1# dt_fd_forward 2 3dt_fd_forward is a jdwpTransport library. It implements the [Java Debug Wire 4Protocol Transport Interface 5(jdwpTransport)](https://docs.oracle.com/javase/7/docs/technotes/guides/jpda/jdwpTransport.html). 6It allows one to handle and proxy JDWP traffic by supplying the implementation 7for Attach. This transport requires an address. The address is a single integer 8value that is the file-descriptor of an open AF\_UNIX socket. 9 10When this transport begins listening or attaching it will send the 11null-terminated string "dt_fd_forward:START-LISTEN\0" over the given socket. 12 13When this transport stops listening for connections it will send the 14null-terminated string "dt_fd_forward:END-LISTEN\0" over the socket. 15 16When this transport has successfully received fds from the proxy it sends the 17message "dt_fd_forward:ATTACHED\0" over the socket. 18 19When this transport has closed its copies of the fds it will send the proxy the 20message "dt_fd_forward:CLOSING\0" over the socket. 21 22When this transport accepts or attaches to a connection it will read from the 23socket a 1 byte message and 3 file-descriptors. The file descriptors are, in 24order, an fd that will be read from to get incoming JDWP packets (read\_fd\_), 25an fd that outgoing JDWP packets will be written to (write\_fd\_), and an 26_eventfd_ (write\_lock\_fd\_). The eventfd should not have any flags set. Prior 27to writing any data to write\_fd\_ the transport will _read_ from the 28write\_lock\_fd\_ and after finishing the write it will _write_ to it. This 29allows one to safely multiplex data on the write\_fd\_. 30 31This transport implements no optional capabilities, though this may change in 32the future. 33