wolfSSL SSL/TLS library, support up to TLS1.3

Dependents:   CyaSSL-Twitter-OAuth4Tw Example-client-tls-cert TwitterReader TweetTest ... more

Revision:
0:d92f9d21154c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/tls.c	Fri Jun 26 00:39:20 2015 +0000
@@ -0,0 +1,2447 @@
+/* tls.c
+ *
+ * Copyright (C) 2006-2015 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL. (formerly known as CyaSSL)
+ *
+ * wolfSSL 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.
+ *
+ * wolfSSL 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+
+#ifdef HAVE_CONFIG_H
+    #include <config.h>
+#endif
+
+#include <wolfssl/wolfcrypt/settings.h>
+
+#include <wolfssl/ssl.h>
+#include <wolfssl/internal.h>
+#include <wolfssl/error-ssl.h>
+#include <wolfssl/wolfcrypt/hmac.h>
+#ifdef NO_INLINE
+    #include <wolfssl/wolfcrypt/misc.h>
+#else
+    #include <wolfcrypt/src/misc.c>
+#endif
+
+
+
+#ifndef NO_TLS
+
+
+#ifndef WOLFSSL_HAVE_MIN
+#define WOLFSSL_HAVE_MIN
+
+    static INLINE word32 min(word32 a, word32 b)
+    {
+        return a > b ? b : a;
+    }
+
+#endif /* WOLFSSL_HAVE_MIN */
+
+
+#ifdef WOLFSSL_SHA384
+    #define P_HASH_MAX_SIZE SHA384_DIGEST_SIZE
+#else
+    #define P_HASH_MAX_SIZE SHA256_DIGEST_SIZE
+#endif
+
+/* compute p_hash for MD5, SHA-1, SHA-256, or SHA-384 for TLSv1 PRF */
+static int p_hash(byte* result, word32 resLen, const byte* secret,
+                   word32 secLen, const byte* seed, word32 seedLen, int hash)
+{
+    word32 len = P_HASH_MAX_SIZE;
+    word32 times;
+    word32 lastLen;
+    word32 lastTime;
+    word32 i;
+    word32 idx = 0;
+    int    ret = 0;
+#ifdef WOLFSSL_SMALL_STACK
+    byte*  previous;
+    byte*  current;
+    Hmac*  hmac;
+#else
+    byte   previous[P_HASH_MAX_SIZE];  /* max size */
+    byte   current[P_HASH_MAX_SIZE];   /* max size */
+    Hmac   hmac[1];
+#endif
+
+#ifdef WOLFSSL_SMALL_STACK
+    previous = (byte*)XMALLOC(P_HASH_MAX_SIZE, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    current  = (byte*)XMALLOC(P_HASH_MAX_SIZE, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    hmac     = (Hmac*)XMALLOC(sizeof(Hmac),    NULL, DYNAMIC_TYPE_TMP_BUFFER);
+
+    if (previous == NULL || current == NULL || hmac == NULL) {
+        if (previous) XFREE(previous, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        if (current)  XFREE(current,  NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        if (hmac)     XFREE(hmac,     NULL, DYNAMIC_TYPE_TMP_BUFFER);
+
+        return MEMORY_E;
+    }
+#endif
+
+    switch (hash) {
+        #ifndef NO_MD5
+            case md5_mac:
+                hash = MD5;
+                len  = MD5_DIGEST_SIZE;
+            break;
+        #endif
+
+        #ifndef NO_SHA256
+            case sha256_mac:
+                hash = SHA256;
+                len  = SHA256_DIGEST_SIZE;
+            break;
+        #endif
+
+        #ifdef WOLFSSL_SHA384
+            case sha384_mac:
+                hash = SHA384;
+                len  = SHA384_DIGEST_SIZE;
+            break;
+        #endif
+
+        #ifndef NO_SHA
+            case sha_mac:
+            default:
+                hash = SHA;
+                len  = SHA_DIGEST_SIZE;
+            break;
+        #endif
+    }
+
+    times   = resLen / len;
+    lastLen = resLen % len;
+
+    if (lastLen)
+        times += 1;
+
+    lastTime = times - 1;
+
+    if ((ret = wc_HmacSetKey(hmac, hash, secret, secLen)) == 0) {
+        if ((ret = wc_HmacUpdate(hmac, seed, seedLen)) == 0) { /* A0 = seed */
+            if ((ret = wc_HmacFinal(hmac, previous)) == 0) {   /* A1 */
+                for (i = 0; i < times; i++) {
+                    ret = wc_HmacUpdate(hmac, previous, len);
+                    if (ret != 0)
+                        break;
+                    ret = wc_HmacUpdate(hmac, seed, seedLen);
+                    if (ret != 0)
+                        break;
+                    ret = wc_HmacFinal(hmac, current);
+                    if (ret != 0)
+                        break;
+
+                    if ((i == lastTime) && lastLen)
+                        XMEMCPY(&result[idx], current,
+                                                 min(lastLen, P_HASH_MAX_SIZE));
+                    else {
+                        XMEMCPY(&result[idx], current, len);
+                        idx += len;
+                        ret = wc_HmacUpdate(hmac, previous, len);
+                        if (ret != 0)
+                            break;
+                        ret = wc_HmacFinal(hmac, previous);
+                        if (ret != 0)
+                            break;
+                    }
+                }
+            }
+        }
+    }
+
+    ForceZero(previous,  P_HASH_MAX_SIZE);
+    ForceZero(current,   P_HASH_MAX_SIZE);
+    ForceZero(hmac,      sizeof(Hmac));
+
+#ifdef WOLFSSL_SMALL_STACK
+    XFREE(previous, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(current,  NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(hmac,     NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return ret;
+}
+
+#undef P_HASH_MAX_SIZE
+
+
+#ifndef NO_OLD_TLS
+
+/* calculate XOR for TLSv1 PRF */
+static INLINE void get_xor(byte *digest, word32 digLen, byte* md5, byte* sha)
+{
+    word32 i;
+
+    for (i = 0; i < digLen; i++)
+        digest[i] = md5[i] ^ sha[i];
+}
+
+
+/* compute TLSv1 PRF (pseudo random function using HMAC) */
+static int doPRF(byte* digest, word32 digLen, const byte* secret,word32 secLen,
+                 const byte* label, word32 labLen, const byte* seed,
+                 word32 seedLen)
+{
+    int    ret  = 0;
+    word32 half = (secLen + 1) / 2;
+
+#ifdef WOLFSSL_SMALL_STACK
+    byte* md5_half;
+    byte* sha_half;
+    byte* labelSeed;
+    byte* md5_result;
+    byte* sha_result;
+#else
+    byte  md5_half[MAX_PRF_HALF];     /* half is real size */
+    byte  sha_half[MAX_PRF_HALF];     /* half is real size */
+    byte  labelSeed[MAX_PRF_LABSEED]; /* labLen + seedLen is real size */
+    byte  md5_result[MAX_PRF_DIG];    /* digLen is real size */
+    byte  sha_result[MAX_PRF_DIG];    /* digLen is real size */
+#endif
+
+    if (half > MAX_PRF_HALF)
+        return BUFFER_E;
+    if (labLen + seedLen > MAX_PRF_LABSEED)
+        return BUFFER_E;
+    if (digLen > MAX_PRF_DIG)
+        return BUFFER_E;
+
+#ifdef WOLFSSL_SMALL_STACK
+    md5_half   = (byte*)XMALLOC(MAX_PRF_HALF,    NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    sha_half   = (byte*)XMALLOC(MAX_PRF_HALF,    NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    labelSeed  = (byte*)XMALLOC(MAX_PRF_LABSEED, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    md5_result = (byte*)XMALLOC(MAX_PRF_DIG,     NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    sha_result = (byte*)XMALLOC(MAX_PRF_DIG,     NULL, DYNAMIC_TYPE_TMP_BUFFER);
+
+    if (md5_half == NULL || sha_half == NULL || labelSeed == NULL ||
+                                     md5_result == NULL || sha_result == NULL) {
+        if (md5_half)   XFREE(md5_half,   NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        if (sha_half)   XFREE(sha_half,   NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        if (labelSeed)  XFREE(labelSeed,  NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        if (md5_result) XFREE(md5_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        if (sha_result) XFREE(sha_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+
+        return MEMORY_E;
+    }
+#endif
+
+    XMEMSET(md5_result, 0, digLen);
+    XMEMSET(sha_result, 0, digLen);
+
+    XMEMCPY(md5_half, secret, half);
+    XMEMCPY(sha_half, secret + half - secLen % 2, half);
+
+    XMEMCPY(labelSeed, label, labLen);
+    XMEMCPY(labelSeed + labLen, seed, seedLen);
+
