generic_sum.c

/*
 *  generic message digest layer demonstration program
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

#include "mbedtls/build_info.h"

#include "mbedtls/platform.h"

#if defined(MBEDTLS_MD_C) && defined(MBEDTLS_FS_IO)
#include "mbedtls/md.h"

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

#if !defined(MBEDTLS_MD_C) || !defined(MBEDTLS_FS_IO)
int main(void)
{
    mbedtls_printf("MBEDTLS_MD_C and/or MBEDTLS_FS_IO not defined.\n");
    mbedtls_exit(0);
}
#else


static int generic_wrapper(const mbedtls_md_info_t *md_info, char *filename, unsigned char *sum)
{
    int ret = mbedtls_md_file(md_info, filename, sum);

    if (ret == 1) {
        mbedtls_fprintf(stderr, "failed to open: %s\n", filename);
    }

    if (ret == 2) {
        mbedtls_fprintf(stderr, "failed to read: %s\n", filename);
    }

    return ret;
}

static int generic_print(const mbedtls_md_info_t *md_info, char *filename)
{
    int i;
    unsigned char sum[MBEDTLS_MD_MAX_SIZE];

    if (generic_wrapper(md_info, filename, sum) != 0) {
        return 1;
    }

    for (i = 0; i < mbedtls_md_get_size(md_info); i++) {
        mbedtls_printf("%02x", sum[i]);
    }

    mbedtls_printf("  %s\n", filename);
    return 0;
}

static int generic_check(const mbedtls_md_info_t *md_info, char *filename)
{
    int i;
    size_t n;
    FILE *f;
    int nb_err1, nb_err2;
    int nb_tot1, nb_tot2;
    unsigned char sum[MBEDTLS_MD_MAX_SIZE];
    char line[1024];
    char diff;
#if defined(__clang_analyzer__)
    char buf[MBEDTLS_MD_MAX_SIZE * 2 + 1] = { };
#else
    char buf[MBEDTLS_MD_MAX_SIZE * 2 + 1];
#endif

    if ((f = fopen(filename, "rb")) == NULL) {
        mbedtls_printf("failed to open: %s\n", filename);
        return 1;
    }

    nb_err1 = nb_err2 = 0;
    nb_tot1 = nb_tot2 = 0;

    memset(line, 0, sizeof(line));

    n = sizeof(line);

    while (fgets(line, (int) n - 1, f) != NULL) {
        n = strlen(line);

        if (n < (size_t) 2 * mbedtls_md_get_size(md_info) + 4) {
            mbedtls_printf("No '%s' hash found on line.\n", mbedtls_md_get_name(md_info));
            continue;
        }

        if (line[2 * mbedtls_md_get_size(md_info)] != ' ' ||
            line[2 * mbedtls_md_get_size(md_info) + 1] != ' ') {
            mbedtls_printf("No '%s' hash found on line.\n", mbedtls_md_get_name(md_info));
            continue;
        }

        if (line[n - 1] == '\n') {
            n--; line[n] = '\0';
        }
        if (line[n - 1] == '\r') {
            n--; line[n] = '\0';
        }

        nb_tot1++;

        if (generic_wrapper(md_info, line + 2 + 2 * mbedtls_md_get_size(md_info), sum) != 0) {
            nb_err1++;
            continue;
        }

        nb_tot2++;

        for (i = 0; i < mbedtls_md_get_size(md_info); i++) {
            sprintf(buf + i * 2, "%02x", sum[i]);
        }

        /* Use constant-time buffer comparison */
        diff = 0;
        for (i = 0; i < 2 * mbedtls_md_get_size(md_info); i++) {
            diff |= line[i] ^ buf[i];
        }

        if (diff != 0) {
            nb_err2++;
            mbedtls_fprintf(stderr, "wrong checksum: %s\n", line + 66);
        }

        n = sizeof(line);
    }

    if (nb_err1 != 0) {
        mbedtls_printf("WARNING: %d (out of %d) input files could "
                       "not be read\n", nb_err1, nb_tot1);
    }

    if (nb_err2 != 0) {
        mbedtls_printf("WARNING: %d (out of %d) computed checksums did "
                       "not match\n", nb_err2, nb_tot2);
    }

    fclose(f);

    return nb_err1 != 0 || nb_err2 != 0;
}

int main(int argc, char *argv[])
{
    int ret = 1, i;
    int exit_code = MBEDTLS_EXIT_FAILURE;
    const mbedtls_md_info_t *md_info;
    mbedtls_md_context_t md_ctx;

    mbedtls_md_init(&md_ctx);

    if (argc < 2) {
        const int *list;

        mbedtls_printf("print mode:  generic_sum <mbedtls_md> <file> <file> ...\n");
        mbedtls_printf("check mode:  generic_sum <mbedtls_md> -c <checksum file>\n");

        mbedtls_printf("\nAvailable message digests:\n");
        list = mbedtls_md_list();
        while (*list) {
            md_info = mbedtls_md_info_from_type(*list);
            mbedtls_printf("  %s\n", mbedtls_md_get_name(md_info));
            list++;
        }

        mbedtls_exit(exit_code);
    }

    /*
     * Read the MD from the command line
     */
    md_info = mbedtls_md_info_from_string(argv[1]);
    if (md_info == NULL) {
        mbedtls_fprintf(stderr, "Message Digest '%s' not found\n", argv[1]);
        mbedtls_exit(exit_code);
    }
    if (mbedtls_md_setup(&md_ctx, md_info, 0)) {
        mbedtls_fprintf(stderr, "Failed to initialize context.\n");
        mbedtls_exit(exit_code);
    }

    ret = 0;
    if (argc == 4 && strcmp("-c", argv[2]) == 0) {
        ret |= generic_check(md_info, argv[3]);
        goto exit;
    }

    for (i = 2; i < argc; i++) {
        ret |= generic_print(md_info, argv[i]);
    }

    if (ret == 0) {
        exit_code = MBEDTLS_EXIT_SUCCESS;
    }

exit:
    mbedtls_md_free(&md_ctx);

    mbedtls_exit(exit_code);
}
#endif /* MBEDTLS_MD_C && MBEDTLS_FS_IO */