udp_send.c

udp发送,在vpn环境下

#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <netdb.h>
#include <linux/types.h>
#include <malloc.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/ioctl.h>


#define DEST_IP  "10.5.1.7"
#define MY_IP  "10.214.50.252"
#define PORT 1701
#define TUNNELID 21494	
#define SESSIONID 1557
#define SIZE 1024


/*the global var */
char hostname[256];
int server_socket;
unsigned int listen_addy=INADDR_ANY;
struct sockaddr_in server,to;
char pck[100]="40 02 00 1c 57 7a a8 d1 ff 03 c0 21 05 08 00 10 26 59 7e 30 00 3c cd 74 00 00 00 00";


/*some important header*/
struct lcp{
	char code;
	char identifier;
	short length;
}t;
struct ppp{
	char address;
	char control;
	short protocol;
};
struct l2tp{
	char  packet_type;
	short length;
	short tunnel_id;
	short session_id;
};


struct buffer{
	int  type;
	void *start;
	void *begin;
	void *end ;
	int len;
	int maxlen;
};
struct buffer *new_buff(int size)
{
    struct buffer *b = (struct buffer *)malloc (sizeof (struct buffer));

/*a buffer with fixed begin buffer->begin and fixed end buffer->end  
the real start is buffer->start 
the real length is buffer->len
the max length is buffer->maxlen
consideration of tcp/ip stack model*/
    b->start = malloc (size);
    if (!b->start)
    {
        free (b);
        return NULL;
    }
    b->begin= b->start;
    b->end = b->start + size - 1;
    b->start=b->end;
    b->len = 0;
    b->maxlen = size;
    return b;
}

int add_l2tpheader(struct buffer * buff)
{
	struct l2tp * p=NULL;
	char *ptr=NULL;
	buff->start-=sizeof(struct l2tp);
	buff->len+=sizeof(struct l2tp);
	
	p=(struct l2tp *)buff->start;

	/*p->packet_type=0x4002 was raw idea*/
	ptr=(char *)&(p->packet_type);
	*ptr=0x40;ptr++;
	*ptr=0x02;

	p->length=htons(28);
	p->tunnel_id=htons(TUNNELID);
	p->session_id=htons(SESSIONID);
	printf("----%d----\n",buff->end-buff->start);
	return 0;
}
int add_pppheader(struct buffer * buff)
{
	struct ppp *p=NULL;
	char *ptr=NULL;
	/*stuff the ppp header*/
	buff->start-=sizeof(struct ppp);
	buff->len+=sizeof(struct ppp);
	p=(struct ppp *)buff->start;
	p->address=0xff;
	p->control=0x03;


	
	/*p->protocol=htonl(0xc021); is the raw idea */
	ptr=(char *)&(p->protocol);
	*ptr=0xc0;ptr++;
	*ptr=0x21;
	
	
	printf("----%d----\n",buff->end-buff->start);
	return 0;
}
int add_lcpheader(struct buffer * buff)
{
	int lcp_last[8]={0,60,205,116,0,0,0,0};
	int lcp_last_[4]={23,51,99,84};
	struct lcp *p=NULL;
	char *ptr=NULL;
	int i=0;
	
	/*stuff the data fields with all zero*/
	buff->start-=12;
	buff->len+=12;
	ptr=(char *)buff->start;


	/*stuff the end of lcp data*/
	for (i=0;i<4;i++){*ptr=lcp_last_[i];ptr++;}/*zero is terperary ,i don't know the real mean of the field*/
	for (i=0;i<8;i++)
		{
			*ptr=0;
			*ptr+=lcp_last[i];ptr++;
		}
//	strcpy(buff->start,tmp);