+    if ((ret = p_hash(md5_result, digLen, md5_half, half, labelSeed,
+                                             labLen + seedLen, md5_mac)) == 0) {
+        if ((ret = p_hash(sha_result, digLen, sha_half, half, labelSeed,
+                                             labLen + seedLen, sha_mac)) == 0) {
+            get_xor(digest, digLen, md5_result, sha_result);
+        }
+    }
+
+#ifdef WOLFSSL_SMALL_STACK
+    XFREE(md5_half,   NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(sha_half,   NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(labelSeed,  NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(md5_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(sha_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return ret;
+}
+
+#endif
+
+
+/* Wrapper to call straight thru to p_hash in TSL 1.2 cases to remove stack
+   use */
+static int PRF(byte* digest, word32 digLen, const byte* secret, word32 secLen,
+            const byte* label, word32 labLen, const byte* seed, word32 seedLen,
+            int useAtLeastSha256, int hash_type)
+{
+    int ret = 0;
+
+    if (useAtLeastSha256) {
+#ifdef WOLFSSL_SMALL_STACK
+        byte* labelSeed;
+#else
+        byte labelSeed[MAX_PRF_LABSEED]; /* labLen + seedLen is real size */
+#endif
+
+        if (labLen + seedLen > MAX_PRF_LABSEED)
+            return BUFFER_E;
+
+#ifdef WOLFSSL_SMALL_STACK
+        labelSeed = (byte*)XMALLOC(MAX_PRF_LABSEED, NULL,
+                                                       DYNAMIC_TYPE_TMP_BUFFER);
+        if (labelSeed == NULL)
+           return MEMORY_E;
+#endif
+
+        XMEMCPY(labelSeed, label, labLen);
+        XMEMCPY(labelSeed + labLen, seed, seedLen);
+
+        /* If a cipher suite wants an algorithm better than sha256, it
+         * should use better. */
+        if (hash_type < sha256_mac)
+            hash_type = sha256_mac;
+        ret = p_hash(digest, digLen, secret, secLen, labelSeed,
+                     labLen + seedLen, hash_type);
+
+#ifdef WOLFSSL_SMALL_STACK
+        XFREE(labelSeed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+    }
+#ifndef NO_OLD_TLS
+    else {
+        ret = doPRF(digest, digLen, secret, secLen, label, labLen, seed,
+                    seedLen);
+    }
+#endif
+
+    return ret;
+}
+
+
+#ifdef WOLFSSL_SHA384
+    #define HSHASH_SZ SHA384_DIGEST_SIZE
+#else
+    #define HSHASH_SZ FINISHED_SZ
+#endif
+
+
+int BuildTlsFinished(WOLFSSL* ssl, Hashes* hashes, const byte* sender)
+{
+    const byte* side;
+    byte        handshake_hash[HSHASH_SZ];
+    word32      hashSz = FINISHED_SZ;
+
+#ifndef NO_OLD_TLS
+    wc_Md5GetHash(&ssl->hsHashes->hashMd5, handshake_hash);
+    wc_ShaGetHash(&ssl->hsHashes->hashSha, &handshake_hash[MD5_DIGEST_SIZE]);
+#endif
+
+    if (IsAtLeastTLSv1_2(ssl)) {
+#ifndef NO_SHA256
+        if (ssl->specs.mac_algorithm <= sha256_mac) {
+            int ret = wc_Sha256GetHash(&ssl->hsHashes->hashSha256,handshake_hash);
+
+            if (ret != 0)
+                return ret;
+
+            hashSz = SHA256_DIGEST_SIZE;
+        }
+#endif
+#ifdef WOLFSSL_SHA384
+        if (ssl->specs.mac_algorithm == sha384_mac) {
+            int ret = wc_Sha384Final(&ssl->hsHashes->hashSha384,handshake_hash);
+
+            if (ret != 0)
+                return ret;
+
+            hashSz = SHA384_DIGEST_SIZE;
+        }
+#endif
+    }
+
+    if ( XSTRNCMP((const char*)sender, (const char*)client, SIZEOF_SENDER) == 0)
+        side = tls_client;
+    else
+        side = tls_server;
+
+    return PRF((byte*)hashes, TLS_FINISHED_SZ, ssl->arrays->masterSecret,
+               SECRET_LEN, side, FINISHED_LABEL_SZ, handshake_hash, hashSz,
+               IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm);
+}
+
+
+#ifndef NO_OLD_TLS
+
+ProtocolVersion MakeTLSv1(void)
+{
+    ProtocolVersion pv;
+    pv.major = SSLv3_MAJOR;
+    pv.minor = TLSv1_MINOR;
+
+    return pv;
+}
+
+
+ProtocolVersion MakeTLSv1_1(void)
+{
+    ProtocolVersion pv;
+    pv.major = SSLv3_MAJOR;
+    pv.minor = TLSv1_1_MINOR;
+
+    return pv;
+}
+
+#endif
+
+
+ProtocolVersion MakeTLSv1_2(void)
+{
+    ProtocolVersion pv;
+    pv.major = SSLv3_MAJOR;
+    pv.minor = TLSv1_2_MINOR;
+
+    return pv;
+}
+
+
+static const byte master_label[MASTER_LABEL_SZ + 1] = "master secret";
+static const byte key_label   [KEY_LABEL_SZ + 1]    = "key expansion";
+
+
+/* External facing wrapper so user can call as well, 0 on success */
+int wolfSSL_DeriveTlsKeys(byte* key_data, word32 keyLen,
+                         const byte* ms, word32 msLen,
+                         const byte* sr, const byte* cr,
+                         int tls1_2, int hash_type)
+{
+    byte  seed[SEED_LEN];
+
+    XMEMCPY(seed,           sr, RAN_LEN);
+    XMEMCPY(seed + RAN_LEN, cr, RAN_LEN);
+
+    return PRF(key_data, keyLen, ms, msLen, key_label, KEY_LABEL_SZ,
+               seed, SEED_LEN, tls1_2, hash_type);
+}
+
+
+int DeriveTlsKeys(WOLFSSL* ssl)
+{
+    int   ret;
+    int   length = 2 * ssl->specs.hash_size +
+                   2 * ssl->specs.key_size  +
+                   2 * ssl->specs.iv_size;
+#ifdef WOLFSSL_SMALL_STACK
+    byte* key_data;
+#else
+    byte  key_data[MAX_PRF_DIG];
+#endif
+
+#ifdef WOLFSSL_SMALL_STACK
+    key_data = (byte*)XMALLOC(MAX_PRF_DIG, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    if (key_data == NULL) {
+        return MEMORY_E;
+    }
+#endif
+
+    ret = wolfSSL_DeriveTlsKeys(key_data, length,
+                           ssl->arrays->masterSecret, SECRET_LEN,
+                           ssl->arrays->serverRandom, ssl->arrays->clientRandom,
+                           IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm);
+    if (ret == 0)
+        ret = StoreKeys(ssl, key_data);
+
+#ifdef WOLFSSL_SMALL_STACK
+    XFREE(key_data, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return ret;
+}
+
+
+/* External facing wrapper so user can call as well, 0 on success */
+int wolfSSL_MakeTlsMasterSecret(byte* ms, word32 msLen,
+                               const byte* pms, word32 pmsLen,
+                               const byte* cr, const byte* sr,
+                               int tls1_2, int hash_type)
+{
+    byte  seed[SEED_LEN];
+
+    XMEMCPY(seed,           cr, RAN_LEN);
+    XMEMCPY(seed + RAN_LEN, sr, RAN_LEN);
+
+    return PRF(ms, msLen, pms, pmsLen, master_label, MASTER_LABEL_SZ,
+               seed, SEED_LEN, tls1_2, hash_type);
+}
+
+
+int MakeTlsMasterSecret(WOLFSSL* ssl)
+{
+    int   ret;
+
+    ret = wolfSSL_MakeTlsMasterSecret(ssl->arrays->masterSecret, SECRET_LEN,
+              ssl->arrays->preMasterSecret, ssl->arrays->preMasterSz,
+              ssl->arrays->clientRandom, ssl->arrays->serverRandom,
+              IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm);
+
+    if (ret == 0) {
+    #ifdef SHOW_SECRETS
+        int i;
+
+        printf("master secret: ");
+        for (i = 0; i < SECRET_LEN; i++)
+            printf("%02x", ssl->arrays->masterSecret[i]);
+        printf("\n");
+    #endif
+
+        ret = DeriveTlsKeys(ssl);
+    }
+
+    return ret;
+}
+
+
+/* Used by EAP-TLS and EAP-TTLS to derive keying material from
+ * the master_secret. */
+int wolfSSL_make_eap_keys(WOLFSSL* ssl, void* msk, unsigned int len,
+                                                              const char* label)
+{
+    int   ret;
+#ifdef WOLFSSL_SMALL_STACK
+    byte* seed;
+#else
+    byte  seed[SEED_LEN];
+#endif
+
+#ifdef WOLFSSL_SMALL_STACK
+    seed = (byte*)XMALLOC(SEED_LEN, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    if (seed == NULL)
+        return MEMORY_E;
+#endif
+
+    /*
+     * As per RFC-5281, the order of the client and server randoms is reversed
+     * from that used by the TLS protocol to derive keys.
