/**
 * parser-quic.c
 *
 * Created on 2020-11-26
 * @author: qyc
 *
 * @explain: QUIC解析
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "parser_quic.h"
#include "wsgcrypt.h"
#include "utils.h"
#include "pint.h"
#include "gcrypt.h"

// #define DEBUG_PARSER_QUIC

int gcry_init()
{
    gcry_check_version("1.8.7");
    //gcry_control(GCRYCTL_SET_THREAD_CBS,&gcry_threads_pthread);
    return 0;
}


#define QUIC_LPT_INITIAL	0x0
#define QUIC_LPT_0RTT		0x1
#define QUIC_LPT_HANDSHAKE	0x2
#define QUIC_LPT_RETRY		0x3
/* Version Negotiation packets don't have any real packet type */
#define QUIC_LPT_VER_NEG	0xfe
/* dummy value that is definitely not LPT */
#define QUIC_SHORT_PACKET	0xff


/*
 * Although the QUIC SCID/DCID length field can store at most 255, v1 limits the
 * CID length to 20.
 */
#define QUIC_MAX_CID_LENGTH  20
typedef struct _quic_cid {
	unsigned char len;
	unsigned char cid[QUIC_MAX_CID_LENGTH];
} quic_cid_t;

/*
 * PROTECTED PAYLOAD DECRYPTION (done in first pass)
 *
 * Long packet types always use a single cipher depending on packet type.
 * Short packet types always use 1-RTT secrets for packet protection (pp).
 *
 * Considerations:
 * - QUIC packets might appear out-of-order (short packets before handshake
 *   message is captured), lost or retransmitted/duplicated.
 * - During live capture, keys might not be immediately be available. 1-RTT
 *   client keys will be ready while client proceses Server Hello (Handshake).
 *   1-RTT server keys will be ready while server creates Handshake message in
 *   response to Initial Handshake.
 * - So delay cipher creation until first short packet is received.
 *
 * Required input from TLS dissector: TLS-Exporter 0-RTT/1-RTT secrets and
 * cipher/hash algorithms.
 *
 * QUIC payload decryption requires proper reconstruction of the packet number
 * which requires proper header decryption. The different states are:
 *
 *  Packet type             Packet number space     Secrets
 *  Long: Initial           Initial                 Initial secrets
 *  Long: Handshake         Handshake               Handshake
 *  Long: 0-RTT             0/1-RTT (appdata)       0-RTT
 *  Short header            0/1-RTT (appdata)       1-RTT (KP0 / KP1)
 *
 * Important to note is that Short Header decryption requires TWO ciphers (one
 * for each key phase), but that header protection uses only KP0. Total state
 * needed for each peer (client and server):
 * - 3 packet number spaces: Initial, Handshake, 0/1-RTT (appdata).
 * - 4 header protection ciphers: initial, 0-RTT, HS, 1-RTT.
 * - 5 payload protection ciphers: initial, 0-RTT, HS, 1-RTT (KP0), 1-RTT (KP1).
 */

typedef struct _quic_decrypt_result {
	// Error message or NULL for success.
	const guchar   *error;
	// Decrypted result on success (file-scoped).
	const guint8   *data;
	// Size of decrypted data.
	guint           data_len;
} quic_decrypt_result_t;

/** QUIC decryption context. */

typedef struct _quic_hp_cipher {
	// Header protection cipher.
	gcry_cipher_hd_t hp_cipher;
} quic_hp_cipher;

typedef struct _quic_pp_cipher {
	// Packet protection cipher.
	gcry_cipher_hd_t pp_cipher;
	guint8 pp_iv[TLS13_AEAD_NONCE_LENGTH];
} quic_pp_cipher;

typedef struct _quic_ciphers {
	quic_hp_cipher hp_cipher;
	quic_pp_cipher pp_cipher;
} quic_ciphers;

/**
 * State for a single QUIC connection, identified by one or more Destination
 * Connection IDs (DCID).
 */
typedef struct _quic_info_data {
	guint32 version;
	quic_ciphers client_initial_ciphers;
	quic_ciphers server_initial_ciphers;
	// Packet number spaces for Initial, Handshake and appdata.
	guint64 max_client_pkn[3];
	guint64 max_server_pkn[3];
} quic_info_data_t;

