NAME

       knet_handle_add_datafd - Install a file descriptor for communication.

SYNOPSIS

       #include <libknet.h>

       int knet_handle_add_datafd(
           knet_handle_t knet_h,
           int          *datafd,
           int8_t       *channel
       );

DESCRIPTION

       knet_handle_add_datafd

       IMPORTANT: In order to add datafd to knet, knet_handle_enable_sock_notify

       MUST  be  set  and  be  able  to handle both errors (-1) and 0 bytes read / write from the
       provided datafd. On read error (< 0) from datafd, the socket is automatically removed from
       polling  to  avoid  spinning on dead sockets. It is safe to call knet_handle_remove_datafd
       even on sockets that have been removed.

       knet_h - pointer to knet_handle_t

       *datafd - read/write file descriptor. knet will read data here to send to the other  hosts
       and  will  write  data  received  from  the  network.  Each data packet can be of max size
       KNET_MAX_PACKET_SIZE! Applications using knet_send/knet_recv will receive a  proper  error
       if  the  packet  size  is not within boundaries. Applications using their own functions to
       write to the datafd should NOT write more than KNET_MAX_PACKET_SIZE.

       Please refer to handle.c on how to set up a socketpair.

       datafd can be 0, and knet_handle_add_datafd will create a properly populated  socket  pair
       the  same  way  as  ping_test,  or a value higher than 0. A negative number will return an
       error. On exit knet_handle_free will take care to cleanup the socketpair only if they have
       been created by knet_handle_add_datafd.

       It  is  possible to pass either sockets or normal fds. User provided datafd will be marked
       as non-blocking and close-on-exit.

       *channel - This value has the same effect of VLAN tagging. A  negative  value  will  auto-
       allocate  a  channel.  Setting a value between 0 and 31 will try to allocate that specific
       channel (unless already in use).

       It is possible to add up to 32 datafds but be aware that each one  of  them  must  have  a
       receiving end on the other host.

       Example: hostA channel 0 will be delivered to datafd on hostB channel 0 hostA channel 1 to
       hostB channel 1.

       Each channel must have a unique file descriptor.

       If your application could have 2 channels on one host and one  channel  on  another  host,
       then you can use dst_host_filter to manipulate channel values on TX and RX.

RETURN VALUE

       knet_handle_add_datafd  returns  0           on  success, *datafd will be populated with a
       socket if the original value was 0 or if a specific fd was set, the  value  is  untouched.
       *channel will be populated with a channel number if the original value was negative or the
       value is untouched if a specific channel was requested.

       -1         on error and errno is set. *datafd and *channel are untouched or empty.

SEE ALSO

       knet_handle_remove_datafd(3), knet_handle_get_stats(3), knet_host_add(3),
       knet_handle_pmtud_setfreq(3), knet_handle_pmtud_get(3), knet_host_get_id_by_host_name(3),
       knet_host_get_status(3), knet_link_get_pong_count(3), knet_link_get_priority(3),
       knet_handle_free(3), knet_handle_enable_sock_notify(3), knet_handle_get_datafd(3),
       knet_recv(3), knet_link_get_ping_timers(3), knet_log_get_subsystem_id(3),
       knet_host_remove(3), knet_host_enable_status_change_notify(3), knet_strtoaddr(3),
       knet_send(3), knet_handle_enable_pmtud_notify(3),
       knet_handle_get_transport_reconnect_interval(3), knet_link_get_enable(3),
       knet_link_set_priority(3), knet_log_set_loglevel(3), knet_handle_get_channel(3),
       knet_link_get_config(3), knet_link_get_link_list(3), knet_get_transport_list(3),
       knet_get_transport_id_by_name(3), knet_log_get_loglevel_id(3), knet_handle_new_ex(3),
       knet_host_set_name(3), knet_addrtostr(3), knet_handle_setfwd(3),
       knet_get_compress_list(3), knet_host_set_policy(3), knet_get_transport_name_by_id(3),
       knet_handle_enable_filter(3), knet_handle_compress(3), knet_link_get_status(3),
       knet_send_sync(3), knet_log_get_loglevel_name(3), knet_host_get_host_list(3),
       knet_host_get_policy(3), knet_link_set_enable(3), knet_link_set_pong_count(3),
       knet_log_get_subsystem_name(3), knet_host_get_name_by_host_id(3),
       knet_link_clear_config(3), knet_log_get_loglevel(3), knet_handle_new(3),
       knet_handle_pmtud_getfreq(3), knet_handle_clear_stats(3), knet_link_set_config(3),
       knet_handle_crypto(3), knet_get_crypto_list(3),
       knet_handle_set_transport_reconnect_interval(3), knet_link_set_ping_timers(3)

COPYRIGHT

       Copyright (C) 2010-2018 Red Hat, Inc. All rights reserved.