/* * 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(); }