echoscan.c

#include <pcap.h>
#include <stdio.h>
#include <stdlib.h> // for exit()
#include <string.h> //for memset
#include <sys/ioctl.h>
#include <net/if.h>
#include <sys/socket.h>
#include <arpa/inet.h> // for inet_ntoa()
#include <net/ethernet.h>
#include <netinet/udp.h> //Provides declarations for udp header
#include <netinet/ip.h>  //Provides declarations for ip header
#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <sys/resource.h>
#include <unistd.h>

void process_packet(void *args, struct pcap_pkthdr *header, void *buffer);

struct buffer
{
        void *data;
        int size;
        struct buffer *next;
        struct buffer *prev;
};
struct buffer *head;

char *ipv4;
int processed,over,total,i,j;
struct sockaddr_in dest;
pthread_mutex_t buf_mutex = PTHREAD_MUTEX_INITIALIZER;
sem_t loop_sem;
int running_threads = 0;
volatile int found_srvs = 0;
volatile unsigned long per_thread = 0;
volatile unsigned long start = 0;
volatile unsigned long scanned = 0;
int sleep_between = 0;
volatile int bytes_sent = 0;
volatile unsigned long hosts_done = 0;
FILE *fd;

void *readthread()
{
        struct buffer *ourhead = head;
        struct sockaddr_in saddr;
        while(1)
        {
                sem_wait(&loop_sem);
                while(ourhead->data == NULL){ ourhead = ourhead->next; }
                pthread_mutex_lock(&buf_mutex);
                void *buf = malloc(ourhead->size);
                int size = ourhead->size;
                memcpy(buf, ourhead->data, ourhead->size);
                free(ourhead->data);
                ourhead->data = NULL;
                ourhead->size = 0;
                pthread_mutex_unlock(&buf_mutex);
                memset(&saddr, 0, sizeof(saddr));
                struct iphdr *iph = (struct iphdr*)(buf + sizeof(struct ethhdr));
                saddr.sin_addr.s_addr = iph->saddr;
                struct udphdr *udph = (struct udphdr *)(buf + sizeof(struct ethhdr) + sizeof(struct iphdr));
                if(ntohs(udph->source) == 7)
                {
                        int body_length = size - sizeof(struct ethhdr) - sizeof(struct iphdr) - sizeof(struct udphdr);
                        fprintf(fd,"%s %d\n",inet_ntoa(saddr.sin_addr),body_length);
                        fflush(fd);
                        found_srvs++;
                }
                free(buf);
                processed++;
                ourhead = ourhead->next;
        }
}

void *flood(void *par1)
{
        running_threads++;
        int thread_id = (int)par1;
        unsigned long start_ip = htonl(ntohl(start)+(per_thread*thread_id));
        unsigned long end = htonl(ntohl(start)+(per_thread*(thread_id+1)));
        unsigned long w;
        int y;
        unsigned char buf[65536];
        memcpy(buf, "\x0D\x0A\x0D\x0A", 4);
        int sizeofpayload = 4;
        int sock;
        if((sock=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))<0) {
                perror("cant open socket");
                exit(-1);
        }
        for(w=ntohl(start_ip);w<htonl(end);w++)
        {
                struct sockaddr_in servaddr;
                bzero(&servaddr, sizeof(servaddr));
                servaddr.sin_family = AF_INET;
                servaddr.sin_addr.s_addr=htonl(w);
                servaddr.sin_port=htons(7);
                sendto(sock,(char *)buf,sizeofpayload,0, (struct sockaddr *)&servaddr,sizeof(servaddr));
                bytes_sent+=sizeofpayload;
                scanned++;
                hosts_done++;
                usleep(sleep_between*1000);
        }
        close(sock);
        running_threads--;
        return;
}

void sighandler(int sig)
{
        fclose(fd);
        printf("\n");
        exit(0);
}

void *printthread(void *argvs)
{
        char **argv = (char **)argvs;
        int threads = atoi(argv[4]);
        pthread_t thread;
        sleep(1);
        char *str_start = malloc(18);
        memset(str_start, 0, 18);
        str_start = argv[1];
        char *str_end = malloc(18);
        memset(str_end, 0, 18);
        str_end = argv[2];
        start = inet_addr(str_start);
        per_thread = (ntohl(inet_addr(str_end)) - ntohl(inet_addr(str_start))) / threads;
        unsigned long toscan = (ntohl(inet_addr(str_end)) - ntohl(inet_addr(str_start)));
        int i;
        for(i = 0;i<threads;i++){
                pthread_create( &thread, NULL, &flood, (void *) i);
        }
        sleep(1);
        char *temp = (char *)malloc(17);
        memset(temp, 0, 17);
        sprintf(temp, "Found");
        printf("%-16s", temp);
        memset(temp, 0, 17);
        sprintf(temp, "Host/s");
        printf("%-16s", temp);
        memset(temp, 0, 17);
        sprintf(temp, "B/s");
        printf("%-16s", temp);
        memset(temp, 0, 17);
        sprintf(temp, "Running Thrds");
        printf("%-16s", temp);
        memset(temp, 0, 17);
        sprintf(temp, "Done");
        printf("%s", temp);
        printf("\n");

