/* ntpdsim.c * * The source code for the ntp discrete event simulator. * * Written By: Sachin Kamboj * University of Delaware * Newark, DE 19711 * Copyright (c) 2006 * (Some code shamelessly based on the original NTP discrete event simulator) */ #ifdef SIM #include "ntpd.h" #include "ntpsim.h" #include "ntp_data_structures.h" /* Global Variable Definitions */ sim_info simulation; /* Simulation Control Variables */ local_clock_info simclock; /* Local Clock Variables */ queue *event_queue; /* Event Queue */ queue *recv_queue; /* Receive Queue */ static double sys_residual = 0; /* adjustment residue (s) */ void (*event_ptr[]) (Event *) = { sim_event_beep, sim_update_clocks, sim_event_timer, sim_event_recv_packet }; /* Function pointer to the events */ /* Define a function to compare two events to determine which one occurs first */ int determine_event_ordering(Event *e1, Event *e2); int determine_event_ordering(Event *e1, Event *e2) { return (e1->time - e2->time); } /* Define a function to compare two received packets to determine which one * is received first */ int determine_recv_buf_ordering(struct recvbuf *b1, struct recvbuf *b2); int determine_recv_buf_ordering(struct recvbuf *b1, struct recvbuf *b2) { double recv_time1, recv_time2; /* Simply convert the time received to double and subtract */ LFPTOD(&b1->recv_time, recv_time1); LFPTOD(&b2->recv_time, recv_time2); return ((int)(recv_time1 - recv_time2)); } /* Define a function to create the server associations */ void create_server_associations() { int i; for (i = 0;i < simulation.num_of_servers;++i) { printf("%s\n", stoa(simulation.servers[i].addr)); if (peer_config(simulation.servers[i].addr, ANY_INTERFACE_CHOOSE(simulation.servers[i].addr), MODE_CLIENT, NTP_VERSION, NTP_MINDPOLL, NTP_MAXDPOLL, 0, /* peerflags */ 0, /* ttl */ 0, /* peerkey */ (u_char *)"*" /* peerkeystr */) == 0) { fprintf(stderr, "ERROR!! Could not create association for: %s", stoa(simulation.servers[i].addr)); } } } /* Main Simulator Code */ int ntpsim(int argc, char *argv[]) { Event *curr_event; struct timeval seed; /* Initialize the local Clock */ simclock.local_time = 0; simclock.adj = 0; simclock.slew = 0; /* Initialize the simulation */ simulation.num_of_servers = 0; simulation.beep_delay = BEEP_DLY; simulation.sim_time = 0; simulation.end_time = SIM_TIME; /* * Initialize ntp variables */ initializing = 1; init_auth(); init_util(); init_restrict(); init_mon(); init_timer(); init_lib(); init_request(); init_control(); init_peer(); init_proto(); init_io(); init_loopfilter(); mon_start(MON_OFF); /* Call getconfig to parse the configuration file */ getconfig(argc, argv); initializing = 0; loop_config(LOOP_DRIFTCOMP, old_drift / 1e6); /* * Watch out here, we want the real time, not the silly stuff. */ gettimeofday(&seed, NULL); ntp_srandom(seed.tv_usec); /* Initialize the event queue */ event_queue = create_priority_queue((int(*)(void *, void*)) determine_event_ordering); /* Initialize the receive queue */ recv_queue = create_priority_queue((int(*)(void *, void*)) determine_recv_buf_ordering); /* Push a beep and a timer on the event queue */ enqueue(event_queue, event(0, BEEP)); enqueue(event_queue, event(simulation.sim_time + 1.0, TIMER)); /* * Pop the queue until nothing is left or time is exceeded */ /* maxtime = simulation.sim_time + simulation.end_time;*/ while (simulation.sim_time <= simulation.end_time && (!empty(event_queue))) { curr_event = dequeue(event_queue); /* Update all the clocks to the time on the event */ sim_update_clocks(curr_event); /* Execute the function associated with the event */ event_ptr[curr_event->function](curr_event); free_node(curr_event); } return (0); } /* Define a function to create an return an Event */ Event *event(double t, funcTkn f) { Event *e; if ((e = get_node(sizeof(*e))) == NULL) abortsim("get_node failed in event"); e->time = t; e->function = f; return (e); } /* NTP SIMULATION FUNCTIONS */ /* Define a function for processing a timer interrupt. * On every timer interrupt, call the NTP timer to send packets and process * the clock and then call the receive function to receive packets. */ void sim_event_timer(Event *e) { struct recvbuf *rbuf; /* Call the NTP timer. * This will be responsible for actually "sending the packets." * Since this is a simulation, the packets sent over the network * will be processed by the simulate_server routine below. */ timer(); /* Process received buffers */ while (!empty(recv_queue)) { rbuf = (struct recvbuf *)dequeue(recv_queue); (rbuf->receiver)(rbuf); free_node(rbuf); } /* Arm the next timer interrupt. */ enqueue(event_queue, event(simulation.sim_time + (1 << EVENT_TIMEOUT), TIMER)); } /* Define a function to simulate a server. * This function processes the sent packet according to the server script, * creates a reply packet and pushes the reply packet onto the event queue */ int simulate_server( sockaddr_u *serv_addr, /* Address of the server */ struct interface *inter, /* Interface on which the reply should be inserted */ struct pkt *rpkt /* Packet sent to the server that needs to be processed. */ ) { struct pkt xpkt; /* Packet to be transmitted back to the client */ struct recvbuf rbuf; /* Buffer for the received packet */ Event *e; /* Packet receive event */ server_info *server; /* Pointer to the server being simulated */ script_info *curr_script; /* Current script being processed */ int i; double d1, d2, d3; /* Delays while the packet is enroute */ double t1, t2, t3, t4; /* The four timestamps in the packet */ memset(&xpkt, 0, sizeof(xpkt)); memset(&rbuf, 0, sizeof(rbuf)); /* Search for the server with the desired address */ server = NULL; for (i = 0; i < simulation.num_of_servers; ++i) { fprintf(stderr,"Checking address: %s\n", stoa(simulation.servers[i].addr)); if (memcmp(simulation.servers[i].addr, serv_addr, sizeof(*serv_addr)) == 0) { server = &simulation.servers[i]; break; } } fprintf(stderr, "Received packet for: %s\n", stoa(serv_addr)); if (server == NULL) abortsim("Server with specified address not found!!!"); /* Get the current script for the server */ curr_script = server->curr_script; /* Create a server reply packet. * Masquerade the reply as a stratum-1 server with a GPS clock */ xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOWARNING, NTP_VERSION, MODE_SERVER); xpkt.stratum = STRATUM_TO_PKT(((u_char)1)); memcpy(&xpkt.refid, "GPS", 4); xpkt.ppoll = rpkt->ppoll; xpkt.precision = rpkt->precision; xpkt.rootdelay = 0; xpkt.rootdisp = 0; /* TIMESTAMP CALCULATIONS t1 t4 \ / d1 \ / d3 \ / t2 ----------------- t3 d2 */ /* Compute the delays */ d1 = poisson(curr_script->prop_delay, curr_script->jitter); d2 = poisson(curr_script->proc_delay, 0); d3 = poisson(curr_script->prop_delay, curr_script->jitter); /* Note: In the transmitted packet: * 1. t1 and t4 are times in the client according to the local clock. * 2. t2 and t3 are server times according to the simulated server. * Compute t1, t2, t3 and t4 * Note: This function is called at time t1. */ LFPTOD(&rpkt->xmt, t1); t2 = server->server_time + d1; t3 = server->server_time + d1 + d2; t4 = t1 + d1 + d2 + d3; /* Save the timestamps */ xpkt.org = rpkt->xmt; DTOLFP(t2, &xpkt.rec); DTOLFP(t3, &xpkt.xmt); xpkt.reftime = xpkt.xmt; /* Ok, we are done with the packet. Now initialize the receive buffer for * the packet. */ rbuf.receiver = receive; /* Function to call to process the packet */ rbuf.recv_length = LEN_PKT_NOMAC; rbuf.recv_pkt = xpkt; rbuf.used = 1; memcpy(&rbuf.srcadr, serv_addr, sizeof(rbuf.srcadr)); memcpy(&rbuf.recv_srcadr, serv_addr, sizeof(rbuf.recv_srcadr)); if ((rbuf.dstadr = malloc(sizeof(*rbuf.dstadr))) == NULL) abortsim("malloc failed in simulate_server"); memcpy(rbuf.dstadr, inter, sizeof(*rbuf.dstadr)); /* rbuf.link = NULL; */ /* Create a packet event and insert it onto the event_queue at the * arrival time (t4) of the packet at the client */ e = event(t4, PACKET); e->rcv_buf = rbuf; enqueue(event_queue, e); /* Check if the time of the script has expired. If yes, delete the script. * If not, re-enqueue the script onto the server script queue */ if (curr_script->duration > simulation.sim_time && !empty(server->script)) { printf("Hello\n"); /* * For some reason freeing up the curr_script memory kills the * simulation. Further debugging is needed to determine why. * free_node(curr_script); */ curr_script = dequeue(server->script); } return (0); } /* Define a function to update all the clocks * Most of the code is modified from the systime.c file by Prof. Mills */ void sim_update_clocks (Event *e) { double time_gap; double adj; int i; /* Compute the time between the last update event and this update */ time_gap = e->time - simulation.sim_time; /* Advance the client clock */ simclock.local_time = e->time + time_gap; /* Advance the simulation time */ simulation.sim_time = e->time; /* Advance the server clocks adjusted for systematic and random frequency * errors. The random error is a random walk computed as the * integral of samples from a Gaussian distribution. */ for (i = 0;i < simulation.num_of_servers; ++i) { simulation.servers[i].curr_script->freq_offset += gauss(0, time_gap * simulation.servers[i].curr_script->wander); simulation.servers[i].server_time += time_gap * (1 + simulation.servers[i].curr_script->freq_offset); } /* Perform the adjtime() function. If the adjustment completed * in the previous interval, amortize the entire amount; if not, * carry the leftover to the next interval. */ adj = time_gap * simclock.slew; if (adj < fabs(simclock.adj)) { if (simclock.adj < 0) { simclock.adj += adj; simclock.local_time -= adj; } else { simclock.adj -= adj; simclock.local_time += adj; } } else { simclock.local_time += simclock.adj; simclock.adj = 0; } } /* Define a function that processes a receive packet event. * This function simply inserts the packet received onto the receive queue */ void sim_event_recv_packet(Event *e) { struct recvbuf *rbuf; /* Allocate a receive buffer and copy the packet to it */ if ((rbuf = get_node(sizeof(*rbuf))) == NULL) abortsim("get_node failed in sim_event_recv_packet"); memcpy(rbuf, &e->rcv_buf, sizeof(*rbuf)); /* Store the local time in the received packet */ DTOLFP(simclock.local_time, &rbuf->recv_time); /* Insert the packet received onto the receive queue */ enqueue(recv_queue, rbuf); } /* Define a function to output simulation statistics on a beep event */ /*** TODO: Need to decide on how to output for multiple servers ***/ void sim_event_beep(Event *e) { #if 0 static int first_time = 1; char *dash = "-----------------"; #endif fprintf(stderr, "BEEP!!!