/** Per-packet information about QUIC, populated on the first pass. */
typedef struct _quic_packet_info {
	// Reconstructed full packet number.
	guint64 packet_number;
	quic_decrypt_result_t decryption;
	// Length of PKN (1/2/3/4) or unknown (0).
	guint8 pkn_len;
	// Decrypted flag byte, valid only if pkn_len is non-zero.
	guint8 first_byte;
} quic_packet_info_t;

/**
 * Given a QUIC message (header + non-empty payload), the actual packet number,
 * try to decrypt it using the PP cipher.
 * As the header points to the original buffer with an encrypted packet number,
 * the (encrypted) packet number length is also included.
 *
 * The actual packet number must be constructed according to
 * https://tools.ietf.org/html/draft-ietf-quic-transport-22#section-12.3
 */
static void quic_decrypt_message(quic_pp_cipher *pp_cipher, const char *payload, guint length, guint header_length, 
	guint8 first_byte, guint pkn_len, guint64 packet_number, quic_decrypt_result_t *result)
{
	gcry_error_t err;
	guint8 *header;
	guint8 nonce[TLS13_AEAD_NONCE_LENGTH];
	guint8 *buffer;
	guint8 atag[16];
	guint buffer_length;
	const guchar **error = &result->error;

	g_assert(pp_cipher != NULL);
	g_assert(pp_cipher->pp_cipher != NULL);
	g_assert(pkn_len < header_length);
	g_assert(1 <= pkn_len && pkn_len <= 4);
	// copy header, but replace encrypted first byte and PKN by plaintext.
	header = (guint8 *)g_malloc(header_length);
	memcpy(header, payload, header_length);
	header[0] = first_byte;
	guint i;
	for (i = 0; i < pkn_len; i++)
		header[header_length - 1 - i] = (guint8)(packet_number >> (8 * i));
	
	// Input is "header || ciphertext (buffer) || auth tag (16 bytes)"
	// buffer_length = length - (header_length + 16);
	// buffer_length = 297 - (2 + 16);
	buffer_length = length - (pkn_len + 16);
	if (buffer_length == 0) {
		*error = (const guchar *)"Decryption not possible, ciphertext is too short";
		return;
	}
	buffer = (guint8 *)g_malloc(buffer_length);
	memcpy(buffer, payload + header_length, buffer_length);
	memcpy(atag, payload + header_length + buffer_length, 16);

	memcpy(nonce, pp_cipher->pp_iv, TLS13_AEAD_NONCE_LENGTH);
	// Packet number is left-padded with zeroes and XORed with write_iv
	phton64(nonce + sizeof(nonce) - 8, pntoh64(nonce + sizeof(nonce) - 8) ^ packet_number);

	gcry_cipher_reset(pp_cipher->pp_cipher);
	err = gcry_cipher_setiv(pp_cipher->pp_cipher, nonce, TLS13_AEAD_NONCE_LENGTH);
	if (err) {
		//printf("Decryption (setiv) failed: %s\n", gcry_strerror(err));
		*error = (const guchar *)"Decryption (setiv) failed";
		return;
	}

	// associated data (A) is the contents of QUIC header
	err = gcry_cipher_authenticate(pp_cipher->pp_cipher, header, header_length);
	if (err) {
		//printf("Decryption (authenticate) failed: %s\n", gcry_strerror(err));
		*error = (const guchar *)"Decryption (authenticate) failed";
		return;
	}

	// Output ciphertext (C)
	err = gcry_cipher_decrypt(pp_cipher->pp_cipher, buffer, buffer_length, NULL, 0);
	if (err) {
		//printf("Decryption (decrypt) failed: %s\n", gcry_strerror(err));
		*error = (const guchar *)"Decryption (decrypt) failed";
		return;
	}

	err = gcry_cipher_checktag(pp_cipher->pp_cipher, atag, 16);
	if (err) {
		//printf("Decryption (checktag) failed: %s\n", gcry_strerror(err));
		*error = (const guchar *)"Decryption (checktag) failed";
		return;
	}

	g_free(header);

	result->error = NULL;
	result->data = buffer;
	result->data_len = buffer_length;
}

static gboolean quic_is_pp_cipher_initialized(quic_pp_cipher *pp_cipher)
{
	return pp_cipher && pp_cipher->pp_cipher;
}

