library/debug.c

/*
 *  Debugging routines
 *
 *  Copyright The Mbed TLS Contributors
 *  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.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include "common.h"

#if defined(MBEDTLS_DEBUG_C)

#include "mbedtls/platform.h"

#include "mbedtls/debug.h"
#include "mbedtls/error.h"

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

#define DEBUG_BUF_SIZE      512

static int debug_threshold = 0;

void mbedtls_debug_set_threshold( int threshold )
{
    debug_threshold = threshold;
}

/*
 * All calls to f_dbg must be made via this function
 */
static inline void debug_send_line( const mbedtls_ssl_context *ssl, int level,
                                    const char *file, int line,
                                    const char *str )
{
    /*
     * If in a threaded environment, we need a thread identifier.
     * Since there is no portable way to get one, use the address of the ssl
     * context instead, as it shouldn't be shared between threads.
     */
#if defined(MBEDTLS_THREADING_C)
    char idstr[20 + DEBUG_BUF_SIZE]; /* 0x + 16 nibbles + ': ' */
    mbedtls_snprintf( idstr, sizeof( idstr ), "%p: %s", (void*)ssl, str );
    ssl->conf->f_dbg( ssl->conf->p_dbg, level, file, line, idstr );
#else
    ssl->conf->f_dbg( ssl->conf->p_dbg, level, file, line, str );
#endif
}

MBEDTLS_PRINTF_ATTRIBUTE(5, 6)
void mbedtls_debug_print_msg( const mbedtls_ssl_context *ssl, int level,
                              const char *file, int line,
                              const char *format, ... )
{
    va_list argp;
    char str[DEBUG_BUF_SIZE];
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    if( NULL == ssl              ||
        NULL == ssl->conf        ||
        NULL == ssl->conf->f_dbg ||
        level > debug_threshold )
    {
        return;
    }

    va_start( argp, format );
    ret = mbedtls_vsnprintf( str, DEBUG_BUF_SIZE, format, argp );
    va_end( argp );

    if( ret >= 0 && ret < DEBUG_BUF_SIZE - 1 )
    {
        str[ret]     = '\n';
        str[ret + 1] = '\0';
    }

    debug_send_line( ssl, level, file, line, str );
}

void mbedtls_debug_print_ret( const mbedtls_ssl_context *ssl, int level,
                      const char *file, int line,
                      const char *text, int ret )
{
    char str[DEBUG_BUF_SIZE];

    if( NULL == ssl              ||
        NULL == ssl->conf        ||
        NULL == ssl->conf->f_dbg ||
        level > debug_threshold )
    {
        return;
    }

    /*
     * With non-blocking I/O and examples that just retry immediately,
     * the logs would be quickly flooded with WANT_READ, so ignore that.
     * Don't ignore WANT_WRITE however, since it is usually rare.
     */
    if( ret == MBEDTLS_ERR_SSL_WANT_READ )
        return;

    mbedtls_snprintf( str, sizeof( str ), "%s() returned %d (-0x%04x)\n",
              text, ret, (unsigned int) -ret );

    debug_send_line( ssl, level, file, line, str );
}

void mbedtls_debug_print_buf( const mbedtls_ssl_context *ssl, int level,
                      const char *file, int line, const char *text,
                      const unsigned char *buf, size_t len )
{
    char str[DEBUG_BUF_SIZE];
    char txt[17];
    size_t i, idx = 0;

    if( NULL == ssl              ||
        NULL == ssl->conf        ||
        NULL == ssl->conf->f_dbg ||
        level > debug_threshold )
    {
        return;
    }

    mbedtls_snprintf( str + idx, sizeof( str ) - idx, "dumping '%s' (%u bytes)\n",
              text, (unsigned int) len );

    debug_send_line( ssl, level, file, line, str );

    idx = 0;
    memset( txt, 0, sizeof( txt ) );
    for( i = 0; i < len; i++ )
    {
        if( i >= 4096 )
            break;

        if( i % 16 == 0 )
        {
            if( i > 0 )
            {
                mbedtls_snprintf( str + idx, sizeof( str ) - idx, "  %s\n", txt );
                debug_send_line( ssl, level, file, line, str );

                idx = 0;
                memset( txt, 0, sizeof( txt ) );
            }

            idx += mbedtls_snprintf( str + idx, sizeof( str ) - idx, "%04x: ",
                             (unsigned int) i );

