eq2go/old/common/packet/packet_functions.hpp

// Copyright (C) 2007 EQ2EMulator Development Team, GPL v3 License

#pragma once

#include <iostream>
#include <iomanip>
#include <cstring>
#include <zlib.h>
#include <netinet/in.h>

#include "eq_packet.hpp"
#include "packet_dump.hpp"
#include "../types.hpp"
#include "../stream/eq_stream.hpp"

#define eqemu_alloc_func Z_NULL
#define eqemu_free_func Z_NULL

// Forward declarations for encryption functions (implementations not provided)
void EncryptProfilePacket(EQApplicationPacket* app);
void EncryptProfilePacket(uchar* pBuffer, int32 size);
void EncryptZoneSpawnPacket(EQApplicationPacket* app);
void EncryptZoneSpawnPacket(uchar* pBuffer, int32 size);
#define EncryptSpawnPacket EncryptZoneSpawnPacket

/**
 * Compresses packet data using zlib deflate algorithm
 * @param in_data Input data buffer to compress
 * @param in_length Length of input data in bytes
 * @param out_data Output buffer for compressed data
 * @param max_out_length Maximum size of output buffer
 * @return Number of bytes written to output buffer, or 0 on failure
 */
int DeflatePacket(unsigned char* in_data, int in_length, unsigned char* out_data, int max_out_length)
{
#ifdef REUSE_ZLIB
	static bool inited = false;
	static z_stream zstream;
	int zerror;
	
	// Special cleanup state - deallocate zlib resources
	if (in_data == nullptr && out_data == nullptr && in_length == 0 && max_out_length == 0) {
		deflateEnd(&zstream);
		return 0;
	}
	
	// Initialize zlib stream on first use
	if (!inited) {
		zstream.zalloc = eqemu_alloc_func;
		zstream.zfree = eqemu_free_func;
		zstream.opaque = Z_NULL;
		deflateInit(&zstream, Z_FINISH);
		inited = true;
	}
	
	// Configure input and output buffers
	zstream.next_in = in_data;
	zstream.avail_in = in_length;
	zstream.next_out = out_data;
	zstream.avail_out = max_out_length;
	
	// Perform compression
	zerror = deflate(&zstream, Z_FINISH);
	deflateReset(&zstream);
	
	if (zerror == Z_STREAM_END) {
		return zstream.total_out;
	}
	else {
		return 0;
	}
#else
	// Return early if no input data provided
	if (in_data == nullptr) {
		return 0;
	}
	
	z_stream zstream;
	int zerror;
	
	// Initialize zlib stream for single-use compression
	zstream.next_in = in_data;
	zstream.avail_in = in_length;
	zstream.zalloc = eqemu_alloc_func;
	zstream.zfree = eqemu_free_func;
	zstream.opaque = Z_NULL;
	deflateInit(&zstream, Z_FINISH);
	zstream.next_out = out_data;
	zstream.avail_out = max_out_length;
	
	// Perform compression
	zerror = deflate(&zstream, Z_FINISH);
	
	if (zerror == Z_STREAM_END) {
		deflateEnd(&zstream);
		return zstream.total_out;
	}
	else {
		deflateEnd(&zstream);
		return 0;
	}
#endif
}

/**
 * Decompresses packet data using zlib inflate algorithm
 * @param indata Input compressed data buffer
 * @param indatalen Length of compressed input data
 * @param outdata Output buffer for decompressed data
 * @param outdatalen Maximum size of output buffer
 * @param iQuiet Suppress error messages if true
 * @return Number of bytes written to output buffer, or 0 on failure
 */
uint32 InflatePacket(uchar* indata, uint32 indatalen, uchar* outdata, uint32 outdatalen, bool iQuiet = false)
{
#ifdef REUSE_ZLIB
	static bool inited = false;
	static z_stream zstream;
	int zerror;
	
	// Special cleanup state - deallocate zlib resources
	if (indata == nullptr && outdata == nullptr && indatalen == 0 && outdatalen == 0) {
		inflateEnd(&zstream);
		return 0;
	}
	
	// Initialize zlib stream on first use
	if (!inited) {
		zstream.zalloc = eqemu_alloc_func;
		zstream.zfree = eqemu_free_func;
		zstream.opaque = Z_NULL;
		inflateInit2(&zstream, 15);
		inited = true;
	}

	// Configure input and output buffers
	zstream.next_in = indata;
	zstream.avail_in = indatalen;
	zstream.next_out = outdata;
	zstream.avail_out = outdatalen;
	
