原始套接字实现

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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#ifdef WIN32
#include <Winsock2.h>
#include <ws2ipdef.h>
#include <WS2tcpip.h>
#else
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
#endif
#ifdef WIN32
#pragma comment(lib,"ws2_32.lib")
#else
#define SOCKET_ERROR -1
typedef int BOOL;
#endif
#define DEFAULT_PORT 10089
typedef struct ip_head
{
union
{
unsigned char Version;
unsigned char HeadLen;
};
unsigned char ServiceType;
unsigned short TotalLen;
unsigned short Identifier;
union
{
unsigned short Flags;
unsigned short FragOffset;
};
unsigned char TimeToLive;
unsigned char Protocol;
unsigned short HeadChecksum;
unsigned int SourceAddr;
unsigned int DestinAddr;
}IP_HEADER;
/*
* TCP header.
* Per RFC 793, September, 1981.
*/
typedef struct tcp_head {
u_short th_sport; /* source port */
u_short th_dport; /* destination port */
unsigned int th_seq; /* sequence number */
unsigned int th_ack; /* acknowledgement number */
unsigned char th_lenres;
u_char th_flags;
u_short th_win; /* window */
u_short th_sum; /* checksum */
u_short th_urp; /* urgent pointer */
}TCP_HEADER;
//tcp伪报头
typedef struct psd_hdr
{
unsigned long saddr;
unsigned long daddr;
char mbz;
char ptcl; //协议类型
unsigned short tcpl; //tcp长度
}PSD_HEADER;
typedef struct udp_head
{
unsigned short uh_sport;
unsigned short uh_dport;
unsigned short uh_len;
unsigned short uh_sum;
}UDP_HEADER;
struct tcpiphdr
{
ip_head ipHead;
tcp_head tcpHead;
};
void InitSocket()
{
#ifdef WIN32
WSADATA wsaData;
WORD wVersionRequested = MAKEWORD(2, 2);
int err = WSAStartup(wVersionRequested, &wsaData);
if(err != 0)
{
printf("windows socket DLL initiates faild\n");
exit(-1);
}
#endif
}
int GetErrNo()
{
#ifdef WIN32
return WSAGetLastError();
#else
return errno;
#endif
}
const char* GetErrStr(int errnum)
{
#ifdef WIN32
return "请查看msdn帮助文档或定义winerror.h";
#else
return strerror(errnum);
#endif
}
//设置虚拟IP地址
void SetVirtualIp(int fd, const char* userIp)
{
bool flag = true;
if(setsockopt(fd,IPPROTO_IP,IP_HDRINCL,(char *) &flag,sizeof(flag))==SOCKET_ERROR)
{
printf("windows socket DLL initiates faild\n");
exit(-1);
}
}
unsigned short CheckSum(unsigned short *buffer, int size)
{
unsigned long cksum = 0;
while(size > 0)
{
cksum += *buffer;
size -= sizeof(unsigned short );
}
if (size)
{
cksum += *(unsigned short*)buffer;
}
cksum = (cksum >> 16) + (cksum & 0xffff);
cksum += (cksum >> 16);
return (unsigned short )(~cksum);
}
void WriteTcpPkg(const char* sourceIp, const char* destIp, unsigned int destPort, char* szBuffer )
{
int iTotalSize = sizeof(ip_head) + sizeof(tcp_head);
int iIpVersion = 4;
int iIpSize = sizeof(ip_head)/sizeof(unsigned long);
ip_head ipHead;
tcp_head tcpHead;
psd_hdr psdHead;
ipHead.Version = (iIpVersion << 4) | iIpSize;
//ipHead.ServiceType = 0;
ipHead.TotalLen = htons(iTotalSize);
ipHead.Identifier = 1;
ipHead.FragOffset = 0;
ipHead.TimeToLive = 128;
ipHead.Protocol = IPPROTO_TCP;
ipHead.HeadChecksum = 0;
ipHead.SourceAddr = inet_addr(sourceIp);
ipHead.DestinAddr = inet_addr(destIp);
tcpHead.th_sport = htons(DEFAULT_PORT);
