vlib/net: add buffered IO, x.net -> net (#6754)

vlib/net/errors.v

@@ -0,0 +1,59 @@
+module net
+
+// Well defined errors that are returned from socket functions
+const (
+	errors_base = 0
+	err_new_socket_failed = error_with_code('net: new_socket failed to create socket', errors_base+1)
+	err_option_not_settable = error_with_code('net: set_option_xxx option not settable', errors_base+2)
+	err_option_wrong_type = error_with_code('net: set_option_xxx option wrong type', errors_base+3)
+	err_port_out_of_range = error_with_code('', errors_base+5)
+	err_no_udp_remote = error_with_code('', errors_base+6)
+	err_connect_failed = error_with_code('net: connect failed', errors_base+7)
+	err_connect_timed_out = error_with_code('net: connect timed out', errors_base+8)
+
+	err_timed_out = error_with_code('net: op timed out', errors_base+9)
+	err_timed_out_code = errors_base+9
+)
+
+pub fn socket_error(potential_code int) ?int {
+	$if windows {
+		if potential_code < 0 {
+			last_error_int := C.WSAGetLastError()
+			last_error := wsa_error(last_error_int)
+			return error_with_code('net: socket error: ($last_error_int) $last_error', last_error)
+		}
+	}
+	$else {
+		if potential_code < 0 {
+			last_error := error_code()
+			return error_with_code('net: socket error: $last_error', last_error)
+		}
+	}
+
+	return potential_code
+}
+
+pub fn wrap_error(error_code int) ? {
+	$if windows {
+		enum_error := wsa_error(error_code)
+		return error_with_code('socket error: $enum_error', error_code)
+	}
+	$else {
+		if error_code == 0 {
+			return
+		}
+		return error_with_code('net: socket error: $error_code', error_code)
+	}
+}
+
+// wrap_read_result takes a read result and sees if it is 0 for graceful
+// connection termination and returns none
+// e.g. res := wrap_read_result(C.recv(c.sock.handle, buf_ptr, len, 0))?
+[inline]
+fn wrap_read_result(result int) ?int {
+	if result > 0 || result < 0 {
+		return result
+	}
+
+	return none
+}