crypt: add TLS stream cipher type

[siplcs.git] / src / core / sipe-tls.c

/**
 * @file sipe-tls.c
 *
 * pidgin-sipe
 *
 * Copyright (C) 2011-2015 SIPE Project <http://sipe.sourceforge.net/>
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *
 * TLS Protocol Version 1.0/1.1/1.2 - Handshake Messages
 *
 * TLS-DSK uses the handshake messages during authentication and session key
 * exchange. This module *ONLY* implements this part of the TLS specification!
 *
 * Specification references:
 *
 *   - RFC2246: http://www.ietf.org/rfc/rfc2246.txt
 *   - RFC3546: http://www.ietf.org/rfc/rfc3546.txt
 *   - RFC4346: http://www.ietf.org/rfc/rfc4346.txt
 */

#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

#include <glib.h>

#include "sipe-common.h"
#include "sipe-backend.h"
#include "sipe-cert-crypto.h"
#include "sipe-crypt.h"
#include "sipe-digest.h"
#include "sipe-svc.h"
#include "sipe-tls.h"

/*
 * Private part of TLS state tracking
 */
enum tls_handshake_state {
        TLS_HANDSHAKE_STATE_START,
        TLS_HANDSHAKE_STATE_SERVER_HELLO,
        TLS_HANDSHAKE_STATE_FINISHED,
        TLS_HANDSHAKE_STATE_COMPLETED,
        TLS_HANDSHAKE_STATE_FAILED
};

struct tls_internal_state {
        struct sipe_tls_state common;
        gpointer certificate;
        enum tls_handshake_state state;
        guchar *msg_current;
        gsize msg_remainder;
        GHashTable *data;
        GString *debug;
        guint cipher_type;
        gpointer md5_context;
        gpointer sha1_context;
        gpointer server_certificate;
        struct sipe_tls_random client_random;
        struct sipe_tls_random server_random;
        struct sipe_tls_random pre_master_secret;
        gsize mac_length;
        gsize key_length;
        guchar *master_secret;
        guchar *key_block;
        guchar *tls_dsk_key_block;
        const guchar *client_write_mac_secret;
        const guchar *server_write_mac_secret;
        const guchar *client_write_secret;
        const guchar *server_write_secret;
        void (*mac_func)(const guchar *key, gsize key_length,
                         const guchar *data, gsize data_length,
                         guchar *digest);
        gpointer cipher_context;
        guint64 sequence_number;
        gboolean encrypted;
};

/*
 * TLS messages & layout descriptors
 */

/* constants */
#define TLS_VECTOR_MAX8       255 /* 2^8  - 1 */
#define TLS_VECTOR_MAX16    65535 /* 2^16 - 1 */
#define TLS_VECTOR_MAX24 16777215 /* 2^24 - 1 */

#define TLS_PROTOCOL_VERSION_1_0 0x0301
#define TLS_PROTOCOL_VERSION_1_1 0x0302
#define TLS_PROTOCOL_VERSION_1_2 0x0303

/* CipherSuites */
#define TLS_RSA_EXPORT_WITH_RC4_40_MD5       0x0003
#define TLS_RSA_WITH_RC4_128_MD5             0x0004
#define TLS_RSA_WITH_RC4_128_SHA             0x0005
#define TLS_DHE_DSS_WITH_AES_256_CBC_SHA     0x0038
#define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA   0xC014
#define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA 0xC00A

/* CompressionMethods */
#define TLS_COMP_METHOD_NULL 0

/* various array lengths */
#define TLS_ARRAY_RANDOM_LENGTH        32
#define TLS_ARRAY_MASTER_SECRET_LENGTH 48
#define TLS_ARRAY_VERIFY_LENGTH        12

#define TLS_RECORD_HEADER_LENGTH            5
#define TLS_RECORD_OFFSET_TYPE              0
#define TLS_RECORD_TYPE_CHANGE_CIPHER_SPEC 20
#define TLS_RECORD_TYPE_HANDSHAKE          22
#define TLS_RECORD_OFFSET_VERSION           1
#define TLS_RECORD_OFFSET_LENGTH            3

#define TLS_HANDSHAKE_HEADER_LENGTH             4
#define TLS_HANDSHAKE_OFFSET_TYPE               0
#define TLS_HANDSHAKE_TYPE_CLIENT_HELLO         1
#define TLS_HANDSHAKE_TYPE_SERVER_HELLO         2
#define TLS_HANDSHAKE_TYPE_CERTIFICATE         11
#define TLS_HANDSHAKE_TYPE_CERTIFICATE_REQ     13
#define TLS_HANDSHAKE_TYPE_SERVER_HELLO_DONE   14
#define TLS_HANDSHAKE_TYPE_CERTIFICATE_VERIFY  15
#define TLS_HANDSHAKE_TYPE_CLIENT_KEY_EXCHANGE 16
#define TLS_HANDSHAKE_TYPE_FINISHED            20
#define TLS_HANDSHAKE_OFFSET_LENGTH             1

struct layout_descriptor;
typedef gboolean parse_func(struct tls_internal_state *state,
                            const struct layout_descriptor *desc);

/* Defines the strictest alignment requirement */
struct tls_compile_integer;
typedef void compile_func(struct tls_internal_state *state,
                          const struct layout_descriptor *desc,
                          const struct tls_compile_integer *data);

struct layout_descriptor {
        const gchar *label;
        parse_func *parser;
        compile_func *compiler;
        gsize min; /* 0 for fixed/array */
        gsize max;
        gsize offset;
};

#define TLS_LAYOUT_DESCRIPTOR_END { NULL, NULL, NULL, 0, 0, 0 }
#define TLS_LAYOUT_IS_VALID(desc) (desc->label)

struct msg_descriptor  {
        const struct msg_descriptor *next;
        const gchar *description;
        const struct layout_descriptor *layouts;
        guint type;
};

/* parsed data */
struct tls_parsed_integer {
        guint value;
};

struct tls_parsed_array {
        gsize length; /* bytes */
        const guchar data[0];
};

/* compile data */
struct tls_compile_integer {
        gsize value;
};

struct tls_compile_array {
        gsize elements; /* unused */
        guchar placeholder[];
};

struct tls_compile_random {
        gsize elements; /* unused */
        guchar random[TLS_ARRAY_RANDOM_LENGTH];
};

struct tls_compile_verify {
        gsize elements; /* unused */
        guchar verify[TLS_ARRAY_VERIFY_LENGTH];
};

struct tls_compile_vector {
        gsize elements; /* VECTOR */
        guint placeholder[];
};

struct tls_compile_sessionid {
        gsize elements; /* VECTOR */
};

struct tls_compile_cipher {
        gsize elements; /* VECTOR */
        guint suites[6];
};

struct tls_compile_compression {
        gsize elements; /* VECTOR */
        guint methods[1];
};

/* compiled message */
struct tls_compiled_message {
        gsize size;
        guchar data[];
};

/*
 * Random byte buffers
 */
void sipe_tls_fill_random(struct sipe_tls_random *random,
                          guint bits)
{
        guint bytes = ((bits + 15) / 16) * 2;
        guint16 *p  = g_malloc(bytes);

        SIPE_DEBUG_INFO("sipe_tls_fill_random: %d bits -> %d bytes",
                        bits, bytes);

        random->buffer = (guint8*) p;
        random->length = bytes;

        for (bytes /= 2; bytes; bytes--)
                *p++ = rand() & 0xFFFF;
}

void sipe_tls_free_random(struct sipe_tls_random *random)
{
        g_free(random->buffer);
}

/*
 * TLS message debugging
 */
static void debug_hex(struct tls_internal_state *state,
                      gsize alternative_length)
{
        GString *str = state->debug;
        const guchar *bytes;
        gsize length;
        gint count;

        if (!str) return;

        bytes  = state->msg_current;
        length = alternative_length ? alternative_length : state->msg_remainder;
        count  = -1;

        while (length-- > 0) {
                if (++count == 0) {
                        /* do nothing */;
                } else if ((count % 16) == 0) {
                        g_string_append(str, "\n");
                } else if ((count %  8) == 0) {
                        g_string_append(str, "  ");
                }
                g_string_append_printf(str, " %02X", *bytes++);
        }
        g_string_append(str, "\n");
}

#define debug_print(state, string) \
        if (state->debug) g_string_append(state->debug, string)
#define debug_printf(state, format, ...) \
        if (state->debug) g_string_append_printf(state->debug, format, __VA_ARGS__)