+     */
+    XMEMCPY(seed,           ssl->arrays->clientRandom, RAN_LEN);
+    XMEMCPY(seed + RAN_LEN, ssl->arrays->serverRandom, RAN_LEN);
+
+    ret = PRF((byte*)msk, len, ssl->arrays->masterSecret, SECRET_LEN,
+              (const byte *)label, (word32)strlen(label), seed, SEED_LEN,
+              IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm);
+
+#ifdef WOLFSSL_SMALL_STACK
+    XFREE(seed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return ret;
+}
+
+
+/*** next for static INLINE s copied internal.c ***/
+
+/* convert 16 bit integer to opaque */
+static INLINE void c16toa(word16 u16, byte* c)
+{
+    c[0] = (u16 >> 8) & 0xff;
+    c[1] =  u16 & 0xff;
+}
+
+#ifdef HAVE_TLS_EXTENSIONS
+/* convert opaque to 16 bit integer */
+static INLINE void ato16(const byte* c, word16* u16)
+{
+    *u16 = (c[0] << 8) | (c[1]);
+}
+
+#ifdef HAVE_SNI
+/* convert a 24 bit integer into a 32 bit one */
+static INLINE void c24to32(const word24 u24, word32* u32)
+{
+    *u32 = (u24[0] << 16) | (u24[1] << 8) | u24[2];
+}
+#endif
+#endif
+
+/* convert 32 bit integer to opaque */
+static INLINE void c32toa(word32 u32, byte* c)
+{
+    c[0] = (u32 >> 24) & 0xff;
+    c[1] = (u32 >> 16) & 0xff;
+    c[2] = (u32 >>  8) & 0xff;
+    c[3] =  u32 & 0xff;
+}
+
+
+static INLINE word32 GetSEQIncrement(WOLFSSL* ssl, int verify)
+{
+#ifdef WOLFSSL_DTLS
+    if (ssl->options.dtls) {
+        if (verify)
+            return ssl->keys.dtls_state.curSeq; /* explicit from peer */
+        else
+            return ssl->keys.dtls_sequence_number - 1; /* already incremented */
+    }
+#endif
+    if (verify)
+        return ssl->keys.peer_sequence_number++;
+    else
+        return ssl->keys.sequence_number++;
+}
+
+
+#ifdef WOLFSSL_DTLS
+
+static INLINE word32 GetEpoch(WOLFSSL* ssl, int verify)
+{
+    if (verify)
+        return ssl->keys.dtls_state.curEpoch;
+    else
+        return ssl->keys.dtls_epoch;
+}
+
+#endif /* WOLFSSL_DTLS */
+
+
+/*** end copy ***/
+
+
+/* return HMAC digest type in wolfSSL format */
+int wolfSSL_GetHmacType(WOLFSSL* ssl)
+{
+    if (ssl == NULL)
+        return BAD_FUNC_ARG;
+
+    switch (ssl->specs.mac_algorithm) {
+        #ifndef NO_MD5
+        case md5_mac:
+        {
+            return MD5;
+        }
+        #endif
+        #ifndef NO_SHA256
+        case sha256_mac:
+        {
+            return SHA256;
+        }
+        #endif
+        #ifdef WOLFSSL_SHA384
+        case sha384_mac:
+        {
+            return SHA384;
+        }
+
+        #endif
+        #ifndef NO_SHA
+        case sha_mac:
+        {
+            return SHA;
+        }
+        #endif
+        #ifdef HAVE_BLAKE2
+        case blake2b_mac:
+        {
+            return BLAKE2B_ID;
+        }
+        #endif
+        default:
+        {
+            return SSL_FATAL_ERROR;
+        }
+    }
+}
+
+
+int wolfSSL_SetTlsHmacInner(WOLFSSL* ssl, byte* inner, word32 sz, int content,
+                           int verify)
+{
+    if (ssl == NULL || inner == NULL)
+        return BAD_FUNC_ARG;
+
+    XMEMSET(inner, 0, WOLFSSL_TLS_HMAC_INNER_SZ);
+
+#ifdef WOLFSSL_DTLS
+    if (ssl->options.dtls)
+        c16toa((word16)GetEpoch(ssl, verify), inner);
+#endif
+    c32toa(GetSEQIncrement(ssl, verify), &inner[sizeof(word32)]);
+    inner[SEQ_SZ] = (byte)content;
+    inner[SEQ_SZ + ENUM_LEN]            = ssl->version.major;
+    inner[SEQ_SZ + ENUM_LEN + ENUM_LEN] = ssl->version.minor;
+    c16toa((word16)sz, inner + SEQ_SZ + ENUM_LEN + VERSION_SZ);
+
+    return 0;
+}
+
+
+/* TLS type HMAC */
+int TLS_hmac(WOLFSSL* ssl, byte* digest, const byte* in, word32 sz,
+              int content, int verify)
+{
+    Hmac hmac;
+    int  ret;
+    byte myInner[WOLFSSL_TLS_HMAC_INNER_SZ];
+
+    if (ssl == NULL)
+        return BAD_FUNC_ARG;
+
+#ifdef HAVE_FUZZER
+    if (ssl->fuzzerCb)
+        ssl->fuzzerCb(ssl, in, sz, FUZZ_HMAC, ssl->fuzzerCtx);
+#endif
+
+    wolfSSL_SetTlsHmacInner(ssl, myInner, sz, content, verify);
+
+    ret = wc_HmacSetKey(&hmac, wolfSSL_GetHmacType(ssl),
+                     wolfSSL_GetMacSecret(ssl, verify), ssl->specs.hash_size);
+    if (ret != 0)
+        return ret;
+    ret = wc_HmacUpdate(&hmac, myInner, sizeof(myInner));
+    if (ret != 0)
+        return ret;
+    ret = wc_HmacUpdate(&hmac, in, sz);                                /* content */
+    if (ret != 0)
+        return ret;
+    ret = wc_HmacFinal(&hmac, digest);
+    if (ret != 0)
+        return ret;
+
+    return 0;
+}
+
+#ifdef HAVE_TLS_EXTENSIONS
+
+
+/** Supports up to 64 flags. Update as needed. */
+#define SEMAPHORE_SIZE 8
+
+
+static INLINE word16 TLSX_ToSemaphore(word16 type)
+{
+    switch (type) {
+        case SECURE_RENEGOTIATION:
+            return 63;
+
+        default:
+            if (type > 62) {
+                /* This message SHOULD only happens during the adding of
+                   new TLS extensions in which its IANA number overflows
+                   the current semaphore's range, or if its number already
+                   is assigned to be used by another extension.
+                   Use this check value for the new extension and decrement
+                   the check value by one. */
+                WOLFSSL_MSG("### TLSX semaphore colision or overflow detected!");
+            }
+    }
+
+    return type;
+}
+
+
+#define IS_OFF(semaphore, light) \
+    ((semaphore)[(light) / 8] ^  (byte) (0x01 << ((light) % 8)))
+
+
+#define TURN_ON(semaphore, light) \
+    ((semaphore)[(light) / 8] |= (byte) (0x01 << ((light) % 8)))
+
+
+static int TLSX_Push(TLSX** list, TLSX_Type type, void* data)
+{
+    TLSX* extension;
+
+    extension = (TLSX*)XMALLOC(sizeof(TLSX), 0, DYNAMIC_TYPE_TLSX);
+    if (extension == NULL)
+        return MEMORY_E;
+
+    extension->type = type;
+    extension->data = data;
+    extension->resp = 0;
+    extension->next = *list;
+    *list = extension;
+
+    /* remove duplicated extensions, there should be only one of each type. */
+    do {
+        if (extension->next && extension->next->type == type) {
+            TLSX *next = extension->next;
+
+            extension->next = next->next;
+            next->next = NULL;
+
+            TLSX_FreeAll(next);
+
+            /* there is no way to occur more than */
+            /* two extensions of the same type.   */
+            break;
+        }
+    } while ((extension = extension->next));
+
+    return 0;
+}
+
+
+#ifndef NO_WOLFSSL_SERVER
+
+void TLSX_SetResponse(WOLFSSL* ssl, TLSX_Type type);
+
+void TLSX_SetResponse(WOLFSSL* ssl, TLSX_Type type)
+{
+    TLSX *ext = TLSX_Find(ssl->extensions, type);
+
+    if (ext)
+        ext->resp = 1;
+}
+
+#endif
+
+/* SNI - Server Name Indication */
+
+#ifdef HAVE_SNI
+
+static void TLSX_SNI_Free(SNI* sni)
+{
+    if (sni) {
+        switch (sni->type) {
+            case WOLFSSL_SNI_HOST_NAME:
+                XFREE(sni->data.host_name, 0, DYNAMIC_TYPE_TLSX);
+            break;
+        }
+
+        XFREE(sni, 0, DYNAMIC_TYPE_TLSX);
+    }
+}
+
+static void TLSX_SNI_FreeAll(SNI* list)
+{
+    SNI* sni;
+
+    while ((sni = list)) {
+        list = sni->next;
+        TLSX_SNI_Free(sni);
+    }
+}
+
+static int TLSX_SNI_Append(SNI** list, byte type, const void* data, word16 size)
+{
+    SNI* sni;
+
+    if (list == NULL)
+        return BAD_FUNC_ARG;
+
+    if ((sni = XMALLOC(sizeof(SNI), 0, DYNAMIC_TYPE_TLSX)) == NULL)
+        return MEMORY_E;
+
+    switch (type) {
+        case WOLFSSL_SNI_HOST_NAME: {
+            sni->data.host_name = XMALLOC(size + 1, 0, DYNAMIC_TYPE_TLSX);
+
+            if (sni->data.host_name) {
+                XSTRNCPY(sni->data.host_name, (const char*)data, size);
+                sni->data.host_name[size] = 0;
+            } else {
+                XFREE(sni, 0, DYNAMIC_TYPE_TLSX);
+                return MEMORY_E;
+            }
+        }
+        break;
+
+        default: /* invalid type */
+            XFREE(sni, 0, DYNAMIC_TYPE_TLSX);
+            return BAD_FUNC_ARG;
+    }
+
+    sni->type = type;
+    sni->next = *list;
+
+#ifndef NO_WOLFSSL_SERVER
+    sni->options = 0;
+    sni->status  = WOLFSSL_SNI_NO_MATCH;
+#endif
+
+    *list = sni;
+
+    return 0;
+}
+
+static word16 TLSX_SNI_GetSize(SNI* list)
+{
+    SNI* sni;
+    word16 length = OPAQUE16_LEN; /* list length */
+
+    while ((sni = list)) {
+        list = sni->next;
+
+        length += ENUM_LEN + OPAQUE16_LEN; /* sni type + sni length */
+
+        switch (sni->type) {
+            case WOLFSSL_SNI_HOST_NAME:
+                length += XSTRLEN((char*)sni->data.host_name);
+            break;
+        }
+    }
+
+    return length;
+}
+
+static word16 TLSX_SNI_Write(SNI* list, byte* output)
+{
+    SNI* sni;
+    word16 length = 0;
+    word16 offset = OPAQUE16_LEN; /* list length offset */
+
+    while ((sni = list)) {
+        list = sni->next;
+
+        output[offset++] = sni->type; /* sni type */
+
+        switch (sni->type) {
+            case WOLFSSL_SNI_HOST_NAME:
+                length = XSTRLEN((char*)sni->data.host_name);
+
+                c16toa(length, output + offset); /* sni length */
+                offset += OPAQUE16_LEN;
+
+                XMEMCPY(output + offset, sni->data.host_name, length);
+
+                offset += length;
+            break;
+        }
+    }
+
+    c16toa(offset - OPAQUE16_LEN, output); /* writing list length */
+
+    return offset;
+}
+
+static SNI* TLSX_SNI_Find(SNI *list, byte type)
+{
+    SNI *sni = list;
+
+    while (sni && sni->type != type)
+        sni = sni->next;
+
+    return sni;
+}
+
+#ifndef NO_WOLFSSL_SERVER
+static void TLSX_SNI_SetStatus(TLSX* extensions, byte type, byte status)
+{
+    TLSX* extension = TLSX_Find(extensions, SERVER_NAME_INDICATION);
+    SNI* sni = TLSX_SNI_Find(extension ? extension->data : NULL, type);
+
+    if (sni) {
+        sni->status = status;
+        WOLFSSL_MSG("SNI did match!");
+    }
+}
+
+byte TLSX_SNI_Status(TLSX* extensions, byte type)
+{
+    TLSX* extension = TLSX_Find(extensions, SERVER_NAME_INDICATION);
+    SNI* sni = TLSX_SNI_Find(extension ? extension->data : NULL, type);
+
+    if (sni)
+        return sni->status;
+
+    return 0;
+}
+#endif
+
+static int TLSX_SNI_Parse(WOLFSSL* ssl, byte* input, word16 length,
+                                                                 byte isRequest)
+{
+#ifndef NO_WOLFSSL_SERVER
+    word16 size = 0;
+    word16 offset = 0;
+#endif
+
+    TLSX *extension = TLSX_Find(ssl->extensions, SERVER_NAME_INDICATION);
+
+    if (!extension)
+        extension = TLSX_Find(ssl->ctx->extensions, SERVER_NAME_INDICATION);
+
+    if (!extension || !extension->data)
+        return isRequest ? 0 : BUFFER_ERROR; /* not using SNI OR unexpected
+                                                SNI response from server. */
+
+    if (!isRequest)
+        return length ? BUFFER_ERROR : 0; /* SNI response must be empty!
