1knet_handle_add_datafd(3)Kronosnet Programmer's Manualknet_handle_add_datafd(3)
2
6 knet_handle_add_datafd - Install a file descriptor for communication.
7
9 #include <libknet.h>
10 int knet_handle_add_datafd(
12 knet_handle_t knet_h,
13 int *datafd,
14 int8_t *channel
15 );
16
18 knet_handle_add_datafd
19 IMPORTANT: In order to add datafd to knet, knet_han‐
21 dle_enable_sock_notify
22 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.
28 knet_h - pointer to knet_handle_t
30 *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 Please refer to handle.c on how to set up a socketpair.
39 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.
45 It is possible to pass either sockets or normal fds. User provided
47 datafd will be marked as non-blocking and close-on-exec.
48 *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).
52 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.
55 Example: hostA channel 0 will be delivered to datafd on hostB channel 0
57 hostA channel 1 to hostB channel 1.
58 Each channel must have a unique file descriptor.
60 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.
64
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 -1 on error and errno is set. *datafd and *channel are
73 untouched or empty.
74
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_add_acl(3),
80 knet_link_get_pong_count(3), knet_link_get_priority(3),
81 knet_handle_free(3), knet_handle_enable_sock_notify(3),
82 knet_handle_get_datafd(3), 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_link_rm_acl(3), 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_handle_enable_access_lists(3),
97 knet_host_get_host_list(3), knet_host_get_policy(3),
98 knet_link_set_enable(3), knet_link_set_pong_count(3),
99 knet_log_get_subsystem_name(3), knet_host_get_name_by_host_id(3),
100 knet_link_clear_config(3), knet_log_get_loglevel(3),
101 knet_handle_new(3), knet_handle_pmtud_getfreq(3),
102 knet_handle_pmtud_set(3), knet_handle_clear_stats(3),
103 knet_link_set_config(3), knet_handle_crypto(3),
104 knet_get_crypto_list(3),
105 knet_handle_set_transport_reconnect_interval(3),
106 knet_link_clear_acl(3), knet_link_set_ping_timers(3),
107 knet_link_insert_acl(3)
108
110 Copyright (C) 2010-2020 Red Hat, Inc. All rights reserved.
111kronosnet 2020-04-23 knet_handle_add_datafd(3)