/* Analyzer only needs the debugging functions */
#ifndef _SIPE_COMPILING_ANALYZER

static void debug_secrets(struct tls_internal_state *state,
                          const gchar *label,
                          const guchar *secret,
                          gsize secret_length)
{
        if (state->debug && secret) {
                g_string_append_printf(state->debug, "%s (%3" G_GSIZE_FORMAT ") = ",
                                       label, secret_length);
                while (secret_length--)
                        g_string_append_printf(state->debug, "%02X", *secret++);
                SIPE_DEBUG_INFO_NOFORMAT(state->debug->str);
                g_string_truncate(state->debug, 0);
        }
}

/*
 * TLS Pseudorandom Function (PRF) - RFC2246, Section 5
 */
static guchar *sipe_tls_p_md5(const guchar *secret,
                              gsize secret_length,
                              const guchar *seed,
                              gsize seed_length,
                              gsize output_length)
{
        guchar *output = NULL;

        /*
         * output_length ==  0     -> illegal
         * output_length ==  1..16 -> iterations = 1
         * output_length == 17..32 -> iterations = 2
         */
        if (secret && seed && (output_length > 0)) {
                guint iterations = (output_length + SIPE_DIGEST_HMAC_MD5_LENGTH - 1) / SIPE_DIGEST_HMAC_MD5_LENGTH;
                guchar *concat   = g_malloc(SIPE_DIGEST_HMAC_MD5_LENGTH + seed_length);
                guchar A[SIPE_DIGEST_HMAC_MD5_LENGTH];
                guchar *p;

                SIPE_DEBUG_INFO("p_md5: secret %" G_GSIZE_FORMAT " bytes, seed %" G_GSIZE_FORMAT " bytes",
                                secret_length, seed_length);
                SIPE_DEBUG_INFO("p_md5: output %" G_GSIZE_FORMAT " bytes -> %d iterations",
                                output_length, iterations);

                /* A(1) = HMAC_MD5(secret, A(0)), A(0) = seed */
                sipe_digest_hmac_md5(secret, secret_length,
                                      seed, seed_length,
                                      A);

                /* Each iteration adds SIPE_DIGEST_HMAC_MD5_LENGTH bytes */
                p = output = g_malloc(iterations * SIPE_DIGEST_HMAC_MD5_LENGTH);

                while (iterations-- > 0) {
                        /* P_MD5(i) = HMAC_MD5(secret, A(i) + seed), i = 1, 2, ... */
                        guchar P[SIPE_DIGEST_HMAC_MD5_LENGTH];
                        memcpy(concat, A, SIPE_DIGEST_HMAC_MD5_LENGTH);
                        memcpy(concat + SIPE_DIGEST_HMAC_MD5_LENGTH, seed, seed_length);
                        sipe_digest_hmac_md5(secret, secret_length,
                                              concat, SIPE_DIGEST_HMAC_MD5_LENGTH + seed_length,
                                              P);
                        memcpy(p, P, SIPE_DIGEST_HMAC_MD5_LENGTH);
                        p += SIPE_DIGEST_HMAC_MD5_LENGTH;

                        /* A(i+1) = HMAC_MD5(secret, A(i)) */
                        sipe_digest_hmac_md5(secret, secret_length,
                                              A, SIPE_DIGEST_HMAC_MD5_LENGTH,
                                              A);
                }
                g_free(concat);
        }

        return(output);
}

guchar *sipe_tls_p_sha1(const guchar *secret,
                        gsize secret_length,
                        const guchar *seed,
                        gsize seed_length,
                        gsize output_length)
{
        guchar *output = NULL;

        /*
         * output_length ==  0     -> illegal
         * output_length ==  1..20 -> iterations = 1
         * output_length == 21..40 -> iterations = 2
         */
        if (secret && seed && (output_length > 0)) {
                guint iterations = (output_length + SIPE_DIGEST_HMAC_SHA1_LENGTH - 1) / SIPE_DIGEST_HMAC_SHA1_LENGTH;
                guchar *concat   = g_malloc(SIPE_DIGEST_HMAC_SHA1_LENGTH + seed_length);
                guchar A[SIPE_DIGEST_HMAC_SHA1_LENGTH];
                guchar *p;

                SIPE_DEBUG_INFO("p_sha1: secret %" G_GSIZE_FORMAT " bytes, seed %" G_GSIZE_FORMAT " bytes",
                                secret_length, seed_length);
                SIPE_DEBUG_INFO("p_sha1: output %" G_GSIZE_FORMAT " bytes -> %d iterations",
                                output_length, iterations);

                /* A(1) = HMAC_SHA1(secret, A(0)), A(0) = seed */
                sipe_digest_hmac_sha1(secret, secret_length,
                                      seed, seed_length,
                                      A);

                /* Each iteration adds SIPE_DIGEST_HMAC_SHA1_LENGTH bytes */
                p = output = g_malloc(iterations * SIPE_DIGEST_HMAC_SHA1_LENGTH);

                while (iterations-- > 0) {
                        /* P_SHA1(i) = HMAC_SHA1(secret, A(i) + seed), i = 1, 2, ... */
                        guchar P[SIPE_DIGEST_HMAC_SHA1_LENGTH];
                        memcpy(concat, A, SIPE_DIGEST_HMAC_SHA1_LENGTH);
                        memcpy(concat + SIPE_DIGEST_HMAC_SHA1_LENGTH, seed, seed_length);
                        sipe_digest_hmac_sha1(secret, secret_length,
                                              concat, SIPE_DIGEST_HMAC_SHA1_LENGTH + seed_length,
                                              P);
                        memcpy(p, P, SIPE_DIGEST_HMAC_SHA1_LENGTH);
                        p += SIPE_DIGEST_HMAC_SHA1_LENGTH;

                        /* A(i+1) = HMAC_SHA1(secret, A(i)) */
                        sipe_digest_hmac_sha1(secret, secret_length,
                                              A, SIPE_DIGEST_HMAC_SHA1_LENGTH,
                                              A);
                }
                g_free(concat);
        }

        return(output);
}

static guchar *sipe_tls_prf(SIPE_UNUSED_PARAMETER struct tls_internal_state *state,
                            const guchar *secret,
                            gsize secret_length,
                            const guchar *label,
                            gsize label_length,
                            const guchar *seed,
                            gsize seed_length,
                            gsize output_length)
{
        gsize half           = (secret_length + 1) / 2;
        gsize newseed_length = label_length + seed_length;
        /* secret: used as S1; secret2: last half of original secret (S2) */
        guchar *secret2 = g_memdup(secret + secret_length - half, half);
        guchar *newseed = g_malloc(newseed_length);
        guchar *md5, *dest;
        guchar *sha1, *src;
        gsize count;

        /* make Coverity happy - lengths could be 0 */
        if (!secret2 || !newseed) {
                g_free(secret2);
                g_free(newseed);
                return(NULL);
        }

        /*
         * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
         *                            P_SHA-1(S2, label + seed);
         */
        memcpy(newseed, label, label_length);
        memcpy(newseed + label_length, seed, seed_length);
#undef __SIPE_TLS_CRYPTO_DEBUG
#ifdef __SIPE_TLS_CRYPTO_DEBUG
        debug_secrets(state, "sipe_tls_prf: secret                    ",
                      secret,  secret_length);
        debug_secrets(state, "sipe_tls_prf: combined seed             ",
                      newseed, newseed_length);
        SIPE_DEBUG_INFO("total seed length %" G_GSIZE_FORMAT,
                        newseed_length);
        debug_secrets(state, "sipe_tls_prf: S1                        ",
                      secret,  half);
        debug_secrets(state, "sipe_tls_prf: S2                        ",
                      secret2, half);
#endif
        md5  = sipe_tls_p_md5(secret,   half, newseed, newseed_length, output_length);
        sha1 = sipe_tls_p_sha1(secret2, half, newseed, newseed_length, output_length);
#ifdef __SIPE_TLS_CRYPTO_DEBUG
        debug_secrets(state, "sipe_tls_prf: P_md5()                   ",
                      md5,  output_length);
        debug_secrets(state, "sipe_tls_prf: P_sha1()                  ",
                      sha1, output_length);
#endif
        for (dest = md5, src = sha1, count = output_length;
             count > 0;
             count--)
                *dest++ ^= *src++;

        g_free(sha1);
        g_free(newseed);
        g_free(secret2);