+                                             Nothing else to do. */
+
+#ifndef NO_WOLFSSL_SERVER
+
+    if (OPAQUE16_LEN > length)
+        return BUFFER_ERROR;
+
+    ato16(input, &size);
+    offset += OPAQUE16_LEN;
+
+    /* validating sni list length */
+    if (length != OPAQUE16_LEN + size)
+        return BUFFER_ERROR;
+
+    for (size = 0; offset < length; offset += size) {
+        SNI *sni;
+        byte type = input[offset++];
+
+        if (offset + OPAQUE16_LEN > length)
+            return BUFFER_ERROR;
+
+        ato16(input + offset, &size);
+        offset += OPAQUE16_LEN;
+
+        if (offset + size > length)
+            return BUFFER_ERROR;
+
+        if (!(sni = TLSX_SNI_Find((SNI*)extension->data, type))) {
+            continue; /* not using this SNI type */
+        }
+
+        switch(type) {
+            case WOLFSSL_SNI_HOST_NAME: {
+                byte matched = (XSTRLEN(sni->data.host_name) == size)
+                            && (XSTRNCMP(sni->data.host_name,
+                                       (const char*)input + offset, size) == 0);
+
+                if (matched || sni->options & WOLFSSL_SNI_ANSWER_ON_MISMATCH) {
+                    int r = TLSX_UseSNI(&ssl->extensions,
+                                                    type, input + offset, size);
+
+                    if (r != SSL_SUCCESS) return r; /* throw error */
+
+                    TLSX_SNI_SetStatus(ssl->extensions, type,
+                      matched ? WOLFSSL_SNI_REAL_MATCH : WOLFSSL_SNI_FAKE_MATCH);
+
+                } else if (!(sni->options & WOLFSSL_SNI_CONTINUE_ON_MISMATCH)) {
+                    SendAlert(ssl, alert_fatal, unrecognized_name);
+
+                    return UNKNOWN_SNI_HOST_NAME_E;
+                }
+                break;
+            }
+        }
+
+        TLSX_SetResponse(ssl, SERVER_NAME_INDICATION);
+    }
+
+#endif
+
+    return 0;
+}
+
+int TLSX_UseSNI(TLSX** extensions, byte type, const void* data, word16 size)
+{
+    TLSX* extension = TLSX_Find(*extensions, SERVER_NAME_INDICATION);
+    SNI*  sni       = NULL;
+    int   ret       = 0;
+
+    if (extensions == NULL || data == NULL)
+        return BAD_FUNC_ARG;
+
+    if ((ret = TLSX_SNI_Append(&sni, type, data, size)) != 0)
+        return ret;
+
+    if (!extension) {
+        if ((ret = TLSX_Push(extensions, SERVER_NAME_INDICATION, (void*)sni))
+                                                                         != 0) {
+            TLSX_SNI_Free(sni);
+            return ret;
+        }
+    }
+    else {
+        /* push new SNI object to extension data. */
+        sni->next = (SNI*)extension->data;
+        extension->data = (void*)sni;
+
+        /* look for another server name of the same type to remove */
+        do {
+            if (sni->next && sni->next->type == type) {
+                SNI *next = sni->next;
+
+                sni->next = next->next;
+                TLSX_SNI_Free(next);
+
+                break;
+            }
+        } while ((sni = sni->next));
+    }
+
+    return SSL_SUCCESS;
+}
+
+#ifndef NO_WOLFSSL_SERVER
+word16 TLSX_SNI_GetRequest(TLSX* extensions, byte type, void** data)
+{
+    TLSX* extension = TLSX_Find(extensions, SERVER_NAME_INDICATION);
+    SNI* sni = TLSX_SNI_Find(extension ? extension->data : NULL, type);
+
+    if (sni && sni->status != WOLFSSL_SNI_NO_MATCH) {
+        switch (sni->type) {
+            case WOLFSSL_SNI_HOST_NAME:
+                *data = sni->data.host_name;
+                return XSTRLEN(*data);
+        }
+    }
+
+    return 0;
+}
+
+void TLSX_SNI_SetOptions(TLSX* extensions, byte type, byte options)
+{
+    TLSX* extension = TLSX_Find(extensions, SERVER_NAME_INDICATION);
+    SNI* sni = TLSX_SNI_Find(extension ? extension->data : NULL, type);
+
+    if (sni)
+        sni->options = options;
+}
+
+int TLSX_SNI_GetFromBuffer(const byte* clientHello, word32 helloSz,
+                           byte type, byte* sni, word32* inOutSz)
+{
+    word32 offset = 0;
+    word32 len32  = 0;
+    word16 len16  = 0;
+
+    if (helloSz < RECORD_HEADER_SZ + HANDSHAKE_HEADER_SZ + CLIENT_HELLO_FIRST)
+        return INCOMPLETE_DATA;
+
+    /* TLS record header */
+    if ((enum ContentType) clientHello[offset++] != handshake)
+        return BUFFER_ERROR;
+
+    if (clientHello[offset++] != SSLv3_MAJOR)
+        return BUFFER_ERROR;
+
+    if (clientHello[offset++] < TLSv1_MINOR)
+        return SNI_UNSUPPORTED;
+
+    ato16(clientHello + offset, &len16);
+    offset += OPAQUE16_LEN;
+
+    if (offset + len16 > helloSz)
+        return INCOMPLETE_DATA;
+
+    /* Handshake header */
+    if ((enum HandShakeType) clientHello[offset] != client_hello)
+        return BUFFER_ERROR;
+
+    c24to32(clientHello + offset + 1, &len32);
+    offset += HANDSHAKE_HEADER_SZ;
+
+    if (offset + len32 > helloSz)
+        return BUFFER_ERROR;
+
+    /* client hello */
+    offset += VERSION_SZ + RAN_LEN; /* version, random */
+
+    if (helloSz < offset + clientHello[offset])
+        return BUFFER_ERROR;
+
+    offset += ENUM_LEN + clientHello[offset]; /* skip session id */
+
+    /* cypher suites */
+    if (helloSz < offset + OPAQUE16_LEN)
+        return BUFFER_ERROR;
+
+    ato16(clientHello + offset, &len16);
+    offset += OPAQUE16_LEN;
+
+    if (helloSz < offset + len16)
+        return BUFFER_ERROR;
+
+    offset += len16; /* skip cypher suites */
+
+    /* compression methods */
+    if (helloSz < offset + 1)
+        return BUFFER_ERROR;
+
+    if (helloSz < offset + clientHello[offset])
+        return BUFFER_ERROR;
+
+    offset += ENUM_LEN + clientHello[offset]; /* skip compression methods */
+
+    /* extensions */
+    if (helloSz < offset + OPAQUE16_LEN)
+        return 0; /* no extensions in client hello. */
+
+    ato16(clientHello + offset, &len16);
+    offset += OPAQUE16_LEN;
+
+    if (helloSz < offset + len16)
+        return BUFFER_ERROR;
+
+    while (len16 >= OPAQUE16_LEN + OPAQUE16_LEN) {
+        word16 extType;
+        word16 extLen;
+
+        ato16(clientHello + offset, &extType);
+        offset += OPAQUE16_LEN;
+
+        ato16(clientHello + offset, &extLen);
+        offset += OPAQUE16_LEN;
+
+        if (helloSz < offset + extLen)
+            return BUFFER_ERROR;
+
+        if (extType != SERVER_NAME_INDICATION) {
+            offset += extLen; /* skip extension */
+        } else {
+            word16 listLen;
+
+            ato16(clientHello + offset, &listLen);
+            offset += OPAQUE16_LEN;
+
+            if (helloSz < offset + listLen)
+                return BUFFER_ERROR;
+
+            while (listLen > ENUM_LEN + OPAQUE16_LEN) {
+                byte   sniType = clientHello[offset++];
+                word16 sniLen;
+
+                ato16(clientHello + offset, &sniLen);
+                offset += OPAQUE16_LEN;
+
+                if (helloSz < offset + sniLen)
+                    return BUFFER_ERROR;
+
+                if (sniType != type) {
+                    offset  += sniLen;
+                    listLen -= min(ENUM_LEN + OPAQUE16_LEN + sniLen, listLen);
+                    continue;
+                }
+
+                *inOutSz = min(sniLen, *inOutSz);
+                XMEMCPY(sni, clientHello + offset, *inOutSz);
+
+                return SSL_SUCCESS;
+            }
+        }
+
+        len16 -= min(2 * OPAQUE16_LEN + extLen, len16);
+    }
+
+    return len16 ? BUFFER_ERROR : 0;
+}
+
+#endif
+
+#define SNI_FREE_ALL TLSX_SNI_FreeAll
+#define SNI_GET_SIZE TLSX_SNI_GetSize
+#define SNI_WRITE    TLSX_SNI_Write
+#define SNI_PARSE    TLSX_SNI_Parse
+
+#else
+
+#define SNI_FREE_ALL(list)
+#define SNI_GET_SIZE(list)    0
+#define SNI_WRITE(a, b)       0
+#define SNI_PARSE(a, b, c, d) 0
+
+#endif /* HAVE_SNI */
+
+#ifdef HAVE_MAX_FRAGMENT
+
+static word16 TLSX_MFL_Write(byte* data, byte* output)
+{
+    output[0] = data[0];
+
+    return ENUM_LEN;
+}
+
+static int TLSX_MFL_Parse(WOLFSSL* ssl, byte* input, word16 length,
+                                                                 byte isRequest)
+{
+    if (length != ENUM_LEN)
+        return BUFFER_ERROR;
+
+    switch (*input) {
+        case WOLFSSL_MFL_2_9 : ssl->max_fragment =  512; break;
+        case WOLFSSL_MFL_2_10: ssl->max_fragment = 1024; break;
+        case WOLFSSL_MFL_2_11: ssl->max_fragment = 2048; break;
+        case WOLFSSL_MFL_2_12: ssl->max_fragment = 4096; break;
+        case WOLFSSL_MFL_2_13: ssl->max_fragment = 8192; break;
+
+        default:
+            SendAlert(ssl, alert_fatal, illegal_parameter);
+
+            return UNKNOWN_MAX_FRAG_LEN_E;
+    }
+
+#ifndef NO_WOLFSSL_SERVER
+    if (isRequest) {
+        int r = TLSX_UseMaxFragment(&ssl->extensions, *input);
