BOF in doproxyconnect function

[h4niz]

I found a bof in doproxyconnect() function:

void doproxyconnect(int socket)
{
	int x;
	char buf[128];

	/* write CONNECT string to proxy */
	sprintf((char *)&buf, "CONNECT %s HTTP/1.0\n\n", connect_str);
	...
}

We should use snprintf() instead of sprintf().

More:

0x555555558912 <client_accept+594> call doproxyconnect <0x555555558370>
rdi: 0x6

In file: /home/h4niz/Downloads/redir-master/redir.c
868 if (connect_str)
► 869 doproxyconnect(sd);

pwndbg> ni
*** stack smashing detected ***: terminated

[Joachim Wiberg]

Great, would you like to do a pull request?