Random IP Generation Program

[charlie]

Hello,I was Designing a Program that has two function the random_ip() and main()
the random_ip() returns an array of random generated ip address

#include<stdio.h>
#include<netinet/in.h>
#include<stdlib.h>
#include<string.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<errno.h>

char* random_ip(char figure,int size,int check)//a thousand,mil,bil etc
{
	printf("Figure %c Size %d\n",figure,size);
	int i=65536;	
	int j=0;
	int  BUFSIZE;
	struct sockaddr_in temp;
	switch(figure)
	{
		case 't':
		BUFSIZE=(size*1024);
		break;

		case 'm':
		BUFSIZE=(size*1024*1024);
		break;
	
		case 'b':
		BUFSIZE=(size*1024*1024*1024);
		break;

		default:printf("Choose btn choices available!\n");
	}	
	printf("BUFSIZE %d\n",BUFSIZE);
	char *ip_buffer[BUFSIZE];
	srand(i);//seed the randomizer
	while(j<BUFSIZE)
	{
		ip_buffer[j]=(char*)malloc(16);
		temp.sin_addr.s_addr=(unsigned long)rand()%4294967295;

		ip_buffer[j]=(char*)malloc(16);

		strcpy(ip_buffer[j],inet_ntoa(temp.sin_addr));
		
		j++;
	
	}
	
	if(check){
	int a;
	int repeated=0;
	char*ip;
	for(j=0;j<BUFSIZE;j++)
	{
		ip=(char*)malloc(16);
		strcpy(ip,ip_buffer[j]);
		
		for(a=++j;a<BUFSIZE;a++)
		{	
			if((strcmp(ip,ip_buffer[a]))==0){//repeated ip	
				repeated++;	
				printf("\t\t\t\tFound %s repeated addresses.\n",ip);
			}	
		}	
		ip=NULL;
	}
	if(repeated>0)
	printf("Found %d repetead Addresses in %d Addresses.\n",repeated,BUFSIZE);
	}
	
return ip_buffer;
}
main(int argc,char**argv)
{

	int i=9;
	int j=0;
	int BUFSIZE;
	srand(i);//seed the randomizer
	switch((char)*argv[1])
	{
		case 't':
		BUFSIZE=(atoi(argv[2])*1024);
		break;

		case 'm':
		BUFSIZE=(atoi(argv[2])*1024*1024);
		break;
	
		case 'b':
		BUFSIZE=(atoi(argv[2])*1024*1024*1024);
		break;

		default:printf("Choose btn choices available!\n");
	}
	printf("BUFSIZE MAIN:%d\n",BUFSIZE);
	char *ip_buffer[BUFSIZE];
	memcpy(ip_buffer,random_ip((char)*argv[1],atoi(argv[2]),0),BUFSIZE);
	
	while(j<BUFSIZE)
	{
	printf("%s\t\t\t %d\n",ip_buffer[j],j);
	//printf("%s\n",inet_addr((char*)ip_buffer[j]));
	j++;
	
	}printf("%d Addresses\n",j);
	
}

it seems the code has a problem with the memcpy() function.Please Help figure this one out!
Thanks.

[kbw]

That code shouldn't compile. If you're going to determine BUFSIZE at runtime, you have to dynamically allocate memory.

The whole things' a bit of a mess. I'd say the memcpy is the least of your problems. You know that code is asking for trouble, right?

[Galik]

There is quite a lot of dangerous code there! ;o)

I would take a look at using std::string instead of your char*s and std::vector instead of your arrays. Also you could look at using C++ streams rather than the old, C printf() functions:

strings
http://cplusplus.com/reference/string/string/

vectors
http://cplusplus.com/reference/stl/vector/

streams
http://cplusplus.com/doc/tutorial/basic_io/

[PanGalactic]

There is a very distinct difference between writing C++ code and writing C code. While C++ does provide backwards compatibility with C, the languages are remarkably different from one another. This is clearly C code. It almost seems off-topic for this site.