+
+        if (r != SSL_SUCCESS) return r; /* throw error */
+
+        TLSX_SetResponse(ssl, MAX_FRAGMENT_LENGTH);
+    }
+#endif
+
+    return 0;
+}
+
+int TLSX_UseMaxFragment(TLSX** extensions, byte mfl)
+{
+    byte* data = NULL;
+    int   ret  = 0;
+
+    if (extensions == NULL)
+        return BAD_FUNC_ARG;
+
+    if (mfl < WOLFSSL_MFL_2_9 || WOLFSSL_MFL_2_13 < mfl)
+        return BAD_FUNC_ARG;
+
+    if ((data = XMALLOC(ENUM_LEN, 0, DYNAMIC_TYPE_TLSX)) == NULL)
+        return MEMORY_E;
+
+    data[0] = mfl;
+
+    /* push new MFL extension. */
+    if ((ret = TLSX_Push(extensions, MAX_FRAGMENT_LENGTH, data)) != 0) {
+        XFREE(data, 0, DYNAMIC_TYPE_TLSX);
+        return ret;
+    }
+
+    return SSL_SUCCESS;
+}
+
+
+#define MFL_FREE_ALL(data) XFREE(data, 0, DYNAMIC_TYPE_TLSX)
+#define MFL_GET_SIZE(data) ENUM_LEN
+#define MFL_WRITE          TLSX_MFL_Write
+#define MFL_PARSE          TLSX_MFL_Parse
+
+#else
+
+#define MFL_FREE_ALL(a)
+#define MFL_GET_SIZE(a)       0
+#define MFL_WRITE(a, b)       0
+#define MFL_PARSE(a, b, c, d) 0
+
+#endif /* HAVE_MAX_FRAGMENT */
+
+#ifdef HAVE_TRUNCATED_HMAC
+
+static int TLSX_THM_Parse(WOLFSSL* ssl, byte* input, word16 length,
+                                                                 byte isRequest)
+{
+    if (length != 0 || input == NULL)
+        return BUFFER_ERROR;
+
+#ifndef NO_WOLFSSL_SERVER
+    if (isRequest) {
+        int r = TLSX_UseTruncatedHMAC(&ssl->extensions);
+
+        if (r != SSL_SUCCESS) return r; /* throw error */
+
+        TLSX_SetResponse(ssl, TRUNCATED_HMAC);
+    }
+#endif
+
+    ssl->truncated_hmac = 1;
+
+    return 0;
+}
+
+int TLSX_UseTruncatedHMAC(TLSX** extensions)
+{
+    int ret = 0;
+
+    if (extensions == NULL)
+        return BAD_FUNC_ARG;
+
+    if ((ret = TLSX_Push(extensions, TRUNCATED_HMAC, NULL)) != 0)
+        return ret;
+
+    return SSL_SUCCESS;
+}
+
+#define THM_PARSE TLSX_THM_Parse
+
+#else
+
+#define THM_PARSE(a, b, c, d) 0
+
+#endif /* HAVE_TRUNCATED_HMAC */
+
+#ifdef HAVE_SUPPORTED_CURVES
+
+#ifndef HAVE_ECC
+#error Elliptic Curves Extension requires Elliptic Curve Cryptography. \
+       Use --enable-ecc in the configure script or define HAVE_ECC.
+#endif
+
+static void TLSX_EllipticCurve_FreeAll(EllipticCurve* list)
+{
+    EllipticCurve* curve;
+
+    while ((curve = list)) {
+        list = curve->next;
+        XFREE(curve, 0, DYNAMIC_TYPE_TLSX);
+    }
+}
+
+static int TLSX_EllipticCurve_Append(EllipticCurve** list, word16 name)
+{
+    EllipticCurve* curve;
+
+    if (list == NULL)
+        return BAD_FUNC_ARG;
+
+    if ((curve = XMALLOC(sizeof(EllipticCurve), 0, DYNAMIC_TYPE_TLSX)) == NULL)
+        return MEMORY_E;
+
+    curve->name = name;
+    curve->next = *list;
+
+    *list = curve;
+
+    return 0;
+}
+
+#ifndef NO_WOLFSSL_CLIENT
+
+static void TLSX_EllipticCurve_ValidateRequest(WOLFSSL* ssl, byte* semaphore)
+{
+    int i;
+
+    for (i = 0; i < ssl->suites->suiteSz; i+= 2)
+        if (ssl->suites->suites[i] == ECC_BYTE)
+            return;
+
+    /* No elliptic curve suite found */
+    TURN_ON(semaphore, TLSX_ToSemaphore(ELLIPTIC_CURVES));
+}
+
+static word16 TLSX_EllipticCurve_GetSize(EllipticCurve* list)
+{
+    EllipticCurve* curve;
+    word16 length = OPAQUE16_LEN; /* list length */
+
+    while ((curve = list)) {
+        list = curve->next;
+        length += OPAQUE16_LEN; /* curve length */
+    }
+
+    return length;
+}
+
+static word16 TLSX_EllipticCurve_WriteR(EllipticCurve* curve, byte* output);
+static word16 TLSX_EllipticCurve_WriteR(EllipticCurve* curve, byte* output)
+{
+    word16 offset = 0;
+
+    if (!curve)
+        return offset;
+
+    offset = TLSX_EllipticCurve_WriteR(curve->next, output);
+    c16toa(curve->name, output + offset);
+
+    return OPAQUE16_LEN + offset;
+}
+
+static word16 TLSX_EllipticCurve_Write(EllipticCurve* list, byte* output)
+{
+    word16 length = TLSX_EllipticCurve_WriteR(list, output + OPAQUE16_LEN);
+
+    c16toa(length, output); /* writing list length */
+
+    return OPAQUE16_LEN + length;
+}
+
+#endif /* NO_WOLFSSL_CLIENT */
+#ifndef NO_WOLFSSL_SERVER
+
+static int TLSX_EllipticCurve_Parse(WOLFSSL* ssl, byte* input, word16 length,
+                                                                 byte isRequest)
+{
+    word16 offset;
+    word16 name;
+    int r;
+
+    (void) isRequest; /* shut up compiler! */
+
+    if (OPAQUE16_LEN > length || length % OPAQUE16_LEN)
+        return BUFFER_ERROR;
+
+    ato16(input, &offset);
+
+    /* validating curve list length */
+    if (length != OPAQUE16_LEN + offset)
+        return BUFFER_ERROR;
+
+    while (offset) {
+        ato16(input + offset, &name);
+        offset -= OPAQUE16_LEN;
+
+        r = TLSX_UseSupportedCurve(&ssl->extensions, name);
+
+        if (r != SSL_SUCCESS) return r; /* throw error */
+    }
+
+    return 0;
+}
+
+int TLSX_ValidateEllipticCurves(WOLFSSL* ssl, byte first, byte second) {
+    TLSX*          extension = (first == ECC_BYTE)
+                             ? TLSX_Find(ssl->extensions, ELLIPTIC_CURVES)
+                             : NULL;
+    EllipticCurve* curve     = NULL;
+    word32         oid       = 0;
+    word16         octets    = 0; /* acording to 'ecc_set_type ecc_sets[];' */
+    int            sig       = 0; /* valitade signature */
+    int            key       = 0; /* validate key       */
+
+    (void)oid;
+    (void)octets;
+
+    if (!extension)
+        return 1; /* no suite restriction */
+
+    for (curve = extension->data; curve && !(sig && key); curve = curve->next) {
+
+        switch (curve->name) {
+#if defined(HAVE_ALL_CURVES) || defined(HAVE_ECC160)
+            case WOLFSSL_ECC_SECP160R1: oid = ECC_160R1; octets = 20; break;
+#endif
+#if defined(HAVE_ALL_CURVES) || defined(HAVE_ECC192)
+            case WOLFSSL_ECC_SECP192R1: oid = ECC_192R1; octets = 24; break;
+#endif
+#if defined(HAVE_ALL_CURVES) || defined(HAVE_ECC224)
+            case WOLFSSL_ECC_SECP224R1: oid = ECC_224R1; octets = 28; break;
+#endif
+#if defined(HAVE_ALL_CURVES) || !defined(NO_ECC256)
+            case WOLFSSL_ECC_SECP256R1: oid = ECC_256R1; octets = 32; break;
+#endif
+#if defined(HAVE_ALL_CURVES) || defined(HAVE_ECC384)
+            case WOLFSSL_ECC_SECP384R1: oid = ECC_384R1; octets = 48; break;
+#endif
+#if defined(HAVE_ALL_CURVES) || defined(HAVE_ECC521)
+            case WOLFSSL_ECC_SECP521R1: oid = ECC_521R1; octets = 66; break;
+#endif
+            default: continue; /* unsupported curve */
+        }
+
+        switch (second) {
+#ifndef NO_DSA
+            /* ECDHE_ECDSA */
+            case TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA:
+            case TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA:
+            case TLS_ECDHE_ECDSA_WITH_RC4_128_SHA:
+            case TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA:
+            case TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256:
+            case TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384:
+            case TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256:
+            case TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384:
+            case TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8:
+            case TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8:
+                sig |= ssl->pkCurveOID == oid;
+                key |= ssl->eccTempKeySz == octets;
+            break;
+
+            /* ECDH_ECDSA */
+            case TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA:
+            case TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA:
+            case TLS_ECDH_ECDSA_WITH_RC4_128_SHA:
+            case TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA:
+            case TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256:
+            case TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384:
+            case TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256:
+            case TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384:
+                sig |= ssl->pkCurveOID == oid;
+                key |= ssl->pkCurveOID == oid;
+            break;
+#endif
+#ifndef NO_RSA
+            /* ECDHE_RSA */
+            case TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:
+            case TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA:
+            case TLS_ECDHE_RSA_WITH_RC4_128_SHA:
+            case TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA:
+            case TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256:
+            case TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384:
+            case TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256:
+            case TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384:
+                sig = 1;
+                key |= ssl->eccTempKeySz == octets;
+            break;
+
+            /* ECDH_RSA */
+            case TLS_ECDH_RSA_WITH_AES_256_CBC_SHA:
+            case TLS_ECDH_RSA_WITH_AES_128_CBC_SHA:
+            case TLS_ECDH_RSA_WITH_RC4_128_SHA:
+            case TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA:
+            case TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256:
+            case TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384:
+            case TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256:
+            case TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384:
+                sig = 1;
+                key |= ssl->pkCurveOID == oid;
+            break;
+#endif
+            default:
+                sig = 1;
+                key = 1;
+            break;
+        }
+    }
+
+    return sig && key;
+}
+
+#endif /* NO_WOLFSSL_SERVER */
+
+int TLSX_UseSupportedCurve(TLSX** extensions, word16 name)
+{
+    TLSX*          extension = TLSX_Find(*extensions, ELLIPTIC_CURVES);
+    EllipticCurve* curve     = NULL;
+    int            ret       = 0;
+
+    if (extensions == NULL)
+        return BAD_FUNC_ARG;
+
+    if ((ret = TLSX_EllipticCurve_Append(&curve, name)) != 0)
+        return ret;
+
+    if (!extension) {
+        if ((ret = TLSX_Push(extensions, ELLIPTIC_CURVES, curve)) != 0) {
+            XFREE(curve, 0, DYNAMIC_TYPE_TLSX);
+            return ret;
+        }
+    }
+    else {
+        /* push new EllipticCurve object to extension data. */
+        curve->next = (EllipticCurve*)extension->data;
+        extension->data = (void*)curve;
+
+        /* look for another curve of the same name to remove (replacement) */
+        do {
+            if (curve->next && curve->next->name == name) {
+                EllipticCurve *next = curve->next;
+
+                curve->next = next->next;
+                XFREE(next, 0, DYNAMIC_TYPE_TLSX);
+
+                break;
+            }
+        } while ((curve = curve->next));
+    }
+
+    return SSL_SUCCESS;
+}
+
+#define EC_FREE_ALL         TLSX_EllipticCurve_FreeAll
+#define EC_VALIDATE_REQUEST TLSX_EllipticCurve_ValidateRequest
+
+#ifndef NO_WOLFSSL_CLIENT
+#define EC_GET_SIZE TLSX_EllipticCurve_GetSize
+#define EC_WRITE    TLSX_EllipticCurve_Write
+#else
+#define EC_GET_SIZE(list)         0
+#define EC_WRITE(a, b)            0
+#endif
+
+#ifndef NO_WOLFSSL_SERVER
+#define EC_PARSE TLSX_EllipticCurve_Parse
+#else
+#define EC_PARSE(a, b, c, d)      0
+#endif
+
+#else
+
+#define EC_FREE_ALL(list)
+#define EC_GET_SIZE(list)         0
+#define EC_WRITE(a, b)            0
+#define EC_PARSE(a, b, c, d)      0
+#define EC_VALIDATE_REQUEST(a, b)
+
+#endif /* HAVE_SUPPORTED_CURVES */
+
+#ifdef HAVE_SECURE_RENEGOTIATION
+
+static byte TLSX_SecureRenegotiation_GetSize(SecureRenegotiation* data,
+                                                                  int isRequest)
+{
+    byte length = OPAQUE8_LEN; /* empty info length */
+
+    if (data->enabled) {
+        /* client sends client_verify_data only */
+        length += TLS_FINISHED_SZ;
+
+        /* server also sends server_verify_data */
+        if (!isRequest)
+            length += TLS_FINISHED_SZ;
+    }
+
+    return length;
+}
+
+static word16 TLSX_SecureRenegotiation_Write(SecureRenegotiation* data,
+                                                    byte* output, int isRequest)
+{
+    word16 offset = OPAQUE8_LEN; /* RenegotiationInfo length */
+
+    if (data->enabled) {
+        /* client sends client_verify_data only */
+        XMEMCPY(output + offset, data->client_verify_data, TLS_FINISHED_SZ);
+        offset += TLS_FINISHED_SZ;
+
+        /* server also sends server_verify_data */
+        if (!isRequest) {
+            XMEMCPY(output + offset, data->server_verify_data, TLS_FINISHED_SZ);
+            offset += TLS_FINISHED_SZ;
+        }
+    }
+
+    output[0] = offset - 1;  /* info length - self */
+
+    return offset;
+}
+
+static int TLSX_SecureRenegotiation_Parse(WOLFSSL* ssl, byte* input,
+                                                  word16 length, byte isRequest)
+{
+    int ret = SECURE_RENEGOTIATION_E;
+
+    if (length >= OPAQUE8_LEN) {
+        if (ssl->secure_renegotiation == NULL) {
+        #ifndef NO_WOLFSSL_SERVER
+            if (isRequest && *input == 0) {
+                ret = 0;  /* don't reply, user didn't enable */
+            }
+        #endif
+        }
+        else if (isRequest) {
+        #ifndef NO_WOLFSSL_SERVER
+            if (*input == TLS_FINISHED_SZ) {
+                /* TODO compare client_verify_data */
+                ret = 0;
+            }
+        #endif
+        }
+        else {
+        #ifndef NO_WOLFSSL_CLIENT
+            if (!ssl->secure_renegotiation->enabled) {
+                if (*input == 0) {
+                    ssl->secure_renegotiation->enabled = 1;
+                    ret = 0;
+                }
+            }
+            else if (*input == 2 * TLS_FINISHED_SZ) {
+                /* TODO compare client_verify_data and server_verify_data */
+                ret = 0;
+            }
+        #endif
+        }
+    }
+
+    if (ret != 0) {
+        /* TODO: turn on fatal error at ssl level too */
+        SendAlert(ssl, alert_fatal, handshake_failure);
+    }
+
+    return ret;
+}
+
+int TLSX_UseSecureRenegotiation(TLSX** extensions)
+{
+    int ret = 0;
+    SecureRenegotiation* data = NULL;
+
+    data = (SecureRenegotiation*)XMALLOC(sizeof(SecureRenegotiation), NULL,
+                                                             DYNAMIC_TYPE_TLSX);
+    if (data == NULL)
+        return MEMORY_E;
+
+    XMEMSET(data, 0, sizeof(SecureRenegotiation));
+
+    ret = TLSX_Push(extensions, SECURE_RENEGOTIATION, data);
+    if (ret != 0) {
+        XFREE(data, 0, DYNAMIC_TYPE_TLSX);
+        return ret;
+    }
+
+    return SSL_SUCCESS;
+}
+
+
+#define SCR_FREE_ALL(data) XFREE(data, NULL, DYNAMIC_TYPE_TLSX)
+#define SCR_GET_SIZE       TLSX_SecureRenegotiation_GetSize
+#define SCR_WRITE          TLSX_SecureRenegotiation_Write
+#define SCR_PARSE          TLSX_SecureRenegotiation_Parse
+
+#else
+
+#define SCR_FREE_ALL(a)
+#define SCR_GET_SIZE(a, b)    0
+#define SCR_WRITE(a, b, c)    0
+#define SCR_PARSE(a, b, c, d) 0
+
+#endif /* HAVE_SECURE_RENEGOTIATION */
+
+#ifdef HAVE_SESSION_TICKET
+
+static void TLSX_SessionTicket_ValidateRequest(WOLFSSL* ssl)
+{
+    TLSX*          extension = TLSX_Find(ssl->extensions, SESSION_TICKET);
+    SessionTicket* ticket    = extension ? extension->data : NULL;
+
+    if (ticket) {
+        /* TODO validate ticket timeout here! */
+        if (ticket->lifetime == 0xfffffff) {
+            /* send empty ticket on timeout */
+            TLSX_UseSessionTicket(&ssl->extensions, NULL);
+        }
+    }
+}
+
+
+static word16 TLSX_SessionTicket_GetSize(SessionTicket* ticket, int isRequest)
+{
+    (void)isRequest;
+    return ticket ? ticket->size : 0;
+}
+
+static word16 TLSX_SessionTicket_Write(SessionTicket* ticket, byte* output,
+                                                                  int isRequest)
+{
+    word16 offset = 0; /* empty ticket */
+
+    if (isRequest && ticket) {
+        XMEMCPY(output + offset, ticket->data, ticket->size);
+        offset += ticket->size;
+    }
+
+    return offset;
+}
+
+
+static int TLSX_SessionTicket_Parse(WOLFSSL* ssl, byte* input, word16 length,
+                                                                 byte isRequest)
+{
+    int ret = 0;
+
+    if (!isRequest) {
+        /* client side */
+        if (length != 0)
+            return BUFFER_ERROR;
+
+        ssl->expect_session_ticket = 1;
+    }
+#ifndef NO_WOLFSSL_SERVER
+    else {
+        /* server side */
+        if (ssl->ctx->ticketEncCb == NULL) {
+            WOLFSSL_MSG("Client sent session ticket, server has no callback");
+            return 0;
+        }
+
+        if (length == 0) {
+            /* blank ticket */
+            ret = TLSX_UseSessionTicket(&ssl->extensions, NULL);
+            if (ret == SSL_SUCCESS) {
+                ret = 0;
+                TLSX_SetResponse(ssl, SESSION_TICKET);  /* send blank ticket */
+                ssl->options.createTicket = 1;  /* will send ticket msg */
+                ssl->options.useTicket    = 1;
+            }
+        } else {
+            /* got actual ticket from client */
+            ret = DoClientTicket(ssl, input, length);
+            if (ret == WOLFSSL_TICKET_RET_OK) {    /* use ticket to resume */
+                WOLFSSL_MSG("Using exisitng client ticket");