tcpHead.th_dport = htons(destPort);
tcpHead.th_seq = htonl(0x12345678);
tcpHead.th_ack = 0;
tcpHead.th_lenres = (sizeof(tcp_head)/4 << 4 | 0);
tcpHead.th_flags = 2; //标志位探测 2是syn
tcpHead.th_win = htons(512);
tcpHead.th_urp = 0;
tcpHead.th_sum = 0;
psdHead.saddr = ipHead.SourceAddr;
psdHead.daddr = ipHead.DestinAddr;
psdHead.mbz = 0;
psdHead.ptcl = IPPROTO_TCP;
psdHead.tcpl = htons(sizeof(tcp_head));
//计算校验和
memcpy(szBuffer, &psdHead, sizeof(psdHead));
memcpy(szBuffer + sizeof(psdHead), &tcpHead, sizeof(tcpHead));
tcpHead.th_sum = CheckSum( (unsigned short*)szBuffer, sizeof(psdHead) + sizeof(tcpHead));
memcpy(szBuffer, &ipHead, sizeof(ipHead));
memcpy(szBuffer + sizeof(ipHead), &tcpHead, sizeof(tcpHead));
memset(szBuffer + sizeof(ipHead) + sizeof(tcpHead), 0, sizeof(int));
ipHead.HeadChecksum = CheckSum((unsigned short*)szBuffer, sizeof(ipHead) + sizeof(tcpHead));
memcpy(szBuffer, &ipHead, sizeof(ipHead));
}
void MyConnectTcp(sockaddr_in &servaddr)
{
int fd = socket(AF_INET, SOCK_DGRAM, 0);
int r = connect(fd, (struct sockaddr*)&servaddr, sizeof(servaddr));
int ret = sendto(fd, "hello", 5, 0, (struct sockaddr*)&servaddr, sizeof(servaddr));
struct sockaddr_in clientaddr;
socklen_t size = sizeof(clientaddr);
char szBuf[1024];
ret = recvfrom(fd, szBuf, 1024, 0,(struct sockaddr*)&clientaddr, &size);
}
int main(int argc, char** argv)
{
if(argc < 5)
{
printf("usage : tm_client servIp servPort data userIp\n");
exit(-1);
}
char servIp[64], userIp[64], workfId[16];
int port = atoi(argv[2]);
strcpy(servIp, argv[1]);
strcpy(workfId, argv[3]);
strcpy(userIp, argv[4]);
struct sockaddr_in servaddr;
InitSocket();
//创建原始套接字，需要有超级用户的权限
int fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
if( fd == SOCKET_ERROR)
{
printf("%s\n", GetErrStr(GetErrNo()));
printf("socket函数执行失败\n");
return 1;
}
//Header is included with data. 报文将由自己组装，以数据的形式进行发送
BOOL flag = true;
if(setsockopt(fd,IPPROTO_IP,IP_HDRINCL,(char *)&flag,sizeof(flag))==SOCKET_ERROR)
{
printf("%d", GetErrNo());
printf("set socket IP_HDRINCL faild\n");
exit(-1);
}
//设置超时
int nTimeOver = 1000;
if(setsockopt(fd,SOL_SOCKET,SO_SNDTIMEO,(char *)&nTimeOver,sizeof(nTimeOver))==SOCKET_ERROR)
{
printf("%d", GetErrNo());
printf("set socket SO_SNDTIMEO faild\n");
exit(-1);
}
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr(servIp);
servaddr.sin_port = htons(port);
char szDataBuf[1024];
memset(szDataBuf, 0, sizeof(szDataBuf));
int ipsize = sizeof(ip_head), tcpsize = sizeof(tcp_head);
int iTotalSize = sizeof(ip_head) + sizeof(tcp_head);
WriteTcpPkg(userIp, servIp, port, szDataBuf);
//此处在XP系统下会返回错误码WSAEINTR，表示通过WSACancelBlockingCall函数中断了，xp sp2及以上版本都会遇到这个问题
if(sendto(fd, szDataBuf, iTotalSize, 0, (struct sockaddr*)&servaddr, sizeof(servaddr)) == SOCKET_ERROR)
{
printf("sendto message faild, errno = %d\n", GetErrNo());
exit(-1);
}
struct sockaddr_in cliaddr;
socklen_t cliLen = sizeof(cliaddr);
if( recvfrom(fd,szDataBuf, sizeof(iTotalSize), 0, (struct sockaddr*)&cliaddr, &cliLen) < 0)
{
printf("recvfrom message faild\n");
exit(-1);
}
#ifdef WIN32
closesocket(fd);
WSACleanup();
#else
close(fd);
#endif
return 0;
}