Sockets refactor: allow any family/type/protocol association

Refactor:

- Socket is now enough to create, configure and use any kind of socket
  association of family, type and protocol is also possible, as long
  as it's supported by the underlying OS implementation.
- The TCPSocket, TCPServer, UDPSocket, UNIXSocket and UNIXServer
  classes are merely sugar to avoid having to deal with socket details.
- UNIXSocket and UNIXServer can now be used in DGRAM type, in addition
  to the default STREAM type.

Features:

- Adds Socket::Server type, included by both TCPServer and UNIXServer.
- Adds Addrinfo DNS resolver, that wraps results from `getaddrinfo`.

Breaking Changes:

- IPAddress now automatically detects the address family, so the
  argument was removed (limited impact).

spec/std/socket_spec.cr

@@ -4,7 +4,7 @@ require "socket"
 describe Socket do
   # Tests from libc-test:
   # http://repo.or.cz/libc-test.git/blob/master:/src/functional/inet_pton.c
-  assert "ip?" do
+  it ".ip?" do
     # dotted-decimal notation
     Socket.ip?("0.0.0.0").should be_true
     Socket.ip?("127.0.0.1").should be_true
@@ -65,29 +65,46 @@ describe Socket do
 end
 
 describe Socket::IPAddress do
-  it "transforms an IPv4 address into a C struct and back again" do
-    addr1 = Socket::IPAddress.new(Socket::Family::INET, "127.0.0.1", 8080.to_i16)
-    addr2 = Socket::IPAddress.new(addr1.sockaddr, addr1.addrlen)
-
-    addr1.family.should eq(addr2.family)
-    addr1.port.should eq(addr2.port)
-    addr1.address.should eq(addr2.address)
-    addr1.to_s.should eq("127.0.0.1:8080")
+  it "transforms an IPv4 address into a C struct and back" do
+    addr1 = Socket::IPAddress.new("127.0.0.1", 8080)
+    addr2 = Socket::IPAddress.from(addr1.to_unsafe, addr1.size)
+
+    addr2.family.should eq(addr1.family)
+    addr2.port.should eq(addr1.port)
+    addr2.address.should eq(addr1.address)
   end
 
-  it "transforms an IPv6 address into a C struct and back again" do
-    addr1 = Socket::IPAddress.new(Socket::Family::INET6, "2001:db8:8714:3a90::12", 8080.to_i16)
-    addr2 = Socket::IPAddress.new(addr1.sockaddr, addr1.addrlen)
+  it "transforms an IPv6 address into a C struct and back" do
+    addr1 = Socket::IPAddress.new("2001:db8:8714:3a90::12", 8080)
+    addr2 = Socket::IPAddress.from(addr1.to_unsafe, addr1.size)
+
+    addr2.family.should eq(addr1.family)
+    addr2.port.should eq(addr1.port)
+    addr2.address.should eq(addr1.address)
+  end
 
-    addr1.family.should eq(addr2.family)
-    addr1.port.should eq(addr2.port)
-    addr1.address.should eq(addr2.address)
-    addr1.to_s.should eq("2001:db8:8714:3a90::12:8080")
+  it "to_s" do
+    Socket::IPAddress.new("127.0.0.1", 80).to_s.should eq("127.0.0.1:80")
+    Socket::IPAddress.new("2001:db8:8714:3a90::12", 443).to_s.should eq("[2001:db8:8714:3a90::12]:443")
   end
 end
 
 describe Socket::UNIXAddress do
-  it "does to_s" do
+  it "transforms into a C struct and back" do
+    addr1 = Socket::UNIXAddress.new("/tmp/service.sock")
+    addr2 = Socket::UNIXAddress.from(addr1.to_unsafe, addr1.size)
+
+    addr2.family.should eq(addr1.family)
+    addr2.path.should eq(addr1.path)
+    addr2.to_s.should eq("/tmp/service.sock")
+  end
+
+  it "raises when path is too long" do
+    path = "/tmp/crystal-test-too-long-unix-socket-#{("a" * 2048)}.sock"
+    expect_raises(ArgumentError, "Path size exceeds the maximum size") { Socket::UNIXAddress.new(path) }
+  end
+
+  it "to_s" do
     Socket::UNIXAddress.new("some_path").to_s.should eq("some_path")
   end
 end
@@ -211,8 +228,6 @@ describe UNIXSocket do
         client.local_address.path.should eq(path)
 
         server.accept do |sock|
-          sock.sync?.should eq(server.sync?)
-
           sock.local_address.family.should eq(Socket::Family::UNIX)
           sock.local_address.path.should eq("")
 