	// Perform decompression
	zerror = inflate(&zstream, Z_FINISH);
	inflateReset(&zstream);
	
	if (zerror == Z_STREAM_END) {
		return zstream.total_out;
	}
	else {
		// Output error information unless quiet mode is enabled
		if (!iQuiet) {
			std::cout << "Error: InflatePacket: inflate() returned " << zerror << " '";
			if (zstream.msg)
				std::cout << zstream.msg;
			std::cout << "'" << std::endl;
		}
		
		// Handle specific error condition
		if (zerror == -4 && zstream.msg == nullptr) {
			return 0;
		}
		
		return 0;
	}
#else
	// Return early if no input data provided
	if (indata == nullptr)
		return 0;
	
	z_stream zstream;
	int zerror = 0;
	
	// Initialize zlib stream for single-use decompression
	zstream.next_in = indata;
	zstream.avail_in = indatalen;
	zstream.next_out = outdata;
	zstream.avail_out = outdatalen;
	zstream.zalloc = eqemu_alloc_func;
	zstream.zfree = eqemu_free_func;
	zstream.opaque = Z_NULL;
	
	// Initialize inflate stream
	int init_result = inflateInit2(&zstream, 15);
	if (init_result != Z_OK) {
		return 0;
	}
	
	// Perform decompression
	zerror = inflate(&zstream, Z_FINISH);
	
	if (zerror == Z_STREAM_END) {
		inflateEnd(&zstream);
		return zstream.total_out;
	}
	else {
		// Output error information unless quiet mode is enabled
		if (!iQuiet) {
			std::cout << "Error: InflatePacket: inflate() returned " << zerror << " '";
			if (zstream.msg)
				std::cout << zstream.msg;
			std::cout << "'" << std::endl;
		}
		
		// Handle specific error condition
		if (zerror == -4 && zstream.msg == nullptr) {
			inflateEnd(&zstream);
			return 0;
		}
		
		inflateEnd(&zstream);
		return 0;
	}
#endif
}

/**
 * Performs left bit rotation on 32-bit integer
 * @param in Input value to rotate
 * @param bits Number of bit positions to rotate left
 * @return Rotated value
 */
int32 roll(int32 in, int8 bits)
{
	return ((in << bits) | (in >> (32 - bits)));
}

/**
 * Performs left bit rotation on 64-bit integer
 * @param in Input value to rotate
 * @param bits Number of bit positions to rotate left
 * @return Rotated value
 */
int64 roll(int64 in, int8 bits)
{
	return ((in << bits) | (in >> (64 - bits)));
}

/**
 * Performs right bit rotation on 32-bit integer
 * @param in Input value to rotate
 * @param bits Number of bit positions to rotate right
 * @return Rotated value
 */
int32 rorl(int32 in, int8 bits)
{
	return ((in >> bits) | (in << (32 - bits)));
}

/**
 * Performs right bit rotation on 64-bit integer
 * @param in Input value to rotate
 * @param bits Number of bit positions to rotate right
 * @return Rotated value
 */
int64 rorl(int64 in, int8 bits)
{
	return ((in >> bits) | (in << (64 - bits)));
}

/**
 * Generates CRC lookup table value for given index
 * Uses recursive algorithm to compute CRC polynomial values
 * @param idx Index value for CRC lookup table
 * @return CRC value for the given index
 */
int32 CRCLookup(uchar idx)
{
	// Handle base cases
	if (idx == 0)
		return 0x00000000;
	
	if (idx == 1)
		return 0x77073096;
	
	if (idx == 2)
		return roll(CRCLookup(1), 1);
	
	if (idx == 4)
		return 0x076DC419;
	
	// Find highest set bit and compute CRC recursively
	for (uchar b = 7; b > 0; b--) {
		uchar bv = 1 << b;
		
		// Check if this bit is the only one set
		if (!(idx ^ bv)) {
			return roll(CRCLookup(4), b - 2);
		}
		
		// If bit is set, use XOR with lower bits
		if (idx & bv) {
			return CRCLookup(bv) ^ CRCLookup(idx & (bv - 1));
		}
	}
	
	// Should not reach here - return failure indicator
	return 0;
}

/**
 * Generates CRC32 checksum for given buffer using custom lookup function
 * @param b Initial CRC seed value
 * @param bufsize Size of buffer in bytes
 * @param buf Pointer to data buffer
 * @return Generated CRC32 checksum in network byte order
 */
uint32 GenerateCRC(int32 b, int32 bufsize, uchar* buf)
{
	int32 CRC = (b ^ 0xFFFFFFFF);
	int32 bufremain = bufsize;
	uchar* bufptr = buf;
	
