measure.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ip.h>

/*
 *  ether packet
 */
typedef struct Etherpkt	Etherpkt;
struct Etherpkt {
	uchar d[6];
	uchar s[6];
	uchar type[2];
	char data[1500];
};
#define	ETHERMINTU	60	/* minimum transmit size */
#define	ETHERMAXTU	1514	/* maximum transmit size */
#define ETHERHDRSIZE	14	/* size of an ethernet header */

/*
 *  ip packets
 */
typedef struct Ippkt	Ippkt;
struct Ippkt
{
	uchar	vihl;		/* Version and header length */
	uchar	tos;		/* Type of service */
	uchar	length[2];	/* packet length */
	uchar	id[2];		/* Identification */
	uchar	frag[2];	/* Fragment information */
	uchar	ttl;		/* Time to live */
	uchar	proto;		/* Protocol */
	uchar	cksum[2];	/* Header checksum */
	uchar	src[4];		/* Ip source */
	uchar	dst[4];		/* Ip destination */
	char	data[1];
};

#define IP_HDRSIZE	20
#define IP_UDPPROTO	17
#define IP_MBONEPROTO	4
#define IP_TCPPROTO	6
#define	IP_ILPROTO	40
#define	IP_ICMPPROTO	1
#define	IP_DF		0x4000
#define	IP_MF		0x2000

#define NetS(x) (((x)[0]<<8) | (x)[1])
#define NetL(x) (((x)[0]<<24) | ((x)[1]<<16) | ((x)[2]<<8) | (x)[3])

/*
 *  run flags
 */
int	debug;
int	mbone;

ulong protoin[256];
ulong protoout[256];
ulong protopin[256];
ulong protopout[256];

void
error(char *s)
{
	char buf[ERRLEN];

	errstr(buf);
	fprint(2, "snoopy: %s %s\n", buf, s);
	exits("death");
}

void
warning(char *s)
{
	char buf[ERRLEN];

	errstr(buf);
	fprint(2, "snoopy: %s %s\n", buf, s);
}

void
printproto(int p)
{
	print("\t%d(%d %d %d %d)", p, protoin[p], protopin[p], protoout[p], protopout[p]);
}

void
main(int argc, char *argv[])
{
	Etherpkt e;
	Ippkt *ip;
	long n;
	int fd, cfd;
	int ts, len, t;
	long start;
	int delta;
	uchar target[6];
	char buf[256];
	ulong samples;

	samples = -1;
	ARGBEGIN{
	case 'd':
		debug++;
		break;
	case 's':
		samples = atoi(ARGF());
		break;
	}ARGEND;

	if(argc < 2){
		fprint(2, "usage: %s device ip-addr [minutes-per-sample]\n", argv0);
		exits("usage");
	}
	if(argc > 2)
		delta = atoi(argv[2])*60*1000;
	else
		delta = 5*60*1000;
	parseether(target, argv[1]);

	fmtinstall('E', eipconv);
	fmtinstall('I', eipconv);

	snprint(buf, sizeof(buf), "%s!-2", argv[0]);
	fd = dial(buf, 0, 0, &cfd);
	if(fd < 0)
		error("opening ether data");
	if(write(cfd, "promiscuous", sizeof("promiscuous")-1) <= 0)
		error("connecting");

	start = 0;
	fd = -1;

	for(;;){
		if(fd < 0){
			fd = dial(buf, 0, 0, &cfd);
			if(fd < 0)
				error("opening ether data");
			if(write(cfd, "promiscuous", sizeof("promiscuous")-1) <= 0)
				error("connecting");
			close(cfd);
		}
		n = read(fd, &e, sizeof(e));
		if(n <= 0)
			break;
		ts = NetL(&e.d[60]);
		n = NetS(&e.d[58]) - ETHERHDRSIZE;
		if(n < 0)
			continue;
		if(start == 0)
			start = ts;
		t = NetS(e.type);
		if(t == 0x0800 || (t&0xFF00) == 0x1000){
			ip = (Ippkt*)e.data;
			len = NetS(ip->length);
			if(len > n)
				len = n;
			if(debug)
				fprint(2, "%I -> %I %d\n", ip->src, ip->dst, len);
			if(memcmp(e.s, target, 6) == 0){
				protopin[0]++;
				protoin[0] += len;
				if(ip->proto){
					protopin[ip->proto]++;
					protoin[ip->proto] += len;
				}
			}
			if(memcmp(e.d, target, 6) == 0){
				protopout[0]++;
				protoout[0] += len;
				if(ip->proto){
					protopout[ip->proto]++;
					protoout[ip->proto] += len;
				}
			}
		}
		if(ts - start >= delta){
			print("%8.8d %d", time(0), ts - start);
			printproto(0);
			printproto(IP_MBONEPROTO);
			printproto(IP_UDPPROTO);
			printproto(IP_TCPPROTO);
			print("\n");
			start = 0;
			memset(protoin, 0, sizeof(protoin));
			memset(protoout, 0, sizeof(protoout));
			memset(protopin, 0, sizeof(protopin));
			memset(protopout, 0, sizeof(protopout));
			close(fd);
			fd = -1;
			if(--samples == 0)
				break;
		}
	}
	exits(0);
}