/* Read exactly n bytes from the DAC connection socket.
*
* This reads exactly len bytes into buf. Data is read in chunks from the
* OS socket library and buffered in the dac_conn_t structure; individual
* sections are then copied out.
*
* Returns 0 on success, -1 on error. If an error occurs, this will call
* log_socket_error() to log the issue. The error code is also available
* from WSAGetLastError().
*/
int dac_read_bytes(dac_t *d, char *buf, int len) {
while (d->conn.size < len) {
// Wait for readability.
int res = wait_for_activity(d, DEFAULT_TIMEOUT);
if (res < 0) {
closesocket(d->conn.sock);
d->conn.sock = INVALID_SOCKET;
return -1;
} else if (res == 0) {
flogd(d, "!! Read from DAC timed out.\n");
closesocket(d->conn.sock);
d->conn.sock = INVALID_SOCKET;
return -1;
}
res = recv(d->conn.sock, d->conn.buf + d->conn.size,
len - d->conn.size, 0);
if (res == 0 || res == SOCKET_ERROR) {
log_socket_error(d, "recv");
return -1;
}
d->conn.size += res;
}
memcpy(buf, d->conn.buf, len);
if (d->conn.size > len) {
memmove(d->conn.buf, d->conn.buf + len, d->conn.size - len);
}
d->conn.size -= len;
return 0;
}
int dac_get_acks(dac_t *d, int wait) {
/* Read any ACKs we are owed */
while (d->conn.pending_meta_acks
|| (d->conn.ackbuf_prod != d->conn.ackbuf_cons)) {
int res;
if (wait_for_activity(d, wait)) {
if ((res = dac_read_resp(d, 1)) < 0)
return res;
if ((res = check_data_response(d)) < 0)
return res;
} else {
break;
}
}
return 0;
}
int main(
int argc,
char **argv)
{
bool command_pipe_open;
struct command_buffer_t command_buffer;
struct net_state_t net_state;
/*
To minimize security risk, the only thing done prior to
dropping SUID should be opening the network state for
raw sockets.
*/
init_net_state_privileged(&net_state);
if (drop_elevated_permissions()) {
perror("Unable to drop elevated permissions");
exit(EXIT_FAILURE);
}
init_net_state(&net_state);
init_command_buffer(&command_buffer, fileno(stdin));
command_pipe_open = true;
/*
Dispatch commands and respond to probe replies until the
command stream is closed.
*/
while (true) {
/* Ensure any responses are written before waiting */
fflush(stdout);
wait_for_activity(&command_buffer, &net_state);
/*
Receive replies first so that the timestamps are as
close to the response arrival time as possible.
*/
receive_replies(&net_state);
if (command_pipe_open) {
if (read_commands(&command_buffer)) {
if (errno == EPIPE) {
command_pipe_open = false;
}
}
}
check_probe_timeouts(&net_state);
/*
Dispatch commands late so that the window between probe
departure and arriving replies is as small as possible.
*/
dispatch_buffer_commands(&command_buffer, &net_state);
/*
If the command pipe has been closed, exit after all
in-flight probes have reported their status.
*/
if (!command_pipe_open) {
if (net_state.outstanding_probe_count == 0) {
break;
}
}
}
return 0;
}
