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电梯直达

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发表于 2010-01-05 16:59 |只看该作者 |倒序浏览

大家好。

我再练习raw socket编程，
写了个小程序。但是在运行的时候（sendto)出现“Permission denied”

我已经加了setuid(getuid()); 怎么会没有权限呢？？？

哪位帮我改改啊？？？

谢谢谢谢:::::::

新手写的代码，大家见谅！
代码：

#define DST 10.117.4.11
#define P 80
struct ipheader {
unsigned char ip_hl:4, ip_v:4; /* this means that each member is 4 bits */
unsigned char ip_tos;
unsigned short int ip_len;
unsigned short int ip_id;
unsigned short int ip_off;
unsigned char ip_ttl;
unsigned char ip_p;
unsigned short int ip_sum;
unsigned int ip_src;
unsigned int ip_dst;
}; /* total ip header length: 20 bytes (=160 bits) */

struct icmpheader {
unsigned char icmp_type;
unsigned char icmp_code;
unsigned short int icmp_cksum;
/* The following data structures are ICMP type specific */
unsigned short int icmp_id;
unsigned short int icmp_seq;
}; /* total icmp header length: 8 bytes (=64 bits) */

struct tcpheader {
unsigned short int th_sport;
unsigned short int th_dport;
unsigned int th_seq;
unsigned int th_ack;
unsigned char th_x2:4, th_off:4;
unsigned char th_flags;
unsigned short int th_win;
unsigned short int th_sum;
unsigned short int th_urp;
}; /* total tcp header length: 20 bytes (=160 bits) */

unsigned short       /* this function generates header checksums */
csum (unsigned short *buf, int nwords)
{
  unsigned long sum;
  for (sum = 0; nwords > 0; nwords--)
sum += *buf++;
  sum = (sum >> 16) + (sum & 0xffff);
  sum += (sum >> 16);
  return ~sum;
}

int main(void)

{

      int sockfd=socket(PF_INET,SOCK_RAW,IPPROTO_TCP);
      printf("socket created succefully and  fd is %d\n",sockfd);
      char buff[4096];
      struct ipheader *iph;
      struct tcpheader *tcph;
      iph=(struct ipheader *) buff;
      tcph=(struct tcpheader *)(buff+sizeof(struct ipheader));
      struct sockaddr_in sin;
      sin.sin_family=AF_INET;
      sin.sin_port=htons(P);
      sin.sin_addr.s_addr=inet_addr("DST");
      memset(buff,0,4096);
      setuid(getuid());
      printf("my uid is %d\n",getuid());
      /*start to make packet*/
      iph->ip_hl = 5;
      iph->ip_v = 4;
      iph->ip_tos = 0;
      iph->ip_len = sizeof (struct ipheader) + sizeof (struct tcpheader); /                                                                            * no payload */
      iph->ip_id = htonl (54321);    /* the value doesn't matter here */
      iph->ip_off = 0;
      iph->ip_ttl = 255;
      iph->ip_p = 6;
      iph->ip_sum = 0;             /* set it to 0 before computing the actu                                                                            al checksum later */
      iph->ip_src = inet_addr ("1.2.3.4");/* SYN's can be blindly spoofed */
      iph->ip_dst = sin.sin_addr.s_addr;
      tcph->th_sport = htons (1234);  /* arbitrary port */
      tcph->th_dport = htons (P);
      tcph->th_seq = random ();/* in a SYN packet, the sequence is a random */
      tcph->th_ack = 0;/* number, and the ack sequence is 0 in the 1st packet                                                                            */
      tcph->th_x2 = 0;
      tcph->th_off = 0;             /* first and only tcp segment */
      tcph->th_flags = 0x02;  /* initial connection request */
      tcph->th_win = htonl (65535); /* maximum allowed window size */
      tcph->th_sum = 0;/* if you set a checksum to zero, your kernel's IP stac                                                                            k
                  should fill in the correct checksum during transmission */
      tcph->th_urp = 0;

      iph->ip_sum = csum ((unsigned short *) buff, iph->ip_len >> 1);

/*t the kernel knows the header is included in the data, and doesn't
insert its own header into the packet before our data */

{                            /* lets do it the ugly way.. */
int one = 1;
const int *val = &one;
if (setsockopt (sockfd, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0)
   printf ("Warning: Cannot set HDRINCL!\n");
  }

while (1)
{
   if (sendto (sockfd,             /* our socket */
               buff, /* the buffer containing headers and data */
               iph->ip_len,  /* total length of our datagram */
               0,          /* routing flags, normally always 0 */
               (struct sockaddr *) &sin,    /* socket addr, just like in */
               sizeof (sin)) < 0)          /* a normal send() */
      {
      perror("error:");
      }
   else
      printf ("date send");
}

      return 0;
}