#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/ip.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<unistd.h>
#include<signal.h>
#include<stdlib.h>
#include<string.h>
#include<string>
using namespace std;

bool authenticate(int fd){
	bool trust = false;
	char buffer[25];
	strcpy(buffer + 20, "bird");
	read(fd, buffer, 200);
//	char *newline = strchr(buffer, '\n');
//	if(newline)
//		*newline = 0;
	string pwd_string = buffer;
	if(pwd_string == "gerbil"){
		trust = true;
	} else {
		printf("Invalid Password:  \"%s\"\n", buffer);
	}
	if(strncmp(buffer + 20, "bird", 4)) {
		printf("Buffer overflow detected!\n");
		return false;
	}
		
	return trust;
}

int main(int argc, char ** argv){
	uint16_t port = 5143;
	struct sockaddr_in sad;
	sad.sin_addr.s_addr = INADDR_ANY;
	sad.sin_family = AF_INET;
top:
	sad.sin_port = htons(port);

	int skt = socket(AF_INET, SOCK_STREAM, 0); // Step 1
	if(skt == -1){
		perror("socket");
		return 1;
	}
	if( bind(skt, (struct sockaddr*)(&sad), sizeof(struct sockaddr_in)) ){ // step 2
		port++;
		goto top;
	}
	if( listen(skt, 5) ){ // step 3
		perror("listen");
		return 1;
	}
	printf("Listening on port %d\n", port);
	while(1){
		int client_fd;
		struct sockaddr_in client_address;
		socklen_t address_size = sizeof(struct sockaddr_in);
		client_fd = accept(skt, (struct sockaddr *)(&client_address), &address_size); // step 4
		if(authenticate(client_fd)){
			printf("Client successfully authenticated\n");
			write(client_fd, "We trust you", 12);
		}

		close(client_fd);
	}
	
	return 0;
}