#ifdef __SIPE_TLS_CRYPTO_DEBUG
        debug_secrets(state, "sipe_tls_prf: PRF()                     ",
                      md5,  output_length);
#endif

        return(md5);
}

#endif /* !_SIPE_COMPILING_ANALYZER */

/*
 * TLS data parsers
 *
 * Low-level data conversion routines
 *
 *  - host alignment agnostic, i.e. can fetch a word from uneven address
 *  - TLS -> host endianess conversion
 *  - no length check, caller has to do it
 *  - don't modify state
 */
static guint lowlevel_integer_to_host(const guchar *bytes,
                                      gsize length)
{
        guint sum = 0;
        while (length--) sum = (sum << 8) + *bytes++;
        return(sum);
}

/*
 * Generic data type parser routines
 */
static gboolean msg_remainder_check(struct tls_internal_state *state,
                                   const gchar *label,
                                   gsize length)
{
        if (length > state->msg_remainder) {
                SIPE_DEBUG_ERROR("msg_remainder_check: '%s' expected %" G_GSIZE_FORMAT " bytes, remaining %" G_GSIZE_FORMAT,
                                 label, length, state->msg_remainder);
                return(FALSE);
        }
        return(TRUE);
}

static gboolean parse_integer_quiet(struct tls_internal_state *state,
                                    const gchar *label,
                                    gsize length,
                                    guint *result)
{
        if (!msg_remainder_check(state, label, length)) return(FALSE);
        *result = lowlevel_integer_to_host(state->msg_current, length);
        state->msg_current   += length;
        state->msg_remainder -= length;
        return(TRUE);
}

static gboolean parse_integer(struct tls_internal_state *state,
                              const struct layout_descriptor *desc)
{
        guint value;
        if (!parse_integer_quiet(state, desc->label, desc->max, &value))
                return(FALSE);
        debug_printf(state, "%s/INTEGER%" G_GSIZE_FORMAT " = %d\n",
                     desc->label, desc->max, value);
        if (state->data) {
                struct tls_parsed_integer *save = g_new0(struct tls_parsed_integer, 1);
                save->value = value;
                g_hash_table_insert(state->data, (gpointer) desc->label, save);
        }
        return(TRUE);
}

static gboolean parse_array(struct tls_internal_state *state,
                            const struct layout_descriptor *desc)
{
        if (!msg_remainder_check(state, desc->label, desc->max))
                return(FALSE);
        debug_printf(state, "%s/ARRAY[%" G_GSIZE_FORMAT "]\n",
                     desc->label, desc->max);
#ifdef _SIPE_COMPILING_ANALYZER
        if (desc->max)
                debug_hex(state, desc->max);
#endif
        if (state->data) {
                struct tls_parsed_array *save = g_malloc0(sizeof(struct tls_parsed_array) +
                                                          desc->max);
                save->length = desc->max;
                memcpy((guchar *)save->data, state->msg_current, desc->max);
                g_hash_table_insert(state->data, (gpointer) desc->label, save);

        }
        state->msg_current   += desc->max;
        state->msg_remainder -= desc->max;
        return(TRUE);
}

static gboolean parse_vector(struct tls_internal_state *state,
                             const struct layout_descriptor *desc)
{
        guint length;
        if (!parse_integer_quiet(state, desc->label,
                                 (desc->max > TLS_VECTOR_MAX16) ? 3 :
                                 (desc->max > TLS_VECTOR_MAX8)  ? 2 : 1,
                                 &length))
                return(FALSE);
        if (length < desc->min) {
                SIPE_DEBUG_ERROR("parse_vector: '%s' too short %d, expected %" G_GSIZE_FORMAT,
                                 desc->label, length, desc->min);
                return(FALSE);
        }
        debug_printf(state, "%s/VECTOR<%d>\n", desc->label, length);
#ifdef _SIPE_COMPILING_ANALYZER
        if (length)
                debug_hex(state, length);
#endif
        if (state->data) {
                struct tls_parsed_array *save = g_malloc0(sizeof(struct tls_parsed_array) +
                                                          length);
                save->length = length;
                memcpy((guchar *)save->data, state->msg_current, length);
                g_hash_table_insert(state->data, (gpointer) desc->label, save);
        }
        state->msg_current   += length;
        state->msg_remainder -= length;
        return(TRUE);
}

/*
 * Specific data type parser routines
 */

/* TBD... */

/*
 * TLS data compilers
 *
 * Low-level data conversion routines
 *
 *  - host alignment agnostic, i.e. can fetch a word from uneven address
 *  - host -> TLS host endianess conversion
 *  - don't modify state
 */
static void lowlevel_integer_to_tls(guchar *bytes,
                                    gsize length,
                                    guint value)
{
        while (length--) {
                bytes[length] = value & 0xFF;
                value >>= 8;
        }
}

/*
 * Generic data type compiler routines
 */
static void compile_integer(struct tls_internal_state *state,
                            const struct layout_descriptor *desc,
                            const struct tls_compile_integer *data)
{
        lowlevel_integer_to_tls(state->msg_current, desc->max, data->value);
        state->msg_current += desc->max;
}

static void compile_array(struct tls_internal_state *state,
                          const struct layout_descriptor *desc,
                          const struct tls_compile_integer *data)
{
        const struct tls_compile_array *array = (struct tls_compile_array *) data;
        memcpy(state->msg_current, array->placeholder, desc->max);
        state->msg_current += desc->max;
}

static void compile_vector(struct tls_internal_state *state,
                           const struct layout_descriptor *desc,
                           const struct tls_compile_integer *data)
{
        const struct tls_compile_vector *vector = (struct tls_compile_vector *) data;
        gsize length = vector->elements;
        gsize length_field = (desc->max > TLS_VECTOR_MAX16) ? 3 :
                             (desc->max > TLS_VECTOR_MAX8)  ? 2 : 1;

        lowlevel_integer_to_tls(state->msg_current, length_field, length);
        state->msg_current += length_field;
        memcpy(state->msg_current, vector->placeholder, length);
        state->msg_current += length;
}

static void compile_vector_int2(struct tls_internal_state *state,
                                const struct layout_descriptor *desc,
                                const struct tls_compile_integer *data)
{
        const struct tls_compile_vector *vector = (struct tls_compile_vector *) data;
        gsize elements = vector->elements;
        gsize length   = elements * sizeof(guint16);
        gsize length_field = (desc->max > TLS_VECTOR_MAX16) ? 3 :
                             (desc->max > TLS_VECTOR_MAX8)  ? 2 : 1;
        const guint *p = vector->placeholder;

        lowlevel_integer_to_tls(state->msg_current, length_field, length);
        state->msg_current += length_field;
        while (elements--) {
                lowlevel_integer_to_tls(state->msg_current, sizeof(guint16), *p++);
                state->msg_current += sizeof(guint16);
        }
}

/*
 * Specific data type compiler routines
 */

/* TBD... */

/*
 * TLS handshake message layout descriptors
 */
struct ClientHello_host {
        struct tls_compile_integer protocol_version;
        struct tls_compile_random random;
        struct tls_compile_sessionid sessionid;
        struct tls_compile_cipher cipher;
        struct tls_compile_compression compression;
};
#define CLIENTHELLO_OFFSET(a) offsetof(struct ClientHello_host, a)

static const struct layout_descriptor ClientHello_l[] = {
        { "Client Protocol Version", parse_integer, compile_integer,     0,  2,                      CLIENTHELLO_OFFSET(protocol_version) },
        { "Random",                  parse_array,   compile_array,       0, TLS_ARRAY_RANDOM_LENGTH, CLIENTHELLO_OFFSET(random) },
        { "SessionID",               parse_vector,  compile_vector,      0, 32,                      CLIENTHELLO_OFFSET(sessionid) },
        { "CipherSuite",             parse_vector,  compile_vector_int2, 2, TLS_VECTOR_MAX16,        CLIENTHELLO_OFFSET(cipher)},
        { "CompressionMethod",       parse_vector,  compile_vector,      1, TLS_VECTOR_MAX8,         CLIENTHELLO_OFFSET(compression) },
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor ClientHello_m = {
        NULL, "Client Hello", ClientHello_l, TLS_HANDSHAKE_TYPE_CLIENT_HELLO
};