        char *new;
        new = (char *)malloc(16*6);
        while (running_threads > 0)
        {
                printf("\r");
                memset(new, '\0', 16*6);
                sprintf(new, "%s|%-15lu", new, found_srvs);
                sprintf(new, "%s|%-15d", new, scanned);
                sprintf(new, "%s|%-15d", new, bytes_sent);
                sprintf(new, "%s|%-15d", new, running_threads);
                memset(temp, 0, 17);
                int percent_done=((double)(hosts_done)/(double)(toscan))*100;
                sprintf(temp, "%d%%", percent_done);
                sprintf(new, "%s|%s", new, temp);
                printf("%s", new);
                fflush(stdout);
                bytes_sent=0;
                scanned = 0;
                sleep(1);
        }
        printf("\n");
        fclose(fd);
        exit(0);
}

int main(int argc, char *argv[ ])
{
        if(argc < 6){
                fprintf(stderr, "Invalid parameters!\n");
                fprintf(stdout, "Usage: %s <ip range start (192.168.0.0)> <ip range end (192.168.255.255)> <outfile> <threads> <scan delay in ms>\n", argv[0]);
                exit(-1);
        }
        fd = fopen(argv[3], "a");
        sleep_between = atoi(argv[5]);
        int num_threads = atoi(argv[4]);

        const rlim_t kOpenFD = 1024 + (num_threads * 2);
        struct rlimit rl;
        int result;
        rl.rlim_cur = kOpenFD;
        rl.rlim_max = kOpenFD;
        result = setrlimit(RLIMIT_NOFILE, &rl);
        if (result != 0)
        {
                perror("setrlimit_nofile");
                fprintf(stderr, "setrlimit_nofile returned result = %d\n", result);
        }
        bzero(&rl, sizeof(struct rlimit));
        rl.rlim_cur = 256 * 1024;
        rl.rlim_max = 4096 * 1024;
        result = setrlimit(RLIMIT_STACK, &rl);
        if (result != 0)
        {
                perror("setrlimit_stack");
                fprintf(stderr, "setrlimit_stack returned result = %d\n", result);
        }

        signal(SIGINT, &sighandler);

        pcap_if_t *alldevsp;
        pcap_t *handle; //Handle of the device that shall be sniffed

        char errbuf[100] , *devname , devs[100][100];
        int count = 1 , n;

        if( pcap_findalldevs( &alldevsp , errbuf) )
        {
                exit(1);
        }

        devname = alldevsp->name;
        ipv4 = malloc(16);
        bzero(ipv4, 16);
        struct ifreq ifc;
    int res;
    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);

        if(sockfd < 0) exit(-1);
    strcpy(ifc.ifr_name, devname);
    res = ioctl(sockfd, SIOCGIFADDR, &ifc);
    close(sockfd);
        if(res < 0) exit(-1);
    strcpy(ipv4, inet_ntoa(((struct sockaddr_in*)&ifc.ifr_addr)->sin_addr));
        printf("Opening device %s for sniffing ... " , devname);
        handle = pcap_open_live(devname , 65536 , 1 , 0 , errbuf);

        if (handle == NULL)
        {
                fprintf(stderr, "Couldn't open device %s : %s\n" , devname , errbuf);
                exit(1);
        }
        printf("Done\n");

        sem_init(&loop_sem, 0, -1);
        i = 1024*1000;
        while(i--)
        {
                if(head == NULL)
                {
                        head = (struct buffer *)malloc(sizeof(struct buffer));
                        bzero(head, sizeof(struct buffer));
                        head->data = NULL;
                        head->size = 0;
                        head->next = head;
                        head->prev = head;
                } else {
                        struct buffer *new_node = (struct buffer *)malloc(sizeof(struct buffer));
                        bzero(new_node, sizeof(struct buffer));
                        new_node->data = NULL;
                        new_node->size = 0;
                        new_node->prev = head;
                        new_node->next = head->next;
                        head->next = new_node;
                }
        }

        pthread_t prnthread;
        pthread_create( &prnthread, NULL, &printthread, (void *)argv);
        pthread_t redthread;
        pthread_create( &redthread, NULL, &readthread, NULL);

        pcap_loop(handle , -1 , process_packet , NULL);

        return 0;
}

void process_packet(void *args, struct pcap_pkthdr *header, void *buffer)
{
        int size = header->len;

        //Get the IP Header part of this packet , excluding the ethernet header
        struct iphdr *iph = (struct iphdr*)(buffer + sizeof(struct ethhdr));
        memset(&dest, 0, sizeof(dest));
        dest.sin_addr.s_addr = iph->daddr;

        if(iph->protocol == 17 && strcmp(inet_ntoa(dest.sin_addr), ipv4) == 0)
        {
                //toss into buffer
                if(head->data != NULL) over++;
                pthread_mutex_lock(&buf_mutex);
                void *temp = malloc(size);
                memcpy(temp, buffer, size);
                head->data = temp;
                head->size = size;
                head = head->next;
                pthread_mutex_unlock(&buf_mutex);
                sem_post(&loop_sem);
                total++;
        }
}