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Annotation of src/usr.bin/ssh/nchan.h, Revision 1.2

1.2     ! markus      1: /* RCSID("$Id: servconf.h,v 1.9 1999/10/12 18:11:54 markus Exp $"); */
        !             2:
1.1       markus      3: #ifndef NCHAN_H
                      4: #define NCHAN_H
                      5:
                      6: /*
1.2     ! markus      7:  * SSH Protocol 1.5 aka New Channel Protocol
        !             8:  * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored.
        !             9:  * Written by Markus Friedl in October 1999
        !            10:  *
        !            11:  * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the
        !            12:  * tear down of channels:
        !            13:  *
        !            14:  * 1.3:        strict request-ack-protocol:
        !            15:  *     CLOSE   ->
        !            16:  *             <-  CLOSE_CONFIRM
        !            17:  *
        !            18:  * 1.5:        uses variations of:
        !            19:  *     IEOF    ->
        !            20:  *             <-  OCLOSE
        !            21:  *             <-  IEOF
        !            22:  *     OCLOSE  ->
        !            23:  *     i.e. both sides have to close the channel
        !            24:  *
        !            25:  * See the debugging output from 'ssh -v' and 'sshd -d' of
        !            26:  * ssh-1.2.27 as an example.
        !            27:  *
        !            28:  * Details: (for Channel data structure see channels.h)
        !            29:  *
        !            30:  * - the output_buffer gets data received from the remote peer and
        !            31:  *   is written to the socket,
        !            32:  * - the input_buffer gets data from the socket and is sent to remote peer.
        !            33:  * - the socket represents the local object communicating with an object
        !            34:  *   reachable via the peer
        !            35:  *
        !            36:  *     PEER A                                  PEER B
        !            37:  *
        !            38:  * read(sock, input_buffer) < 0;
        !            39:  * shutdown_read();
        !            40:  * flush(input_buffer) =: DATA
        !            41:  * send(DATA)                  ->      rcvd(DATA)
        !            42:  *                                     write(sock, output_buffer:=DATA);
        !            43:  * send(IEOF)                  ->      rcvd(IEOF)
        !            44:  *                                     shutdown_write() if:
        !            45:  *                                             a) write fails
        !            46:  *                                             b) rcvd_IEOF==true &&
        !            47:  *                                                output_buffer==empty
        !            48:  * rcvd(OCLOSE)                        <-      send(OCLOSE)
        !            49:  *
        !            50:  * The channel is now half closed. No data will flow from A to B.
        !            51:  *
        !            52:  * Note that each side can remove the channel only if 2 messages
        !            53:  * have been sent and received and the associated socket has been
        !            54:  * shutdown, see below:
        !            55:  */
1.1       markus     56:
                     57: enum {
                     58:        /* ssh-proto-1.5 overloads message-types */
1.2     ! markus     59:        CHAN_IEOF   = SSH_MSG_CHANNEL_CLOSE,
        !            60:                        /* there will be no more data from sender */
        !            61:        CHAN_OCLOSE = SSH_MSG_CHANNEL_CLOSE_CONFIRMATION,
        !            62:                        /* all received data has been written to the socket */
1.1       markus     63:
                     64:        /* channel close flags */
1.2     ! markus     65:        CHAN_IEOF_SENT          = 0x01,
        !            66:        CHAN_IEOF_RCVD          = 0x02,
1.1       markus     67:        CHAN_OCLOSE_SENT        = 0x04,
                     68:        CHAN_OCLOSE_RCVD        = 0x08,
                     69:        CHAN_SHUT_RD            = 0x10,
1.2     ! markus     70:        CHAN_SHUT_WR            = 0x20,
1.1       markus     71:
                     72:        /* a channel can be removed if ALL the following flags are set: */
                     73:        CHAN_CLOSED             = CHAN_IEOF_SENT | CHAN_IEOF_RCVD |
                     74:                                  CHAN_OCLOSE_SENT | CHAN_OCLOSE_RCVD |
                     75:                                  CHAN_SHUT_RD | CHAN_SHUT_WR
                     76: };
                     77:
                     78: void chan_del_if_dead(Channel *c);
                     79: void chan_rcvd_ieof(Channel *c);
                     80: void chan_rcvd_oclose(Channel *c);
                     81: void chan_send_ieof(Channel *c);
                     82: void chan_send_oclose(Channel *c);
                     83: void chan_shutdown_read(Channel *c);
                     84: void chan_shutdown_write(Channel *c);
                     85: #endif