static int
_recv_short_message (lcm_udpm_t *lcm, lcm_buf_t *lcmb, int sz)
{
lcm2_header_short_t *hdr2 = (lcm2_header_short_t*) lcmb->buf;
// shouldn't have to worry about buffer overflow here because we
// zeroed out byte #65536, which is never written to by recv
const char *pkt_channel_str = (char*) (hdr2 + 1);
lcmb->channel_size = strlen (pkt_channel_str);
if (lcmb->channel_size > LCM_MAX_CHANNEL_NAME_LENGTH) {
dbg (DBG_LCM, "bad channel name length\n");
lcm->udp_discarded_bad++;
return 0;
}
lcm->udp_rx++;
// if the packet has no subscribers, drop the message now.
if (!lcm_has_handlers (lcm->lcm, pkt_channel_str))
return 0;
strcpy (lcmb->channel_name, pkt_channel_str);
lcmb->data_offset =
sizeof (lcm2_header_short_t) + lcmb->channel_size + 1;
lcmb->data_size = sz - lcmb->data_offset;
return 1;
}
static int lcm_memq_publish(lcm_memq_t *self, const char *channel, const void *data,
unsigned int datalen)
{
if (!lcm_has_handlers(self->lcm, channel)) {
dbg(DBG_LCM, "Publishing [%s] size [%d] - dropping (no subscribers)\n", channel, datalen);
return 0;
}
dbg(DBG_LCM, "Publishing to [%s] message size [%d]\n", channel, datalen);
memq_msg_t *msg = memq_msg_new(self->lcm, channel, data, datalen, timestamp_now());
g_mutex_lock(self->mutex);
int was_empty = g_queue_is_empty(self->queue);
g_queue_push_tail(self->queue, msg);
if (was_empty) {
if (lcm_internal_pipe_write(self->notify_pipe[1], "+", 1) < 0) {
perror(__FILE__ " - write to notify pipe (lcm_memq_publish)");
}
}
g_mutex_unlock(self->mutex);
return 0;
}
static int
_recv_message_fragment (lcm_udpm_t *lcm, lcm_buf_t *lcmb, uint32_t sz)
{
lcm2_header_long_t *hdr = (lcm2_header_long_t*) lcmb->buf;
// any existing fragment buffer for this message source?
lcm_frag_buf_t *fbuf = lcm_frag_buf_store_lookup(lcm->frag_bufs,
&lcmb->from);
uint32_t msg_seqno = ntohl (hdr->msg_seqno);
uint32_t data_size = ntohl (hdr->msg_size);
uint32_t fragment_offset = ntohl (hdr->fragment_offset);
// uint16_t fragment_no = ntohs (hdr->fragment_no);
uint16_t fragments_in_msg = ntohs (hdr->fragments_in_msg);
uint32_t frag_size = sz - sizeof (lcm2_header_long_t);
char *data_start = (char*) (hdr + 1);
// discard any stale fragments from previous messages
if (fbuf && ((fbuf->msg_seqno != msg_seqno) ||
(fbuf->data_size != data_size))) {
lcm_frag_buf_store_remove (lcm->frag_bufs, fbuf);
dbg(DBG_LCM, "Dropping message (missing %d fragments)\n",
fbuf->fragments_remaining);
fbuf = NULL;
}
// printf ("fragment %d/%d (offset %d/%d) seq %d packet sz: %d %p\n",
// ntohs(hdr->fragment_no) + 1, fragments_in_msg,
// fragment_offset, data_size, msg_seqno, sz, fbuf);
if (data_size > LCM_MAX_MESSAGE_SIZE) {
dbg (DBG_LCM, "rejecting huge message (%d bytes)\n", data_size);
return 0;
}
// create a new fragment buffer if necessary
if (!fbuf && hdr->fragment_no == 0) {
char *channel = (char*) (hdr + 1);
int channel_sz = strlen (channel);
if (channel_sz > LCM_MAX_CHANNEL_NAME_LENGTH) {
dbg (DBG_LCM, "bad channel name length\n");
lcm->udp_discarded_bad++;
return 0;
}
// if the packet has no subscribers, drop the message now.
if(!lcm_has_handlers(lcm->lcm, channel))
return 0;
fbuf = lcm_frag_buf_new (*((struct sockaddr_in*) &lcmb->from),
channel, msg_seqno, data_size, fragments_in_msg,
lcmb->recv_utime);
lcm_frag_buf_store_add (lcm->frag_bufs, fbuf);
data_start += channel_sz + 1;
frag_size -= (channel_sz + 1);
}
if (!fbuf) return 0;
#ifdef __linux__
if(lcm->kernel_rbuf_sz < 262145 &&
data_size > lcm->kernel_rbuf_sz &&
! lcm->warned_about_small_kernel_buf) {
fprintf(stderr,
"==== LCM Warning ===\n"
"LCM detected that large packets are being received, but the kernel UDP\n"
"receive buffer is very small. The possibility of dropping packets due to\n"
"insufficient buffer space is very high.\n"
"\n"
"For more information, visit:\n"
" http://lcm-proj.github.io/multicast_setup.html\n\n");
lcm->warned_about_small_kernel_buf = 1;
}
#endif
if (fragment_offset + frag_size > fbuf->data_size) {
dbg (DBG_LCM, "dropping invalid fragment (off: %d, %d / %d)\n",
fragment_offset, frag_size, fbuf->data_size);
lcm_frag_buf_store_remove (lcm->frag_bufs, fbuf);
return 0;
}
// copy data
memcpy (fbuf->data + fragment_offset, data_start, frag_size);
fbuf->last_packet_utime = lcmb->recv_utime;
fbuf->fragments_remaining --;
if (0 == fbuf->fragments_remaining) {
// complete message received. Is there a subscriber that still
// wants it? (i.e., does any subscriber have space in its queue?)
if(!lcm_try_enqueue_message(lcm->lcm, fbuf->channel)) {
// no... sad... free the fragment buffer and return
lcm_frag_buf_store_remove (lcm->frag_bufs, fbuf);
return 0;
}
// yes, transfer the message into the lcm_buf_t
// deallocate the ringbuffer-allocated buffer
g_static_rec_mutex_lock (&lcm->mutex);
lcm_buf_free_data(lcmb, lcm->ringbuf);
g_static_rec_mutex_unlock (&lcm->mutex);
// transfer ownership of the message's payload buffer
lcmb->buf = fbuf->data;
fbuf->data = NULL;
strcpy (lcmb->channel_name, fbuf->channel);
lcmb->channel_size = strlen (lcmb->channel_name);
lcmb->data_offset = 0;
lcmb->data_size = fbuf->data_size;
lcmb->recv_utime = fbuf->last_packet_utime;
// don't need the fragment buffer anymore
lcm_frag_buf_store_remove (lcm->frag_bufs, fbuf);
return 1;
}
return 0;
}
