你确定一下你发送数据包的目的端点是不是有在监听这个端口，如果没有，那么对方主机会发一个代表错误的数据包过来，然后你的recvfrom就失败了（返回-1）
#define RCVALL_ON 1#define MAX_ADDR_LEN 16 //点分十进制地址的最大长度
#define MAX_PROTO_TEXT_LEN 16 //子协议名称(如"TCP")最大长度
#define WINSOCK_VERSION MAKEWORD(2, 2)
#pragma comment(lib, "Ws2_32.lib")
#include <stdio.h>
#include <winsock2.h>
#include <mstcpip.h>
#include <conio.h>
typedef struct iphdr //定义IP首部
{
unsigned char h_lenver//4位首部长度+4位IP版本号
unsigned char tos//8位服务类型TOS
unsigned short total_len//16位总长度（字节）
unsigned short ident//16位标识
unsigned short frag_and_flags//3位标志位
unsigned char ttl//8位生存时间 TTL
unsigned char proto//8位协议 (TCP, UDP 或其他)
unsigned short checksum//16位IP首部校验和
unsigned int sourceIP//32位源IP地址
unsigned int destIP//32位目的IP地址
}IPHeader
typedef struct _tcphdr//定义TCP首部
{
USHORT th_sport//16位源端口
USHORT th_dport//16位目的端口
unsigned int th_seq//32位序列号
unsigned int th_ack//32位确认号
unsigned char th_lenres//4位首部长度/6位保留字
unsigned char th_flag//6位标志位
USHORT th_win//16位窗口大小
USHORT th_sum//16位校验和
USHORT th_urp//16位紧急数据偏移量
}TCP_HEADER
typedef struct _udphdr //定义UDP首部
{
unsigned short uh_sport//16位源端口
unsigned short uh_dport//16位目的端口
unsigned short uh_len//16位长度
unsigned short uh_sum//16位校验和
}UDP_HEADER
typedef struct _icmphdr //定义ICMP首部
{
BYTE i_type //8位类型
BYTE i_code //8位代码
USHORT i_cksum //16位校验和
USHORT i_id //识别号（一般用进程号作为识别号）
USHORT i_seq //报文序列号
ULONG timestamp //时间戳
}ICMP_HEADER
int iTTL,iLEN,iBYTES
char szSourceIP[MAX_ADDR_LEN], szDestIP[MAX_ADDR_LEN]
int iSourcePort,iDestPort
int fflag=0//file flag
#define PACKAGE_SIZE sizeof(IPHeader)+1000
void HandleError(char *func)
//functions
int DecodeTcpPack(char *, int,FILE *)//TCP解包函数
int DecodeUdpPack(char *, int,FILE *)//UDP解包函数
int DecodeIcmpPack(char *, int,FILE *)//ICMP解包函数
//MAIN
int main(int argc, char *argv[])
{
sockaddr_in saSource,saDest
WSAData wsaData
char buf[PACKAGE_SIZE]
WSAStartup(WINSOCK_VERSION, &wsaData)
SOCKET sock = socket(AF_INET, SOCK_RAW, IPPROTO_IP)
if(sock == SOCKET_ERROR)
{
HandleError("socket")
WSACleanup()
return -1
}
//获取本机IP地址
struct sockaddr_in addr
memset(&addr, 0, sizeof(addr))
//addr.sin_addr.S_un.S_addr = inet_addr("192.168.1.101")
char name[256]
PHOSTENT hostinfo
if( gethostname ( name, sizeof(name)) == 0)
{
if((hostinfo = gethostbyname(name)) != NULL)
{
memcpy(&(addr.sin_addr.S_un.S_addr) , (struct in_addr *)*hostinfo->h_addr_list , sizeof((struct in_addr *)*hostinfo->h_addr_list ))
}
}
addr.sin_family = AF_INET
if(bind(sock, (struct sockaddr*)&addr, sizeof(addr)) == SOCKET_ERROR)//bind
{
HandleError("bind")
}
//设置SOCK_RAW为SIO_RCVALL，以便接收所有的IP包
int on = RCVALL_ON
DWORD num
if(WSAIoctl(sock, SIO_RCVALL, &on, sizeof(on), NULL, 0, &num, NULL, NULL) == SOCKET_ERROR)
{
HandleError("wsaIoctl set")
}
struct sockaddr_in from
int fromlen
int size
FILE *fp
if((fp=fopen("log.txt","w+"))==NULL)
{
printf("open file errer,can't save list to file")
fflag=1
}
//侦听IP报文
while(!kbhit())
{
memset(buf, 0, sizeof(num))
memset(&from, 0, sizeof(from))
fromlen = sizeof(from)
size=recvfrom(sock, buf, PACKAGE_SIZE, 0, (struct sockaddr*)&from, &fromlen)
