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-exec.

       *channel - This value is analogous to the tag in 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_handle_crypto_use_config(3), knet_host_get_id_by_host_name(3),
       knet_host_get_status(3), knet_link_add_acl(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_link_rm_acl(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_crypto_rx_clear_traffic(3), knet_handle_compress(3), knet_link_get_status(3),
       knet_send_sync(3), knet_log_get_loglevel_name(3), knet_handle_enable_access_lists(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_pmtud_set(3), knet_handle_clear_stats(3), knet_link_set_config(3),
       knet_handle_crypto_set_config(3), knet_handle_crypto(3), knet_get_crypto_list(3),
       knet_handle_set_transport_reconnect_interval(3), knet_link_clear_acl(3), knet_link_set_ping_timers(3),
       knet_link_insert_acl(3)

COPYRIGHT

       Copyright (C) 2010-2024 Red Hat, Inc. All rights reserved.

kronosnet                                          2024-06-06                          KNET_HANDLE_ADD_DATAFD(3)