Beispiel #1
0
static void auth_generate_auth_hmac(struct login_ctx *l) {
        struct buf* buf = buf_new();
	
	buf_append_data(buf, l->client_parameters->ptr,
                        l->client_parameters->len);
	buf_append_data(buf,  l->server_parameters->ptr,
                        l->server_parameters->len);
        buf_append_u8(buf, 0); /* random data length */
        buf_append_u8(buf, 0); /* unknown */
        buf_append_u16(buf, 8); /* puzzle solution length */
        buf_append_u32(buf, 0); /* unknown */
        /* <-- random data would go here */
        buf_append_data(buf, l->puzzle_solution, 8);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("auth_generate_auth_hmac, HMAC message", buf->ptr,
		     buf->len);
	hexdump8x32 ("auth_generate_auth_hmac, HMAC key", l->key_hmac,
		     sizeof (l->key_hmac));
#endif

	sha1_hmac(l->key_hmac, sizeof(l->key_hmac),
		    buf->ptr, buf->len, l->auth_hmac);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("auth_generate_auth_hmac, HMAC digest", l->auth_hmac,
		     sizeof(l->auth_hmac));
#endif

	buf_free(buf);
}
Beispiel #2
0
void auth_generate_auth_hmac (SESSION * session, unsigned char *auth_hmac,
		unsigned int mac_len)
{
	(void)mac_len;
	struct buf* buf = buf_new();

	buf_append_data(buf, session->init_client_packet->ptr,
			session->init_client_packet->len);
	buf_append_data(buf,  session->init_server_packet->ptr,
			session->init_server_packet->len);
	buf_append_u8(buf, 0); /* random data length */
	buf_append_u8(buf, 0); /* unknown */
	buf_append_u16(buf, 8); /* puzzle solution length */
	buf_append_u32(buf, 0); /* unknown */
	/* <-- random data would go here */
	buf_append_data(buf, session->puzzle_solution, 8);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("auth_generate_auth_hmac, HMAC message", buf->ptr,
			buf->len);
	hexdump8x32 ("auth_generate_auth_hmac, HMAC key", session->key_hmac,
			sizeof (session->key_hmac));
#endif

	sha1_hmac ( session->key_hmac, sizeof (session->key_hmac),
			buf->ptr, buf->len, auth_hmac);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("auth_generate_auth_hmac, HMAC digest", auth_hmac,
			mac_len);
#endif

	buf_free(buf);
}
Beispiel #3
0
int read_server_auth_response (SESSION * session)
{
	unsigned char buf[256];
	unsigned char payload_len;
	int ret;

	ret = block_read(session->ap_sock, buf, 2);
	if (ret != 2) {
		DSFYDEBUG("Failed to read 'status' + length byte, got %d bytes\n", ret);
		return -1;
	}

	if (buf[0] != 0x00) {
		DSFYDEBUG("Authentication failed with error 0x%02x, bad password?\n", buf[1]);
		return -1;
	}

	/* Payload length + this byte must not be zero(?) */
	assert (buf[1] > 0);

	payload_len = buf[1];

	ret = block_read (session->ap_sock, buf, payload_len);
	if (ret != payload_len) {
		DSFYDEBUG("Failed to read 'payload', got %d of %u bytes\n",
				ret, payload_len);
		return -1;
	}
#ifdef DEBUG_LOGIN
	hexdump8x32 ("read_server_auth_response, payload", buf, payload_len);
#endif

	return 0;
}
Beispiel #4
0
int send_client_auth (SESSION * session)
{
	int ret;
	struct buf* buf = buf_new();

	buf_append_data(buf, session->auth_hmac, 20);
	buf_append_u8(buf, 0); /* random data length */
	buf_append_u8(buf, 0); /* unknown */
	buf_append_u16(buf, 8); /* puzzle solution length */
	buf_append_u32(buf, 0);
	/* <-- random data would go here */
	buf_append_data (buf, session->puzzle_solution, 8);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("send_client_auth, second client packet", buf->ptr,
			buf->len);
#endif

	ret = send(session->ap_sock, buf->ptr, buf->len, 0);
	if (ret <= 0) {
		DSFYDEBUG("send_client_auth(): connection lost\n");
		buf_free(buf);
		return -1;
	}
	else if (ret != buf->len) {
		DSFYDEBUG("send_client_auth(): only wrote %d of %d bytes\n",
				ret, buf->len);
		buf_free(buf);
		return -1;
	}