static const struct layout_descriptor ServerHello_l[] = {
        { "Server Protocol Version", parse_integer, NULL, 0,  2,                      0 },
        { "Random",                  parse_array,   NULL, 0, TLS_ARRAY_RANDOM_LENGTH, 0 },
        { "SessionID",               parse_vector,  NULL, 0, 32,                      0 },
        { "CipherSuite",             parse_integer, NULL, 0,  2,                      0 },
        { "CompressionMethod",       parse_integer, NULL, 0,  1,                      0 },
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor ServerHello_m = {
        &ClientHello_m, "Server Hello", ServerHello_l, TLS_HANDSHAKE_TYPE_SERVER_HELLO
};

struct Certificate_host {
        struct tls_compile_vector certificate;
};
#define CERTIFICATE_OFFSET(a) offsetof(struct Certificate_host, a)

static const struct layout_descriptor Certificate_l[] = {
        { "Certificate",             parse_vector, compile_vector, 0, TLS_VECTOR_MAX24, CERTIFICATE_OFFSET(certificate) },
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor Certificate_m = {
        &ServerHello_m, "Certificate", Certificate_l, TLS_HANDSHAKE_TYPE_CERTIFICATE
};

static const struct layout_descriptor CertificateRequest_l[] = {
        { "CertificateType",         parse_vector, NULL, 1, TLS_VECTOR_MAX8,  0 },
        { "DistinguishedName",       parse_vector, NULL, 0, TLS_VECTOR_MAX16, 0 },
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor CertificateRequest_m = {
        &Certificate_m, "Certificate Request", CertificateRequest_l, TLS_HANDSHAKE_TYPE_CERTIFICATE_REQ
};

static const struct layout_descriptor ServerHelloDone_l[] = {
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor ServerHelloDone_m = {
        &CertificateRequest_m, "Server Hello Done", ServerHelloDone_l, TLS_HANDSHAKE_TYPE_SERVER_HELLO_DONE
};

struct ClientKeyExchange_host {
        struct tls_compile_vector secret;
};
#define CLIENTKEYEXCHANGE_OFFSET(a) offsetof(struct ClientKeyExchange_host, a)

static const struct layout_descriptor ClientKeyExchange_l[] = {
        { "Exchange Keys",           parse_vector, compile_vector, 0, TLS_VECTOR_MAX16, CLIENTKEYEXCHANGE_OFFSET(secret) },
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor ClientKeyExchange_m = {
        &ServerHelloDone_m, "Client Key Exchange", ClientKeyExchange_l, TLS_HANDSHAKE_TYPE_CLIENT_KEY_EXCHANGE
};

struct CertificateVerify_host {
        struct tls_compile_vector signature;
};
#define CERTIFICATEVERIFY_OFFSET(a) offsetof(struct CertificateVerify_host, a)

static const struct layout_descriptor CertificateVerify_l[] = {
        { "Signature",               parse_vector, compile_vector, 0, TLS_VECTOR_MAX16, CERTIFICATEVERIFY_OFFSET(signature) },
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor CertificateVerify_m = {
        &ClientKeyExchange_m, "Certificate Verify", CertificateVerify_l, TLS_HANDSHAKE_TYPE_CERTIFICATE_VERIFY
};

struct Finished_host {
        struct tls_compile_verify verify;
};
#define FINISHED_OFFSET(a) offsetof(struct Finished_host, a)

static const struct layout_descriptor Finished_l[] = {
        { "Verify Data",             parse_array, compile_array, 0, TLS_ARRAY_VERIFY_LENGTH, FINISHED_OFFSET(verify) },
        TLS_LAYOUT_DESCRIPTOR_END
};
static const struct msg_descriptor Finished_m = {
        &CertificateVerify_m, "Finished", Finished_l, TLS_HANDSHAKE_TYPE_FINISHED
};

#define HANDSHAKE_MSG_DESCRIPTORS &Finished_m

/*
 * TLS message parsers
 */
static gboolean handshake_parse(struct tls_internal_state *state)
{
        const guchar *bytes = state->msg_current;
        gsize length        = state->msg_remainder;
        gboolean success    = FALSE;

        while (length > 0) {
                const struct msg_descriptor *desc;
                gsize msg_length;
                guint msg_type;

                /* header check */
                if (length < TLS_HANDSHAKE_HEADER_LENGTH) {
                        debug_print(state, "CORRUPTED HANDSHAKE HEADER");
                        break;
                }

                /* msg length check */
                msg_length = lowlevel_integer_to_host(bytes + TLS_HANDSHAKE_OFFSET_LENGTH,
                                                      3);
                if (msg_length > length) {
                        debug_print(state, "HANDSHAKE MESSAGE TOO LONG");
                        break;
                }

                /* msg type */
                msg_type = bytes[TLS_HANDSHAKE_OFFSET_TYPE];
                for (desc = HANDSHAKE_MSG_DESCRIPTORS;
                     desc;
                     desc = desc->next)
                        if (msg_type == desc->type)
                                break;

                debug_printf(state, "TLS handshake (%" G_GSIZE_FORMAT " bytes) (%d)",
                             msg_length, msg_type);

                state->msg_current   = (guchar *) bytes + TLS_HANDSHAKE_HEADER_LENGTH;
                state->msg_remainder = msg_length;

                if (desc && desc->layouts) {
                        const struct layout_descriptor *ldesc = desc->layouts;

                        debug_printf(state, "%s\n", desc->description);
                        while (TLS_LAYOUT_IS_VALID(ldesc)) {
                                success = ldesc->parser(state, ldesc);
                                if (!success)
                                        break;
                                ldesc++;
                        }
                        if (!success)
                                break;
                } else {
                        debug_print(state, "ignored\n");
                        debug_hex(state, 0);
                }

                /* next message */
                bytes  += TLS_HANDSHAKE_HEADER_LENGTH + msg_length;
                length -= TLS_HANDSHAKE_HEADER_LENGTH + msg_length;
                if (length > 0) {
                        debug_print(state, "------\n");
                } else {
                        success = TRUE;
                }
        }

        return(success);
}

static void free_parse_data(struct tls_internal_state *state)
{
        if (state->data) {
                g_hash_table_destroy(state->data);
                state->data = NULL;
        }
}

static gboolean tls_record_parse(struct tls_internal_state *state,
                                 gboolean incoming)
{
        const guchar *bytes  = incoming ? state->common.in_buffer : state->common.out_buffer;
        gsize length         = incoming ? state->common.in_length : state->common.out_length;
        guint version;
        const gchar *version_str;
        gsize record_length;
        gboolean success = TRUE;

        /* reject empty incoming messages */
        if (incoming && (length == 0)) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_record_parse: empty TLS message received");
                return(FALSE);
        }

#ifndef _SIPE_COMPILING_ANALYZER
        debug_printf(state, "TLS MESSAGE %s\n", incoming ? "INCOMING" : "OUTGOING");
#endif

        /* Collect parser data for incoming messages */
        if (incoming)
                state->data = g_hash_table_new_full(g_str_hash, g_str_equal,
                                                    NULL, g_free);

        while (success && (length > 0)) {

                /* truncated header check */
                if (length < TLS_RECORD_HEADER_LENGTH) {
                        SIPE_DEBUG_ERROR("tls_record_parse: too short TLS record header (%" G_GSIZE_FORMAT " bytes)",
                                         length);
                        success = FALSE;
                        break;
                }

                /* protocol version check */
                version = lowlevel_integer_to_host(bytes + TLS_RECORD_OFFSET_VERSION, 2);
                if (version < TLS_PROTOCOL_VERSION_1_0) {
                        SIPE_DEBUG_ERROR_NOFORMAT("tls_record_parse: SSL1/2/3 not supported");
                        success = FALSE;
                        break;
                }
                switch (version) {
                case TLS_PROTOCOL_VERSION_1_0:
                        version_str = "1.0 (RFC2246)";
                        break;
                case TLS_PROTOCOL_VERSION_1_1:
                        version_str = "1.1 (RFC4346)";
                        break;
                case TLS_PROTOCOL_VERSION_1_2:
                        version_str = "1.2 (RFC5246)";
                        break;
                default:
                        version_str = "<future protocol version>";
                        break;
                }

                /* record length check */
                record_length = TLS_RECORD_HEADER_LENGTH +
                        lowlevel_integer_to_host(bytes + TLS_RECORD_OFFSET_LENGTH, 2);
                if (record_length > length) {
                        SIPE_DEBUG_ERROR_NOFORMAT("tls_record_parse: record too long");
                        success = FALSE;
                        break;
                }

