stdlib_libraries/socket_recvmsg_no_parens.rb

tests/_examples/stdlib_libraries/socket_recvmsg_no_parens.rb in the metorex repository.

# recvmsg answers a message, where it came from, and the flags it arrived
# with. A datagram names the socket that sent it, and a message read off a
# connection names no address at all.
require "socket"

server = Socket.new(:INET, :DGRAM)
server.bind(Socket.sockaddr_in(0, "127.0.0.1"))
client = Socket.new(:INET, :DGRAM)
client.connect(server.getsockname)
client.write "hello"
message, from, flags = server.recvmsg
p [message, from.ip_address, from.ip_port == client.local_address.ip_port, flags]
client.write "truncated"
p server.recvmsg(2)[0]
p server.recvmsg_nonblock(exception: false)

listener = Socket.new(:INET, :STREAM)
listener.bind(Socket.sockaddr_in(0, "127.0.0.1"))
listener.listen(1)
caller = Socket.new(:INET, :STREAM)
caller.connect(listener.getsockname)
caller.write "over a connection"
accepted, = listener.accept
read, empty, = accepted.recvmsg
p [read, empty.inspect, empty.afamily, empty.pfamily]
begin
  Socket.new(:INET, :STREAM).recvmsg_nonblock
rescue SystemCallError => error
  p error.class
end
caller.close
p accepted.recvmsg

Output:

["hello", "127.0.0.1", true, 0]
"tr"
:wait_readable
["over a connection", "#<Addrinfo: empty-sockaddr SOCK_STREAM>", 0, 0]
Errno::ENOTCONN
nil