@@ -225,8 +240,19 @@ describe UNIXSocket do
           client.gets(4).should eq("pong")
         end
       end
+    end
+  end
+
+  it "sync flag after accept" do
+    path = "/tmp/crystal-test-unix-sock"
+
+    UNIXServer.open(path) do |server|
+      UNIXSocket.open(path) do |client|
+        server.accept do |sock|
+          sock.sync?.should eq(server.sync?)
+        end
+      end
 
-      # test sync flag propagation after accept
       server.sync = !server.sync?
 
       UNIXSocket.open(path) do |client|
@@ -244,6 +270,7 @@ describe UNIXSocket do
 
       left << "ping"
       right.gets(4).should eq("ping")
+
       right << "pong"
       left.gets(4).should eq("pong")
     end
@@ -382,31 +409,25 @@ describe TCPSocket do
   end
 
   it "fails when host doesn't exist" do
-    expect_raises(Socket::Error, /^getaddrinfo: (.+ not known|no address .+|Non-recoverable failure in name resolution|Name does not resolve)$/i) do
+    expect_raises(Socket::Error, /No address found for localhostttttt:12345/) do
       TCPSocket.new("localhostttttt", 12345)
     end
   end
 end
 
 describe UDPSocket do
-  it "sends and receives messages by reading and writing" do
+  it "reads and writes data to server" do
     port = free_udp_socket_port
 
     server = UDPSocket.new(Socket::Family::INET6)
     server.bind("::", port)
-
-    server.local_address.family.should eq(Socket::Family::INET6)
-    server.local_address.port.should eq(port)
-    server.local_address.address.should eq("::")
+    server.local_address.should eq(Socket::IPAddress.new("::", port))
 
     client = UDPSocket.new(Socket::Family::INET6)
     client.connect("::1", port)
-
     client.local_address.family.should eq(Socket::Family::INET6)
     client.local_address.address.should eq("::1")
-    client.remote_address.family.should eq(Socket::Family::INET6)
-    client.remote_address.port.should eq(port)
-    client.remote_address.address.should eq("::1")
+    client.remote_address.should eq(Socket::IPAddress.new("::1", port))
 
     client << "message"
     server.gets(7).should eq("message")
@@ -415,51 +436,62 @@ describe UDPSocket do
     server.close
   end
 
-  it "sends and receives messages by send and receive over IPv4" do
+  it "sends and receives messages over IPv4" do
+    buffer = uninitialized UInt8[256]
+
     server = UDPSocket.new(Socket::Family::INET)
     server.bind("127.0.0.1", 0)
 
     client = UDPSocket.new(Socket::Family::INET)
-
-    buffer = uninitialized UInt8[256]
-
     client.send("message equal to buffer", server.local_address)
-    bytes_read, addr1 = server.receive(buffer.to_slice[0, 23])
-    message1 = String.new(buffer.to_slice[0, bytes_read])
-    message1.should eq("message equal to buffer")
-    addr1.family.should eq(server.local_address.family)
-    addr1.address.should eq(server.local_address.address)
+
+    bytes_read, client_addr = server.receive(buffer.to_slice[0, 23])
+    message = String.new(buffer.to_slice[0, bytes_read])
+    message.should eq("message equal to buffer")
+    client_addr.should eq(Socket::IPAddress.new("127.0.0.1", client.local_address.port))
 
     client.send("message less than buffer", server.local_address)
-    bytes_read, addr2 = server.receive(buffer.to_slice)
-    message2 = String.new(buffer.to_slice[0, bytes_read])
-    message2.should eq("message less than buffer")
-    addr2.family.should eq(server.local_address.family)
-    addr2.address.should eq(server.local_address.address)
+
+    bytes_read, client_addr = server.receive(buffer.to_slice)
+    message = String.new(buffer.to_slice[0, bytes_read])
+    message.should eq("message less than buffer")
+
+    client.connect server.local_address
+    client.send "ip4 message"
+
+    message, client_addr = server.receive
+    message.should eq("ip4 message")
+    client_addr.should eq(Socket::IPAddress.new("127.0.0.1", client.local_address.port))
 
     server.close
     client.close
   end
 
-  it "sends and receives messages by send and receive over IPv6" do
+  it "sends and receives messages over IPv6" do
+    buffer = uninitialized UInt8[1500]
+
     server = UDPSocket.new(Socket::Family::INET6)
     server.bind("::1", 0)
 
     client = UDPSocket.new(Socket::Family::INET6)
+    client.send("some message", server.local_address)
 
