/* dumpnetload.c   by Michael Thorpe   2006-07-13 */

#include <ctype.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>

struct result {
	unsigned int sequence;
	float latency; /* in msec */
};

static const char usage[]="usage: dumpnetload [-d] [-l <logfile>] <host> <directory>\n";
static char *errorfile=0;
static char *host;

static void error(const char *msg) {
	FILE *f;

	if(errorfile) {
		f=fopen(errorfile,"w");
		if(f) {
			fputs(msg,f);
			fclose(f);
		}
	}
	exit(1);
}

int parseline(char *s,struct result *result) {
	while(isdigit(*s))
		s++;
	if(strncmp(s," bytes from ",12))
		return(1);
	s+=12;
	while(!isspace(*s))
		s++;
	if(2 != sscanf(s," icmp_seq=%u ttl=%*u time=%f ms",&result->sequence,&result->latency))
		return(1);
	return(0);
}

static const char *makefilename(const struct tm *tm) {
	static char t[16];

	snprintf(t,sizeof(t),"%04u-%02u-%02u",1900+tm->tm_year,tm->tm_mon+1,tm->tm_mday);
	return(t);
}

void writeall(int fd,char *s) {
	int i,j;

	i=strlen(s);
	while(i) {
		j=write(fd,s,i);
		if(j<=0)
			error("Couldn't write output file!\n");
		s+=j;
		i-=j;
	}
}

int doit(int fout,unsigned int numsamples,int firsttime) {
	FILE *f;
	int i,seq;
	char s[128];
	struct result res;

	i=snprintf(s,sizeof(s),"ping -n -i 5 -s 8 -c %u %s",numsamples,host);
	if(i<=0 || i>=sizeof(s)-1)
		return(1);
	f=popen(s,"r");
	if(!f)
		return(1);
	if(firsttime)
		writeall(fout,"restart\n");
	seq=0;
	while(s==fgets(s,sizeof(s),f)) {
		if(parseline(s,&res))
			continue;
		while(seq<res.sequence) {
			writeall(fout,"nodata\n");
			seq++;
		}
/*
		if(seq>res.sequence)
			writeall(fout,"restart\n");
*/
		snprintf(s,sizeof(s),"%.2f\n",res.latency);
		writeall(fout,s);
		seq=res.sequence+1;
	}
	while(seq<numsamples) {
		writeall(fout,"nodata\n");
		seq++;
	}
	pclose(f);
	return(0);
}

int main(int argc,char **argv) {
	int daemonmode=0,f=-1,i,oldday=0,firsttime=1;
	struct tm *tm;
	time_t dumbassesdesignedlibc;
	const char *fname;

	while(EOF != (i=getopt(argc,argv,"dhl:"))) {
		switch(i) {
		case 'd':
			daemonmode=1;
			break;
		case 'h':
			fputs(usage,stdout);
			fputs("\t-d         daemon mode; fork to background\n",stdout);
			fputs("\t-l <file>  error log filename\n",stdout);
			return(0);
		case 'l':
			if(errorfile) {
				fputs("Why specify two log files for errors?\n",stderr);
				return(1);
			}
			errorfile=optarg;
			break;
		case '?':
			return(1);
		}
	}
	if(argc != optind+2) {
		fputs(usage,stderr);
		return(1);
	}
	host=argv[optind++];
	if(chdir(argv[optind])) {
		fprintf(stderr,"Couldn't chdir to %s!\n",argv[optind]);
		return(1);
	}
	if(daemonmode) {
		i=fork();
		if(i<0) {
			fprintf(stderr,"Couldn't fork!\n");
			return(-1);
		} else if(i>0)
			return(0);
		close(0);
		close(1);
		close(2);
	}
	signal(SIGCHLD,SIG_IGN);
	time(&dumbassesdesignedlibc);
	tm=gmtime(&dumbassesdesignedlibc);
	while(1) {
		i=fork();
		if(i<0) {
			fprintf(stderr,"Couldn't fork!\n");
			return(-1);
		} else if(i>0) {
			oldday=(tm->tm_year*512)+(tm->tm_mon*32)+tm->tm_mday;
			do {
				i=(60-tm->tm_sec)+60*((59-tm->tm_min)+60*(23-tm->tm_hour));
				sleep(i);
				time(&dumbassesdesignedlibc);
				tm=gmtime(&dumbassesdesignedlibc);
				i=(tm->tm_year*512)+(tm->tm_mon*32)+tm->tm_mday;
			} while(i==oldday);
		} else {
			i=(60-tm->tm_sec)+60*((59-tm->tm_min)+60*(23-tm->tm_hour));
			if(i<5)
				exit(0);
			fname=makefilename(tm);
			f=open(fname,O_WRONLY|O_CREAT|O_APPEND,0666);
			if(f==-1)
				error("Couldn't open output file!\n");
			doit(f,i/5,firsttime);
			exit(0);
		}
		firsttime=0;
	}
	error("How'd we get here?!?");
	return(42);
}