                /* TLS record header OK */
                debug_printf(state, "TLS %s record (%" G_GSIZE_FORMAT " bytes)\n",
                             version_str, record_length);
                state->msg_current   = (guchar *) bytes + TLS_RECORD_HEADER_LENGTH;
                state->msg_remainder = record_length - TLS_RECORD_HEADER_LENGTH;

/* Analyzer only needs the debugging functions */
#ifndef _SIPE_COMPILING_ANALYZER
                /* Add incoming message contents to digest contexts */
                if (incoming) {
                        sipe_digest_md5_update(state->md5_context,
                                               state->msg_current,
                                               state->msg_remainder);
                        sipe_digest_sha1_update(state->sha1_context,
                                                state->msg_current,
                                                state->msg_remainder);
                }
#endif /* !_SIPE_COMPILING_ANALYZER */

                switch (bytes[TLS_RECORD_OFFSET_TYPE]) {
                case TLS_RECORD_TYPE_CHANGE_CIPHER_SPEC:
                        debug_print(state, "Change Cipher Spec\n");
                        if (incoming) state->encrypted = TRUE;
                        break;

                case TLS_RECORD_TYPE_HANDSHAKE:
                        if (incoming && state->encrypted) {
                                debug_print(state, "Encrypted handshake message\n");
                                debug_hex(state, 0);
                        } else {
                                success = handshake_parse(state);
                        }
                        break;

                default:
                        debug_print(state, "Unsupported TLS message\n");
                        debug_hex(state, 0);
                        break;
                }

                /* next fragment */
                bytes  += record_length;
                length -= record_length;
        }

        if (!success)
                free_parse_data(state);

        if (state->debug) {
                SIPE_DEBUG_INFO_NOFORMAT(state->debug->str);
                g_string_truncate(state->debug, 0);
        }

        return(success);
}

/* Analyzer only needs the debugging functions */
#ifndef _SIPE_COMPILING_ANALYZER

/*
 * TLS message compiler
 */
static void compile_tls_record(struct tls_internal_state *state,
                               ...)
{
        gsize total_size = 0;
        guchar *current;
        va_list ap;

        /* calculate message size */
        va_start(ap, state);
        while (1) {
                const struct tls_compiled_message *msg = va_arg(ap, struct tls_compiled_message *);
                if (!msg) break;
                total_size += msg->size;
        }
        va_end(ap);

        SIPE_DEBUG_INFO("compile_tls_record: total size %" G_GSIZE_FORMAT,
                        total_size);

        state->common.out_buffer = current = g_malloc(total_size + TLS_RECORD_HEADER_LENGTH);
        state->common.out_length = total_size + TLS_RECORD_HEADER_LENGTH;

        /* add TLS record header */
        current[TLS_RECORD_OFFSET_TYPE] = TLS_RECORD_TYPE_HANDSHAKE;
        lowlevel_integer_to_tls(current + TLS_RECORD_OFFSET_VERSION, 2,
                                TLS_PROTOCOL_VERSION_1_0);
        lowlevel_integer_to_tls(current + TLS_RECORD_OFFSET_LENGTH, 2,
                                total_size);
        current += TLS_RECORD_HEADER_LENGTH;

        /* copy messages */
        va_start(ap, state);
        while (1) {
                const struct tls_compiled_message *msg = va_arg(ap, struct tls_compiled_message *);
                if (!msg) break;

                memcpy(current, msg->data, msg->size);
                current += msg->size;
        }
        va_end(ap);
}

static void compile_encrypted_tls_record(struct tls_internal_state *state,
                                         const struct tls_compiled_message *msg)
{
        guchar *plaintext;
        gsize plaintext_length;
        guchar *mac;
        gsize mac_length;
        guchar *message;
        guchar *encrypted;
        gsize encrypted_length;

        /* Create plaintext TLS record */
        compile_tls_record(state, msg, NULL);
        plaintext        = state->common.out_buffer;
        plaintext_length = state->common.out_length;
        if (plaintext_length == 0) /* make Coverity happy */
                return;

        /* Prepare encryption buffer */
        encrypted_length = plaintext_length + state->mac_length;
        SIPE_DEBUG_INFO("compile_encrypted_tls_record: total size %" G_GSIZE_FORMAT,
                        encrypted_length - TLS_RECORD_HEADER_LENGTH);
        message          = g_malloc(encrypted_length);
        memcpy(message, plaintext, plaintext_length);
        lowlevel_integer_to_tls(message + TLS_RECORD_OFFSET_LENGTH, 2,
                                encrypted_length - TLS_RECORD_HEADER_LENGTH);

        /*
         * Calculate MAC
         *
         * HMAC_hash(client_write_mac_secret,
         *           sequence_number + type + version + length + fragment)
         *                             \---  == original TLS record  ---/
         */
        mac_length = sizeof(guint64) + plaintext_length;
        mac        = g_malloc(mac_length);
        lowlevel_integer_to_tls(mac,
                                sizeof(guint64),
                                state->sequence_number++);
        memcpy(mac + sizeof(guint64), plaintext, plaintext_length);
        g_free(plaintext);
        state->mac_func(state->client_write_mac_secret,
                        state->mac_length,
                        mac,
                        mac_length,
                        message + plaintext_length);
        g_free(mac);

        /* Encrypt message + MAC */
        encrypted = g_malloc(encrypted_length);
        memcpy(encrypted, message, TLS_RECORD_HEADER_LENGTH);
        sipe_crypt_tls_stream(state->cipher_context,
                              message + TLS_RECORD_HEADER_LENGTH,
                              encrypted_length - TLS_RECORD_HEADER_LENGTH,
                              encrypted + TLS_RECORD_HEADER_LENGTH);
        g_free(message);

        /* swap buffers */
        state->common.out_buffer = encrypted;
        state->common.out_length = encrypted_length;
}

static struct tls_compiled_message *compile_handshake_msg(struct tls_internal_state *state,
                                                          const struct msg_descriptor *desc,
                                                          gpointer data,
                                                          gsize size)
{
        /*
         * Estimate the size of the compiled message
         *
         * The data structures in the host format have zero or more padding
         * bytes added by the compiler to ensure correct element alignments.
         * So the sizeof() of the data structure is always equal or greater
         * than the space needed for the compiled data. By adding the space
         * required for the headers we arrive at a safe estimate
         *
         * Therefore we don't need space checks in the compiler functions
         */
        gsize total_size = sizeof(struct tls_compiled_message) +
                size + TLS_HANDSHAKE_HEADER_LENGTH;
        struct tls_compiled_message *msg = g_malloc(total_size);
        guchar *handshake = msg->data;
        const struct layout_descriptor *ldesc = desc->layouts;
        gsize length;

        SIPE_DEBUG_INFO("compile_handshake_msg: buffer size %" G_GSIZE_FORMAT,
                        total_size);

        /* add TLS handshake header */
        handshake[TLS_HANDSHAKE_OFFSET_TYPE] = desc->type;
        state->msg_current = handshake  + TLS_HANDSHAKE_HEADER_LENGTH;

        while (TLS_LAYOUT_IS_VALID(ldesc)) {
                /*
                 * Avoid "cast increases required alignment" errors
                 *
                 * (void *) tells the compiler that we know what we're
                 * doing, i.e. we know that the calculated address
                 * points to correctly aligned data.
                 */
                ldesc->compiler(state, ldesc,
                                (void *) ((guchar *) data + ldesc->offset));
                ldesc++;
        }

        length = state->msg_current - handshake - TLS_HANDSHAKE_HEADER_LENGTH;
        lowlevel_integer_to_tls(handshake + TLS_HANDSHAKE_OFFSET_LENGTH,
                                3, length);
        SIPE_DEBUG_INFO("compile_handshake_msg: (%d)%s, size %" G_GSIZE_FORMAT,
                        desc->type, desc->description, length);

        msg->size = length + TLS_HANDSHAKE_HEADER_LENGTH;

        /* update digest contexts */
        sipe_digest_md5_update(state->md5_context, handshake, msg->size);
        sipe_digest_sha1_update(state->sha1_context, handshake, msg->size);

        return(msg);
}

/*
 * Specific TLS data verficiation & message compilers
 */
static struct tls_compiled_message *tls_client_certificate(struct tls_internal_state *state)
{
        struct Certificate_host *certificate;
        gsize certificate_length = sipe_cert_crypto_raw_length(state->certificate);
        struct tls_compiled_message *msg;