-    buffer = uninitialized UInt8[1500]
+    bytes_read, client_addr = server.receive(buffer.to_slice)
+    String.new(buffer.to_slice[0, bytes_read]).should eq("some message")
+    client_addr.should eq(Socket::IPAddress.new("::1", client.local_address.port))
+
+    client.connect server.local_address
+    client.send "ip6 message"
 
-    client.send("message", server.local_address)
-    bytes_read, addr = server.receive(buffer.to_slice)
-    String.new(buffer.to_slice[0, bytes_read]).should eq("message")
-    addr.family.should eq(server.local_address.family)
-    addr.address.should eq(server.local_address.address)
+    message, client_addr = server.receive(20)
+    message.should eq("ip6 message")
+    client_addr.should eq(Socket::IPAddress.new("::1", client.local_address.port))
 
     server.close
     client.close
   end
 
-  it "broadcast messages" do
+  it "broadcasts messages" do
     port = free_udp_socket_port
 
     client = UDPSocket.new(Socket::Family::INET)

src/errno.cr

@@ -212,8 +212,7 @@ class Errno < Exception
   #   raise Errno.new("some_call")
   # end
   # ```
-  def initialize(message)
-    errno = Errno.value
+  def initialize(message, errno = Errno.value)
     @errno = errno
     super "#{message}: #{String.new(LibC.strerror(errno))}"
   end

src/lib_c/amd64-unknown-openbsd/c/sys/socket.cr

@@ -36,6 +36,14 @@ lib LibC
     sa_data : StaticArray(Char, 14)
   end
 
+  struct SockaddrStorage
+    ss_len : UChar
+    ss_family : SaFamilyT
+    __ss_pad1 : StaticArray(Char, 6)
+    __ss_pad2 : ULongLong
+    __ss_pad3 : StaticArray(Char, 240)
+  end
+
   struct Linger
     l_onoff : Int
     l_linger : Int

src/lib_c/i686-linux-gnu/c/netdb.cr

@@ -3,6 +3,24 @@ require "./sys/socket"
 require "./stdint"
 
 lib LibC
+  AI_PASSIVE     = 0x0001
+  AI_CANONNAME   = 0x0002
+  AI_NUMERICHOST = 0x0004
+  AI_NUMERICSERV = 0x0400
+  AI_V4MAPPED    = 0x0008
+  AI_ALL         = 0x0010
+  AI_ADDRCONFIG  = 0x0020
+  EAI_AGAIN      =     -3
+  EAI_BADFLAGS   =     -1
+  EAI_FAIL       =     -4
+  EAI_FAMILY     =     -6
+  EAI_MEMORY     =    -10
+  EAI_NONAME     =     -2
+  EAI_SERVICE    =     -8
+  EAI_SOCKTYPE   =     -7
+  EAI_SYSTEM     =    -11
+  EAI_OVERFLOW   =    -12
+
   struct Addrinfo
     ai_flags : Int
     ai_family : Int
@@ -14,7 +32,8 @@ lib LibC
     ai_next : Addrinfo*
   end
 