	
	/*stuff the lcp header*/
	buff->start-=sizeof(struct lcp);
	buff->len+=sizeof(struct lcp);
	p=(struct lcp*)buff->start;
	p->code=0x05;
	p->identifier=0x08;
	p->length=htons(16);
	printf("----%d----\n",buff->end-buff->start);
	return 0;
}

int _packet_send (struct buffer  * buff, struct sockaddr_in  to)
{
	int a=0;
	
	if ((a=add_lcpheader(buff))){printf("error at lcp%d\n",a);}
	printf("add packet header lcp sucessfully!\n");
	if (add_pppheader(buff)!=0){printf("error at ppp\n");}
	printf("add packet header ppp sucessfully!\n");
	if (add_l2tpheader(buff)!=0){printf("error at l2tp\n");}
	printf("add packet header l2tp sucessfully!\n");

	printf("the buffer data is %s\n",buff->start);


	char tmp[100]="abcd";
	for (a=0;a<10;a++)
	if((a=sendto(server_socket,buff->start,buff->len,0,(struct sockaddr *)&to,sizeof(to)))==-1){printf("socket send function error!\n");return 6;}
	//if(a=sendto(server_socket,tmp,sizeof(tmp),0,(struct sockaddr *)&to,sizeof(to))){printf("socket send function error!---%d\n",a);return 6;}
	
	/*	for (int i=0;i<65000;i++)
		{
			if (add_l2tpheader(buff)){printf("error at l2tp\n");return 3;}
			if(sendto(socket,buff,sizeof(buff),0,to)){printf("error at lcp\n");return 6;}
		}*/
	return 0;
}
int packet_send(struct buffer * buff,struct sockaddr_in to)
{
	int a=0;
	int tmp=0;
	char c=' ';/*tmp char to save the var*/
	buff->start-=28;
	char *p=(char *)buff->start;
	buff->len=28;

	for(a=0;a<strlen(pck);a+=3)
	{		
		sscanf(pck+a,"%x",&tmp);
		c=0;
		c+=tmp;
		*p=c;
		p++;
	}
	/*printf("%x\n",buff->start);*/
	if((a=sendto(server_socket,buff->start,buff->len,0,(struct sockaddr *)&to,sizeof(to)))==-1){printf("socket send function error!---%d\n",a);return 6;}
}

int init_network (void)
{
 	long arg;
	int length = sizeof (server);
	/*destnation address family,ip and port*/
	to.sin_family = AF_INET;
	to.sin_addr.s_addr = (inet_addr(DEST_IP));//htonl 
	to.sin_port = htons (PORT);
	
    
	/*    struct   hostent   *ht=NULL; 
	gethostname (hostname, sizeof (hostname));	
    	ht=gethostbyname(const   char   *hostname);   ht->h_addr_list[0]*/
	
	/*set the send's address family ,ip and port*/
	
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = htonl (inet_addr(MY_IP));/*set a statical ip address*/
    server.sin_port = htons (PORT);

/*create socket, bind and test*/
    if ((server_socket = socket (PF_INET, SOCK_DGRAM, 0)) < 0)
    {
    	printf("socket create error\n");
        return -1;
    };
	
    if (arg=bind (server_socket, (struct sockaddr *) &server, sizeof(server)))
    {
    	 printf("%d----%d-----%d\n",server.sin_family,server.sin_port,server.sin_addr.s_addr);
   	 printf("%d----%d----%d\n",to.sin_family,to.sin_port,to.sin_addr.s_addr);
    	 printf("socket bind error%d---\n",arg);
        close (server_socket);


        return -1;
    };
    if (getsockname (server_socket, (struct sockaddr *) &server, &length))
    {
    	printf("socket test error\n");
        return -1;
    }
	/*set the file flags*/
    arg = fcntl (server_socket, F_GETFL);/*get file flag*/
    arg |= O_NONBLOCK;/*non block type */
    fcntl (server_socket, F_SETFL, arg);/*set the file flag*/
	
    return 0;
}

int main()
{	
	int type=0;
	struct buffer *buff;
	buff=new_buff(SIZE);
	printf("network init.  waiting ........\n");

	if(init_network()){return -1;}
	printf("initial is ok\n");

	_packet_send(buff,to);
	return 0;
}