/**
 * Process (protected) payload, adding the encrypted payload to the tree. If
 * decryption is possible, frame dissection is also attempted.
 *
 * The given offset must correspond to the end of the QUIC header and begin of
 * the (protected) payload. Dissected frames are appended to "tree" and expert
 * info is attached to "ti" (the field with the encrypted payload).
 */
static void quic_process_payload(const char *payload, guint length, guint offset, quic_info_data_t *quic_info, 
	quic_packet_info_t *quic_packet, gboolean from_server, quic_pp_cipher *pp_cipher, guint8 first_byte, guint pkn_len)
{
	/*
	 * If no decryption error has occurred yet, try decryption on the first
	 * pass and store the result for later use.
	 */
	if (quic_is_pp_cipher_initialized(pp_cipher))
		quic_decrypt_message(pp_cipher, payload, length, offset, first_byte, pkn_len, quic_packet->packet_number, &quic_packet->decryption);
}

/* Inspired from ngtcp2 */
static guint64 quic_pkt_adjust_pkt_num(guint64 max_pkt_num, guint64 pkt_num, size_t n)
{
	guint64 k = max_pkt_num == G_MAXUINT64 ? max_pkt_num : max_pkt_num + 1;
	guint64 u = k & ~((G_GUINT64_CONSTANT(1) << n) - 1);
	guint64 a = u | pkt_num;
	guint64 b = (u + (G_GUINT64_CONSTANT(1) << n)) | pkt_num;
	guint64 a1 = k < a ? a - k : k - a;
	guint64 b1 = k < b ? b - k : k - b;

	if (a1 < b1)
		return a;
	return b;
}

/**
 * Retrieve the maximum valid packet number space for a peer.
 */
static guint64 *quic_max_packet_number(quic_info_data_t *quic_info, gboolean from_server, guint8 first_byte)
{
	int pkn_space;
	if ((first_byte & 0x80) && (first_byte & 0x30) >> 4 == QUIC_LPT_INITIAL)
		// Long header, Initial
		pkn_space = 0;
	else if ((first_byte & 0x80) && (first_byte & 0x30) >> 4 == QUIC_LPT_HANDSHAKE)
		// Long header, Handshake
		pkn_space = 1;
	else
		// Long header (0-RTT) or Short Header (1-RTT appdata).
		pkn_space = 2;
	if (from_server)
		return &quic_info->max_server_pkn[pkn_space];
	else
		return &quic_info->max_client_pkn[pkn_space];
}

/**
 * Calculate the full packet number and store it for later use.
 */
static void quic_set_full_packet_number(quic_info_data_t *quic_info, quic_packet_info_t *quic_packet, gboolean from_server, guint8 first_byte, guint32 pkn32)
{
	guint pkn_len = (first_byte & 3) + 1;
	guint64 pkn_full;
	guint64 max_pn = *quic_max_packet_number(quic_info, from_server, first_byte);

	// Sequential first pass, try to reconstruct full packet number.
	pkn_full = quic_pkt_adjust_pkt_num(max_pn, pkn32, 8 * pkn_len);
	quic_packet->pkn_len = pkn_len;
	quic_packet->packet_number = pkn_full;
}

/**
 * Given a header protection cipher, a buffer and the packet number offset,
 * return the unmasked first byte and packet number.
 */
static gboolean quic_decrypt_header(const char *payload, guint pn_offset, quic_hp_cipher *hp_cipher, int hp_cipher_algo, guint8 *first_byte, guint32 *pn)
{
	if (!hp_cipher->hp_cipher)
		// need to know the cipher.
		return FALSE;
	gcry_cipher_hd_t h = hp_cipher->hp_cipher;

	// Sample is always 16 bytes and starts after PKN (assuming length 4).
	// https://tools.ietf.org/html/draft-ietf-quic-tls-22#section-5.4.2
	guint8 sample[16];
	memcpy(sample, payload + pn_offset + 4, 16);

	guint8  mask[5] = { 0 };
	switch (hp_cipher_algo) {
		case GCRY_CIPHER_AES128:
		case GCRY_CIPHER_AES256:
			// Encrypt in-place with AES-ECB and extract the mask.
			if (gcry_cipher_encrypt(h, sample, sizeof(sample), NULL, 0))
				return FALSE;
			memcpy(mask, sample, sizeof(mask));
			break;
#ifdef HAVE_LIBGCRYPT_CHACHA20
		case GCRY_CIPHER_CHACHA20:
 			// If Gcrypt receives a 16 byte IV, it will assume the buffer to be
			// counter || nonce (in little endian), as desired. */
			if (gcry_cipher_setiv(h, sample, 16))
				return FALSE;
			// Apply ChaCha20, encrypt in-place five zero bytes.
			if (gcry_cipher_encrypt(h, mask, sizeof(mask), NULL, 0))
				return FALSE;
			break;
#endif // HAVE_LIBGCRYPT_CHACHA20
		default:
			return FALSE;
	}

