| 附send-arp.c测试代码：
----------------------------------------- start ----------------------------------------------------------
/* send_arp.c
这个程序发送ARP包，由使用者提供源/目的IP和网卡地址。编译并运行在Linux环境下，
也可以运行在其它的有SOCK_PACKET的Unix系统上。
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define ETH_HW_ADDR_LEN 6
#define IP_ADDR_LEN 4
#define ARP_FRAME_TYPE 0x0806
#define ETHER_HW_TYPE 1
#define IP_PROTO_TYPE 0x0800
#define OP_ARP_REQUEST 2
#define DEFAULT_DEVICE "eth0"
char usage[]={"send_arp: sends out custom ARP packet.\n
\tusage: send_arp src_ip_addr src_hw_addr targ_ip_addr tar_hw_addr\n\n"};
struct arp_packet {
u_char targ_hw_addr[ETH_HW_ADDR_LEN];
u_char src_hw_addr[ETH_HW_ADDR_LEN];
u_short frame_type;
u_short hw_type;
u_short prot_type;
u_char hw_addr_size;
u_char prot_addr_size;
u_short op;
u_char sndr_hw_addr[ETH_HW_ADDR_LEN];
u_char sndr_ip_addr[IP_ADDR_LEN];
u_char rcpt_hw_addr[ETH_HW_ADDR_LEN];
u_char rcpt_ip_addr[IP_ADDR_LEN];
u_char padding[18];
}; /*arp包结构*/
void die(char *);
void get_ip_addr(struct in_addr*,char*);
void get_hw_addr(char*,char*);
int main(int argc,char** argv){
struct in_addr src_in_addr,targ_in_addr;
struct arp_packet pkt;
struct sockaddr sa;
int sock;
if(argc != 5)die(usage);
sock=socket(AF_INET,SOCK_PACKET,htons(ETH_P_RARP)); /*与目标建立连接*/
if(sock<0){
perror("socket");
exit(1);
}
/* 构造arp包*/
pkt.frame_type = htons(ARP_FRAME_TYPE);
pkt.hw_type = htons(ETHER_HW_TYPE);
pkt.prot_type = htons(IP_PROTO_TYPE);
pkt.hw_addr_size = ETH_HW_ADDR_LEN;
pkt.prot_addr_size = IP_ADDR_LEN;
pkt.op=htons(OP_ARP_REQUEST);
get_hw_addr(pkt.targ_hw_addr,argv[4]);
get_hw_addr(pkt.rcpt_hw_addr,argv[4]);
get_hw_addr(pkt.src_hw_addr,argv[2]);
get_hw_addr(pkt.sndr_hw_addr,argv[2]);
get_ip_addr(&src_in_addr,argv[1]);
get_ip_addr(&targ_in_addr,argv[3]);
memcpy(pkt.sndr_ip_addr,&src_in_addr,IP_ADDR_LEN);
memcpy(pkt.rcpt_ip_addr,&targ_in_addr,IP_ADDR_LEN);
bzero(pkt.padding,18);
strcpy(sa.sa_data,DEFAULT_DEVICE); /*发送arp包*/
if(sendto(sock,&pkt,sizeof(pkt),0,&sa,sizeof(sa)) < 0){
perror("sendto");
exit(1);
}
exit(0);
}
void die(char* str){
fprintf(stderr,"%s\n",str);
exit(1);
}
void get_ip_addr(struct in_addr* in_addr,char* str){
struct hostent *hostp;
in_addr->s_addr=inet_addr(str);
if(in_addr->s_addr == -1){
if( (hostp = gethostbyname(str)))
bcopy(hostp->h_addr,in_addr,hostp->h_length);
else {
fprintf(stderr,"send_arp: unknown host %s\n",str);
exit(1);
}
}
}
void get_hw_addr(char* buf,char* str){
int i;
char c,val;
for(i=0;i= ';a'; && c <= ';f';) val = c-';a';+10;
else die("Invalid hardware address");
*buf = val << 4;
if( !(c = tolower(*str++))) die("Invalid hardware address");
if(isdigit?) val = c-';0';;
else if(c >= ';a'; && c <= ';f';) val = c-';a';+10;
else die("Invalid hardware address");
*buf++ |= val;
if(*str == ';:';)str++;
}
}
-------------------------------------------- end -------------------------------------------------------
（二）
int initsockid, newsockid;
if ((initsockid = socket(...)) <0) {
error("can';t create socket");
}
if (bind(initsockid, ...) <0) {
error("bind error");
}
if (listen(initsockid, 5) <0) {
error("listen error");
}
for (;;) {
newsockid = accept(initsockid, ...); /* 阻塞 */
if (newsockid <0) {
error("accept error");
}
if (fork() == 0) { /* 子进程 */
close(initsockid);
do(newsockid); /* 处理客户方请求 */
exit(0);
}
close(newsockid);
}
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