        /* setup our response */
        /* Client Certificate is VECTOR_MAX24 of VECTOR_MAX24s */
        certificate = g_malloc0(sizeof(struct Certificate_host) + 3 +
                                certificate_length);
        certificate->certificate.elements = certificate_length + 3;
        lowlevel_integer_to_tls((guchar *) certificate->certificate.placeholder, 3,
                                certificate_length);
        memcpy((guchar *) certificate->certificate.placeholder + 3,
               sipe_cert_crypto_raw(state->certificate),
               certificate_length);

        msg = compile_handshake_msg(state, &Certificate_m, certificate,
                                    sizeof(struct Certificate_host) + certificate_length + 3);
        g_free(certificate);

        return(msg);
}

static gboolean check_cipher_suite(struct tls_internal_state *state)
{
        struct tls_parsed_integer *cipher_suite = g_hash_table_lookup(state->data,
                                                                      "CipherSuite");
        const gchar *label = NULL;

        if (!cipher_suite) {
                SIPE_DEBUG_ERROR_NOFORMAT("check_cipher_suite: server didn't specify the cipher suite");
                return(FALSE);
        }

        switch (cipher_suite->value) {
        case TLS_RSA_EXPORT_WITH_RC4_40_MD5:
                state->mac_length = SIPE_DIGEST_HMAC_MD5_LENGTH;
                state->key_length = 40 / 8;
                state->mac_func   = sipe_digest_hmac_md5;
                label             = "MD5";
                state->common.algorithm = SIPE_TLS_DIGEST_ALGORITHM_MD5;
                state->cipher_type      = SIPE_CRYPT_STREAM_RC4;
                break;

        case TLS_RSA_WITH_RC4_128_MD5:
                state->mac_length = SIPE_DIGEST_HMAC_MD5_LENGTH;
                state->key_length = 128 / 8;
                state->mac_func   = sipe_digest_hmac_md5;
                label             = "MD5";
                state->common.algorithm = SIPE_TLS_DIGEST_ALGORITHM_MD5;
                state->cipher_type      = SIPE_CRYPT_STREAM_RC4;
                break;

        case TLS_RSA_WITH_RC4_128_SHA:
                state->mac_length = SIPE_DIGEST_HMAC_SHA1_LENGTH;
                state->key_length = 128 / 8;
                state->mac_func   = sipe_digest_hmac_sha1;
                label             = "SHA-1";
                state->common.algorithm = SIPE_TLS_DIGEST_ALGORITHM_SHA1;
                state->cipher_type      = SIPE_CRYPT_STREAM_RC4;
                break;

        case TLS_DHE_DSS_WITH_AES_256_CBC_SHA:
        case TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:
        case TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA:
                state->mac_length = SIPE_DIGEST_HMAC_SHA1_LENGTH;
                state->key_length = 256 / 8;
                state->mac_func   = sipe_digest_hmac_sha1;
                label             = "SHA-1";
                state->common.algorithm = SIPE_TLS_DIGEST_ALGORITHM_SHA1;
                state->cipher_type      = SIPE_CRYPT_STREAM_AES_CBC;
                break;

        default:
                SIPE_DEBUG_ERROR("check_cipher_suite: unsupported cipher suite %d",
                                 cipher_suite->value);
                break;
        }

        if (label)
                SIPE_DEBUG_INFO("check_cipher_suite: KEY(stream cipher RC4) %" G_GSIZE_FORMAT ", MAC(%s) %" G_GSIZE_FORMAT,
                                state->key_length, label, state->mac_length);

        return(label != NULL);
}

static void tls_calculate_secrets(struct tls_internal_state *state)
{
        gsize length = 2 * (state->mac_length + state->key_length);
        guchar *random;

        /* Generate pre-master secret */
        sipe_tls_fill_random(&state->pre_master_secret,
                             TLS_ARRAY_MASTER_SECRET_LENGTH * 8); /* bits */
        lowlevel_integer_to_tls(state->pre_master_secret.buffer, 2,
                                TLS_PROTOCOL_VERSION_1_0);
        debug_secrets(state, "tls_calculate_secrets: pre-master secret",
                      state->pre_master_secret.buffer,
                      state->pre_master_secret.length);

        /*
         * Calculate master secret
         *
         * master_secret = PRF(pre_master_secret,
         *                     "master secret",
         *                     ClientHello.random + ServerHello.random)
         */
        random = g_malloc(TLS_ARRAY_RANDOM_LENGTH * 2);
        memcpy(random,
               state->client_random.buffer,
               TLS_ARRAY_RANDOM_LENGTH);
        memcpy(random + TLS_ARRAY_RANDOM_LENGTH,
               state->server_random.buffer,
               TLS_ARRAY_RANDOM_LENGTH);
        state->master_secret = sipe_tls_prf(state,
                                            state->pre_master_secret.buffer,
                                            state->pre_master_secret.length,
                                            (guchar *) "master secret",
                                            13,
                                            random,
                                            TLS_ARRAY_RANDOM_LENGTH * 2,
                                            TLS_ARRAY_MASTER_SECRET_LENGTH);
        debug_secrets(state, "tls_calculate_secrets: master secret    ",
                      state->master_secret,
                      TLS_ARRAY_MASTER_SECRET_LENGTH);

        /*
         * Calculate session key material
         *
         * key_block = PRF(master_secret,
         *                 "key expansion",
         *                 ServerHello.random + ClientHello.random)
         */
        SIPE_DEBUG_INFO("tls_calculate_secrets: key_block length %" G_GSIZE_FORMAT,
                        length);
        memcpy(random,
               state->server_random.buffer,
               TLS_ARRAY_RANDOM_LENGTH);
        memcpy(random + TLS_ARRAY_RANDOM_LENGTH,
               state->client_random.buffer,
               TLS_ARRAY_RANDOM_LENGTH);
        state->key_block = sipe_tls_prf(state,
                                        state->master_secret,
                                        TLS_ARRAY_MASTER_SECRET_LENGTH,
                                        (guchar *) "key expansion",
                                        13,
                                        random,
                                        TLS_ARRAY_RANDOM_LENGTH * 2,
                                        length);
        g_free(random);
        debug_secrets(state, "tls_calculate_secrets: key block        ",
                      state->key_block, length);

        /* partition key block */
        state->client_write_mac_secret = state->key_block;
        state->server_write_mac_secret = state->key_block + state->mac_length;
        state->client_write_secret     = state->key_block + 2 * state->mac_length;
        state->server_write_secret     = state->key_block + 2 * state->mac_length + state->key_length;

        /* initialize cipher context */
        state->cipher_context = sipe_crypt_tls_start(state->cipher_type,
                                                     state->client_write_secret,
                                                     state->key_length);
}

#if 0 /* NOT NEEDED? */
/* signing */
static guchar *tls_pkcs1_private_padding(SIPE_UNUSED_PARAMETER struct tls_internal_state *state,
                                         const guchar *data,
                                         gsize data_length,
                                         gsize buffer_length)
{
        gsize pad_length;
        guchar *pad_buffer;

        if (data_length + 3 > buffer_length) ||
            (buffer_length == 0)) /* this is dead code, but makes Coverity happy */)
                return(NULL);

        pad_length = buffer_length - data_length - 3;
        pad_buffer = g_malloc(buffer_length);

        /* PKCS1 private key block padding */
        pad_buffer[0]                       = 0; /* +1 */
        pad_buffer[1]                       = 1; /* +2 */
        memset(pad_buffer + 2,              0xFF, pad_length);
        pad_buffer[2 + pad_length]          = 0; /* +3 */
        memcpy(pad_buffer + 3 + pad_length, data, data_length);

#ifdef __SIPE_TLS_CRYPTO_DEBUG
        debug_secrets(state, "tls_pkcs1_private_padding:              ",
                      pad_buffer, buffer_length);
#endif

        return(pad_buffer);
}
#endif

/* encryption */
static guchar *tls_pkcs1_public_padding(SIPE_UNUSED_PARAMETER struct tls_internal_state *state,
                                        const guchar *data,
                                        gsize data_length,
                                        gsize buffer_length)
{
        gsize pad_length, random_count;
        guchar *pad_buffer, *random;

        if ((data_length + 3 > buffer_length) ||
            (buffer_length == 0)) /* this is dead code, but makes Coverity happy */
                return(NULL);

        pad_length = buffer_length - data_length - 3;
        pad_buffer = g_malloc(buffer_length);