	// https://tools.ietf.org/html/draft-ietf-quic-tls-22#section-5.4.1
	guint8 packet0 = payload[0];
	if ((packet0 & 0x80) == 0x80)
		// Long header: 4 bits masked
		packet0 ^= mask[0] & 0x0f;
	else
		// Short header: 5 bits masked
		packet0 ^= mask[0] & 0x1f;
	guint pkn_len = (packet0 & 0x03) + 1;

	guint8 pkn_bytes[4];
	memcpy(pkn_bytes, payload + pn_offset, pkn_len);
	guint32 pkt_pkn = 0;
	guint i;
	for (i = 0; i < pkn_len; i++)
		pkt_pkn |= (pkn_bytes[i] ^ mask[1 + i]) << (8 * (pkn_len - 1 - i));
	*first_byte = packet0;
	*pn = pkt_pkn;

	return TRUE;
}

static gboolean quic_hkdf_expand_label(int hash_algo, guint8 *secret, guint secret_len, const char *label, guint8 *out, guint out_len)
{
	const StringInfo secret_si = { secret, secret_len };
	guchar *out_mem = NULL;

	if (tls13_hkdf_expand_label(hash_algo, &secret_si, "tls13 ", label, out_len, &out_mem)) {
		memcpy(out, out_mem, out_len);
		g_free(out_mem);
		return TRUE;
	}

	return FALSE;
}

/**
 * Expands the secret (length MUST be the same as the "hash_algo" digest size)
 * and initialize cipher with the new key.
 */
static gboolean quic_hp_cipher_init(quic_hp_cipher *hp_cipher, int hash_algo, guint8 key_length, guint8 *secret)
{
	guchar hp_key[256/8];
	guint hash_len = gcry_md_get_algo_dlen(hash_algo);

	if (!quic_hkdf_expand_label(hash_algo, secret, hash_len, "quic hp", hp_key, key_length))
		return FALSE;

	return gcry_cipher_setkey(hp_cipher->hp_cipher, hp_key, key_length) == 0;
}

static gboolean quic_pp_cipher_init(quic_pp_cipher *pp_cipher, int hash_algo, guint8 key_length, guint8 *secret)
{
	// Maximum key size is for AES256 cipher.
	guchar write_key[256/8];
	guint hash_len = gcry_md_get_algo_dlen(hash_algo);

	if (key_length > sizeof(write_key))
		return FALSE;

	if (!quic_hkdf_expand_label(hash_algo, secret, hash_len, "quic key", write_key, key_length) || 
		!quic_hkdf_expand_label(hash_algo, secret, hash_len, "quic iv", pp_cipher->pp_iv, sizeof(pp_cipher->pp_iv)))
		return FALSE;

	return gcry_cipher_setkey(pp_cipher->pp_cipher, write_key, key_length) == 0;
}

static void quic_hp_cipher_reset(quic_hp_cipher *hp_cipher)
{
	gcry_cipher_close(hp_cipher->hp_cipher);
	memset(hp_cipher, 0, sizeof(*hp_cipher));
}

static void quic_pp_cipher_reset(quic_pp_cipher *pp_cipher)
{
	gcry_cipher_close(pp_cipher->pp_cipher);
	memset(pp_cipher, 0, sizeof(*pp_cipher));
}

/**
 * Maps a Packet Protection cipher to the Packet Number protection cipher.
 * See https://tools.ietf.org/html/draft-ietf-quic-tls-22#section-5.4.3
 */
static gboolean quic_get_pn_cipher_algo(int cipher_algo, int *hp_cipher_mode)
{
	switch (cipher_algo) {
		case GCRY_CIPHER_AES128:
		case GCRY_CIPHER_AES256:
			*hp_cipher_mode = GCRY_CIPHER_MODE_ECB;
			return TRUE;
#ifdef HAVE_LIBGCRYPT_CHACHA20
		case GCRY_CIPHER_CHACHA20:
			*hp_cipher_mode = GCRY_CIPHER_MODE_STREAM;
			return TRUE;
#endif // HAVE_LIBGCRYPT_CHACHA20
		default:
			return FALSE;
	}
}

