+/* this application captures packets destined to and from
+ * a specified host, it then tries to calculate in and out
+ * traffic statistics and display it like ifstat
+ * by nocturnal [at] swehack [dot] se */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+/* gethostbyname(3) */
+#include <netdb.h>
+
+/* networking(4) */
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <net/route.h>
+#include <net/if_dl.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netinet/if_ether.h>
+#include <ifaddrs.h>
+
+/* setitimer(2) */
+#include <sys/time.h>
+
+/* signal(3) */
+#include <signal.h>
+
+/* get_windowsize */
+#include <termios.h>
+#ifndef TIOCGWINSZ
+#include <sys/ioctl.h>
+#endif
+
+/* duh -lpcap */
+#include <pcap.h>
+
+#define APP_NAME "snifstat"
+#define APP_VERSION 0.2
+
+unsigned int calc_traf_io(char *, struct ether_header *);
+int ethaddrsncmp(const char *, const char *, size_t);
+void reset_count(int);
+unsigned short get_windowsize(void);
+void usage(const char *);
+
+unsigned int reset = 0;
+
+int main(int argc, char **argv) {
+ char *ifname = NULL;
+ int argch;
+ unsigned int show_in_bits = 0;
+ char bits_prefix[] = "Kbps";
+ char bytes_prefix[] = "KB/s";
+ unsigned int max_iteration = 0;
+
+ char errbuf[PCAP_ERRBUF_SIZE];
+ pcap_t *pcap = NULL;
+ struct bpf_program filterd;
+ bpf_u_int32 netp, netmask;
+ char *filter = NULL;
+ const u_char *packet = NULL;
+ struct pcap_pkthdr header;
+
+ unsigned char *ether_addrs = NULL;
+ struct ifaddrs *ifa = NULL;
+ struct sockaddr_dl *sdl = NULL;
+
+ struct itimerval itv, oitv;
+ struct itimerval *itvp = &itv;
+
+
+ struct ether_header *ethernet = NULL;
+
+ unsigned int iteration = 0, total_iteration = 0;
+ double cur_in, cur_out;
+ unsigned short cur_ws = 0, new_ws, old_ws, ws_change;
+ unsigned int traf_io = 2;
+
+ unsigned int *resetp = &reset;
+
+ if(argc < 4) {
+ usage(argv[0]);
+ exit(-1);
+ }
+
+ while((argch = getopt(argc, argv, "i:bc:hv")) != -1) {
+ switch(argch) {
+ case 'i':
+ if(strlen(optarg) < 16) {
+ ifname = optarg;
+ optreset = 1;
+ } else {
+ usage(argv[0]);
+ exit(-1);
+ }
+ break;
+ case 'b':
+ show_in_bits = 1;
+ optreset = 1;
+ break;
+ case 'c':
+ max_iteration = (unsigned int)atoi(optarg);
+ break;
+ case 'h':
+ usage(argv[0]);
+ exit(-1);
+ case 'v': /* LOL WUT?! */
+ printf("%s v%.1f by nocturnal [at] swehack [dot] se\n", APP_NAME, APP_VERSION);
+ exit(-1);
+ }
+ }
+
+ if(argc - optind < 1) {
+ usage(argv[0]);
+ exit(-1);
+ }
+
+ filter = argv[optind];
+
+ if(pcap_lookupnet(ifname, &netp, &netmask, errbuf) == -1) {
+ fprintf(stderr, "pcap_lookupnet: %s\n", errbuf);
+ exit(-1);
+ }
+
+ if((pcap = pcap_open_live(ifname, 65535, 1, 10, errbuf)) == NULL) {
+ fprintf(stderr, "pcap_open_live: %s\n", errbuf);
+ exit(-1);
+ }
+
+ if(pcap_compile(pcap, &filterd, filter, 1, netmask) == -1) {
+ fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(pcap));
+ exit(-1);
+ }
+
+ if(pcap_setfilter(pcap, &filterd) == -1) {
+ fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(pcap));
+ exit(-1);
+ }
+
+ if(signal(SIGALRM, reset_count) == SIG_ERR) {
+ perror("signal: ");
