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Ivan's ping.c
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‎sockets/RAW/ping.c‎

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/*
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* ping.c
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* written by Ivan Ryabtsov ivriabtsov at gmail dot com
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*/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <limits.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include <netinet/ip_icmp.h>
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#include <netinet/ip.h>
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#include <string.h>
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struct stuff {
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int recv_sock, send_sock;
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struct sockaddr_in recv_sockaddr, send_sockaddr;
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struct hostent *h_ent;
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};
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int ping(const char *name);
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int routines(struct stuff *conn);
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unsigned short in_cksum(unsigned short *addr, size_t len);
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int main(int argc, char *argv[])
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{
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if (argc < 2) {
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printf("need hostname\n");
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exit(1);
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}
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if (ping(argv[1])) {
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printf("host %s is alive\n", argv[1]);
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} else {
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printf("host %s is not alive\n", argv[1]);
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}
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return 0;
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}
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int ping(const char *name)
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{
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struct stuff *conn;
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conn = malloc(sizeof(struct stuff));
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conn->h_ent = gethostbyname(name);
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if (!conn->h_ent) {
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perror("gethostbyname: ");
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return 0;
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}
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if ( (conn->send_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) ==
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-1) {
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perror("socket: ");
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return 0;
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}
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conn->send_sockaddr.sin_family = AF_INET;
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conn->send_sockaddr.sin_addr.s_addr =
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*(in_addr_t *)conn->h_ent->h_addr_list[0];
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/*printf("0x%X\n", send_sockaddr.sin_addr.s_addr);*/
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if ( (conn->recv_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) ==
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-1) {
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perror("socket: ");
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return 0;
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}
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conn->recv_sockaddr.sin_family = AF_INET;
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conn->recv_sockaddr.sin_addr.s_addr = *(long *)conn->
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h_ent->h_addr_list[0];
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/*printf("0x%X\n", recv_sockaddr.sin_addr.s_addr);*/
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if (routines(conn) >= 3) {
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return 1;
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} else {
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return 0;
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}
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}
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#define BUF_SIZ 100
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#define LOAD_SIZ 5
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struct s_frame {
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struct icmphdr _icmphdr;
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char payload[LOAD_SIZ];
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};
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int routines(struct stuff *conn)
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{
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struct s_frame *send_frame;
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void *recv_frame;
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unsigned short cksum, seqtmp;
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int i, succ_cnt = 0;
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time_t t;
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int iphdrlen, icmplen;
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socklen_t len = sizeof(struct sockaddr_in);
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srand((unsigned int)time(&t));
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send_frame = malloc(sizeof(struct s_frame));
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if (!send_frame) {
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perror("malloc: ");
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return 0;
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}
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recv_frame = malloc(BUF_SIZ);
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if (!recv_frame) {
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perror("malloc: ");
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return 0;
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}
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send_frame->_icmphdr.type = ICMP_ECHO;
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send_frame->_icmphdr.code = ICMP_ECHOREPLY;
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/*send_frame->_icmphdr.un.echo.id = rand() % (USHRT_MAX + 1);*/
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send_frame->_icmphdr.un.echo.id = rand() % (USHRT_MAX + 1);
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send_frame->_icmphdr.un.echo.sequence = htons(1);
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/*send_frame->payload = rand() % (UINT_MAX + 1);*/
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for (i = 0; i < 4; i++) {
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memset(recv_frame, 0, 1400);
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send_frame->_icmphdr.checksum = 0;
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send_frame->_icmphdr.checksum =
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in_cksum((unsigned short *)send_frame,
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sizeof(struct s_frame));
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if (sendto(conn->send_sock, send_frame, sizeof(struct s_frame),
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0, (struct sockaddr *)&conn->
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send_sockaddr,
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sizeof(struct sockaddr_in)) == -1) {
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perror("!!!!!sendto: ");
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goto cont;
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}
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if (recvfrom(conn->recv_sock, recv_frame, BUF_SIZ,
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MSG_WAITALL,