if(size == SOCKET_ERROR)
{
if(WSAGetLastError() == WSAEMSGSIZE)
{
HandleError("recvfrom")
continue
}
}
IPHeader *iph=(IPHeader *)buf
/**/
//源地址
saSource.sin_addr.s_addr = iph->sourceIP
strncpy(szSourceIP, inet_ntoa(saSource.sin_addr), MAX_ADDR_LEN)
//目的地址
saDest.sin_addr.s_addr = iph->destIP
strncpy(szDestIP, inet_ntoa(saDest.sin_addr), MAX_ADDR_LEN)
iTTL = iph->ttl
//计算IP首部的长度
int IpHeadLen = 4 * (iph->h_lenver &0xf)
//根据协议类型分别调用相应的函数
switch(iph->proto)
{
case IPPROTO_ICMP:
DecodeIcmpPack(buf+IpHeadLen, size,fp)
break
case IPPROTO_IGMP:
printf("IGMP ")
printf("%15s: ->%15s: ", szSourceIP, szDestIP)
printf("%d",size)
printf("%s/n", buf)
break
case IPPROTO_TCP:
DecodeTcpPack((buf+IpHeadLen),size,fp)
break
case IPPROTO_UDP:
DecodeUdpPack(buf+IpHeadLen, size,fp)
break
default:
printf("unknown datagram from %s/n", inet_ntoa(from.sin_addr))
printf("%s/n", buf)
break
}//end switch
Sleep(200)
}//end while
fclose(fp)
closesocket(sock)
WSACleanup()
printf("Stopped!/n")
getch()
return 0
}//end of main
//TCP解包程序
int DecodeTcpPack(char * TcpBuf, int iBufSize,FILE *fp)
{
unsigned char FlagMaskFlagMask = 1
int i
TCP_HEADER *tcph
tcph = (TCP_HEADER*)TcpBuf
//计算TCP首部长度
int TcpHeadLen = tcph->th_lenres>>4
TcpHeadLen *= sizeof(unsigned long)
char *TcpData=TcpBuf+TcpHeadLen
iSourcePort = ntohs(tcph->th_sport)
iDestPort = ntohs(tcph->th_dport)
//输出
printf("TCP ")
printf("%15s:%5d ->%15s:%5d ", szSourceIP, iSourcePort, szDestIP, iDestPort)
printf("TTL=%3d ", iTTL)
if(fflag==1)
//判断TCP标志位
for( i=0i<6i++ )
{
if((tcph->th_flag) &FlagMask)
printf("1")
else printf("0")
FlagMask=FlagMask<<1
}
printf(" bytes=%4d", iBufSize)
printf("/n")
if(fflag=1)//写入文件
fprintf(fp,"TCP %15s:%5d ->%15s:%5d TTL=%3d ------ bytes=%4d/n"
,szSourceIP, iSourcePort, szDestIP, iDestPort, iTTL,iBufSize)
return 0
}
//UDP解包程序
int DecodeUdpPack(char * UdpBuf, int iBufSize,FILE *fp)
{
UDP_HEADER *udph
udph = (UDP_HEADER*)UdpBuf
iSourcePort = ntohs(udph->uh_sport)
iDestPort = ntohs(udph->uh_dport)
//输出
printf("UDP ")
printf("%15s:%5d ->%15s:%5d ", szSourceIP, iSourcePort, szDestIP, iDestPort)
printf("TTL=%3d ", iTTL)
printf("Len=%4d ", ntohs(udph->uh_len))
printf("bytes=%4d", iBufSize)
printf("/n")
if(fflag=1)//写入文件
fprintf(fp,"UDP %15s:%5d ->%15s:%5d TTL=%3d Len=%4d bytes=%4d/n"
,szSourceIP, iSourcePort, szDestIP, iDestPort, iTTL, ntohs(udph->uh_len), iBufSize)
return 0
}
//ICMP解包程序
int DecodeIcmpPack(char * IcmpBuf, int iBufSize,FILE *fp)
{
ICMP_HEADER * icmph
icmph = (ICMP_HEADER * )IcmpBuf
int iIcmpType = icmph->i_type
int iIcmpCode = icmph->i_code
//输出
printf("ICMP ")
printf("%15s ->%15s", szSourceIP, szDestIP)
printf("TTL=%3d ", iTTL)
printf("Type%2d,%d ",iIcmpType,iIcmpCode)
printf("bytes=%4d", iBufSize)
printf("/n")
if(fflag=1)//写入文件
fprintf(fp,"ICMP %15s ->%15sTTL=%3d Type%2d,%d bytes=%4d"
, szSourceIP, szDestIP, iTTL,iIcmpType,iIcmpCode, iBufSize)
return 0
}
void HandleError(char *func)
{
char info[65]= {0}
_snprintf(info, 64, "%s: %d/n", func, WSAGetLastError())
printf(info)
}
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