+ exit(-1);
+ }
+
+ if(getifaddrs(&ifa) == -1) {
+ perror("getifaddrs: ");
+ exit(-1);
+ }
+
+ for(;ifa;ifa = ifa->ifa_next) {
+ if(strncmp(ifname, ifa->ifa_name, sizeof(ifa->ifa_name)) == 0) {
+ sdl = (struct sockaddr_dl *)ifa->ifa_addr;
+ if((ether_addrs = malloc(sdl->sdl_alen)) == NULL) {
+ perror("malloc: ");
+ exit(-1);
+ }
+ memcpy(ether_addrs, LLADDR(sdl), sdl->sdl_alen);
+ break;
+ }
+ }
+
+ timerclear(&itvp->it_interval);
+ itvp->it_value.tv_sec = 1;
+ itvp->it_value.tv_usec = 0;
+
+ while(1) {
+ *resetp = 0;
+
+ old_ws = cur_ws;
+ new_ws = get_windowsize();
+ if(new_ws != old_ws) {
+ cur_ws = new_ws;
+ }
+ ws_change = cur_ws-2;
+
+ if(setitimer(ITIMER_REAL, itvp, &oitv) < 0) {
+ fprintf(stderr, "setitimer: \n");
+ exit(-1);
+ }
+
+ cur_in = 0.0;
+ cur_out = 0.0;
+ while(*resetp == 0) {
+ if((packet = pcap_next(pcap, &header)) != NULL) {
+ ethernet = (struct ether_header *)packet;
+
+ if(header.len == 671429858) {
+ cur_in += 0.0;
+ cur_out += 0.0;
+ } else {
+ traf_io = calc_traf_io(ether_addrs, ethernet);
+ if(traf_io == 0) {
+ cur_in += header.len;
+ } else if(traf_io == 1) {
+ cur_out += header.len;
+ }
+ traf_io = 2;
+ }
+ }
+ }
+
+ cur_in /= 1024;
+ cur_out /= 1024;
+
+ if(show_in_bits == 1) {
+ cur_in *= 8;
+ cur_out *= 8;
+ }
+
+ if(iteration >= ws_change || total_iteration == 0) {
+ printf("%11s\n%5s in %5s out\n", ifname, (show_in_bits == 1) ? bits_prefix : bytes_prefix, (show_in_bits == 1) ? bits_prefix : bytes_prefix);
+ if(iteration > 1) {
+ iteration = 1;
+ }
+ }
+
+ if(total_iteration > 0) {
+ printf("%8.2lf %9.2lf\n", cur_in, cur_out);
+ }
+
+ if(max_iteration > 0 && max_iteration == total_iteration) {
+ break;
+ }
+
+ iteration++;
+ total_iteration++;
+ }
+
+ pcap_close(pcap);
+
+ exit(0);
+}
+
+/* calculate if the packet is going in or out */
+unsigned int calc_traf_io(char *ether_addrs, struct ether_header *ethernet) {
+ /* 0 = in
+ * 1 = out
+ * 2 = error
+ * GET IT!? GET IT?!?!??!!? :/ */
+ if(ethaddrsncmp(ether_addrs, ethernet->ether_shost, sizeof(ether_addrs)) == 0) {
+ return(1);
+ }
+ if(ethaddrsncmp(ether_addrs, ethernet->ether_dhost, sizeof(ether_addrs)) == 0) {
+ return(0);
+ }
+ return(2);
+}
+
+/* compare ethernet addresses */
+int ethaddrsncmp(const char *s1, const char *s2, size_t len) {
+ if(len == 0) {
+ return(0);
+ }
+
+ do {
+ if(*s1++ != *s2++) {
+ return(*(const unsigned char *)s1 - *(const unsigned char *)(s2 - 1));
+ }
+ } while(--len != 0);
+
+ return(0);
+}
+
+/* resets a global value */
+void reset_count(int signal) {
+ int *resetp = NULL;
+ resetp = &reset;
+
+ *resetp = 1;
+
+ return;
+}
+
+/* get windowsize */
+unsigned short get_windowsize(void) {
+ struct winsize ws;
+
+ if(ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0) {
+ return(-1);
+ }
+
+ return(ws.ws_row);
+}
+
+void usage(const char *appname) {
+ printf("Usage: %s -i <interface> [-bhv] <filter>\n", appname);
+ printf("\t-i <interface>\t Specify interface to capture from\n"
+ "\t-b\t\t Show values in bits instead of bytes\n"
+ "\t-h\t\t Show this help text\n"
+ "\t-v\t\t Show version\n");
+
+ return;
+}