C语言模拟路由DV算法

/***************************************************************** * DVsim.c Distance Vector Routing Simulation Package * * Event driven simulation of distributed, asynchronous, * distance vector routing. This file contains the network * simulation code which emulates layer 2 and below: * * - simulates packet tranmissions between two * physically connected nodes * * - assumes with no packet loss or corruption * * - calls initializations routines rtinit0, etc., before * beginning simulation * * * Original code from Kurose and Ross, Computer Networking * * Modified by S. Dykes Apr. 2000 * 1. Changed RNG to use drand48() with seed = getpid() * 2. Replaced 999 with INF * 3. created common include file DVsim.h * 4. extended to 6 node network * *---------------------------------------------------------------*/ #define DVSIM_H #include "DVsim.h" #include "time.h" #define FROM_LAYER2 2 #define LINK_CHANGE 10 /*---------------------------------------- * Event list and possible events *---------------------------------------*/ struct event { double evtime; /* event time */ int evtype; /* event type code */ int eventity; /* entity where event occurs */ struct rtpkt *rtpktptr; /* ptr to packet (if any) assoc w/ this event */ struct event *prev; struct event *next; }; struct event *evlist = NULL; /*-------------------------------- * Simulation clock *-------------------------------*/ double clocktime = 0.000; double get_clock() { return clocktime; } /*-------------------------------- * Function prototypes *-------------------------------*/ void init(); void insertevent (struct event *); void printevlist(); void tolayer2 (struct rtpkt ); /*------------------------------- * MAIN *-------------------------------*/ main() { int i; struct event *eventptr; /*---------------------------------------- * Loop until we run out of events *---------------------------------------*/ init(); while (1) { /*---------------------------------------- * Get next event from top of list * Done if event list is empty *---------------------------------------*/ if (! (eventptr = evlist) ) break; evlist = evlist->next; if (evlist) evlist->prev=NULL; /*---------------------------------------- * Trace info *---------------------------------------*/ if (TRACE>1) { printf("\nMAIN: rcv event, t=%.3f, at %d", eventptr->evtime, eventptr->eventity); if (eventptr->evtype == FROM_LAYER2 ) { printf(" src:%2d,", eventptr->rtpktptr->sourceid); printf(" dest:%2d,", eventptr->rtpktptr->destid); printf(" contents: "); for (i=0; i<NODES; i++) printf ("%3d ",eventptr->rtpktptr->mincost[i]); printf("\n"); } } /*---------------------------------------- * Update clock to next event time *---------------------------------------*/ clocktime = eventptr->evtime; /*---------------------------------------- * Call event handler *---------------------------------------*/ if (eventptr->evtype == FROM_LAYER2 ) { if (eventptr->eventity == 0) rtupdate0(eventptr->rtpktptr); else if (eventptr->eventity == 1) rtupdate1(eventptr->rtpktptr); else if (eventptr->eventity == 2) rtupdate2(eventptr->rtpktptr); else if (eventptr->eventity == 3) rtupdate3(eventptr->rtpktptr); else if (eventptr->eventity == 4) rtupdate4(eventptr->rtpktptr); else if (eventptr->eventity == 5) rtupdate5(eventptr->rtpktptr); else { printf("Panic: unknown event entity\n"); exit(0); } } else if (eventptr->evtype == LINK_CHANGE ) { if (clocktime < 10001.0) { linkhandler0(1,20); linkhandler1(0,20); } else { linkhandler0(1,1); linkhandler1(0,1); } } else { printf("Panic: unknown event type\n"); exit(0); } /*-------------------------------------------------------- * Free memory for packet (if any) and event struct *-------------------------------------------------------*/ if (eventptr->evtype == FROM_LAYER2 ) free(eventptr->rtpktptr); free(eventptr); } /*------------------------------- * SIMULATION TERMINATED *-------------------------------*/ printf("\nSimulator terminated at t=%f, no packets in medium\n", clocktime); } /*------------------------------- * init *-------------------------------*/ void init() { int i; double sum, avg; struct event *evptr; /*--------------------- * Input TRACE *--------------------*/ printf ("Enter value for TRACE (no trace =0, user= 1 or 2, developer= 3): "); scanf ("%d", &TRACE); /*--------------------- * Test RNG *--------------------*/ srand ((long) getpid()); for (i=0, sum=0.; i<1000; i++) sum+= drand(); avg = sum/1000.0; if (avg < 0.25 || avg > 0.75) { printf("RNG PROBLEM\n"); printf("Average of 1000 random numbers is %g (expected 0.5).\n", avg); printf("It is likely that random number generation on your machine\n"); printf("is different from what this emulator expects. Please take\n"); printf("a look at the routine init() in the emulator code. \n"); exit(0); } /*------------------------------------- * Initialize clock and nodes *------------------------------------*/ clocktime=0.0; rtinit0(); rtinit1(); rtinit2(); rtinit3(); rtinit4(); rtinit5(); /*------------------------------------- * Initialize future link changes *------------------------------------*/ if (LINKCHANGES==1) { evptr = (struct event *)malloc(sizeof(struct event)); evptr->evtime = 10000.0; evptr->evtype = LINK_CHANGE; evptr->eventity = -1; evptr->rtpktptr = NULL; insertevent(evptr); evptr = (struct event *)malloc(sizeof(struct event)); evptr->evtype = LINK_CHANGE; evptr->evtime = 20000.0; evptr->rtpktptr = NULL; insertevent(evptr); } } /********************* EVENT HANDLING ROUTINES ******* * * These routines handle the event list * *****************************************************/ /*------------------------------------------------------------ * insertevent * * Inserts object in event list. List is sorted by time. * p -> object to be inserted * q -> top of list *------------------------------------------------------------*/ void insertevent (struct event *p) { struct event *q,*qold; if (TRACE>3) { printf(" INSERTEVENT: time is %lf\n",clocktime); printf(" INSERTEVENT: future time will be %lf\n",p->evtime); } q = evlist; if (q==NULL) { /*-------------------------------- * Empty list - insert at top *-------------------------------*/ evlist=p; p->next=NULL; p->prev=NULL; } else { /*---------------------------------------- * Find event time > p's time *---------------------------------------*/ for (qold=q; q !=NULL && p->evtime > q->evtime; q=q->next) qold=q; if (q==NULL) { /*--------------------- * End of list *--------------------*/ qold->next = p; p->prev = qold; p->next = NULL; } else if (q==evlist) { /*--------------------- * Top of list *---------------------*/ p->next=evlist; p->prev=NULL; p->next->prev=p; evlist = p; } else { /*--------------------- * Middle of list *---------------------*/ p->next=q; p->prev=q->prev; q->prev->next=p; q->prev=p; } } } /*------------------------------------------------------------ * printevlist - prints event list *-----------