/*
 * (Re)initialize the PNE/PP ciphers using the given cipher algorithm.
 * If the optional base secret is given, then its length MUST match the hash
 * algorithm output.
 */
static gboolean quic_hp_cipher_prepare(quic_hp_cipher *hp_cipher, int hash_algo, int cipher_algo, guint8 *secret, const char **error)
{
	// Clear previous state (if any).
	quic_hp_cipher_reset(hp_cipher);

	int hp_cipher_mode;
	if (!quic_get_pn_cipher_algo(cipher_algo, &hp_cipher_mode)) {
		*error = "Unsupported cipher algorithm";
		return FALSE;
	}

	if (gcry_cipher_open(&hp_cipher->hp_cipher, cipher_algo, hp_cipher_mode, 0)) {
		quic_hp_cipher_reset(hp_cipher);
		*error = "Failed to create HP cipher";
		return FALSE;
	}

	if (secret) {
		guint cipher_keylen = (guint8)gcry_cipher_get_algo_keylen(cipher_algo);
		if (!quic_hp_cipher_init(hp_cipher, hash_algo, cipher_keylen, secret)) {
			quic_hp_cipher_reset(hp_cipher);
			*error = "Failed to derive key material for HP cipher";
			return FALSE;
		}
	}

	return TRUE;
}

static gboolean quic_pp_cipher_prepare(quic_pp_cipher *pp_cipher, int hash_algo, int cipher_algo, int cipher_mode, guint8 *secret, const char **error)
{
	// Clear previous state (if any).
	quic_pp_cipher_reset(pp_cipher);

	int hp_cipher_mode;
	if (!quic_get_pn_cipher_algo(cipher_algo, &hp_cipher_mode)) {
		*error = "Unsupported cipher algorithm";
		return FALSE;
	}

	if (gcry_cipher_open(&pp_cipher->pp_cipher, cipher_algo,cipher_mode, 0)) {
		quic_pp_cipher_reset(pp_cipher);
		*error = "Failed to create PP cipher";
		return FALSE;
	}

	if (secret) {
		guint cipher_keylen = (guint8) gcry_cipher_get_algo_keylen(cipher_algo);
		if (!quic_pp_cipher_init(pp_cipher, hash_algo, cipher_keylen, secret)) {
			quic_pp_cipher_reset(pp_cipher);
			*error = "Failed to derive key material for PP cipher";
			return FALSE;
		}
	}

	return TRUE;
}

static gboolean quic_ciphers_prepare(quic_ciphers *ciphers, int hash_algo, int cipher_algo, int cipher_mode, guint8 *secret, const char **error)
{
	return quic_hp_cipher_prepare(&ciphers->hp_cipher, hash_algo, cipher_algo, secret, error) && 
		quic_pp_cipher_prepare(&ciphers->pp_cipher, hash_algo, cipher_algo, cipher_mode, secret, error);
}

/* Returns the QUIC draft version or 0 if not applicable. */
static inline guint8 quic_draft_version(guint32 version) {
	if ((version >> 8) == 0xff0000)
		return (guint8) version;

	// Facebook mvfst, based on draft -22.
	if (version == 0xfaceb001)
		return 22;

	// Facebook mvfst, based on draft -27.
	if (version == 0xfaceb002 || version == 0xfaceb00e)
		return 27;

	// GQUIC Q050, T050 and T051: they are not really based on any drafts,
	// but we must return a sensible value
	if (version == 0x51303530 || version == 0x54303530 || version == 0x54303531)
		return 27;

	/* 
	 * https://tools.ietf.org/html/draft-ietf-quic-transport-32#section-15
	 * "Versions that follow the pattern 0x?a?a?a?a are reserved for use in
	 * forcing version negotiation to be exercised"
	 * It is tricky to return a correct draft version: such number is primarly
	 * used to select a proper salt (which depends on the version itself), but
	 * we don't have a real version here! Let's hope that we need to handle
	 * only latest drafts... 
	 */
	if ((version & 0x0F0F0F0F) == 0x0a0a0a0a)
		return 29;

	return 0;
}

static inline gboolean is_quic_draft_max(guint32 version, guint8 max_version) {
	guint8 draft_version = quic_draft_version(version);
	return draft_version && draft_version <= max_version;
}

