Add IPSocket#ipv6_only (#16347)

stakach · web-flow · commit 92a1b2696da2 · 2025-11-16T12:42:54.000+01:00
diff --git a/spec/std/socket/tcp_server_spec.cr b/spec/std/socket/tcp_server_spec.cr
@@ -147,5 +147,37 @@ describe TCPServer, tags: "network" do
         end
       end
     end
+
+    it "supports IPv6 dual stack" do
+      server = TCPServer.new(:inet6)
+      server.ipv6_only = false
+      server.bind("::", 0)
+      server.listen
+
+      TCPSocket.open("127.0.0.1", server.local_address.port) do |client|
+        server.accept? do |sock|
+          sock.ipv6_only?.should be_false
+
+          # should raise when changing ipv6_only when not applicable
+          expect_raises(Socket::Error, /invalid argument/i) do
+            sock.ipv6_only = true
+          end
+        end
+      end
+
+      server.close
+    end
+
+    it "supports IPv6 only" do
+      server = TCPServer.new(:inet6)
+      server.ipv6_only = true
+      server.bind("::", 0)
+      server.listen
+
+      expect_raises(Socket::ConnectError) do
+        TCPSocket.new("127.0.0.1", server.local_address.port, connect_timeout: 1.second)
+      end
+      server.close
+    end
   end
 end
diff --git a/spec/std/socket/udp_socket_spec.cr b/spec/std/socket/udp_socket_spec.cr
@@ -18,6 +18,24 @@ describe UDPSocket, tags: "network" do
     socket.close
   end
 
+  it "supports IPv6 dual stack" do
+    socket = UDPSocket.new(:inet6)
+
+    socket.ipv6_only = false
+    socket.ipv6_only?.should be_false
+
+    socket.ipv6_only = true
+    socket.ipv6_only?.should be_true
+
+    socket = UDPSocket.new
+    expect_raises(Socket::Error, "Unsupported IP address family: INET. For use with IPv6 only") do
+      socket.ipv6_only?
+    end
+    expect_raises(Socket::Error, "Unsupported IP address family: INET. For use with IPv6 only") do
+      socket.ipv6_only = false
+    end
+  end
+
   each_ip_family do |family, address, unspecified_address|
     it "#bind" do
       port = unused_local_udp_port
diff --git a/src/lib_c/aarch64-android/c/netinet/in.cr b/src/lib_c/aarch64-android/c/netinet/in.cr
@@ -57,6 +57,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/aarch64-darwin/c/netinet/in.cr b/src/lib_c/aarch64-darwin/c/netinet/in.cr
@@ -58,6 +58,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 13
   IPV6_LEAVE_GROUP   = 13
 
+  IPV6_V6ONLY = 27
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/aarch64-linux-gnu/c/netinet/in.cr b/src/lib_c/aarch64-linux-gnu/c/netinet/in.cr
@@ -56,6 +56,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/aarch64-linux-musl/c/netinet/in.cr b/src/lib_c/aarch64-linux-musl/c/netinet/in.cr
@@ -56,6 +56,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/arm-linux-gnueabihf/c/netinet/in.cr b/src/lib_c/arm-linux-gnueabihf/c/netinet/in.cr
@@ -56,6 +56,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/i386-linux-gnu/c/netinet/in.cr b/src/lib_c/i386-linux-gnu/c/netinet/in.cr
@@ -56,6 +56,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/i386-linux-musl/c/netinet/in.cr b/src/lib_c/i386-linux-musl/c/netinet/in.cr
@@ -56,6 +56,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/wasm32-wasi/c/netinet/in.cr b/src/lib_c/wasm32-wasi/c/netinet/in.cr
@@ -49,6 +49,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-darwin/c/netinet/in.cr b/src/lib_c/x86_64-darwin/c/netinet/in.cr
@@ -58,6 +58,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 13
   IPV6_LEAVE_GROUP   = 13
 
+  IPV6_V6ONLY = 27
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-dragonfly/c/netinet/in.cr b/src/lib_c/x86_64-dragonfly/c/netinet/in.cr
@@ -58,6 +58,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 13
   IPV6_LEAVE_GROUP   = 13
 
+  IPV6_V6ONLY = 27
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-freebsd/c/netinet/in.cr b/src/lib_c/x86_64-freebsd/c/netinet/in.cr
@@ -58,6 +58,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 13
   IPV6_LEAVE_GROUP   = 13
 
+  IPV6_V6ONLY = 27
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-linux-gnu/c/netinet/in.cr b/src/lib_c/x86_64-linux-gnu/c/netinet/in.cr
@@ -56,6 +56,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-linux-musl/c/netinet/in.cr b/src/lib_c/x86_64-linux-musl/c/netinet/in.cr
@@ -56,6 +56,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 36
   IPV6_LEAVE_GROUP   = 21
 
+  IPV6_V6ONLY = 26
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-netbsd/c/netinet/in.cr b/src/lib_c/x86_64-netbsd/c/netinet/in.cr
@@ -58,6 +58,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 13
   IPV6_LEAVE_GROUP   = 13
 
+  IPV6_V6ONLY = 27
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-openbsd/c/netinet/in.cr b/src/lib_c/x86_64-openbsd/c/netinet/in.cr
@@ -58,6 +58,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 13
   IPV6_LEAVE_GROUP   = 13
 
+  IPV6_V6ONLY = 27
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-solaris/c/netinet/in.cr b/src/lib_c/x86_64-solaris/c/netinet/in.cr
@@ -58,6 +58,8 @@ lib LibC
   IP_DROP_MEMBERSHIP = 0x14
   IPV6_LEAVE_GROUP   =  0xa
 
+  IPV6_V6ONLY = 27
+
   struct IpMreq
     imr_multiaddr : InAddr
     imr_interface : InAddr
diff --git a/src/lib_c/x86_64-windows-msvc/c/ws2def.cr b/src/lib_c/x86_64-windows-msvc/c/ws2def.cr
@@ -134,6 +134,8 @@ lib LibC
   IPV6_DROP_MEMBERSHIP = 13
   IPV6_LEAVE_GROUP     = 13
 
+  IPV6_V6ONLY = 27
+
   enum IPPROTO
     IPPROTO_HOPOPTS  =   0 # IPv6 Hop-by-Hop options
     IPPROTO_ICMP     =   1
diff --git a/src/socket/ip_socket.cr b/src/socket/ip_socket.cr
@@ -26,4 +26,28 @@ class IPSocket < Socket
     @local_address = nil
     @remote_address = nil
   end
+
+  # Reports whether IPv4 packets are accepted by the socket.
+  def ipv6_only? : Bool
+    raise Socket::Error.new("Unsupported IP address family: #{family}. For use with IPv6 only") unless family.inet6?
+    getsockopt_bool(LibC::IPV6_V6ONLY, level: LibC::IPPROTO_IPV6)
+  end
+
+  # Sets whether an IPv6 socket will accept IPv4 clients / packets
+  #
+  # ```
+  # require "socket"
+  #
+  # server = UDPSocket.new(:inet6)
+  # # enable IPv6 dual stack, accepting IPv4 clients
+  # server.ipv6_only = false
+  # server.bind "::1", 1234
+  #
+  # message = Bytes.new(32)
+  # bytes_read, client_addr = server.receive(message)
+  # ```
+  def ipv6_only=(val : Bool) : Bool
+    raise Socket::Error.new("Unsupported IP address family: #{family}. For use with IPv6 only") unless family.inet6?
+    setsockopt_bool LibC::IPV6_V6ONLY, val, level: LibC::IPPROTO_IPV6
+  end
 end