	buf_free(buf);

	return 0;
}
Beispiel #5
0
int send_client_initial_packet (SESSION * session)
{
	int ret;
	unsigned int len_idx;
	
	struct buf* b = buf_new();

	buf_append_u16 (b, 3); /* protocol version */

	len_idx = b->len;
	buf_append_u16(b, 0); /* packet length - updated later */
	buf_append_u32(b, 0x00000300); /* unknown */
	buf_append_u32(b, 0x00030c00); /* unknown */
	buf_append_u32(b, session->client_revision);
	buf_append_u32(b, 0); /* unknown */
	buf_append_u32(b, 0x01000000); /* unknown */
	buf_append_data(b, session->client_id, 4);
	buf_append_u32(b, 0); /* unknown */
	buf_append_data (b, session->client_random_16, 16);
	buf_append_data (b, session->my_pub_key, 96);

	BN_bn2bin (session->rsa->n, session->rsa_pub_exp);
	buf_append_data (b, session->rsa_pub_exp, sizeof(session->rsa_pub_exp));

	buf_append_u8 (b, 0); /* length of random data */
	buf_append_u8 (b, session->username_len);
	buf_append_u16(b, 0x0100); /* unknown */
        /* <-- random data would go here */
	buf_append_data (b, (unsigned char *) session->username,
			   session->username_len);
	buf_append_u8 (b, 0x40); /* unknown */

	/*
	 * Update length bytes
	 *
	 */
	b->ptr[len_idx] = (b->len >> 8) & 0xff;
	b->ptr[len_idx+1] = b->len & 0xff;

#ifdef DEBUG_LOGIN
	hexdump8x32 ("initial client packet", b->ptr, b->len);
#endif
        ret = send (session->ap_sock, b->ptr, b->len, 0);
	if (ret <= 0) {
		DSFYDEBUG("connection lost\n");
		buf_free(b);
		return -1;
	}
	else if (ret != b->len) {
                DSFYDEBUG("only wrote %d of %d bytes\n", ret, b->len);
		buf_free(b);
		return -1;
	}

        /* save initial server packet for auth hmac generation */
        session->init_client_packet = b;
	
	return 0;
}
Beispiel #6
0
static void puzzle_solve (struct login_ctx *l) {
	SHA1_CTX ctx;
	unsigned char digest[20];
	unsigned int *nominator_from_hash;
	unsigned int denominator;
	unsigned int seed;
	int i;

	/*
	 * Modulus operation by a power of two.
	 * "Most programmers learn this trick early"
	 * Well, f**k me. I'm just here for the party.
	 *
	 */
	denominator = 1 << l->puzzle_denominator;
	denominator--;

	/*
	 * Compute a hash over random data until
	 * (last dword byteswapped XOR magic number) mod
	 * denominator by server produces zero.
	 *
	 */

	seed = get_millisecs() ^ (get_millisecs() << 9);
	srandom(seed);
	nominator_from_hash = (unsigned int *) (digest + 16);
	do {
		SHA1Init (&ctx);
		SHA1Update (&ctx, l->server_random_16, 16);

		/* Let's waste some precious pseudorandomness */
		for (i = 0; i < 8; i++)
			l->puzzle_solution[i] = random ();
		SHA1Update (&ctx, l->puzzle_solution, 8);

		SHA1Final (digest, &ctx);

		/* byteswap (XXX - htonl() won't work on bigendian machines!) */
		*nominator_from_hash = htonl (*nominator_from_hash);

		/* XOR with a fancy magic */
		*nominator_from_hash ^= l->puzzle_magic;
	} while (*nominator_from_hash & denominator);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("auth_solve_puzzle, puzzle_solution", l->puzzle_solution, 8);
#endif
}
Beispiel #7
0
static void auth_generate_auth_hash(struct login_ctx *l) {
	unsigned char space = ' ';
	SHA1_CTX ctx;

	SHA1Init(&ctx);

	SHA1Update(&ctx, l->salt, 10);
	SHA1Update(&ctx, &space, 1);
	SHA1Update(&ctx, (unsigned char *)l->password, strlen(l->password));

	SHA1Final(l->auth_hash, &ctx);

#ifdef DEBUG_LOGIN
	hexdump8x32("auth_generate_auth_hash, auth_hash", l->auth_hash, 20);
#endif
}
Beispiel #8
0
void auth_generate_auth_hash (SESSION * session)
{
	SHA1_CTX ctx;