/**
 * Compute the client and server initial secrets given Connection ID "cid".
 *
 * On success TRUE is returned and the two initial secrets are set.
 * FALSE is returned on error (see "error" parameter for the reason).
 */
static gboolean quic_derive_initial_secrets(const quic_cid_t *cid, guint8 client_initial_secret[HASH_SHA2_256_LENGTH], guint8 server_initial_secret[HASH_SHA2_256_LENGTH], guint32 version, const gchar **error)
{
	/*
	 * https://tools.ietf.org/html/draft-ietf-quic-tls-29#section-5.2
	 *
	 * initial_salt = 0xafbfec289993d24c9e9786f19c6111e04390a899
	 * initial_secret = HKDF-Extract(initial_salt, client_dst_connection_id)
	 *
	 * client_initial_secret = HKDF-Expand-Label(initial_secret,
	 *                                           "client in", "", Hash.length)
	 * server_initial_secret = HKDF-Expand-Label(initial_secret,
	 *                                           "server in", "", Hash.length)
	 *
	 * Hash for handshake packets is SHA-256 (output size 32).
	 */
	static const guint8 handshake_salt_draft_22[20] = {
		0x7f, 0xbc, 0xdb, 0x0e, 0x7c, 0x66, 0xbb, 0xe9, 0x19, 0x3a,
		0x96, 0xcd, 0x21, 0x51, 0x9e, 0xbd, 0x7a, 0x02, 0x64, 0x4a
	};
	static const guint8 handshake_salt_draft_23[20] = {
		0xc3, 0xee, 0xf7, 0x12, 0xc7, 0x2e, 0xbb, 0x5a, 0x11, 0xa7,
		0xd2, 0x43, 0x2b, 0xb4, 0x63, 0x65, 0xbe, 0xf9, 0xf5, 0x02,
	};
	static const guint8 handshake_salt_draft_29[20] = {
		0xaf, 0xbf, 0xec, 0x28, 0x99, 0x93, 0xd2, 0x4c, 0x9e, 0x97,
		0x86, 0xf1, 0x9c, 0x61, 0x11, 0xe0, 0x43, 0x90, 0xa8, 0x99
	};
	static const guint8 handshake_salt_v1[20] = {
        0x38, 0x76, 0x2c, 0xf7, 0xf5, 0x59, 0x34, 0xb3, 0x4d, 0x17,
        0x9a, 0xe6, 0xa4, 0xc8, 0x0c, 0xad, 0xcc, 0xbb, 0x7f, 0x0a
    };
	static const guint8 hanshake_salt_draft_q50[20] = {
		0x50, 0x45, 0x74, 0xEF, 0xD0, 0x66, 0xFE, 0x2F, 0x9D, 0x94,
		0x5C, 0xFC, 0xDB, 0xD3, 0xA7, 0xF0, 0xD3, 0xB5, 0x6B, 0x45
	};
	static const guint8 hanshake_salt_draft_t50[20] = {
		0x7f, 0xf5, 0x79, 0xe5, 0xac, 0xd0, 0x72, 0x91, 0x55, 0x80,
		0x30, 0x4c, 0x43, 0xa2, 0x36, 0x7c, 0x60, 0x48, 0x83, 0x10
	};
	static const guint8 hanshake_salt_draft_t51[20] = {
		0x7a, 0x4e, 0xde, 0xf4, 0xe7, 0xcc, 0xee, 0x5f, 0xa4, 0x50,
		0x6c, 0x19, 0x12, 0x4f, 0xc8, 0xcc, 0xda, 0x6e, 0x03, 0x3d
	};

	gcry_error_t err;
	guint8 secret[HASH_SHA2_256_LENGTH];