        }

        idx += mbedtls_snprintf( str + idx, sizeof( str ) - idx, " %02x",
                         (unsigned int) buf[i] );
        txt[i % 16] = ( buf[i] > 31 && buf[i] < 127 ) ? buf[i] : '.' ;
    }

    if( len > 0 )
    {
        for( /* i = i */; i % 16 != 0; i++ )
            idx += mbedtls_snprintf( str + idx, sizeof( str ) - idx, "   " );

        mbedtls_snprintf( str + idx, sizeof( str ) - idx, "  %s\n", txt );
        debug_send_line( ssl, level, file, line, str );
    }
}

#if defined(MBEDTLS_ECP_C)
void mbedtls_debug_print_ecp( const mbedtls_ssl_context *ssl, int level,
                      const char *file, int line,
                      const char *text, const mbedtls_ecp_point *X )
{
    char str[DEBUG_BUF_SIZE];

    if( NULL == ssl              ||
        NULL == ssl->conf        ||
        NULL == ssl->conf->f_dbg ||
        level > debug_threshold )
    {
        return;
    }

    mbedtls_snprintf( str, sizeof( str ), "%s(X)", text );
    mbedtls_debug_print_mpi( ssl, level, file, line, str, &X->X );

    mbedtls_snprintf( str, sizeof( str ), "%s(Y)", text );
    mbedtls_debug_print_mpi( ssl, level, file, line, str, &X->Y );
}
#endif /* MBEDTLS_ECP_C */

#if defined(MBEDTLS_BIGNUM_C)
void mbedtls_debug_print_mpi( const mbedtls_ssl_context *ssl, int level,
                      const char *file, int line,
                      const char *text, const mbedtls_mpi *X )
{
    char str[DEBUG_BUF_SIZE];
    size_t bitlen;
    size_t idx = 0;

    if( NULL == ssl              ||
        NULL == ssl->conf        ||
        NULL == ssl->conf->f_dbg ||
        NULL == X                ||
        level > debug_threshold )
    {
        return;
    }

    bitlen = mbedtls_mpi_bitlen( X );

    mbedtls_snprintf( str, sizeof( str ), "value of '%s' (%u bits) is:\n",
                      text, (unsigned) bitlen );
    debug_send_line( ssl, level, file, line, str );

    if( bitlen == 0 )
    {
        str[0] = ' '; str[1] = '0'; str[2] = '0';
        idx = 3;
    }
    else
    {
        int n;
        for( n = (int) ( ( bitlen - 1 ) / 8 ); n >= 0; n-- )
        {
            size_t limb_offset = n / sizeof( mbedtls_mpi_uint );
            size_t offset_in_limb = n % sizeof( mbedtls_mpi_uint );
            unsigned char octet =
                ( X->p[limb_offset] >> ( offset_in_limb * 8 ) ) & 0xff;
            mbedtls_snprintf( str + idx, sizeof( str ) - idx, " %02x", octet );
            idx += 3;
            /* Wrap lines after 16 octets that each take 3 columns */
            if( idx >= 3 * 16 )
            {
                mbedtls_snprintf( str + idx, sizeof( str ) - idx, "\n" );
                debug_send_line( ssl, level, file, line, str );
                idx = 0;
            }
        }
    }

    if( idx != 0 )
    {
        mbedtls_snprintf( str + idx, sizeof( str ) - idx, "\n" );
        debug_send_line( ssl, level, file, line, str );
    }
}
#endif /* MBEDTLS_BIGNUM_C */

#if defined(MBEDTLS_X509_CRT_PARSE_C) && !defined(MBEDTLS_X509_REMOVE_INFO)
static void debug_print_pk( const mbedtls_ssl_context *ssl, int level,
                            const char *file, int line,
                            const char *text, const mbedtls_pk_context *pk )
{
    size_t i;
    mbedtls_pk_debug_item items[MBEDTLS_PK_DEBUG_MAX_ITEMS];
    char name[16];

    memset( items, 0, sizeof( items ) );

    if( mbedtls_pk_debug( pk, items ) != 0 )
    {
        debug_send_line( ssl, level, file, line,
                          "invalid PK context\n" );
        return;
    }