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(struct sockaddr *)&conn->recv_sockaddr,
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&len) == -1) {
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perror("!!!!!recvfrom: ");
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goto cont;
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}
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/*sleep(1);*/
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/* comparison src and dest addresses */
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if ( *(unsigned int *)conn->h_ent->h_addr_list[0] ==
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((struct iphdr *)recv_frame)->saddr) {
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printf("package with a valid addresses\n");
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} else {
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printf("!!!!!src and dest addresses is not walid\n");
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goto cont;
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}
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/*
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printf("s 0x%X, d 0x%X\n", ((struct iphdr *)recv_frame)->saddr,
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((struct iphdr *)recv_frame)->daddr);
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*/
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iphdrlen = ((struct iphdr *)recv_frame)->ihl * sizeof(int);
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/* check chksum in ip header */
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cksum = ((struct iphdr *)recv_frame)->check;
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((struct iphdr *)recv_frame)->check = 0;
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if (cksum == in_cksum((unsigned short *)recv_frame, iphdrlen)){
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printf("ip cksum is equal %hu\n", cksum);
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} else {
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printf("!!!!!ip cksum is not equal %hu\n", cksum);
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goto cont;
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}
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/* compute len of icmp header */
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icmplen = ntohs(((struct iphdr *)recv_frame)->tot_len) -
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iphdrlen;
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/*printf("iphdr len: %d, icmp len: %d, all frame len: %hu\n",
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iphdrlen, icmplen,
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ntohs(((struct iphdr *)recv_frame)->tot_len));
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printf("%p, %p\n", recv_frame, recv_frame + iphdrlen);
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printf("%p, %p\n", recv_frame, (struct icmphdr *)(recv_frame +
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iphdrlen));
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printf("%d\n", ((struct icmphdr *)(recv_frame + iphdrlen))->
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checksum);*/
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/* check icmp id and sequence number */
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if (((struct icmphdr *)(recv_frame + iphdrlen))->un.echo.id ==
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send_frame->_icmphdr.un.echo.id) {
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printf("recv and send id is equal %hu\n",
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ntohs(send_frame->_icmphdr.un.echo.id));
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} else {
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printf("!!!!!id is not equal %hu\n",
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ntohs(send_frame->_icmphdr.un.echo.id));
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goto cont;
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}
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if (((struct icmphdr *)(recv_frame + iphdrlen))->
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un.echo.sequence ==
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send_frame->_icmphdr.un.echo.sequence) {
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printf("recv end send seq is equal %hu\n",
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ntohs(send_frame->
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_icmphdr.un.echo.sequence));
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} else {
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printf("!!!!sequence is not equal l %hu, r %hu\n",
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ntohs(send_frame->
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_icmphdr.un.echo.sequence),
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htons(((struct icmphdr *)
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(recv_frame + iphdrlen))
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->un.echo.sequence));
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// goto cont;
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}
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/* check chksum of icmp header */
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cksum = ((struct icmphdr *)(recv_frame + iphdrlen))->
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checksum;
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/*printf("recv chsum: %hu\n", cksum);*/
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((struct icmphdr *)(recv_frame + iphdrlen))->checksum = 0;
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if (cksum == in_cksum((unsigned short *)
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(recv_frame + iphdrlen), icmplen)) {
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printf("icmp cksum is equal %d\n", cksum);
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succ_cnt++;
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printf("%d\n", succ_cnt);
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} else {
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printf("!!!!!icmp checksum is not walid %hu\n", cksum);
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goto cont;
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}
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cont:
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seqtmp = ntohs(send_frame->_icmphdr.un.echo.sequence);
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seqtmp++;
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send_frame->_icmphdr.un.echo.sequence = htons(seqtmp);
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printf("next sequence is %hu\n=============\n", seqtmp);
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}
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return succ_cnt;
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}
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unsigned short in_cksum(unsigned short *addr, size_t len)
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{
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int nleft = len;
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int sum = 0;
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unsigned short *w = addr;
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unsigned short answer = 0;
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while (nleft > 1) {
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sum += *w++;
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nleft -= 2;
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}
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if (nleft == 1) {
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*(unsigned char *)(&answer) += *(unsigned char *)w;
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sum += answer;
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}
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sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
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sum += (sum >> 16); /* add carry */
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answer = ~sum; /* truncate to 16 bits */
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return(answer);
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}
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