1knet_handle_add_datafd(3)Kronosnet Programmer's Manualknet_handle_add_datafd(3)
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NAME

6       knet_handle_add_datafd - Install a file descriptor for communication.
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SYNOPSIS

9       #include <libknet.h>
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11       int knet_handle_add_datafd(
12           knet_handle_t  knet_h,
13           int           *datafd,
14           int8_t        *channel
15       );
16

DESCRIPTION

18       knet_handle_add_datafd
19
20       IMPORTANT:    In    order    to   add   datafd   to   knet,   knet_han‐
21       dle_enable_sock_notify
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23       MUST be set and be able to handle both errors (-1) and 0 bytes  read  /
24       write  from  the  provided datafd. On read error (< 0) from datafd, the
25       socket is automatically removed from polling to avoid spinning on  dead
26       sockets.  It  is safe to call knet_handle_remove_datafd even on sockets
27       that have been removed.
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29       knet_h - pointer to knet_handle_t
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31       *datafd - read/write file descriptor. knet will read data here to  send
32       to  the other hosts and will write data received from the network. Each
33       data packet can be of max size KNET_MAX_PACKET_SIZE! Applications using
34       knet_send/knet_recv  will  receive a proper error if the packet size is
35       not within boundaries. Applications using their own functions to  write
36       to the datafd should NOT write more than KNET_MAX_PACKET_SIZE.
37
38       Please refer to handle.c on how to set up a socketpair.
39
40       datafd can be 0, and knet_handle_add_datafd will create a properly pop‐
41       ulated socket pair the same way as ping_test, or a value higher than 0.
42       A  negative  number will return an error. On exit knet_handle_free will
43       take care to cleanup the socketpair only if they have been  created  by
44       knet_handle_add_datafd.
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46       It  is  possible  to  pass  either sockets or normal fds. User provided
47       datafd will be marked as non-blocking and close-on-exec.
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49       *channel - This value is analogous to the tag in VLAN tagging. A  nega‐
50       tive  value will auto-allocate a channel. Setting a value between 0 and
51       31 will try to allocate that specific channel (unless already in use).
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53       It is possible to add up to 32 datafds but be aware that  each  one  of
54       them must have a receiving end on the other host.
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56       Example: hostA channel 0 will be delivered to datafd on hostB channel 0
57       hostA channel 1 to hostB channel 1.
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59       Each channel must have a unique file descriptor.
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61       If your application could have 2 channels on one host and  one  channel
62       on another host, then you can use dst_host_filter to manipulate channel
63       values on TX and RX.
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RETURN VALUE

66       knet_handle_add_datafd returns 0          on success, *datafd  will  be
67       populated with a socket if the original value was 0 or if a specific fd
68       was set, the value is untouched. *channel  will  be  populated  with  a
69       channel  number  if  the  original  value  was negative or the value is
70       untouched if a specific channel was requested.
71
72       -1         on  error  and  errno  is  set.  *datafd  and  *channel  are
73       untouched or empty.
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SEE ALSO

76       knet_handle_remove_datafd(3), knet_handle_get_stats(3),
77       knet_host_add(3), knet_handle_pmtud_setfreq(3),
78       knet_handle_pmtud_get(3), knet_host_get_id_by_host_name(3),
79       knet_host_get_status(3), knet_link_get_pong_count(3),
80       knet_link_get_priority(3), knet_handle_free(3),
81       knet_handle_enable_sock_notify(3), knet_handle_get_datafd(3),
82       knet_recv(3), knet_link_get_ping_timers(3),
83       knet_log_get_subsystem_id(3), knet_host_remove(3),
84       knet_host_enable_status_change_notify(3), knet_strtoaddr(3),
85       knet_send(3), knet_handle_enable_pmtud_notify(3),
86       knet_handle_get_transport_reconnect_interval(3),
87       knet_link_get_enable(3), knet_link_set_priority(3),
88       knet_log_set_loglevel(3), knet_handle_get_channel(3),
89       knet_link_get_config(3), knet_link_get_link_list(3),
90       knet_get_transport_list(3), knet_get_transport_id_by_name(3),
91       knet_log_get_loglevel_id(3), knet_handle_new_ex(3),
92       knet_host_set_name(3), knet_addrtostr(3), knet_handle_setfwd(3),
93       knet_get_compress_list(3), knet_host_set_policy(3),
94       knet_get_transport_name_by_id(3), knet_handle_enable_filter(3),
95       knet_handle_compress(3), knet_link_get_status(3), knet_send_sync(3),
96       knet_log_get_loglevel_name(3), knet_host_get_host_list(3),
97       knet_host_get_policy(3), knet_link_set_enable(3),
98       knet_link_set_pong_count(3), knet_log_get_subsystem_name(3),
99       knet_host_get_name_by_host_id(3), knet_link_clear_config(3),
100       knet_log_get_loglevel(3), knet_handle_new(3),
101       knet_handle_pmtud_getfreq(3), knet_handle_clear_stats(3),
102       knet_link_set_config(3), knet_handle_crypto(3),
103       knet_get_crypto_list(3),
104       knet_handle_set_transport_reconnect_interval(3),
105       knet_link_set_ping_timers(3)
106
108       Copyright (C) 2010-2019 Red Hat, Inc. All rights reserved.
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112kronosnet                         2019-05-09         knet_handle_add_datafd(3)
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