which is defined in RFC 3493
+#
+# Implementation based on Mathias Bynens `punnycode.js` project
+# https://github.com/bestiejs/punycode.js/
+#
+# RFC 3492:
+# Method to use non-ascii characters as host name of URI
+# https://www.ietf.org/rfc/rfc3492.txt
+#
+# RFC 5980:
+# Internationalized Domain Names in Application
+# https://www.ietf.org/rfc/rfc5980.txt
+class URI
+  class Punycode
+    private BASE         =  36
+    private TMIN         =   1
+    private TMAX         =  26
+    private SKEW         =  38
+    private DAMP         = 700
+    private INITIAL_BIAS =  72
+    private INITIAL_N    = 128
+
+    private DELIMITER = '-'
+
+    private BASE36 = "abcdefghijklmnopqrstuvwxyz0123456789"
+
+    private def self.adapt(delta, numpoints, firsttime)
+      delta /= firsttime ? DAMP : 2
+      delta += delta / numpoints
+      k = 0
+      while delta > ((BASE - TMIN) * TMAX) / 2
+        delta /= BASE - TMIN
+        k += BASE
+      end
+      k + (((BASE - TMIN + 1) * delta) / (delta + SKEW))
+    end
+
+    def self.encode(string)
+      String.build { |io| encode string, io }
+    end
+
+    def self.encode(string, io)
+      others = [] of Char
+
+      string.each_char do |c|
+        if c < '\u0080'
+          io << c
+        else
+          others.push c
+        end
+      end
+
+      return if others.empty?
+      others.sort!
+
+      h = string.size - others.size + 1
+      delta = 0_u32
+      n = INITIAL_N
+      bias = INITIAL_BIAS
+      firsttime = true
+      prev = nil
+
+      io << DELIMITER if h > 1
+
+      others.each do |m|
+        next if m == prev
+        prev = m
+
+        raise Exception.new("Overflow: input needs wider integers to process") if m.ord - n > (Int32::MAX - delta) / h
+        delta += (m.ord - n) * h
+        n = m.ord + 1
+
+        string.each_char do |c|
+          if c < m
+            raise Exception.new("Overflow: input needs wider integers to process") if delta > Int32::MAX - 1
+            delta += 1
+          elsif c == m
+            q = delta
+            k = BASE
+            loop do
+              t = k <= bias ? TMIN : k >= bias + TMAX ? TMAX : k - bias
+              break if q < t
+              io << BASE36[t + ((q - t) % (BASE - t))]
+              q = (q - t) / (BASE - t)
+              k += BASE
+            end
+            io << BASE36[q]
+
+            bias = adapt delta, h, firsttime
+            delta = 0
+            h += 1
+            firsttime = false
+          end
+        end
+        delta += 1
+      end
+    end
+
+    def self.decode(string)
+      output, _, rest = string.rpartition(DELIMITER)
+      output = output.chars
+
+      n = INITIAL_N
+      bias = INITIAL_BIAS
+      i = 0
+      init = true
+      w = oldi = k = 0
+
+      rest.each_char do |c|
+        if init
+          w = 1
+          oldi = i
+          k = BASE
+          init = false
+        end
+
+        digit = case c
+                when .ascii_lowercase?
+                  c.ord - 0x61
+                when .ascii_uppercase?
+                  c.ord - 0x41
+                when .ascii_number?
+                  c.ord - 0x30 + 26
+                else
+                  raise ArgumentError.new("Invalid input")
+                end
+
+        i += digit * w
+        t = k <= bias ? TMIN : k >= bias + TMAX ? TMAX : k - bias
+
+        unless digit < t
+          w *= BASE - t
+          k += BASE
+        else
+          outsize = output.size + 1
+          bias = adapt i - oldi, outsize, oldi == 0
+          n += i / outsize
+          i %= outsize
+          output.insert i, n.chr
+          i += 1
+          init = true
+        end
+      end
+
+      raise ArgumentError.new("Invalid input") unless init
+
+      output.join
+    end
+
+    def self.to_ascii(string)
+      return string if string.ascii_only?
+
+      String.build do |io|
+        first = true
+        string.split('.') do |part|
+          unless first
+            io << "."
+          end
+
+          if part.ascii_only?
+            io << part
+          else
+            io << "xn--"
+            encode part, io
+          end
+
+          first = false
+        end
+      end
+    end
+  end
+end