Import mbedtls-2.16.0

Imports mbedTLS 2.16.0 from https://github.com/ARMmbed/mbedtls.git
commit fb1972db23da ("Merge pull request #544 from ARMmbed/version-2.16")
(tag mbedtls-2.16.0).

Certain files will never be needed and are thus removed (reducing number
of lines to almost 50%):
rm -f circle.yml CMakeLists.txt DartConfiguration.tcl Makefile
rm -f .gitignore .travis.yml .pylint
rm -f include/.gitignore include/CMakeLists.txt library/.gitignore
rm -f library/CMakeLists.txt library/Makefile
rm -rf .git .github doxygen configs programs scripts tests visualc yotta

This is a complete overwrite of previous code so earlier changes in the
branch import/mbedtls-2.6.1 will be added on top of this commit to bring
the changes forward.

Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/x509write_crt.c b/lib/libmbedtls/mbedtls/library/x509write_crt.c
index 92e18fe..b1ef216 100644
--- a/lib/libmbedtls/mbedtls/library/x509write_crt.c
+++ b/lib/libmbedtls/mbedtls/library/x509write_crt.c
@@ -1,8 +1,8 @@
-// SPDX-License-Identifier: Apache-2.0
 /*
  *  X.509 certificate writing
  *
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
  *  not use this file except in compliance with the License.
@@ -37,6 +37,7 @@
 #include "mbedtls/oid.h"
 #include "mbedtls/asn1write.h"
 #include "mbedtls/sha1.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -44,14 +45,9 @@
 #include "mbedtls/pem.h"
 #endif /* MBEDTLS_PEM_WRITE_C */
 
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
-}
-
 void mbedtls_x509write_crt_init( mbedtls_x509write_cert *ctx )
 {
-    memset( ctx, 0, sizeof(mbedtls_x509write_cert) );
+    memset( ctx, 0, sizeof( mbedtls_x509write_cert ) );
 
     mbedtls_mpi_init( &ctx->serial );
     ctx->version = MBEDTLS_X509_CRT_VERSION_3;
@@ -65,7 +61,7 @@
     mbedtls_asn1_free_named_data_list( &ctx->issuer );
     mbedtls_asn1_free_named_data_list( &ctx->extensions );
 
-    mbedtls_zeroize( ctx, sizeof(mbedtls_x509write_cert) );
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_cert ) );
 }
 
 void mbedtls_x509write_crt_set_version( mbedtls_x509write_cert *ctx, int version )
@@ -177,8 +173,11 @@
     memset( buf, 0, sizeof(buf) );
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, ctx->subject_key ) );
 
-    mbedtls_sha1( buf + sizeof(buf) - len, len, buf + sizeof(buf) - 20 );
-    c = buf + sizeof(buf) - 20;
+    ret = mbedtls_sha1_ret( buf + sizeof( buf ) - len, len,
+                            buf + sizeof( buf ) - 20 );
+    if( ret != 0 )
+        return( ret );
+    c = buf + sizeof( buf ) - 20;
     len = 20;
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
@@ -193,14 +192,17 @@
 {
     int ret;
     unsigned char buf[MBEDTLS_MPI_MAX_SIZE * 2 + 20]; /* tag, length + 2xMPI */
-    unsigned char *c = buf + sizeof(buf);
+    unsigned char *c = buf + sizeof( buf );
     size_t len = 0;
 
     memset( buf, 0, sizeof(buf) );
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, ctx->issuer_key ) );
 
-    mbedtls_sha1( buf + sizeof(buf) - len, len, buf + sizeof(buf) - 20 );
-    c = buf + sizeof(buf) - 20;
+    ret = mbedtls_sha1_ret( buf + sizeof( buf ) - len, len,
+                            buf + sizeof( buf ) - 20 );
+    if( ret != 0 )
+        return( ret );
+    c = buf + sizeof( buf ) - 20;
     len = 20;
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
@@ -212,7 +214,7 @@
 
     return mbedtls_x509write_crt_set_extension( ctx, MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER,
                                    MBEDTLS_OID_SIZE( MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER ),
-                                   0, buf + sizeof(buf) - len, len );
+                                   0, buf + sizeof( buf ) - len, len );
 }
 #endif /* MBEDTLS_SHA1_C */
 
@@ -313,12 +315,18 @@
     c = tmp_buf + sizeof( tmp_buf );
 
     /* Signature algorithm needed in TBS, and later for actual signature */
-    pk_alg = mbedtls_pk_get_type( ctx->issuer_key );
-    if( pk_alg == MBEDTLS_PK_ECKEY )
+
+    /* There's no direct way of extracting a signature algorithm
+     * (represented as an element of mbedtls_pk_type_t) from a PK instance. */
+    if( mbedtls_pk_can_do( ctx->issuer_key, MBEDTLS_PK_RSA ) )
+        pk_alg = MBEDTLS_PK_RSA;
+    else if( mbedtls_pk_can_do( ctx->issuer_key, MBEDTLS_PK_ECDSA ) )
         pk_alg = MBEDTLS_PK_ECDSA;
+    else
+        return( MBEDTLS_ERR_X509_INVALID_ALG );
 
     if( ( ret = mbedtls_oid_get_oid_by_sig_alg( pk_alg, ctx->md_alg,
-                                        &sig_oid, &sig_oid_len ) ) != 0 )
+                                          &sig_oid, &sig_oid_len ) ) != 0 )
     {
         return( ret );
     }
@@ -326,13 +334,18 @@
     /*
      *  Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension
      */
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, tmp_buf, ctx->extensions ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
-                                                    MBEDTLS_ASN1_SEQUENCE ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
-                                                    MBEDTLS_ASN1_CONSTRUCTED | 3 ) );
+
+    /* Only for v3 */
+    if( ctx->version == MBEDTLS_X509_CRT_VERSION_3 )
+    {
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, tmp_buf, ctx->extensions ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
+                                                           MBEDTLS_ASN1_SEQUENCE ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
+                                                           MBEDTLS_ASN1_CONSTRUCTED | 3 ) );
+    }
 
     /*
      *  SubjectPublicKeyInfo
@@ -384,21 +397,30 @@
     /*
      *  Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
      */
-    sub_len = 0;
-    MBEDTLS_ASN1_CHK_ADD( sub_len, mbedtls_asn1_write_int( &c, tmp_buf, ctx->version ) );
-    len += sub_len;
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, sub_len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
-                                                    MBEDTLS_ASN1_CONSTRUCTED | 0 ) );
+
+    /* Can be omitted for v1 */
+    if( ctx->version != MBEDTLS_X509_CRT_VERSION_1 )
+    {
+        sub_len = 0;
+        MBEDTLS_ASN1_CHK_ADD( sub_len, mbedtls_asn1_write_int( &c, tmp_buf, ctx->version ) );
+        len += sub_len;
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, sub_len ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
+                                                           MBEDTLS_ASN1_CONSTRUCTED | 0 ) );
+    }
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
-                                                    MBEDTLS_ASN1_SEQUENCE ) );
+                                                       MBEDTLS_ASN1_SEQUENCE ) );
 
     /*
      * Make signature
      */
-    mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash );
+    if( ( ret = mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c,
+                            len, hash ) ) != 0 )
+    {
+        return( ret );
+    }
 
     if( ( ret = mbedtls_pk_sign( ctx->issuer_key, ctx->md_alg, hash, 0, sig, &sig_len,
                          f_rng, p_rng ) ) != 0 )