\n"); enqueue(event_queue, event(e->time + simulation.beep_delay, BEEP)); #if 0 if(simulation.beep_delay > 0) { if (first_time) { printf("\t%4c T %4c\t%4c T+ERR %3c\t%5cT+ERR+NTP\n", ' ', ' ', ' ', ' ',' '); printf("\t%s\t%s\t%s\n", dash, dash, dash); first_time = 0; printf("\t%16.6f\t%16.6f\t%16.6f\n", n->time, n->clk_time, n->ntp_time); return; } printf("\t%16.6f\t%16.6f\t%16.6f\n", simclock.local_time, n->time, n->clk_time, n->ntp_time); #endif } /* Define a function to abort the simulation on an error and spit out an * error message */ void abortsim(char *errmsg) { perror(errmsg); exit(1); } /* CODE ORIGINALLY IN libntp/systime.c * ----------------------------------- * This code was a part of the original NTP simulator and originally * had its home in the libntp/systime.c file. * * It has been shamelessly moved to here and has been modified for the * purposes of the current simulator. */ /* * get_systime - return the system time in NTP timestamp format */ void get_systime( l_fp *now /* current system time in l_fp */ ) { /* * To fool the code that determines the local clock precision, * we advance the clock a minimum of 200 nanoseconds on every * clock read. This is appropriate for a typical modern machine * with nanosecond clocks. Note we make no attempt here to * simulate reading error, since the error is so small. This may * change when the need comes to implement picosecond clocks. */ if (simclock.local_time == simclock.last_read_time) simclock.local_time += 200e-9; simclock.last_read_time = simclock.local_time; DTOLFP(simclock.local_time, now); /* OLD Code if (ntp_node.ntp_time == ntp_node.last_time) ntp_node.ntp_time += 200e-9; ntp_node.last_time = ntp_node.ntp_time; DTOLFP(ntp_node.ntp_time, now); */ } /* * adj_systime - advance or retard the system clock exactly like the * real thng. */ int /* always succeeds */ adj_systime( double now /* time adjustment (s) */ ) { struct timeval adjtv; /* new adjustment */ double dtemp; long ticks; int isneg = 0; /* * Most Unix adjtime() implementations adjust the system clock * in microsecond quanta, but some adjust in 10-ms quanta. We * carefully round the adjustment to the nearest quantum, then * adjust in quanta and keep the residue for later. */ dtemp = now + sys_residual; if (dtemp < 0) { isneg = 1; dtemp = -dtemp; } adjtv.tv_sec = (long)dtemp; dtemp -= adjtv.tv_sec; ticks = (long)(dtemp / sys_tick + .5); adjtv.tv_usec = (long)(ticks * sys_tick * 1e6); dtemp -= adjtv.tv_usec / 1e6; sys_residual = dtemp; /* * Convert to signed seconds and microseconds for the Unix * adjtime() system call. Note we purposely lose the adjtime() * leftover. */ if (isneg) { adjtv.tv_sec = -adjtv.tv_sec; adjtv.tv_usec = -adjtv.tv_usec; sys_residual = -sys_residual; } simclock.adj = now; /* ntp_node.adj = now; */ return (1); } /* * step_systime - step the system clock. We are religious here. */ int /* always succeeds */ step_systime( double now /* step adjustment (s) */ ) { #ifdef DEBUG if (debug) printf("step_systime: time %.6f adj %.6f\n", simclock.local_time, now); #endif simclock.local_time += now; return (1); } /* * gauss() - returns samples from a gaussion distribution */ double /* Gaussian sample */ gauss( double m, /* sample mean */ double s /* sample standard deviation (sigma) */ ) { double q1, q2; /* * Roll a sample from a Gaussian distribution with mean m and * standard deviation s. For m = 0, s = 1, mean(y) = 0, * std(y) = 1. */ if (s == 0) return (m); while ((q1 = drand48()) == 0); q2 = drand48(); return (m + s * sqrt(-2. * log(q1)) * cos(2. * PI * q2)); } /* * poisson() - returns samples from a network delay distribution */ double /* delay sample (s) */ poisson( double m, /* fixed propagation delay (s) */ double s /* exponential parameter (mu) */ ) { double q1; /* * Roll a sample from a composite distribution with propagation * delay m and exponential distribution time with parameter s. * For m = 0, s = 1, mean(y) = std(y) = 1. */ if (s == 0) return (m); while ((q1 = drand48()) == 0); return (m - s * log(q1 * s)); } #endif