	SHA1Init (&ctx);

	SHA1Update (&ctx, (unsigned char *)session->salt, 10);
	SHA1Update (&ctx, (unsigned char *)" ", 1);
	SHA1Update (&ctx, (unsigned char *)session->password, strlen (session->password));

	SHA1Final (session->auth_hash, &ctx);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("auth_generate_auth_hash, auth_hash", session->auth_hash,
			20);
#endif
}
Beispiel #9
0
static int receive_server_auth_response(struct login_ctx *l) {
	unsigned char buf[256];
	unsigned char payload_len;
	int ret;

        ret = block_read(l->sock, buf, 2);
	if (ret != 2) {
		DSFYDEBUG("Failed to read 'status' + length byte, got %d bytes\n", ret);
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}

	if (buf[0] != 0x00) {
		DSFYDEBUG("Authentication failed with error 0x%02x, bad password?\n", buf[1]);
		l->error = SP_LOGIN_ERROR_BAD_PASSWORD;
		return -1;
	}

	/* Payload length + this byte must not be zero(?) */
	assert (buf[1] > 0);

	payload_len = buf[1];

        ret = block_read (l->sock, buf, payload_len);
	if (ret != payload_len) {
		DSFYDEBUG("Failed to read 'payload', got %d of %u bytes\n",
			ret, payload_len);
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
       		return -1;
	}
#ifdef DEBUG_LOGIN
	hexdump8x32("receive_server_auth_response, payload", buf, payload_len);
#endif

	return 0;
}
Beispiel #10
0
static int send_client_auth_packet(struct login_ctx *l) {
	int ret;
        struct buf* buf = buf_new();

	buf_append_data(buf, l->auth_hmac, 20);
        buf_append_u8(buf, 0); /* random data length */
        buf_append_u8(buf, 0); /* unknown */
        buf_append_u16(buf, 8); /* puzzle solution length */
        buf_append_u32(buf, 0);
        /* <-- random data would go here */
	buf_append_data (buf, l->puzzle_solution, 8);

#ifdef DEBUG_LOGIN
	hexdump8x32("send_client_auth_packet, second client packet", buf->ptr,
		     buf->len);
#endif

        ret = send(l->sock, buf->ptr, buf->len, 0);
	if (ret <= 0) {
		DSFYDEBUG("Connection was reset\n");
		buf_free(buf);
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
	else if (ret != buf->len) {
		DSFYDEBUG("Only wrote %d of %d bytes\n",
			ret, buf->len);
		buf_free(buf);
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}

	buf_free(buf);
	
	return 0;
}
Beispiel #11
0
/*
 * Initialize common crypto keys used for communication
 *
 * This step takes place after the initial two packets
 * have been exchanged.
 *
 */
static void key_init(struct login_ctx *l) {
	BIGNUM *pub_key;
	unsigned char message[53];
	unsigned char hmac_output[20 * 5];
	unsigned char *ptr, *hmac_ptr;
	unsigned int mac_len;
	int i;


	/*
	 * Compute DH shared key
	 * It's used in the call to HMAC() below
	 *
	 */
	pub_key = BN_bin2bn(l->remote_pub_key, 96, NULL);
	if((i = DH_compute_key(l->shared_key, pub_key, l->dh)) < 0) {
		/* XXX */
		return;
	}

#ifdef DEBUG_LOGIN
	hexdump8x32 ("key_init, my private key", l->my_priv_key, 96);
	hexdump8x32 ("key_init, my public key", l->client_pub_key, 96);
	hexdump8x32 ("key_init, remote public key", l->remote_pub_key,
		     96);
	hexdump8x32 ("key_init, shared key", l->shared_key, 96);
#endif
        BN_free(pub_key);



	/*
	 * Prepare a message to authenticate.
	 *
	 * Prior to the 19th of December 2008 Spotify happily told clients 
	 * (including ours!) almost everything it knew about a particular
	 * user, if they asked for it.
	 *
	 * Legitimate requests for this is for example when you add
	 * someone else's shared playlist.
	 *
	 * This allowed clients to see not only the last four digits of the 
	 * credit card used to subscribe to the premium service, whether
	 * the user was a paying customer or preferred commercials, but 
	 * also very interesting stuff such as the hash computed from
	 * SHA(salt || " " || password).
	 *
	 * In theory (HE HE!) this allowed any registered user to request
	 * somebody else's user data, get ahold of the hash, and then use
	 * it to authenticate as that user.
	 *
	 * Fortunately, at lest for Spotify and it's users, this is not
	 * the case anymore. (R.I.P poor misfeature)
	 *
	 * However, we urge people to change their passwords for reasons
	 * left as an exercise for the reader to figure out.
	 *
	 */
	ptr = message;
	memcpy (ptr, l->auth_hash, sizeof (l->auth_hash));
	ptr += sizeof (l->auth_hash);

	memcpy (ptr, l->client_random_16, 16);
	ptr += 16;

	memcpy (ptr, l->server_random_16, 16);
	ptr += 16;

