头文件
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/*myarp.h used by myarp.c */
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#ifndef _MYARP_H
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#define _MYARP_H
" Z" F0 g3 F1 l: Q#include <stdio.h>
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#include <string.h>
1 W c6 ]2 b+ J+ l#include <sys/types.h>
( J! W4 I4 U* S' @* Z#include <netdb.h>
9 v: V+ q4 p ~0 {1 f#include <arpa/inet.h>
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#include <netinet/in.h>
, c6 } f) l l5 c#include <net/if_arp.h>
% n4 |" r" }- j) x' S# v# z#include <signal.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <net/if.h>
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#include <net/ethernet.h>
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#include <netinet/ip.h>
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#define INTERFACE "eth0"
) }/ s8 ~- i9 q: S6 c4 @8 m#define MAX_WAIT_TIME 5
/ U3 [% b1 h) s# p" D#define PACKET_SIZE 4096
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struct myarphdr
' X4 v, G* O6 q% g, ^, \{ unsigned char ether_dhost[ETH_ALEN];
& @; [% _8 j8 _/ \7 c% Aunsigned char ether_shost[ETH_ALEN];
8 |- Y2 y+ d! \7 R" Y$ C: v' s1 J+ Gunsigned short ether_type;
?' ~0 i# O) n* w" e4 J* ]unsigned short ar_hrd;
5 Z3 ~$ P% C3 ?' N Aunsigned short ar_pro;
0 L1 Z0 c4 [6 I4 [ S, Munsigned char ar_hln;
3 J( O5 n+ a0 L, Uunsigned char ar_pln;
# V8 \1 P( ]+ bunsigned char ar_op;
3 j# d6 e3 x2 n }+ F$ }unsigned char ar_sha[ETH_ALEN];
- w0 Q: a/ M- Ounsigned char ar_sip[4];
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unsigned char ar_tha[ETH_ALEN];
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unsigned char ar_tip[4];
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unsigned char padding[18];
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};
: l! C# f- Q4 _" c. {void onTerm();
/ @, X4 M/ U; u+ A1 a5 @" O#endif
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---------------------------------------
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主程序：
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#include "myarp.h"
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struct myarppack
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{
- F0 I) H; }7 J% p4 D struct ether_header eth_hdr;
% |- h4 ]1 S9 [- c# a struct myarphdr arp_hdr;
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};
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int sockfd;
* ~0 I0 X; v, {7 c. p J6 \void onTerm()
9 U# a# Q; y/ I{
- A: W: Q1 m( ?" C! V7 B printf("Time out.\n");
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close(sockfd);
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}
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void print_mac(unsigned char *mac)
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printf(" %02x:%02x:%02x:%02x:%02x:%02x\n",\
3 X) c+ Y. m& M4 t; R *mac, *(mac+1), *(mac+2), *(mac+3), *(mac+4), *(mac+5));
& D5 z; P, e N2 ^# A}
4 d8 }9 g: c8 R9 o1 j% t3 ~* hint main(int argc, char *argv[])
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{
" E8 Q" H7 r; A# J* Q+ y. m+ R int n;
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char interface[16]; //"eth0"
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char packet[PACKET_SIZE];
) Q- B S( R! j struct in_addr srchost, dstaddr;
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struct ifreq ifr;
* M# R" Q% X3 \* ~% ]7 X struct sockaddr_in *sin_ptr;
' e% ~# U" A8 P- L6 Y1 m unsigned char *ptr;
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struct myarppack *arp;
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struct sockaddr from, to;
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printf("Usage: %s IP\n", argv[0]);
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exit(1);
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- e6 c# f* x6 U, K strcpy(interface, INTERFACE);
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dstaddr.s_addr = inet_addr(argv[1]);