+  fun freeaddrinfo(ai : Addrinfo*) : Void
   fun gai_strerror(ecode : Int) : Char*
-  fun getaddrinfo(hostname : Char*, servname : Char*, hints : Addrinfo*, res : Addrinfo**) : Int
-  fun freeaddrinfo(ai : Addrinfo*)
+  fun getaddrinfo(name : Char*, service : Char*, req : Addrinfo*, pai : Addrinfo**) : Int
+  fun getnameinfo(sa : Sockaddr*, salen : SocklenT, host : Char*, hostlen : SocklenT, serv : Char*, servlen : SocklenT, flags : Int) : Int
 end

src/lib_c/i686-linux-gnu/c/sys/socket.cr

@@ -35,6 +35,12 @@ lib LibC
     sa_data : StaticArray(Char, 14)
   end
 
+  struct SockaddrStorage
+    ss_family : SaFamilyT
+    __ss_align : ULong
+    __ss_padding : StaticArray(Char, 120)
+  end
+
   struct Linger
     l_onoff : Int
     l_linger : Int
@@ -47,10 +53,10 @@ lib LibC
   fun getsockname(fd : Int, addr : Sockaddr*, len : SocklenT*) : Int
   fun getsockopt(fd : Int, level : Int, optname : Int, optval : Void*, optlen : SocklenT*) : Int
   fun listen(fd : Int, n : Int) : Int
-  fun recv(fd : Int, buf : Void*, n : SizeT, flags : Int) : SSizeT
-  fun recvfrom(fd : Int, buf : Void*, n : SizeT, flags : Int, addr : Sockaddr*, addr_len : SocklenT*) : SSizeT
-  fun send(fd : Int, buf : Void*, n : SizeT, flags : Int) : SSizeT
-  fun sendto(fd : Int, buf : Void*, n : SizeT, flags : Int, addr : Sockaddr*, addr_len : SocklenT) : SSizeT
+  fun recv(fd : Int, buf : Void*, n : Int, flags : Int) : SSizeT
+  fun recvfrom(fd : Int, buf : Void*, n : Int, flags : Int, addr : Sockaddr*, addr_len : SocklenT*) : SSizeT
+  fun send(fd : Int, buf : Void*, n : Int, flags : Int) : SSizeT
+  fun sendto(fd : Int, buf : Void*, n : Int, flags : Int, addr : Sockaddr*, addr_len : SocklenT) : SSizeT
   fun setsockopt(fd : Int, level : Int, optname : Int, optval : Void*, optlen : SocklenT) : Int
   fun shutdown(fd : Int, how : Int) : Int
   fun socket(domain : Int, type : Int, protocol : Int) : Int

src/lib_c/i686-linux-musl/c/netdb.cr

@@ -3,6 +3,24 @@ require "./sys/socket"
 require "./stdint"
 
 lib LibC
+  AI_PASSIVE     =  0x01
+  AI_CANONNAME   =  0x02
+  AI_NUMERICHOST =  0x04
+  AI_NUMERICSERV = 0x400
+  AI_V4MAPPED    =  0x08
+  AI_ALL         =  0x10
+  AI_ADDRCONFIG  =  0x20
+  EAI_AGAIN      =    -3
+  EAI_BADFLAGS   =    -1
+  EAI_FAIL       =    -4
+  EAI_FAMILY     =    -6
+  EAI_MEMORY     =   -10
+  EAI_NONAME     =    -2
+  EAI_SERVICE    =    -8
+  EAI_SOCKTYPE   =    -7
+  EAI_SYSTEM     =   -11
+  EAI_OVERFLOW   =   -12
+
   struct Addrinfo
     ai_flags : Int
     ai_family : Int
@@ -14,7 +32,8 @@ lib LibC
     ai_next : Addrinfo*
   end
 
+  fun freeaddrinfo(x0 : Addrinfo*) : Void
   fun gai_strerror(x0 : Int) : Char*
-  fun getaddrinfo(hostname : Char*, servname : Char*, hints : Addrinfo*, res : Addrinfo**) : Int
-  fun freeaddrinfo(ai : Addrinfo*)
+  fun getaddrinfo(x0 : Char*, x1 : Char*, x2 : Addrinfo*, x3 : Addrinfo**) : Int
+  fun getnameinfo(x0 : Sockaddr*, x1 : SocklenT, x2 : Char*, x3 : SocklenT, x4 : Char*, x5 : SocklenT, x6 : Int) : Int
 end

src/lib_c/i686-linux-musl/c/sys/socket.cr

@@ -35,6 +35,12 @@ lib LibC
     sa_data : StaticArray(Char, 14)
   end
 
+  struct SockaddrStorage
+    ss_family : SaFamilyT
+    __ss_align : ULong
+    __ss_padding : StaticArray(Char, 112)
+  end
+
   struct Linger
     l_onoff : Int
     l_linger : Int