	if (version == 0x51303530)
	{
		err = hkdf_extract(GCRY_MD_SHA256, hanshake_salt_draft_q50, sizeof(hanshake_salt_draft_q50), cid->cid, cid->len, secret);
	}
	else if (version == 0x54303530)
	{
		err = hkdf_extract(GCRY_MD_SHA256, hanshake_salt_draft_t50, sizeof(hanshake_salt_draft_t50), cid->cid, cid->len, secret);
	}
	else if (version == 0x54303531)
	{
		err = hkdf_extract(GCRY_MD_SHA256, hanshake_salt_draft_t51, sizeof(hanshake_salt_draft_t51), cid->cid, cid->len, secret);
	}
	else if (is_quic_draft_max(version, 22))
	{
		err = hkdf_extract(GCRY_MD_SHA256, handshake_salt_draft_22, sizeof(handshake_salt_draft_22), cid->cid, cid->len, secret);
	}
	else if (is_quic_draft_max(version, 28))
	{
		err = hkdf_extract(GCRY_MD_SHA256, handshake_salt_draft_23, sizeof(handshake_salt_draft_23), cid->cid, cid->len, secret);
	}
	else if (is_quic_draft_max(version, 32))
	{
		err = hkdf_extract(GCRY_MD_SHA256, handshake_salt_draft_29, sizeof(handshake_salt_draft_29), cid->cid, cid->len, secret);
	}
	else 
	{
	   err = hkdf_extract(GCRY_MD_SHA256, handshake_salt_v1, sizeof(handshake_salt_v1), cid->cid, cid->len, secret);
	}

	if (err) {
		//printf("Failed to extract secrets: %s\n", gcry_strerror(err));
		*error = "Failed to extract secrets";
		return FALSE;
	}

	if (!quic_hkdf_expand_label(GCRY_MD_SHA256, secret, sizeof(secret), "client in", client_initial_secret, HASH_SHA2_256_LENGTH)) {
		*error = "Key expansion (client) failed";
		return FALSE;
	}

	if (!quic_hkdf_expand_label(GCRY_MD_SHA256, secret, sizeof(secret), "server in", server_initial_secret, HASH_SHA2_256_LENGTH)) {
		*error = "Key expansion (server) failed";
		return FALSE;
	}

	*error = NULL;
	
	return TRUE;
}

static gboolean quic_create_initial_decoders(const quic_cid_t *cid, const gchar **error, quic_info_data_t *quic_info)
{
	unsigned char client_secret[HASH_SHA2_256_LENGTH];
	unsigned char server_secret[HASH_SHA2_256_LENGTH];

	if (!quic_derive_initial_secrets(cid, client_secret, server_secret, quic_info->version, error))
		return -1;

	// Packet numbers are protected with AES128-CTR,
	// initial packets are protected with AEAD_AES_128_GCM.
	if (!quic_ciphers_prepare(&quic_info->client_initial_ciphers, GCRY_MD_SHA256, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_GCM, client_secret, error))
	{		
		return FALSE;
	}
	
	if(!quic_ciphers_prepare(&quic_info->server_initial_ciphers, GCRY_MD_SHA256, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_GCM, server_secret, error))
	{
		quic_hp_cipher_reset(&quic_info->client_initial_ciphers.hp_cipher);
		quic_pp_cipher_reset(&quic_info->client_initial_ciphers.pp_cipher);

		return FALSE;
	}
	
	return TRUE;
}

static int quic_extract_header(const char *payload, unsigned char *long_packet_type, unsigned int *version, quic_cid_t *dcid, quic_cid_t *scid)
{
	unsigned int offset = 0;
	
	unsigned char packet_type = payload[offset];
	unsigned char is_long_header = packet_type & 0x80;
	if (is_long_header)
		// long header form
		*long_packet_type = (packet_type & 0x30) >> 4;
	else
		// short header form, store dummy value that is not a long packet type.
		*long_packet_type = QUIC_SHORT_PACKET;
	offset++;
	
	*version = pntoh32((unsigned int *)&payload[offset]);
	
	if (is_long_header) {
		// VN packets don't have any real packet type field, 
		// even if they have a long header: use a dummy value */
		if (*version == 0x00000000)
			*long_packet_type = QUIC_LPT_VER_NEG;
		
		// skip version
		offset += 4;
		