	/*
	 * Run HMAC over the message, using the DH shared key as key
	 *
	 */
	hmac_ptr = hmac_output;
	mac_len = 20;
	for (i = 1; i <= 5; i++) {
		/*
		 * Change last byte of message to authenticate
		 *
		 */
		*ptr = i;

#ifdef DEBUG_LOGIN
		hexdump8x32 ("key_init, HMAC message", message,
			     sizeof (message));
#endif

	        sha1_hmac(l->shared_key, 96, message,
			  sizeof (message), hmac_ptr);

		/*
		 * Overwrite the 20 first bytes of the message with output from this round
		 *
		 */
		memcpy (message, hmac_ptr, 20);
		hmac_ptr += 20;
	}

	/*
	 * Use computed HMAC to setup keys for the
	 * stream cipher
	 *
	 */
	memcpy (l->key_send, hmac_output + 20, 32);
	memcpy (l->key_recv, hmac_output + 52, 32);


	/*
	 * The first 20 bytes of the HMAC output is used
	 * to key another HMAC computed for the second
	 * authentication packet sent by the client.
	 *
	 */
	memcpy (l->key_hmac, hmac_output, 20);

#ifdef DEBUG_LOGIN
	hexdump8x32 ("key_init, key_hmac", l->key_hmac, 20);
	hexdump8x32 ("key_init, key_send", l->key_send, 32);
	hexdump8x32 ("key_init, key_recv", l->key_recv, 32);
#endif
}
Beispiel #12
0
static int receive_server_parameters(struct login_ctx *l) {
	char buf[512];
	unsigned char padlen, username_len;
        unsigned short chalen[4];
	int normalize;
	int ret;
        struct buf* save = buf_new();

        /* read 2 status bytes */
        ret = block_read(l->sock, l->server_random_16, 2);
	if(ret < 2) {
       		DSFYDEBUG("Failed to read status bytes, return value was %d, errno is %d\n", ret, errno);
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}

        if (l->server_random_16[0] != 0) {
		DSFYDEBUG("Bad response: %#02x %#02x\n",
				l->server_random_16[0], l->server_random_16[1]);
		switch (l->server_random_16[1]) {
                case 1: /* client upgrade required */
			l->error = SP_LOGIN_ERROR_UPGRADE_REQUIRED;
			return -1;

                case 3: /* user not found */
			l->error = SP_LOGIN_ERROR_USER_NOT_FOUND;
                    	return -1;

                case 4: /* account has been disabled */
			l->error = SP_LOGIN_ERROR_USER_BANNED;
                    	return -1;

                case 6: /* you need to complete your account details */
			l->error = SP_LOGIN_ERROR_USER_NEED_TO_COMPLETE_DETAILS;
                    	return -1;

                case 9: /* country mismatch */
			l->error = SP_LOGIN_ERROR_USER_COUNTRY_MISMATCH;
                    	return -1;

                default: /* unknown error */
			l->error = SP_LOGIN_ERROR_OTHER_PERMANENT;
                    	return -1;
            }
        }


        /* read remaining 14 random bytes */
        ret = block_read(l->sock, l->server_random_16 + 2, 14);
	if(ret < 14) {
		DSFYDEBUG("Failed to read server random\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
        buf_append_data(save, l->server_random_16, 16);


        /* read public key */
        ret = block_read(l->sock, l->remote_pub_key, 96);
	if (ret != 96) {
		DSFYDEBUG("Failed to read 'remote_pub_key'\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
        buf_append_data(save, l->remote_pub_key, 96);


        /* read server blob */
        ret = block_read(l->sock, buf, 256);
	if (ret != 256) {
		DSFYDEBUG("Failed to read 'random_256', got %d of 256 bytes\n", ret);
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
        buf_append_data(save, buf, 256);


