0
我一直试图在下面的代码。此代码我在互联网上找到的地方发送使用原始套接字的数据包。我创建了自己的ipheader和udp头文件。整个数据包使用原始套接字上的sendto（）函数发送。 sendto（）返回0.这意味着一个长度为0的数据包被发送出去，因此即使wireshark也没有检测到任何数据包。我的错误在哪里？Wireshark没有检测到任何发送的数据包。 SENDTO返回0
// Must be run by root lol! Just datagram, no payload/data
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <cstdlib>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
// The packet length
#define PCKT_LEN 35
// Can create separate header file (.h) for all headers' structure
// The IP header's structure
struct ipheader {
unsigned char iph_ihl:4, iph_ver:4;
unsigned char iph_tos;
unsigned short int iph_len;
unsigned short int iph_ident;
unsigned char iph_flag;
unsigned short int iph_offset;
unsigned char iph_ttl;
unsigned char iph_protocol;
unsigned short int iph_chksum;
unsigned int iph_sourceip;
unsigned int iph_destip;
};
// UDP header's structure
struct udpheader {
unsigned short int udph_srcport;
unsigned short int udph_destport;
unsigned short int udph_len;
unsigned short int udph_chksum;
};
// total udp header length: 8 bytes (=64 bits)
// Function for checksum calculation. From the RFC,
// the checksum algorithm is:
// "The checksum field is the 16 bit one's complement of the one's
// complement sum of all 16 bit words in the header. For purposes of
// computing the checksum, the value of the checksum field is zero."
unsigned short 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 (unsigned short)(~sum);
}
// Source IP, source port, target IP, target port from the command line arguments
int main(int argc, char *argv[])
{
int sd;
// No data/payload just datagram
char buffer[PCKT_LEN];
// Our own headers' structures
struct ipheader *ip = (struct ipheader *) buffer;
struct udpheader *udp = (struct udpheader *) (buffer + sizeof(struct ipheader));
// Source and destination addresses: IP and port
struct sockaddr_in sin, din;
int one = 1;
const int *val = &one;
memset(buffer, 0, PCKT_LEN);
if(argc != 5)
{
printf("- Invalid parameters!!!\n");
printf("- Usage %s <source hostname/IP> <source port> <target hostname/IP> <target port>\n", argv[0]);
exit(-1);
}
// Create a raw socket with UDP protocol
sd = socket(PF_INET, SOCK_RAW, IPPROTO_UDP);
if(sd < 0)
{
perror("socket() error");
// If something wrong just exit
exit(-1);
}
else
printf("socket() - Using SOCK_RAW socket and UDP protocol is OK.\n");
// The source is redundant, may be used later if needed
// The address family
sin.sin_family = AF_INET;
din.sin_family = AF_INET;
// Port numbers
sin.sin_port = htons(atoi(argv[2]));
din.sin_port = htons(atoi(argv[4]));
// IP addresses
sin.sin_addr.s_addr = inet_addr(argv[1]);
din.sin_addr.s_addr = inet_addr(argv[3]);
// Fabricate the IP header or we can use the
// standard header structures but assign our own values.
ip->iph_ihl = 5;
ip->iph_ver = 4;
ip->iph_tos = 16; // Low delay
ip->iph_len = sizeof(struct ipheader) + sizeof(struct udpheader);
ip->iph_ident = htons(54321);
ip->iph_ttl = 64; // hops
ip->iph_protocol = 17; // UDP
// Source IP address, can use spoofed address here!!!
ip->iph_sourceip = inet_addr(argv[1]);
// The destination IP address
ip->iph_destip = inet_addr(argv[3]);
// Fabricate the UDP header. Source port number, redundant
udp->udph_srcport = htons(atoi(argv[2]));
// Destination port number
udp->udph_destport = htons(atoi(argv[4]));
udp->udph_len = htons(sizeof(struct udpheader));
// Calculate the checksum for integrity
ip->iph_chksum = csum((unsigned short *)buffer, sizeof(struct ipheader) + sizeof(struct udpheader));
// Inform the kernel do not fill up the packet structure. we will build our own...
if(setsockopt(sd, IPPROTO_IP, IP_HDRINCL, val, sizeof(one)) < 0)
{
perror("setsockopt() error");
exit(-1);
}
else
printf("setsockopt() is OK.\n");
// Send loop, send for every 2 second for 100 count
printf("Trying...\n");
printf("Using raw socket and UDP protocol\n");
printf("Using Source IP: %s port: %u, Target IP: %s port: %u.\n", argv[1], atoi(argv[2]), argv[3], atoi(argv[4]));
int count;
int i;
for(count = 1; count <=20; count++)
{
if(i = sendto(sd, buffer, PCKT_LEN, 0, (struct sockaddr *)&sin, sizeof(sin)) < 0)
// Verify
{
perror("sendto() error");
exit(-1);
}
else
{
printf("Count #%u - sendto() is OK. Data Length#%d\n", count,i);
sleep(2);
}
}
close(sd);
return 0;
}
这太难以阅读。 – eve
我编辑它使其“更好”，但我认为一些原始空间丢失了。也许Shashi可以编辑和使用{}来标记代码而不是''。 –
然而，我认为0数据包len意味着“什么都没有发送”，所以wireshark不会看到任何东西，因为你从未发送过数据包。至于为什么，我不确定。 –