	// Process each byte in the buffer
	while (bufremain--) {
		CRC = CRCLookup(static_cast<uchar>(*(bufptr++) ^ (CRC & 0xFF))) ^ (CRC >> 8);
	}
	
	return htonl(CRC ^ 0xFFFFFFFF);
}

// Pre-computed CRC32 lookup table for standard polynomial
constexpr long int CRCArray[] = {
	0, 1996959894, 3993919788, 2567524794, 124634137, 1886057615, 3915621685, 2657392035,
	249268274, 2044508324, 3772115230, 2547177864, 162941995, 2125561021, 3887607047, 2428444049,
	498536548, 1789927666, 4089016648, 2227061214, 450548861, 1843258603, 4107580753, 2211677639,
	325883990, 1684777152, 4251122042, 2321926636, 335633487, 1661365465, 4195302755, 2366115317,
	997073096, 1281953886, 3579855332, 2724688242, 1006888145, 1258607687, 3524101629, 2768942443,
	901097722, 1119000684, 3686517206, 2898065728, 853044451, 1172266101, 3705015759, 2882616665,
	651767980, 1373503546, 3369554304, 3218104598, 565507253, 1454621731, 3485111705, 3099436303,
	671266974, 1594198024, 3322730930, 2970347812, 795835527, 1483230225, 3244367275, 3060149565,
	1994146192, 31158534, 2563907772, 4023717930, 1907459465, 112637215, 2680153253, 3904427059,
	2013776290, 251722036, 2517215374, 3775830040, 2137656763, 141376813, 2439277719, 3865271297,
	1802195444, 476864866, 2238001368, 4066508878, 1812370925, 453092731, 2181625025, 4111451223,
	1706088902, 314042704, 2344532202, 4240017532, 1658658271, 366619977, 2362670323, 4224994405,
	1303535960, 984961486, 2747007092, 3569037538, 1256170817, 1037604311, 2765210733, 3554079995,
	1131014506, 879679996, 2909243462, 3663771856, 1141124467, 855842277, 2852801631, 3708648649,
	1342533948, 654459306, 3188396048, 3373015174, 1466479909, 544179635, 3110523913, 3462522015,
	1591671054, 702138776, 2966460450, 3352799412, 1504918807, 783551873, 3082640443, 3233442989,
	3988292384, 2596254646, 62317068, 1957810842, 3939845945, 2647816111, 81470997, 1943803523,
	3814918930, 2489596804, 225274430, 2053790376, 3826175755, 2466906013, 167816743, 2097651377,
	4027552580, 2265490386, 503444072, 1762050814, 4150417245, 2154129355, 426522225, 1852507879,
	4275313526, 2312317920, 282753626, 1742555852, 4189708143, 2394877945, 397917763, 1622183637,
	3604390888, 2714866558, 953729732, 1340076626, 3518719985, 2797360999, 1068828381, 1219638859,
	3624741850, 2936675148, 906185462, 1090812512, 3747672003, 2825379669, 829329135, 1181335161,
	3412177804, 3160834842, 628085408, 1382605366, 3423369109, 3138078467, 570562233, 1426400815,
	3317316542, 2998733608, 733239954, 1555261956, 3268935591, 3050360625, 752459403, 1541320221,
	2607071920, 3965973030, 1969922972, 40735498, 2617837225, 3943577151, 1913087877, 83908371,
	2512341634, 3803740692, 2075208622, 213261112, 2463272603, 3855990285, 2094854071, 198958881,
	2262029012, 4057260610, 1759359992, 534414190, 2176718541, 4139329115, 1873836001, 414664567,
	2282248934, 4279200368, 1711684554, 285281116, 2405801727, 4167216745, 1634467795, 376229701,
	2685067896, 3608007406, 1308918612, 956543938, 2808555105, 3495958263, 1231636301, 1047427035,
	2932959818, 3654703836, 1088359270, 936918000, 2847714899, 3736837829, 1202900863, 817233897,
	3183342108, 3401237130, 1404277552, 615818150, 3134207493, 3453421203, 1423857449, 601450431,
	3009837614, 3294710456, 1567103746, 711928724, 3020668471, 3272380065, 1510334235, 755167117
};

/**
 * Generates CRC32 checksum using pre-computed lookup table
 * More efficient than custom CRCLookup function for standard CRC32 calculations
 * @param initial Initial CRC seed value (typically 0xFFFFFFFF)
 * @param buf Pointer to data buffer
 * @param len Length of data buffer in bytes
 * @return Generated CRC32 checksum
 */
uint32 GenerateCRCRecipe(uint32 initial, void* buf, uint32 len)
{
	uint32 c = 0xFFFFFFFF;
	sint8* u = static_cast<sint8*>(buf);
	
	// Process each byte using lookup table
	for (size_t i = 0; i < len; ++i) {
		c = CRCArray[(c ^ u[i]) & 0xFF] ^ (c >> 8);
	}
	
	return c;
}