/*
* Sleep in select() until we can do something. This will initialize the
* select masks. Upon return, the masks will indicate which descriptors
* have data or can accept data. Optionally, a maximum time can be specified
* for the duration of the wait (0 = infinite).
*/
static void
wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
u_int *nallocp, u_int64_t max_time_milliseconds)
{
struct timeval tv, *tvp;
int ret;
time_t minwait_secs = 0;
int client_alive_scheduled = 0;
int program_alive_scheduled = 0;
/* Allocate and update select() masks for channel descriptors. */
channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
&minwait_secs, 0);
if (minwait_secs != 0)
max_time_milliseconds = MIN(max_time_milliseconds,
(u_int)minwait_secs * 1000);
/*
* if using client_alive, set the max timeout accordingly,
* and indicate that this particular timeout was for client
* alive by setting the client_alive_scheduled flag.
*
* this could be randomized somewhat to make traffic
* analysis more difficult, but we're not doing it yet.
*/
if (compat20 &&
max_time_milliseconds == 0 && options.client_alive_interval) {
client_alive_scheduled = 1;
max_time_milliseconds =
(u_int64_t)options.client_alive_interval * 1000;
}
if (compat20) {
#if 0
/* wrong: bad condition XXX */
if (channel_not_very_much_buffered_data())
#endif
FD_SET(connection_in, *readsetp);
} else {
/*
* Read packets from the client unless we have too much
* buffered stdin or channel data.
*/
if (buffer_len(&stdin_buffer) < buffer_high &&
channel_not_very_much_buffered_data())
FD_SET(connection_in, *readsetp);
/*
* If there is not too much data already buffered going to
* the client, try to get some more data from the program.
*/
if (packet_not_very_much_data_to_write()) {
program_alive_scheduled = child_terminated;
if (!fdout_eof)
FD_SET(fdout, *readsetp);
if (!fderr_eof)
FD_SET(fderr, *readsetp);
}
/*
* If we have buffered data, try to write some of that data
* to the program.
*/
if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
FD_SET(fdin, *writesetp);
}
notify_prepare(*readsetp);
/*
* If we have buffered packet data going to the client, mark that
* descriptor.
*/
if (packet_have_data_to_write())
FD_SET(connection_out, *writesetp);
/*
* If child has terminated and there is enough buffer space to read
* from it, then read as much as is available and exit.
*/
if (child_terminated && packet_not_very_much_data_to_write())
if (max_time_milliseconds == 0 || client_alive_scheduled)
max_time_milliseconds = 100;
if (max_time_milliseconds == 0)
tvp = NULL;
else {
tv.tv_sec = max_time_milliseconds / 1000;
tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
tvp = &tv;
}
/* Wait for something to happen, or the timeout to expire. */
ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
if (ret == -1) {
memset(*readsetp, 0, *nallocp);
memset(*writesetp, 0, *nallocp);
if (errno != EINTR)
error("select: %.100s", strerror(errno));
} else {
if (ret == 0 && client_alive_scheduled)
client_alive_check();
if (!compat20 && program_alive_scheduled && fdin_is_tty) {
if (!fdout_eof)
FD_SET(fdout, *readsetp);
if (!fderr_eof)
FD_SET(fderr, *readsetp);
}
}
notify_done(*readsetp);
}
static void
client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
int *maxfdp, int *nallocp, int rekeying)
{
struct timeval tv, *tvp;
int ret;
/* Add any selections by the channel mechanism. */
channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, rekeying);
if (!compat20) {
/* Read from the connection, unless our buffers are full. */
if (buffer_len(&stdout_buffer) < buffer_high &&
buffer_len(&stderr_buffer) < buffer_high &&
channel_not_very_much_buffered_data())
FD_SET(connection_in, *readsetp);
/*
* Read from stdin, unless we have seen EOF or have very much
* buffered data to send to the server.
*/
if (!stdin_eof && packet_not_very_much_data_to_write())
FD_SET(fileno(stdin), *readsetp);
/* Select stdout/stderr if have data in buffer. */
if (buffer_len(&stdout_buffer) > 0)
FD_SET(fileno(stdout), *writesetp);
if (buffer_len(&stderr_buffer) > 0)
FD_SET(fileno(stderr), *writesetp);
} else {
/* channel_prepare_select could have closed the last channel */
if (session_closed && !channel_still_open() &&
!packet_have_data_to_write()) {
/* clear mask since we did not call select() */
memset(*readsetp, 0, *nallocp);
memset(*writesetp, 0, *nallocp);
return;
} else {
FD_SET(connection_in, *readsetp);
}
}
/* Select server connection if have data to write to the server. */
if (packet_have_data_to_write())
FD_SET(connection_out, *writesetp);
/*
* Wait for something to happen. This will suspend the process until
* some selected descriptor can be read, written, or has some other
* event pending.
*/
if (options.server_alive_interval == 0 || !compat20)
tvp = NULL;
else {
tv.tv_sec = options.server_alive_interval;
tv.tv_usec = 0;
tvp = &tv;
}
ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
if (ret < 0) {
char buf[100];
/*
* We have to clear the select masks, because we return.
* We have to return, because the mainloop checks for the flags
* set by the signal handlers.
*/
memset(*readsetp, 0, *nallocp);
memset(*writesetp, 0, *nallocp);
if (errno == EINTR)
return;
/* Note: we might still have data in the buffers. */
snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
buffer_append(&stderr_buffer, buf, strlen(buf));
quit_pending = 1;
} else if (ret == 0)
server_alive_check();
}