		// read DCID and SCID (both are prefixed by a length byte).
		unsigned char dcil = payload[offset];
		offset++;
		
		if (dcil && dcil <= QUIC_MAX_CID_LENGTH) {
			memcpy(dcid->cid, &payload[offset], dcil);
			dcid->len = dcil;
		}
		offset += dcil;
		
		unsigned char scil = payload[offset];
		offset++;
		
		if (scil && scil <= QUIC_MAX_CID_LENGTH) {
			memcpy(scid->cid, &payload[offset], scil);
			scid->len = scil;
		}
		offset += scil;
	}
	else {
		// Definitely not draft -10, set version to dummy value.
		*version = 0;
		// For short headers, the DCID length is unknown and could be 0 or
		// anything from 1 to 20 bytes. Copy the maximum possible and let the
		// consumer truncate it as necessary.
		memcpy(dcid->cid, &payload[offset], QUIC_MAX_CID_LENGTH);
		dcid->len = QUIC_MAX_CID_LENGTH;
		offset += QUIC_MAX_CID_LENGTH;
	}
	
	return offset;
}

int dissect_quic(const char *payload, unsigned int length, unsigned char *out, unsigned int *out_length)
{
	guint offset = 0;
	quic_packet_info_t quic_packet;
	quic_info_data_t conn;
	unsigned char long_packet_type;
	quic_cid_t dcid = {.len=0}, scid = {.len=0};
	guint64 token_length, payload_length;
	const char *error = NULL;
	guint8 first_byte = 0;
	const gboolean from_server = FALSE;
	quic_ciphers *ciphers = NULL;
	int ret;

	memset(&quic_packet, 0, sizeof(quic_packet_info_t));
	memset(&conn, 0, sizeof(quic_info_data_t));

	ret = quic_extract_header(payload, &long_packet_type, &conn.version, &dcid, &scid);
	if (ret < 0)
	{
		return -1;
	}
	
	if (long_packet_type == QUIC_LPT_INITIAL) 
	{
		// Create new decryption context based on the Client Connection ID 
		// from the *very first* Client Initial packet.
		quic_create_initial_decoders(&dcid, &error, &conn);
		if (!error) 
		{
			guint32 pkn32 = 0;
			// PKN is after type(1) + version(4) + DCIL+DCID + SCIL+SCID
			guint pn_offset = 1 + 4 + 1 + dcid.len + 1 + scid.len;
			pn_offset += tvb_get_varint(payload, pn_offset, 8, &token_length, ENC_VARINT_QUIC);
			pn_offset += (guint)token_length;
			// printf("%d\n", token_length);

			pn_offset += tvb_get_varint(payload, pn_offset, 8, &payload_length, ENC_VARINT_QUIC);
			// printf("%d\n", payload_length);

			// Assume failure unless proven otherwise.
			ciphers = &conn.client_initial_ciphers;
			error = "Header deprotection failed";
			if (quic_decrypt_header(payload, pn_offset, &ciphers->hp_cipher, GCRY_CIPHER_AES128, &first_byte, &pkn32))
				error = NULL;
			if (!error) {
				quic_set_full_packet_number(&conn, &quic_packet, from_server, first_byte, pkn32);
				quic_packet.first_byte = first_byte;
			}

			// Payload
			// skip type(1) + version(4) + DCIL+DCID + SCIL+SCID + len_token_length + token_length + len_payload_length + len_packet_number
			offset = pn_offset + quic_packet.pkn_len;
			//quic_process_payload(payload, length, offset, &conn, &quic_packet, from_server, &ciphers->pp_cipher, first_byte, quic_packet.pkn_len);
			quic_process_payload(payload, payload_length, offset, &conn, &quic_packet, from_server, &ciphers->pp_cipher, first_byte, quic_packet.pkn_len);
			
			// Out
			if (!quic_packet.decryption.error) 
			{
				memcpy(out, quic_packet.decryption.data, quic_packet.decryption.data_len);
				*out_length = quic_packet.decryption.data_len;

				g_free((gpointer)quic_packet.decryption.data);
				quic_packet.decryption.data = NULL;

				ret=1;
			}
			else
			{
				ret=0;
			}

			quic_hp_cipher_reset(&conn.client_initial_ciphers.hp_cipher);
			quic_pp_cipher_reset(&conn.client_initial_ciphers.pp_cipher);
			quic_hp_cipher_reset(&conn.server_initial_ciphers.hp_cipher);
			quic_pp_cipher_reset(&conn.server_initial_ciphers.pp_cipher);

			return ret;
		}
	}

	return 0;
}