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
10 #include <libknet.h>
11 int knet_handle_add_datafd(
13 knet_handle_t knet_h,
14 int *datafd,
15 int8_t *channel
16 );
17
19 knet_handle_add_datafd
20 IMPORTANT: In order to add datafd to knet, knet_handle_enable_sock_no‐
22 tify MUST be set and be able to handle both errors (-1) and 0 bytes
23 read / write from the provided datafd. On read error (< 0) from datafd,
24 the socket is automatically removed from polling to avoid spinning on
25 dead sockets. It is safe to call knet_handle_remove_datafd even on
26 sockets that have been removed.
27 knet_h - pointer to knet_handle_t
29 *datafd - read/write file descriptor. knet will read data here to send
31 to the other hosts and will write data received from the network. Each
32 data packet can be of max size KNET_MAX_PACKET_SIZE! Applications using
33 knet_send/knet_recv will receive a proper error if the packet size is
34 not within boundaries. Applications using their own functions to write
35 to the datafd should NOT write more than KNET_MAX_PACKET_SIZE.
36 Please refer to handle.c on how to set up a socketpair.
38 datafd can be 0, and knet_handle_add_datafd will create a properly pop‐
40 ulated socket pair the same way as ping_test, or a value higher than 0.
41 A negative number will return an error. On exit knet_handle_free will
42 take care to cleanup the socketpair only if they have been created by
43 knet_handle_add_datafd.
44 It is possible to pass either sockets or normal fds. User provided
46 datafd will be marked as non-blocking and close-on-exec.
47 *channel - This value is analogous to the tag in VLAN tagging. A nega‐
49 tive value will auto-allocate a channel. Setting a value between 0 and
50 31 will try to allocate that specific channel (unless already in use).
51 It is possible to add up to 32 datafds but be aware that each one of
53 them must have a receiving end on the other host.
54 Example: hostA channel 0 will be delivered to datafd on hostB channel 0
56 hostA channel 1 to hostB channel 1.
57 Each channel must have a unique file descriptor.
59 If your application could have 2 channels on one host and one channel
61 on another host, then you can use dst_host_filter to manipulate channel
62 values on TX and RX.
63
65 knet_handle_add_datafd returns
66 0 on success, *datafd will be populated with a socket if the
68 original value was 0 or if a specific fd was set, the value is un‐
69 touched. *channel will be populated with a channel number if the origi‐
70 nal value was negative or the value is untouched if a specific channel
71 was requested.
72 -1 on error and errno is set. *datafd and *channel are un‐
74 touched or empty.
75
77 knet_handle_remove_datafd(3), knet_handle_get_stats(3),
78 knet_host_add(3), knet_handle_pmtud_setfreq(3),
79 knet_handle_pmtud_get(3), knet_handle_crypto_use_config(3),
80 knet_host_get_id_by_host_name(3), knet_host_get_status(3),
81 knet_link_add_acl(3), knet_link_get_pong_count(3),
82 knet_link_get_priority(3), knet_handle_free(3),
83 knet_handle_enable_sock_notify(3), knet_handle_get_datafd(3),
84 knet_recv(3), knet_link_get_ping_timers(3),
85 knet_log_get_subsystem_id(3), knet_host_remove(3),
86 knet_host_enable_status_change_notify(3), knet_strtoaddr(3),
87 knet_link_rm_acl(3), knet_send(3), knet_handle_enable_pmtud_notify(3),
88 knet_handle_get_transport_reconnect_interval(3),
89 knet_link_get_enable(3), knet_link_set_priority(3),
90 knet_log_set_loglevel(3), knet_handle_get_channel(3),
91 knet_link_get_config(3), knet_link_get_link_list(3),
92 knet_get_transport_list(3), knet_get_transport_id_by_name(3),
93 knet_log_get_loglevel_id(3), knet_handle_new_ex(3),
94 knet_host_set_name(3), knet_addrtostr(3), knet_handle_setfwd(3),
95 knet_get_compress_list(3), knet_host_set_policy(3),
96 knet_get_transport_name_by_id(3), knet_handle_enable_filter(3),
97 knet_handle_crypto_rx_clear_traffic(3), knet_handle_compress(3),
98 knet_link_get_status(3), knet_send_sync(3),
99 knet_log_get_loglevel_name(3), knet_handle_enable_access_lists(3),
100 knet_host_get_host_list(3), knet_host_get_policy(3),
101 knet_link_set_enable(3), knet_link_set_pong_count(3),
102 knet_log_get_subsystem_name(3), knet_host_get_name_by_host_id(3),
103 knet_link_clear_config(3), knet_log_get_loglevel(3),
104 knet_handle_new(3), knet_handle_pmtud_getfreq(3),
105 knet_handle_pmtud_set(3), knet_handle_clear_stats(3),
106 knet_link_set_config(3), knet_handle_crypto_set_config(3),
107 knet_handle_crypto(3), knet_get_crypto_list(3),
108 knet_handle_set_transport_reconnect_interval(3),
109 knet_link_clear_acl(3), knet_link_set_ping_timers(3),
110 knet_link_insert_acl(3)
111
113 Copyright (C) 2010-2022 Red Hat, Inc. All rights reserved.
114kronosnet 2022-05-30 KNET_HANDLE_ADD_DATAFD(3)