        /* read salt */
        ret = block_read(l->sock, l->salt, 10);
	if (ret != 10) {
		DSFYDEBUG("Failed to read 'salt'\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
        buf_append_data(save, l->salt, 10);


        /* read padding length */
        ret = block_read(l->sock, &padlen, 1);
	if (ret != 1) {
		DSFYDEBUG("Failed to read 'padding length'\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
	assert (padlen > 0);
        buf_append_u8(save, padlen);

        /* read username length */
        ret = block_read(l->sock, &username_len, 1);
	if (ret != 1) {
		DSFYDEBUG("Failed to read 'username_len'\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
        buf_append_u8(save, username_len);


        /* read challenge lengths */
        ret = block_read(l->sock, chalen, 8);
	if (ret != 8) {
		DSFYDEBUG("Failed to read challenge lengths\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
        buf_append_data(save, chalen, 8);


        /* read packet padding */
        ret = block_read(l->sock, buf, padlen);
	if (ret != padlen) {
		DSFYDEBUG("Failed to read 'padding'\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}
        buf_append_data(save, buf, padlen);


        /* read username */
        ret = block_read(l->sock,
                         l->username, username_len);
	if (ret != username_len) {
		DSFYDEBUG("Failed to read 'username'\n");
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
		return -1;
	}

        buf_append_data(save, l->username, username_len);
	l->username[username_len] = 0;


        /* read puzzle challenge */
        {
            int puzzle_len = ntohs(chalen[0]);
            int len1 = ntohs(chalen[1]);
            int len2 = ntohs(chalen[2]);
            int len3 = ntohs(chalen[3]);
            int totlen = puzzle_len + len1 + len2 + len3;

            struct buf* b = buf_new();
            buf_extend(b, totlen);

		DSFYDEBUG("Reading a total of %d bytes puzzle challenge\n", totlen);
            ret = block_read(l->sock, b->ptr, totlen);
            if (ret != totlen) {
                DSFYDEBUG("Failed to read puzzle\n");
                buf_free(b);
		l->error = SP_LOGIN_ERROR_SOCKET_ERROR;
                return -1;
            }
            buf_append_data(save, b->ptr, totlen);


            if (b->ptr[0] == 1) {
		l->puzzle_denominator = b->ptr[1];
		memcpy(&normalize, b->ptr + 2, sizeof(int));
		l->puzzle_magic = ntohl(normalize);
            }
            else {
		DSFYDEBUG("Unexpected puzzle challenge with first byte 0x%02x\n", b->ptr[0]);
		hexdump8x32("receive_server_parameters, puzzle", b->ptr, totlen);
		l->error = SP_LOGIN_ERROR_OTHER_PERMANENT;
		buf_free(b);
		return -1;
            }

            buf_free(b);
        }

        l->server_parameters = save;

	return 0;
}
Beispiel #13
0
int read_server_initial_packet (SESSION * session)
{
	char buf[512];
	unsigned char padlen;
	int ret;
        struct buf* save = buf_new();

        /* read 2 status bytes */
        ret = block_read(session->ap_sock, session->server_random_16, 2);
	if (ret < 2) {
            DSFYDEBUG("Failed to read status bytes\n");
            DSFYDEBUG("Remote host was %s:%d\n",
                      session->server_host, session->server_port);
            if (ret > 0)
                hexdump8x32
                    ("read_server_initial_packet, server_random_16",
                     session->server_random_16, ret);
            return -90;
	}

#ifdef DEBUG_LOGIN
	hexdump8x32 ("read_server_initial_packet, server_random_16",
		     session->server_random_16, ret);
#endif

        if (session->server_random_16[0] != 0) {
            DSFYDEBUG("Bad response: %#02x %#02x\n",
                      session->server_random_16[0],
                      session->server_random_16[1]);
            switch (session->server_random_16[1]) {
                case 1: /* client upgrade required */
                    return -11;
                    
                case 3: /* user not found */
                    return -13;
                    
                case 4: /* account has been disabled */
                    return -14;
                    
                case 6: /* you need to complete your account details */
                    return -16;
                    
                case 9: /* country mismatch */
                    return -19;
                    
                default: /* unknown error */
                    return -91;
            }
        }

        /* read remaining 14 random bytes */
        ret = block_read(session->ap_sock, session->server_random_16 + 2, 14);
	if (ret < 14) {
            DSFYDEBUG("Failed to read server random\n");
            DSFYDEBUG("Remote host was %s:%d\n",
                      session->server_host, session->server_port);
            if (ret > 0)
                hexdump8x32("read_server_initial_packet, server_random_16",
                            session->server_random_16+2, ret);
            return -92;
	}
        buf_append_data(save, session->server_random_16, 16);
	