+                ssl->options.useTicket = 1;
+                ssl->options.resuming  = 1;
+            } else if (ret == WOLFSSL_TICKET_RET_CREATE) {
+                WOLFSSL_MSG("Using existing client ticket, creating new one");
+                ret = TLSX_UseSessionTicket(&ssl->extensions, NULL);
+                if (ret == SSL_SUCCESS) {
+                    ret = 0;
+                    TLSX_SetResponse(ssl, SESSION_TICKET);
+                                                    /* send blank ticket */
+                    ssl->options.createTicket = 1;  /* will send ticket msg */
+                    ssl->options.useTicket    = 1;
+                    ssl->options.resuming     = 1;
+                }
+            } else if (ret == WOLFSSL_TICKET_RET_REJECT) {
+                WOLFSSL_MSG("Process client ticket rejected, not using");
+                ret = 0;  /* not fatal */
+            } else if (ret == WOLFSSL_TICKET_RET_FATAL || ret < 0) {
+                WOLFSSL_MSG("Process client ticket fatal error, not using");
+            }
+        }
+    }
+#endif /* NO_WOLFSSL_SERVER */
+
+    return ret;
+}
+
+WOLFSSL_LOCAL SessionTicket* TLSX_SessionTicket_Create(word32 lifetime,
+                                                       byte* data, word16 size)
+{
+    SessionTicket* ticket = (SessionTicket*)XMALLOC(sizeof(SessionTicket),
+                                                       NULL, DYNAMIC_TYPE_TLSX);
+    if (ticket) {
+        ticket->data = (byte*)XMALLOC(size, NULL, DYNAMIC_TYPE_TLSX);
+        if (ticket->data == NULL) {
+            XFREE(ticket, NULL, DYNAMIC_TYPE_TLSX);
+            return NULL;
+        }
+
+        XMEMCPY(ticket->data, data, size);
+        ticket->size     = size;
+        ticket->lifetime = lifetime;
+    }
+
+    return ticket;
+}
+WOLFSSL_LOCAL void TLSX_SessionTicket_Free(SessionTicket* ticket)
+{
+    if (ticket) {
+        XFREE(ticket->data, NULL, DYNAMIC_TYPE_TLSX);
+        XFREE(ticket,       NULL, DYNAMIC_TYPE_TLSX);
+    }
+}
+
+int TLSX_UseSessionTicket(TLSX** extensions, SessionTicket* ticket)
+{
+    int ret = 0;
+
+    if (extensions == NULL)
+        return BAD_FUNC_ARG;
+
+    /* If the ticket is NULL, the client will request a new ticket from the
+       server. Otherwise, the client will use it in the next client hello. */
+    if ((ret = TLSX_Push(extensions, SESSION_TICKET, (void*)ticket)) != 0)
+        return ret;
+
+    return SSL_SUCCESS;
+}
+
+#define STK_VALIDATE_REQUEST TLSX_SessionTicket_ValidateRequest
+#define STK_GET_SIZE         TLSX_SessionTicket_GetSize
+#define STK_WRITE            TLSX_SessionTicket_Write
+#define STK_PARSE            TLSX_SessionTicket_Parse
+
+#else
+
+#define STK_VALIDATE_REQUEST(a)
+#define STK_GET_SIZE(a, b)      0
+#define STK_WRITE(a, b, c)      0
+#define STK_PARSE(a, b, c, d)   0
+
+#endif /* HAVE_SESSION_TICKET */
+
+
+TLSX* TLSX_Find(TLSX* list, TLSX_Type type)
+{
+    TLSX* extension = list;
+
+    while (extension && extension->type != type)
+        extension = extension->next;
+
+    return extension;
+}
+
+void TLSX_FreeAll(TLSX* list)
+{
+    TLSX* extension;
+
+    while ((extension = list)) {
+        list = extension->next;
+
+        switch (extension->type) {
+            case SERVER_NAME_INDICATION:
+                SNI_FREE_ALL((SNI*)extension->data);
+                break;
+
+            case MAX_FRAGMENT_LENGTH:
+                MFL_FREE_ALL(extension->data);
+                break;
+
+            case TRUNCATED_HMAC:
+                /* Nothing to do. */
+                break;
+
+            case ELLIPTIC_CURVES:
+                EC_FREE_ALL(extension->data);
+                break;
+
+            case SECURE_RENEGOTIATION:
+                SCR_FREE_ALL(extension->data);
+                break;
+
+            case SESSION_TICKET:
+                /* Nothing to do. */
+                break;
+        }
+
+        XFREE(extension, 0, DYNAMIC_TYPE_TLSX);
+    }
+}
+
+int TLSX_SupportExtensions(WOLFSSL* ssl) {
+    return ssl && (IsTLS(ssl) || ssl->version.major == DTLS_MAJOR);
+}
+
+static word16 TLSX_GetSize(TLSX* list, byte* semaphore, byte isRequest)
+{
+    TLSX* extension;
+    word16 length = 0;
+
+    while ((extension = list)) {
+        list = extension->next;
+
+        if (!isRequest && !extension->resp)
+            continue; /* skip! */
+
+        if (!IS_OFF(semaphore, TLSX_ToSemaphore(extension->type)))
+            continue; /* skip! */
+
+        /* type + data length */
+        length += HELLO_EXT_TYPE_SZ + OPAQUE16_LEN;
+
+        switch (extension->type) {
+            case SERVER_NAME_INDICATION:
+                if (isRequest)
+                    length += SNI_GET_SIZE(extension->data);
+                break;
+            case MAX_FRAGMENT_LENGTH:
+                length += MFL_GET_SIZE(extension->data);
+                break;
+
+            case TRUNCATED_HMAC:
+                /* empty extension. */
+                break;
+
+            case ELLIPTIC_CURVES:
+                length += EC_GET_SIZE(extension->data);
+                break;
+
+            case SECURE_RENEGOTIATION:
+                length += SCR_GET_SIZE(extension->data, isRequest);
+                break;
+
+            case SESSION_TICKET:
+                length += STK_GET_SIZE(extension->data, isRequest);
+                break;
+        }
+
+        TURN_ON(semaphore, TLSX_ToSemaphore(extension->type));
+    }
+
+    return length;
+}
+
+static word16 TLSX_Write(TLSX* list, byte* output, byte* semaphore,
+                                                                 byte isRequest)
+{
+    TLSX* extension;
+    word16 offset = 0;
+    word16 length_offset = 0;
+
+    while ((extension = list)) {
+        list = extension->next;
+
+        if (!isRequest && !extension->resp)
+            continue; /* skip! */
+
+        if (!IS_OFF(semaphore, TLSX_ToSemaphore(extension->type)))
+            continue; /* skip! */
+
+        /* extension type */
+        c16toa(extension->type, output + offset);
+        offset += HELLO_EXT_TYPE_SZ + OPAQUE16_LEN;
+        length_offset = offset;
+
+        /* extension data should be written internally */
+        switch (extension->type) {
+            case SERVER_NAME_INDICATION:
+                if (isRequest)
+                    offset += SNI_WRITE(extension->data, output + offset);
+                break;
+
+            case MAX_FRAGMENT_LENGTH:
+                offset += MFL_WRITE(extension->data, output + offset);
+                break;
+
+            case TRUNCATED_HMAC:
+                /* empty extension. */
+                break;
+
+            case ELLIPTIC_CURVES:
+                offset += EC_WRITE(extension->data, output + offset);
+                break;
+
+            case SECURE_RENEGOTIATION:
+                offset += SCR_WRITE(extension->data, output + offset,
+                                                                     isRequest);
+                break;
+
+            case SESSION_TICKET:
+                offset += STK_WRITE(extension->data, output + offset,
+                                                                     isRequest);
+                break;
+        }
+
+        /* writing extension data length */
+        c16toa(offset - length_offset, output + length_offset - OPAQUE16_LEN);
+
+        TURN_ON(semaphore, TLSX_ToSemaphore(extension->type));
+    }
+
+    return offset;
+}
+
+#ifndef NO_WOLFSSL_CLIENT
+
+word16 TLSX_GetRequestSize(WOLFSSL* ssl)
+{
+    word16 length = 0;
+
+    if (TLSX_SupportExtensions(ssl)) {
+        byte semaphore[SEMAPHORE_SIZE] = {0};
+
+        EC_VALIDATE_REQUEST(ssl, semaphore);
+        STK_VALIDATE_REQUEST(ssl);
+
+        if (ssl->extensions)
+            length += TLSX_GetSize(ssl->extensions, semaphore, 1);
+
+        if (ssl->ctx && ssl->ctx->extensions)
+            length += TLSX_GetSize(ssl->ctx->extensions, semaphore, 1);
+
+        if (IsAtLeastTLSv1_2(ssl) && ssl->suites->hashSigAlgoSz)
+            length += ssl->suites->hashSigAlgoSz + HELLO_EXT_LEN;
+    }
+
+    if (length)
+        length += OPAQUE16_LEN; /* for total length storage */
+
+    return length;
+}
+
+word16 TLSX_WriteRequest(WOLFSSL* ssl, byte* output)
+{
+    word16 offset = 0;
+
+    if (TLSX_SupportExtensions(ssl) && output) {
+        byte semaphore[SEMAPHORE_SIZE] = {0};
+
+        offset += OPAQUE16_LEN; /* extensions length */
+
+        EC_VALIDATE_REQUEST(ssl, semaphore);
+
+        if (ssl->extensions)
+            offset += TLSX_Write(ssl->extensions, output + offset,
+                                                                  semaphore, 1);
+
+        if (ssl->ctx && ssl->ctx->extensions)