    for( i = 0; i < MBEDTLS_PK_DEBUG_MAX_ITEMS; i++ )
    {
        if( items[i].type == MBEDTLS_PK_DEBUG_NONE )
            return;

        mbedtls_snprintf( name, sizeof( name ), "%s%s", text, items[i].name );
        name[sizeof( name ) - 1] = '\0';

        if( items[i].type == MBEDTLS_PK_DEBUG_MPI )
            mbedtls_debug_print_mpi( ssl, level, file, line, name, items[i].value );
        else
#if defined(MBEDTLS_ECP_C)
        if( items[i].type == MBEDTLS_PK_DEBUG_ECP )
            mbedtls_debug_print_ecp( ssl, level, file, line, name, items[i].value );
        else
#endif
            debug_send_line( ssl, level, file, line,
                              "should not happen\n" );
    }
}

static void debug_print_line_by_line( const mbedtls_ssl_context *ssl, int level,
                                      const char *file, int line, const char *text )
{
    char str[DEBUG_BUF_SIZE];
    const char *start, *cur;

    start = text;
    for( cur = text; *cur != '\0'; cur++ )
    {
        if( *cur == '\n' )
        {
            size_t len = cur - start + 1;
            if( len > DEBUG_BUF_SIZE - 1 )
                len = DEBUG_BUF_SIZE - 1;

            memcpy( str, start, len );
            str[len] = '\0';

            debug_send_line( ssl, level, file, line, str );

            start = cur + 1;
        }
    }
}

void mbedtls_debug_print_crt( const mbedtls_ssl_context *ssl, int level,
                      const char *file, int line,
                      const char *text, const mbedtls_x509_crt *crt )
{
    char str[DEBUG_BUF_SIZE];
    int i = 0;

    if( NULL == ssl              ||
        NULL == ssl->conf        ||
        NULL == ssl->conf->f_dbg ||
        NULL == crt              ||
        level > debug_threshold )
    {
        return;
    }

    while( crt != NULL )
    {
        char buf[1024];

        mbedtls_snprintf( str, sizeof( str ), "%s #%d:\n", text, ++i );
        debug_send_line( ssl, level, file, line, str );

        mbedtls_x509_crt_info( buf, sizeof( buf ) - 1, "", crt );
        debug_print_line_by_line( ssl, level, file, line, buf );

        debug_print_pk( ssl, level, file, line, "crt->", &crt->pk );

        crt = crt->next;
    }
}
#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_X509_REMOVE_INFO */

#if defined(MBEDTLS_ECDH_C)
static void mbedtls_debug_printf_ecdh_internal( const mbedtls_ssl_context *ssl,
                                                int level, const char *file,
                                                int line,
                                                const mbedtls_ecdh_context *ecdh,
                                                mbedtls_debug_ecdh_attr attr )
{
#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
    const mbedtls_ecdh_context* ctx = ecdh;
#else
    const mbedtls_ecdh_context_mbed* ctx = &ecdh->ctx.mbed_ecdh;
#endif

    switch( attr )
    {
        case MBEDTLS_DEBUG_ECDH_Q:
            mbedtls_debug_print_ecp( ssl, level, file, line, "ECDH: Q",
                                     &ctx->Q );
            break;
        case MBEDTLS_DEBUG_ECDH_QP:
            mbedtls_debug_print_ecp( ssl, level, file, line, "ECDH: Qp",
                                     &ctx->Qp );
            break;
        case MBEDTLS_DEBUG_ECDH_Z:
            mbedtls_debug_print_mpi( ssl, level, file, line, "ECDH: z",
                                     &ctx->z );
            break;
        default:
            break;
    }
}

void mbedtls_debug_printf_ecdh( const mbedtls_ssl_context *ssl, int level,
                                const char *file, int line,
                                const mbedtls_ecdh_context *ecdh,
                                mbedtls_debug_ecdh_attr attr )
{
#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
    mbedtls_debug_printf_ecdh_internal( ssl, level, file, line, ecdh, attr );
#else
    switch( ecdh->var )
    {
        default:
            mbedtls_debug_printf_ecdh_internal( ssl, level, file, line, ecdh,
                                                attr );
    }
#endif
}
#endif /* MBEDTLS_ECDH_C */

#endif /* MBEDTLS_DEBUG_C */