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//create socket, only support arp protocol
7 w7 I0 [0 D" x* y& J. Q* Z if ((sockfd = socket(AF_INET, SOCK_PACKET, htons(ETH_P_ARP))) < 0) {
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perror("Create arp socket errr");
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}
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//get local IP
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strcpy(ifr.ifr_name, interface);
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if (ioctl(sockfd, SIOCGIFADDR, &ifr) < 0) {
0 T% R* W$ f9 f+ }2 T& u perror("ioctl SIOCGIFADDR error");
5 f( u$ |8 ?, Y: w5 _& U exit(-1);
& F- u) X& R9 ? }
9 L8 E% {+ k6 o" Q sin_ptr = (struct sockaddr_in *)(&(ifr.ifr_addr));
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srchost = sin_ptr->sin_addr;
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//get local MAC
: b+ s: c2 |8 _: C1 R' ~( T if (ioctl(sockfd, SIOCGIFHWADDR, &ifr) < 0) {
+ Y) F# B' O/ b) r+ P/ K0 q4 z perror("ioctl SIOCGIFHWADDR error");
$ N0 J: z/ L# z1 \ exit(-1);
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}
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ptr = (char *)(&(ifr.ifr_ifru.ifru_hwaddr.sa_data[0]));
/ B5 L; N9 O& h" M ^; U( E printf("Request machine: %s --->", inet_ntoa(srchost));
. K- w" V, D3 j print_mac(ptr);
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arp = (struct myarppack *)packet;
! [% @/ O/ L. j; V //feed ethernet head and arp head
+ f; J4 c) `- p* ? Z6 H: c memset(arp->eth_hdr.ether_dhost, 0xff, 6);
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bcopy(ptr, arp->eth_hdr.ether_shost, 6);
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arp->eth_hdr.ether_type = htons(ETHERTYPE_ARP);
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arp->arp_hdr.ar_hrd = htons(ARPHRD_ETHER);
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arp->arp_hdr.ar_pro = htons(ETHERTYPE_IP);
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arp->arp_hdr.ar_hln = 6;
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. B% t# `$ ~$ _4 g: N arp->arp_hdr.ar_op = htons(ARPOP_REQUEST);
* {$ n" _9 Z- c bcopy(ptr, arp->arp_hdr.ar_sha, 6);
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bcopy(&srchost, arp->arp_hdr.ar_sip, 4);
' a2 |- z8 m) y bzero(arp->arp_hdr.ar_tha, 6);
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bcopy(&dstaddr, arp->arp_hdr.ar_tip, 4);
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bzero(arp->arp_hdr.padding, 18);
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//send arp request
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strcpy(to.sa_data, interface);
4 f& c0 Q" [/ S4 x" I3 S if ((n = sendto(sockfd, packet, sizeof(struct myarppack), 0, &to, sizeof(to))) < 0) {
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perror("send arp request error");
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exit(-1);
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//receive
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strcpy(from.sa_data, interface);
: u/ O- C* [6 r2 v3 l1 h signal(SIGALRM, onTerm);
; o2 @' e( Q% }, }8 f while(2) {
9 s& v' L" |% V# [ alarm(MAX_WAIT_TIME);
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if ((n = recvfrom(sockfd, packet, PACKET_SIZE, 0, &from, &n)) >0) {
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//only show replay which is from request ip
! a/ V1 I0 |1 U5 c5 X if (arp->arp_hdr.ar_op == htons(ARPOP_REPLY) ||
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!memcmp(arp->arp_hdr.ar_sip, &dstaddr, 4)) {
# l. \0 i$ d: j7 M3 Q* x/ ] printf("Reply machine: %s --->",\
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inet_ntoa(*((struct in_addr *)&(arp->arp_hdr.ar_sip[0]))));
6 U5 h& y: `; o- O- E2 n- p print_mac((unsigned char *)&(arp->arp_hdr.ar_sha));
+ C3 g6 q' L/ @" Y: C" d/ Q }
6 Y" W4 b3 S+ d break;
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}
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return 0;
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}