        /* read public key */
        ret = block_read(session->ap_sock, session->remote_pub_key, 96);
	if (ret != 96) {
            DSFYDEBUG("Failed to read 'remote_pub_key'\n");
            return -93;
	}
        buf_append_data(save, session->remote_pub_key, 96);
#ifdef DEBUG_LOGIN
	hexdump8x32 ("read_server_initial_packet, server pub key",
		     session->remote_pub_key, 96);
#endif

        /* read server blob */
        ret = block_read(session->ap_sock, session->random_256, 256);
	if (ret != 256) {
            DSFYDEBUG("Failed to read 'random_256', got %d of 256 bytes\n", ret);
            return -94;
	}
        buf_append_data(save, session->random_256, 256);
#ifdef DEBUG_LOGIN
	hexdump8x32 ("read_server_initial_packet, random_256",
		     session->random_256, 256);
#endif

        /* read salt */
        ret = block_read(session->ap_sock, session->salt, 10);
	if (ret != 10) {
            DSFYDEBUG("Failed to read 'salt'\n");
            return -95;
	}
        buf_append_data(save, session->salt, 10);
#ifdef DEBUG_LOGIN
	hexdump8x32 ("read_server_initial_packet, salt", session->salt, 10);
#endif

        /* read padding length */
        ret = block_read(session->ap_sock, &padlen, 1);
	if (ret != 1) {
            DSFYDEBUG("Failed to read 'padding length'\n");
            return -96;
	}
	assert (padlen > 0);
        buf_append_u8(save, padlen);

        /* read username length */
        ret = block_read(session->ap_sock, &session->username_len, 1);
	if (ret != 1) {
            DSFYDEBUG("Failed to read 'username_len'\n");
            return -97;
	}
        buf_append_u8(save, session->username_len);
                
        /* read challenge lengths */
        unsigned short chalen[4];
        ret = block_read(session->ap_sock, chalen, 8);
	if (ret != 8) {
            DSFYDEBUG("Failed to read challenge lengths\n");
            return -98;
	}
        buf_append_data(save, chalen, 8);
        
        /* read packet padding */
        ret = block_read(session->ap_sock, buf, padlen);
	if (ret != padlen) {
            DSFYDEBUG("Failed to read 'padding'\n");
            return -99;
	}
        buf_append_data(save, buf, padlen);
#ifdef DEBUG_LOGIN
	hexdump8x32 ("read_server_initial_packet, padding", buf, padlen);
#endif

        /* read username */
        ret = block_read(session->ap_sock,
                         session->username, session->username_len);
	if (ret != session->username_len) {
            DSFYDEBUG("Failed to read 'username'\n");
            return -100;
	}
        buf_append_data(save, session->username, session->username_len);
	session->username[session->username_len] = 0;
#ifdef DEBUG_LOGIN
	hexdump8x32 ("read_server_initial_packet, username",
		     session->username, session->username_len);
#endif

        /* read puzzle challenge */
        {
            int puzzle_len = ntohs(chalen[0]);
            int len1 = ntohs(chalen[1]);
            int len2 = ntohs(chalen[2]);
            int len3 = ntohs(chalen[3]);
            int totlen = puzzle_len + len1 + len2 + len3;
            int normalize = 0;

            struct buf* b = buf_new();
            buf_extend(b, totlen);
            
            ret = block_read(session->ap_sock, b->ptr, totlen);
            if (ret != totlen) {
                DSFYDEBUG("Failed to read puzzle\n");
                buf_free(b);
                return -101;
            }
            buf_append_data(save, b->ptr, totlen);
#ifdef DEBUG_LOGIN
            hexdump8x32("read_server_initial_packet, puzzle", b->ptr, totlen);
#endif
            

            if (b->ptr[0] == 1) {
                session->puzzle_denominator = b->ptr[1];
                memcpy(&normalize, b->ptr+2, sizeof(int));
                session->puzzle_magic = ntohl(normalize);
            }
            else {
                DSFYDEBUG("Unexpected puzzle challenge\n");
                hexdump8x32("read_server_initial_packet, puzzle", b->ptr, totlen);
                buf_free(b);
                return -102;
            }

            buf_free(b);
        }

        session->init_server_packet = save;
        
	return 0;
}