        /* PKCS1 public key block padding */
        pad_buffer[0]                       = 0; /* +1 */
        pad_buffer[1]                       = 2; /* +2 */
        for (random = pad_buffer + 2, random_count = pad_length;
             random_count > 0;
             random_count--) {
                guchar byte;
                /* non-zero random byte */
                while ((byte = rand() & 0xFF) == 0);
                *random++ = byte;
        }
        pad_buffer[2 + pad_length]          = 0; /* +3 */
        memcpy(pad_buffer + 3 + pad_length, data, data_length);

#ifdef __SIPE_TLS_CRYPTO_DEBUG
        debug_secrets(state, "tls_pkcs1_private_padding:              ",
                      pad_buffer, buffer_length);
#endif

        return(pad_buffer);
}

static struct tls_compiled_message *tls_client_key_exchange(struct tls_internal_state *state)
{
        struct tls_parsed_array *server_random;
        struct tls_parsed_array *server_certificate;
        struct ClientKeyExchange_host *exchange;
        gsize server_certificate_length;
        guchar *padded;
        struct tls_compiled_message *msg;

        /* check for required data fields */
        if (!check_cipher_suite(state))
                return(NULL);
        server_random = g_hash_table_lookup(state->data, "Random");
        if (!server_random) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_client_key_exchange: no server random");
                return(NULL);
        }
        server_certificate = g_hash_table_lookup(state->data, "Certificate");
        /* Server Certificate is VECTOR_MAX24 of VECTOR_MAX24s */
        if (!server_certificate || (server_certificate->length < 3)) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_client_key_exchange: no server certificate");
                return(FALSE);
        }
        SIPE_DEBUG_INFO("tls_client_key_exchange: server certificate list %" G_GSIZE_FORMAT" bytes",
                        server_certificate->length);
        /* first certificate is the server certificate */
        server_certificate_length = lowlevel_integer_to_host(server_certificate->data,
                                                             3);
        SIPE_DEBUG_INFO("tls_client_key_exchange: server certificate %" G_GSIZE_FORMAT" bytes",
                        server_certificate_length);
        if ((server_certificate_length + 3) > server_certificate->length) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_client_key_exchange: truncated server certificate");
        }
        state->server_certificate = sipe_cert_crypto_import(server_certificate->data + 3,
                                                            server_certificate_length);
        if (!state->server_certificate) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_client_key_exchange: corrupted server certificate");
                return(FALSE);
        }
        /* server public key modulus length */
        server_certificate_length = sipe_cert_crypto_modulus_length(state->server_certificate);
        if (server_certificate_length < TLS_ARRAY_MASTER_SECRET_LENGTH) {
                SIPE_DEBUG_ERROR("tls_client_key_exchange: server public key strength too low (%" G_GSIZE_FORMAT ")",
                                 server_certificate_length);
                return(FALSE);
        }
        SIPE_DEBUG_INFO("tls_client_key_exchange: server public key strength = %" G_GSIZE_FORMAT,
                        server_certificate_length);

        /* found all the required fields */
        state->server_random.length = server_random->length;
        state->server_random.buffer = g_memdup(server_random->data,
                                               server_random->length);
        tls_calculate_secrets(state);

        /* ClientKeyExchange */
        padded = tls_pkcs1_public_padding(state,
                                          state->pre_master_secret.buffer,
                                          state->pre_master_secret.length,
                                          server_certificate_length);
        if (!padded) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_client_key_exchange: padding of pre-master secret failed");
                return(NULL);
        }
        exchange = g_malloc0(sizeof(struct ClientKeyExchange_host) +
                             server_certificate_length);
        exchange->secret.elements = server_certificate_length;
        if (!sipe_crypt_rsa_encrypt(sipe_cert_crypto_public_key(state->server_certificate),
                                    server_certificate_length,
                                    padded,
                                    (guchar *) exchange->secret.placeholder)) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_client_key_exchange: encryption of pre-master secret failed");
                g_free(exchange);
                g_free(padded);
                return(NULL);
        }
        g_free(padded);

#ifdef __SIPE_TLS_CRYPTO_DEBUG
        debug_secrets(state, "tls_client_key_exchange: secret (encr)  ",
                      (guchar *) exchange->secret.placeholder,
                      server_certificate_length);
#endif

        msg = compile_handshake_msg(state, &ClientKeyExchange_m, exchange,
                                    sizeof(struct ClientKeyExchange_host) + server_certificate_length);
        g_free(exchange);

        return(msg);
}

static struct tls_compiled_message *tls_certificate_verify(struct tls_internal_state *state)
{
        struct CertificateVerify_host *verify;
        struct tls_compiled_message *msg;
        guchar *digests = g_malloc(SIPE_DIGEST_MD5_LENGTH + SIPE_DIGEST_SHA1_LENGTH);
        guchar *signature;
        gsize length;

        /* calculate digests */
        sipe_digest_md5_end(state->md5_context, digests);
        sipe_digest_sha1_end(state->sha1_context, digests + SIPE_DIGEST_MD5_LENGTH);

        /* sign digests */
        signature = sipe_crypt_rsa_sign(sipe_cert_crypto_private_key(state->certificate),
                                        digests,
                                        SIPE_DIGEST_MD5_LENGTH + SIPE_DIGEST_SHA1_LENGTH,
                                        &length);
        g_free(digests);
        if (!signature) {
                SIPE_DEBUG_ERROR_NOFORMAT("tls_certificate_verify: signing of handshake digests failed");
                return(NULL);
        }

        /* CertificateVerify */
        verify = g_malloc0(sizeof(struct CertificateVerify_host) +
                           length);
        verify->signature.elements = length;
        memcpy(verify->signature.placeholder, signature, length);
        g_free(signature);

        msg = compile_handshake_msg(state, &CertificateVerify_m, verify,
                                    sizeof(struct CertificateVerify_host) + length);
        g_free(verify);

        return(msg);
}

static struct tls_compiled_message *tls_client_finished(struct tls_internal_state *state)
{
        guchar *digests = g_malloc(SIPE_DIGEST_MD5_LENGTH + SIPE_DIGEST_SHA1_LENGTH);
        guchar *verify;
        struct tls_compiled_message *cmsg;
        struct Finished_host msg;

        /* calculate digests */
        sipe_digest_md5_end(state->md5_context, digests);
        sipe_digest_sha1_end(state->sha1_context, digests + SIPE_DIGEST_MD5_LENGTH);

        /*
         * verify_data = PRF(master_secret, "client finished",
         *                   MD5(handshake_messages) +
         *                   SHA-1(handshake_messages)) [0..11];
         */
        verify = sipe_tls_prf(state,
                              state->master_secret,
                              TLS_ARRAY_MASTER_SECRET_LENGTH,
                              (guchar *) "client finished",
                              15,
                              digests,
                              SIPE_DIGEST_MD5_LENGTH + SIPE_DIGEST_SHA1_LENGTH,
                              TLS_ARRAY_VERIFY_LENGTH);
        g_free(digests);
        memcpy(msg.verify.verify, verify, TLS_ARRAY_VERIFY_LENGTH);
        g_free(verify);

        cmsg = compile_handshake_msg(state, &Finished_m, &msg, sizeof(msg));

        return(cmsg);
}

/*
 * TLS state handling
 */

static gboolean tls_client_hello(struct tls_internal_state *state)
{
        guint32 now   = time(NULL);
        guint32 now_N = GUINT32_TO_BE(now);
        struct ClientHello_host msg = {
                { TLS_PROTOCOL_VERSION_1_0 },
                { 0, { 0 } },
                { 0 /* empty SessionID */ },
                { 6,
                  {
                          TLS_RSA_WITH_RC4_128_MD5,
                          TLS_RSA_WITH_RC4_128_SHA,
                          TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
                          TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
                          TLS_DHE_DSS_WITH_AES_256_CBC_SHA,
                          TLS_RSA_EXPORT_WITH_RC4_40_MD5
                  }
                },
                { 1,
                  {
                          TLS_COMP_METHOD_NULL
                  }
                }
        };
        struct tls_compiled_message *cmsg;

