knet_send_sync3
Synchronously send data to knet nodes.
Usage
#include <libknet.h>
int knet_send_sync(
knet_handle_t knet_h,
const char *buff,
const size_t buff_len,
const int8_t channel
);
Overview
knet_send_sync
knet_h - pointer to knet_handle_t
buff - pointer to the buffer of data to send
buff_len - length of data to send
channel - data channel to use (see knet_handle_add_datafd(3))
All knet RX/TX operations are async for performance reasons. There are applications that might need a sync version of data transmission and receive errors in case of failure to deliver to another host. knet_send_sync bypasses the whole TX async layer and delivers data directly to the link layer, and returns errors accordingly. knet_send_sync sends only one packet to one host at a time. It does NOT support multiple destinations or multicast packets. Decision is still based on dst_host_filter_fn.
Return value
knet_send_sync returns 0 on success and -1 on error. In addition to normal sendmmsg errors, knet_send_sync can fail due to:
ECANCELED - data forward is disabled
EFAULT - dst_host_filter fatal error
EINVAL - dst_host_filter did not provide dst_host_ids_entries on unicast pckts
E2BIG - dst_host_filter did return more than one dst_host_ids_entries on unicast pckts
ENOMSG - received unknown message type
EHOSTDOWN - unicast pckt cannot be delivered because dest host is not connected yet
ECHILD - crypto failed
EAGAIN - sendmmsg was unable to send all messages and there was no progress during retry
ENETDOWN - a packet filter was not installed (necessary for knet_send_sync, but not knet_send)
Releases
4 releases since Debian 10 (Buster); the text changed 3 times.