netpong/connect_code.cpp

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <iomanip>
#include <cstring>
#include <cstdint>
#include "includes/connect_code.hpp"
#include "includes/numeric_base.hpp"
#include "includes/easysock.h"

#if defined(_WIN32)
	#include <In6addr.h>
	#include <Ws2tcpip.h>
#else
	#include <sys/socket.h>
	#include <arpa/inet.h>
#endif

namespace connect_code {

	 /* Tokenizes a string, based on the given delimiter */
	std::vector<std::string> tokenize_str(std::string str, std::string delim) {
		std::vector<std::string> result;
		/* &str[0] is used to convert an std::string to a char*. I tried using string.data(),
		but that appears to return a const char*.  */
		char* c_str = &str[0];
		char* c_delim = &delim[0];

		char* tok = strtok(c_str, c_delim);
		while (tok != NULL) {
			result.push_back(std::string(tok));
			tok = strtok(NULL, c_delim);
		}

		return result;
	}

	/* Convert an IPv4 address from decimal to dotted decimal notation */
	std::string dec_to_dotted_dec(std::string addr) {
		uint32_t addr_val = std::stoul(addr); /* 32 bit address */
		uint8_t addr_1 = (addr_val & (0xFF << 24)) >> 24;   /* First octet (Bitwise AND the address with 255.0.0.0, and shift it to the right to obtain the first octet) */
		uint8_t addr_2 = (addr_val & (0xFF << 16)) >> 16;
		uint8_t addr_3 = (addr_val & (0xFF << 8)) >> 8;
		uint8_t addr_4 = (addr_val & 0xFF);

		std::string ret_val = std::string(std::to_string(addr_1) + "." + std::to_string(addr_2) + "." + std::to_string(addr_3) + "." + std::to_string(addr_4));

		return ret_val;
	}

	/* Convert an IPv4 address from dotted deecimal to decimal */
	std::string dotted_dec_to_dec(std::string addr) {
		std::vector<std::string> octets = tokenize_str(addr, ".");
		uint32_t addr_val = (std::stoul(octets[0]) << 24) + (std::stoul(octets[1]) << 16) + (std::stoul(octets[2]) << 8) + (std::stoul(octets[3]));
		return std::to_string(addr_val);
	}
	
	/* Expand an IPv6 address (expand '::' into ':0000:', for example).
	This is done by first converting the address into a binary representation,
	and then printing every character of the binary representation into a string. */
	std::string expand_ip6_addr(std::string addr) {
		char ip6_string[40]; // 32 characters + 7 colons
		struct in6_addr* ip6_s_ptr = (struct in6_addr *)malloc(sizeof(in6_addr)); // Struct pointer, to store the binary representation of the address
		inet_pton(AF_INET6, addr.data(), ip6_s_ptr); // Convert the string representation into a binary form
		
		/* This abomination, converts the binary representation into a string.
		It uses sprintf to print every byte in the binary representation into a string. 
		The bytes are formatted as 2-character hexadecimal values. */
		sprintf(ip6_string,
			"%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x", 
			ip6_s_ptr->s6_addr[0], ip6_s_ptr->s6_addr[1],
			ip6_s_ptr->s6_addr[2], ip6_s_ptr->s6_addr[3],
			ip6_s_ptr->s6_addr[4], ip6_s_ptr->s6_addr[5],
			ip6_s_ptr->s6_addr[6], ip6_s_ptr->s6_addr[7],
			ip6_s_ptr->s6_addr[8], ip6_s_ptr->s6_addr[9],
			ip6_s_ptr->s6_addr[10], ip6_s_ptr->s6_addr[11],
			ip6_s_ptr->s6_addr[12], ip6_s_ptr->s6_addr[13],
			ip6_s_ptr->s6_addr[14], ip6_s_ptr->s6_addr[15]);
			
		return std::string(ip6_string);
	}


	std::string encode(std::string address, std::string port) {
		std::string addr_coded = "";
		if (check_ip_ver(address.data()) == 4) {
			/* First, convert the address into a decimal format. Then convert this decimal format
			into base-32, and also convert the port number into base-32. Join these together with
			a "_". */
			