+            offset += TLSX_Write(ssl->ctx->extensions, output + offset,
+                                                                  semaphore, 1);
+
+        if (IsAtLeastTLSv1_2(ssl) && ssl->suites->hashSigAlgoSz)
+        {
+            int i;
+            /* extension type */
+            c16toa(HELLO_EXT_SIG_ALGO, output + offset);
+            offset += HELLO_EXT_TYPE_SZ;
+
+            /* extension data length */
+            c16toa(OPAQUE16_LEN + ssl->suites->hashSigAlgoSz, output + offset);
+            offset += OPAQUE16_LEN;
+
+            /* sig algos length */
+            c16toa(ssl->suites->hashSigAlgoSz, output + offset);
+            offset += OPAQUE16_LEN;
+
+            /* sig algos */
+            for (i = 0; i < ssl->suites->hashSigAlgoSz; i++, offset++)
+                output[offset] = ssl->suites->hashSigAlgo[i];
+        }
+
+        if (offset > OPAQUE16_LEN)
+            c16toa(offset - OPAQUE16_LEN, output); /* extensions length */
+    }
+
+    return offset;
+}
+
+#endif /* NO_WOLFSSL_CLIENT */
+
+#ifndef NO_WOLFSSL_SERVER
+
+word16 TLSX_GetResponseSize(WOLFSSL* ssl)
+{
+    word16 length = 0;
+    byte semaphore[SEMAPHORE_SIZE] = {0};
+
+    if (TLSX_SupportExtensions(ssl))
+        length += TLSX_GetSize(ssl->extensions, semaphore, 0);
+
+    /* All the response data is set at the ssl object only, so no ctx here. */
+
+    if (length)
+        length += OPAQUE16_LEN; /* for total length storage */
+
+    return length;
+}
+
+word16 TLSX_WriteResponse(WOLFSSL *ssl, byte* output)
+{
+    word16 offset = 0;
+
+    if (TLSX_SupportExtensions(ssl) && output) {
+        byte semaphore[SEMAPHORE_SIZE] = {0};
+
+        offset += OPAQUE16_LEN; /* extensions length */
+
+        offset += TLSX_Write(ssl->extensions, output + offset, semaphore, 0);
+
+        if (offset > OPAQUE16_LEN)
+            c16toa(offset - OPAQUE16_LEN, output); /* extensions length */
+    }
+
+    return offset;
+}
+
+#endif /* NO_WOLFSSL_SERVER */
+
+int TLSX_Parse(WOLFSSL* ssl, byte* input, word16 length, byte isRequest,
+                                                                 Suites *suites)
+{
+    int ret = 0;
+    word16 offset = 0;
+
+    if (!ssl || !input || (isRequest && !suites))
+        return BAD_FUNC_ARG;
+
+    while (ret == 0 && offset < length) {
+        word16 type;
+        word16 size;
+
+        if (length - offset < HELLO_EXT_TYPE_SZ + OPAQUE16_LEN)
+            return BUFFER_ERROR;
+
+        ato16(input + offset, &type);
+        offset += HELLO_EXT_TYPE_SZ;
+
+        ato16(input + offset, &size);
+        offset += OPAQUE16_LEN;
+
+        if (offset + size > length)
+            return BUFFER_ERROR;
+
+        switch (type) {
+            case SERVER_NAME_INDICATION:
+                WOLFSSL_MSG("SNI extension received");
+
+                ret = SNI_PARSE(ssl, input + offset, size, isRequest);
+                break;
+
+            case MAX_FRAGMENT_LENGTH:
+                WOLFSSL_MSG("Max Fragment Length extension received");
+
+                ret = MFL_PARSE(ssl, input + offset, size, isRequest);
+                break;
+
+            case TRUNCATED_HMAC:
+                WOLFSSL_MSG("Truncated HMAC extension received");
+
+                ret = THM_PARSE(ssl, input + offset, size, isRequest);
+                break;
+
+            case ELLIPTIC_CURVES:
+                WOLFSSL_MSG("Elliptic Curves extension received");
+
+                ret = EC_PARSE(ssl, input + offset, size, isRequest);
+                break;
+
+            case SECURE_RENEGOTIATION:
+                WOLFSSL_MSG("Secure Renegotiation extension received");
+
+                ret = SCR_PARSE(ssl, input + offset, size, isRequest);
+                break;
+
+            case SESSION_TICKET:
+                WOLFSSL_MSG("Session Ticket extension received");
+
+                ret = STK_PARSE(ssl, input + offset, size, isRequest);
+                break;
+
+            case HELLO_EXT_SIG_ALGO:
+                if (isRequest) {
+                    /* do not mess with offset inside the switch! */
+                    if (IsAtLeastTLSv1_2(ssl)) {
+                        ato16(input + offset, &suites->hashSigAlgoSz);
+
+                        if (suites->hashSigAlgoSz > size - OPAQUE16_LEN)
+                            return BUFFER_ERROR;
+
+                        XMEMCPY(suites->hashSigAlgo,
+                                input + offset + OPAQUE16_LEN,
+                                min(suites->hashSigAlgoSz,
+                                                        HELLO_EXT_SIGALGO_MAX));
+                    }
+                } else {
+                    WOLFSSL_MSG("Servers MUST NOT send SIG ALGO extension.");
+                }
+
+                break;
+        }
+
+        /* offset should be updated here! */
+        offset += size;
+    }
+
+    return ret;
+}
+
+/* undefining semaphore macros */
+#undef IS_OFF
+#undef TURN_ON
+#undef SEMAPHORE_SIZE
+
+#endif
+
+
+#ifndef NO_WOLFSSL_CLIENT
+
+#ifndef NO_OLD_TLS
+
+    WOLFSSL_METHOD* wolfTLSv1_client_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                             (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                      DYNAMIC_TYPE_METHOD);
+        if (method)
+            InitSSL_Method(method, MakeTLSv1());
+        return method;
+    }
+
+
+    WOLFSSL_METHOD* wolfTLSv1_1_client_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                              (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                       DYNAMIC_TYPE_METHOD);
+        if (method)
+            InitSSL_Method(method, MakeTLSv1_1());
+        return method;
+    }
+
+#endif /* !NO_OLD_TLS */
+
+#ifndef NO_SHA256   /* can't use without SHA256 */
+
+    WOLFSSL_METHOD* wolfTLSv1_2_client_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                              (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                       DYNAMIC_TYPE_METHOD);
+        if (method)
+            InitSSL_Method(method, MakeTLSv1_2());
+        return method;
+    }
+
+#endif
+
+
+    WOLFSSL_METHOD* wolfSSLv23_client_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                              (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                       DYNAMIC_TYPE_METHOD);
+        if (method) {
+#ifndef NO_SHA256         /* 1.2 requires SHA256 */
+            InitSSL_Method(method, MakeTLSv1_2());
+#else
+            InitSSL_Method(method, MakeTLSv1_1());
+#endif
+#ifndef NO_OLD_TLS
+            method->downgrade = 1;
+#endif
+        }
+        return method;
+    }
+
+
+#endif /* NO_WOLFSSL_CLIENT */
+
+
+
+#ifndef NO_WOLFSSL_SERVER
+
+#ifndef NO_OLD_TLS
+
+    WOLFSSL_METHOD* wolfTLSv1_server_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                              (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                       DYNAMIC_TYPE_METHOD);
+        if (method) {
+            InitSSL_Method(method, MakeTLSv1());
+            method->side = WOLFSSL_SERVER_END;
+        }
+        return method;
+    }
+
+
+    WOLFSSL_METHOD* wolfTLSv1_1_server_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                              (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                       DYNAMIC_TYPE_METHOD);
+        if (method) {
+            InitSSL_Method(method, MakeTLSv1_1());
+            method->side = WOLFSSL_SERVER_END;
+        }
+        return method;
+    }
+
+#endif /* !NO_OLD_TLS */
+
+#ifndef NO_SHA256   /* can't use without SHA256 */
+
+    WOLFSSL_METHOD* wolfTLSv1_2_server_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                              (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                       DYNAMIC_TYPE_METHOD);
+        if (method) {
+            InitSSL_Method(method, MakeTLSv1_2());
+            method->side = WOLFSSL_SERVER_END;
+        }
+        return method;
+    }
+
+#endif
+
+
+    WOLFSSL_METHOD* wolfSSLv23_server_method(void)
+    {
+        WOLFSSL_METHOD* method =
+                              (WOLFSSL_METHOD*) XMALLOC(sizeof(WOLFSSL_METHOD), 0,
+                                                       DYNAMIC_TYPE_METHOD);
+        if (method) {
+#ifndef NO_SHA256         /* 1.2 requires SHA256 */
+            InitSSL_Method(method, MakeTLSv1_2());
+#else
+            InitSSL_Method(method, MakeTLSv1_1());
+#endif
+            method->side      = WOLFSSL_SERVER_END;
+#ifndef NO_OLD_TLS
+            method->downgrade = 1;
+#endif /* !NO_OLD_TLS */
+        }
+        return method;
+    }
+
+
+
+#endif /* NO_WOLFSSL_SERVER */
+#endif /* NO_TLS */
+
+