        /* First 4 bytes of client_random is the current timestamp */
        sipe_tls_fill_random(&state->client_random,
                             TLS_ARRAY_RANDOM_LENGTH * 8); /* -> bits */
        memcpy(state->client_random.buffer, &now_N, sizeof(now_N));
        memcpy(msg.random.random, state->client_random.buffer,
               TLS_ARRAY_RANDOM_LENGTH);

        cmsg = compile_handshake_msg(state, &ClientHello_m, &msg, sizeof(msg));
        compile_tls_record(state, cmsg, NULL);
        g_free(cmsg);

        if (sipe_backend_debug_enabled())
                state->debug = g_string_new("");

        state->state = TLS_HANDSHAKE_STATE_SERVER_HELLO;
        return(tls_record_parse(state, FALSE));
}

static gboolean tls_server_hello(struct tls_internal_state *state)
{
        struct tls_compiled_message *certificate = NULL;
        struct tls_compiled_message *exchange    = NULL;
        struct tls_compiled_message *verify      = NULL;
        struct tls_compiled_message *finished    = NULL;
        gboolean success = FALSE;

        if (!tls_record_parse(state, TRUE))
                return(FALSE);

        if (((certificate = tls_client_certificate(state))  != NULL) &&
            ((exchange    = tls_client_key_exchange(state)) != NULL) &&
            ((verify      = tls_certificate_verify(state))  != NULL) &&
            ((finished    = tls_client_finished(state))     != NULL)) {

                /* Part 1 */
                compile_tls_record(state, certificate, exchange, verify, NULL);

                success = tls_record_parse(state, FALSE);
                if (success) {
                        guchar *part1      = state->common.out_buffer;
                        gsize part1_length = state->common.out_length;
                        guchar *part3;
                        gsize part3_length;
                        guchar *merged;
                        gsize length;
                        /* ChangeCipherSpec is always the same */
                        static const guchar part2[] = {
                                TLS_RECORD_TYPE_CHANGE_CIPHER_SPEC,
                                (TLS_PROTOCOL_VERSION_1_0 >> 8) & 0xFF,
                                TLS_PROTOCOL_VERSION_1_0 & 0xFF,
                                0x00, 0x01, /* length: 1 byte        */
                                0x01        /* change_cipher_spec(1) */
                        };

                        state->common.out_buffer = NULL;

                        /* Part 3 - this is the first encrypted record */
                        compile_encrypted_tls_record(state, finished);
                        part3        = state->common.out_buffer;
                        part3_length = state->common.out_length;

                                /* merge TLS records */
                        length = part1_length + sizeof(part2) + part3_length;
                        merged = g_malloc(length);

                        memcpy(merged,                                part1, part1_length);
                        memcpy(merged + part1_length,                 part2, sizeof(part2));
                        memcpy(merged + part1_length + sizeof(part2), part3, part3_length);
                        g_free(part3);
                        g_free(part1);

                        /* replace output buffer with merged message */
                        state->common.out_buffer = merged;
                        state->common.out_length = length;

                        state->state = TLS_HANDSHAKE_STATE_FINISHED;
                }
        }

        g_free(finished);
        g_free(verify);
        g_free(exchange);
        g_free(certificate);
        free_parse_data(state);

        return(success);
}

static gboolean tls_finished(struct tls_internal_state *state)
{
        guchar *random;

        if (!tls_record_parse(state, TRUE))
                return(FALSE);

        /* we don't need the data */
        free_parse_data(state);

        /*
         * Calculate session keys [MS-SIPAE section 3.2.5.1]
         *
         * key_material = PRF (master_secret,
         *                     "client EAP encryption",
         *                     ClientHello.random + ServerHello.random)[128]
         *              = 4 x 32 Bytes
         *
         * client key = key_material[3rd 32 Bytes]
         * server key = key_material[4th 32 Bytes]
         */
        random = g_malloc(TLS_ARRAY_RANDOM_LENGTH * 2);
        memcpy(random,
               state->client_random.buffer,
               TLS_ARRAY_RANDOM_LENGTH);
        memcpy(random + TLS_ARRAY_RANDOM_LENGTH,
               state->server_random.buffer,
               TLS_ARRAY_RANDOM_LENGTH);
        state->tls_dsk_key_block = sipe_tls_prf(state,
                                                state->master_secret,
                                                TLS_ARRAY_MASTER_SECRET_LENGTH,
                                                (guchar *) "client EAP encryption",
                                                21,
                                                random,
                                                TLS_ARRAY_RANDOM_LENGTH * 2,
                                                4 * 32);
        g_free(random);

#ifdef __SIPE_TLS_CRYPTO_DEBUG
        debug_secrets(state, "tls_finished: TLS-DSK key block         ",
                      state->tls_dsk_key_block, 4 * 32);
#endif

        state->common.client_key = state->tls_dsk_key_block + 2 * 32;
        state->common.server_key = state->tls_dsk_key_block + 3 * 32;
        state->common.key_length = 32;

        debug_secrets(state, "tls_finished: TLS-DSK client key        ",
                      state->common.client_key,
                      state->common.key_length);
        debug_secrets(state, "tls_finished: TLS-DSK server key        ",
                      state->common.server_key,
                      state->common.key_length);

        state->common.out_buffer = NULL;
        state->common.out_length = 0;
        state->state             = TLS_HANDSHAKE_STATE_COMPLETED;

        return(TRUE);
}

/*
 * TLS public API
 */

struct sipe_tls_state *sipe_tls_start(gpointer certificate)
{
        struct tls_internal_state *state;

        if (!certificate)
                return(NULL);

        state = g_new0(struct tls_internal_state, 1);
        state->certificate  = certificate;
        state->state        = TLS_HANDSHAKE_STATE_START;
        state->md5_context  = sipe_digest_md5_start();
        state->sha1_context = sipe_digest_sha1_start();
        state->common.algorithm = SIPE_TLS_DIGEST_ALGORITHM_NONE;

        return((struct sipe_tls_state *) state);
}

gboolean sipe_tls_next(struct sipe_tls_state *state)
{
        /* Avoid "cast increases required alignment" errors */
        struct tls_internal_state *internal = (void *) state;
        gboolean success = FALSE;

        if (!state)
                return(FALSE);

        state->out_buffer = NULL;

        switch (internal->state) {
        case TLS_HANDSHAKE_STATE_START:
                success = tls_client_hello(internal);
                break;

        case TLS_HANDSHAKE_STATE_SERVER_HELLO:
                success = tls_server_hello(internal);
                break;

        case TLS_HANDSHAKE_STATE_FINISHED:
                success = tls_finished(internal);
                break;

        case TLS_HANDSHAKE_STATE_COMPLETED:
        case TLS_HANDSHAKE_STATE_FAILED:
                /* This should not happen */
                SIPE_DEBUG_ERROR_NOFORMAT("sipe_tls_next: called in incorrect state!");
                break;
        }

        if (!success) {
                internal->state = TLS_HANDSHAKE_STATE_FAILED;
        }

        return(success);
}

guint sipe_tls_expires(struct sipe_tls_state *state)
{
        /* Avoid "cast increases required alignment" errors */
        struct tls_internal_state *internal = (void *) state;

        if (!state)
                return(0);

        return(sipe_cert_crypto_expires(internal->certificate));
}

void sipe_tls_free(struct sipe_tls_state *state)
{
        if (state) {
                /* Avoid "cast increases required alignment" errors */
                struct tls_internal_state *internal = (void *) state;

                free_parse_data(internal);
                if (internal->debug)
                        g_string_free(internal->debug, TRUE);
                g_free(internal->tls_dsk_key_block);
                g_free(internal->key_block);
                g_free(internal->master_secret);
                sipe_tls_free_random(&internal->pre_master_secret);
                sipe_tls_free_random(&internal->client_random);
                sipe_tls_free_random(&internal->server_random);
                if (internal->cipher_context)
                        sipe_crypt_tls_destroy(internal->cipher_context);
                if (internal->md5_context)
                        sipe_digest_md5_destroy(internal->md5_context);
                if (internal->sha1_context)
                        sipe_digest_sha1_destroy(internal->sha1_context);
                sipe_cert_crypto_destroy(internal->server_certificate);
                g_free(state->out_buffer);
                g_free(state);
        }
}

#endif /* !_SIPE_COMPILING_ANALYZER */

/*
  Local Variables:
  mode: c
  c-file-style: "bsd"
  indent-tabs-mode: t
  tab-width: 8
  End:
*/