			/* I don't really have a reason to use my own function (dotted_dec_to_dec() 
			and dec_to_dotted_dec()), to convert the IP address from text to binary.
			The inet_pton() and inet_ntop() functions can do this just fine, and also
			take care of edge cases. Maybe someday, I might change this code. I could probably
			repurpose the functions for something else, though. */
			
			/* First, convert the address into a 32-bit integer (the integer is stored as a string).
			Then, convert the address into base-32. */
			addr_coded = dotted_dec_to_dec(address);
			addr_coded = base_convert(addr_coded, 10, 32);
		}
		if (check_ip_ver(address.data()) == 6) {
			/* First, expand the address into the full 39-character format (32 hex values + 7 colons).
			Then, tokenize the string, using colons as the delimiters.
			Finally, take each token in the string, and convert it from base-16 to base-32, appending a '-' as a delimiter. */
			std::string addr_expanded = expand_ip6_addr(address);
			std::vector<std::string> addr_tokenized = tokenize_str(addr_expanded, ":");
			
			for (size_t i = 0; i < addr_tokenized.size()-1; i++ ) {
				addr_coded += base_convert(addr_tokenized[i], 16, 32);
				addr_coded += "-";
			}
			addr_coded += base_convert(addr_tokenized[addr_tokenized.size()-1], 16, 32); // I put this outside the loop, because I don't want a hyphen after it
			
			/* TODO - Check if the IP address is actually converted properly, and test if the server socket is created correctly.
			 Also do the same for client side, and check client-server connection. */
						
		}
		
		/* Convert the port to hex */
		std::string port_coded = base_convert(port, 10, 32);
		std::string ret_val = addr_coded + "_" + port_coded;

		return ret_val;

	}

	std::vector<std::string> decode(std::string connect_code) {
		if (connect_code.find("_") == std::string::npos) {
			throw std::invalid_argument("Invalid code entered."); // There must be an underscore, to separate the address part from the port part
		}
		
		int ip_ver = 0;
		if (connect_code.find("-") != std::string::npos) {
			ip_ver = 6; // If the string contains hyphens, it must be an IPv6 address encoding.
		} else {
			ip_ver = 4;
		}
		
		std::vector<std::string> result = tokenize_str(connect_code, "_"); /* Split the string into address and port */
		std::string address = result[0]; /* Address (in base 32) */
		std::string port = result[1]; /* Port (in base 32) */
		
		std::vector<std::string> ret_val;
		
		/* The IPv6 and IPv4 encodings are slightly different - I use a hyphen as a delimiter
		for IPv6, while there is no delimiter for IPv4. This is why I need to check if the address
		is IPv4 or IPv6. */
		if (ip_ver == 4) {
			/* Base 32 to base 10 - These lines convert the string to a base 10 number, and convert the result back into a string */
			address = std::to_string(std::stoul(address, 0, 32));
			port = std::to_string(std::stoul(port, 0, 32));

			/* Convert decimal address to dotted decimal */
			address = dec_to_dotted_dec(address);

			/* Create a vector containing the address and the port, which will be returned */
			ret_val.push_back(address);
			ret_val.push_back(port);
		} else {
			/* IPv6 */
			/* There are three main steps to decoding for IPv6:
			1. Tokenize the address using the delimiter set while encoding ('-', in my case).
			2. Convert each token from base-32 to base-16.
			3. Join the string vector back together into a string, this time using ':' as a delimiter. This will give us our IP address. */

			std::string conv_addr = ""; // Stores the final address
			std::vector<std::string> address_tokenized = tokenize_str(address, "-"); // Step 1
			
			for (size_t i = 0; i < address_tokenized.size()-1; i++) {
				address_tokenized[i] = base_convert(address_tokenized[i], 32, 16); // Step 2
				conv_addr += address_tokenized[i] + ":"; // Step 3
			}
			conv_addr += base_convert(address_tokenized[address_tokenized.size()-1], 32, 16); // Add the last token

			port = std::to_string(std::stoul(port, 0, 32));

			std::cout << conv_addr << std::endl;
			abort();

			ret_val.push_back(conv_addr);
			ret_val.push_back(port);
		}
		
		return ret_val;
	}
}