/*
 * Copyright (C) 2011-2012 ANSSI
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * \author Pierre Chifflier <pierre.chifflier@ssi.gouv.fr>
 *
 */

#include "suricata-common.h"

#include "util-decode-der.h"
#include "util-decode-der-get.h"

static const uint8_t SEQ_IDX_ISSUER[] = { 0, 2 };
static const uint8_t SEQ_IDX_SUBJECT[] = { 0, 4 };

static const char *Oid2ShortStr(const char *oid)
{
    if (strcmp(oid, "1.2.840.113549.1.9.1")==0)
        return "emailAddress";

    if (strcmp(oid, "2.5.4.3")==0)
        return "CN";

    if (strcmp(oid, "2.5.4.5")==0)
        return "serialNumber";

    if (strcmp(oid, "2.5.4.6")==0)
        return "C";

    if (strcmp(oid, "2.5.4.7")==0)
        return "L";

    if (strcmp(oid, "2.5.4.8")==0)
        return "ST";

    if (strcmp(oid, "2.5.4.10")==0)
        return "O";

    if (strcmp(oid, "2.5.4.11")==0)
        return "OU";

    if (strcmp(oid, "0.9.2342.19200300.100.1.25")==0)
        return "DC";

    return "unknown";
}

/**
 * \brief Iterate through an ASN.1 structure, following the index sequence.
 *        Context specific elements are skipped.
 *
 * \retval The matching node, or NULL
 */
const Asn1Generic * Asn1DerGet(const Asn1Generic *top, const uint8_t *seq_index, const uint32_t seqsz, uint32_t *errcode)
{
    const Asn1Generic * node;
    uint8_t idx, i;
    uint8_t offset = 0;

    if (errcode)
        *errcode = ERR_DER_MISSING_ELEMENT;

    node = top;
    if (node == NULL || seq_index == NULL)
        return NULL;

    for (offset=0; offset<seqsz; offset++) {

        idx = seq_index[offset];
        for (i=0; i<idx; i++) {
            if (node == NULL || node->data == NULL)
                return NULL;

            /* skip context-specific elements */
            while (node->data->header.cls == ASN1_CLASS_CONTEXTSPEC) {
                node = node->next;
                if (node == NULL || node->data == NULL)
                    return NULL;
            }

            node = node->next;
            if (node == NULL || node->data == NULL)
                return NULL;
        }

        /* skip context-specific elements */
        if (node == NULL || node->data == NULL)
            return NULL;
        while (node->data->header.cls == ASN1_CLASS_CONTEXTSPEC) {
            node = node->next;
            if (node == NULL || node->data == NULL)
                return NULL;
        }

        node = node->data;
    }

    if (errcode)
        *errcode = 0;

    return node;
}

int Asn1DerGetIssuerDN(const Asn1Generic *cert, char *buffer, uint32_t length, uint32_t *errcode)
{
    const Asn1Generic *node_oid;
    const Asn1Generic *node, *it;
    const Asn1Generic *node_set;
    const Asn1Generic *node_str;
    const char *shortname;
    int rc = -1;
    const char *separator = ", ";

    if (errcode)
        *errcode = ERR_DER_MISSING_ELEMENT;

    if (length < 10)
        goto issuer_dn_error;
    buffer[0] = '\0';

    node = Asn1DerGet(cert, SEQ_IDX_ISSUER, sizeof(SEQ_IDX_ISSUER), errcode);
    if ((node == NULL) || node->type != ASN1_SEQUENCE)
        goto issuer_dn_error;

    it = node;
    while (it != NULL) {
        if (it->data == NULL)
            goto issuer_dn_error;
        node_set = it->data;
        if (node_set->type != ASN1_SET || node_set->data == NULL)
            goto issuer_dn_error;
        node = node_set->data;
        if (node->type != ASN1_SEQUENCE || node->data == NULL)
            goto issuer_dn_error;
        node_oid = node->data;
        if (node_oid->str == NULL || node_oid->type != ASN1_OID)
            goto issuer_dn_error;
        shortname = Oid2ShortStr(node_oid->str);
        if (node->next == NULL)
            goto issuer_dn_error;
        node = node->next;
        node_str = node->data;
        if (node_str == NULL || node_str->str == NULL)
            goto issuer_dn_error;

        switch (node_str->type) {
            case ASN1_PRINTSTRING:
            case ASN1_IA5STRING:
            case ASN1_T61STRING:
            case ASN1_UTF8STRING:
            case ASN1_OCTETSTRING:
                strlcat(buffer, shortname, length);
                strlcat(buffer, "=", length);
                strlcat(buffer, node_str->str, length);
                break;
            default:
                if (errcode)
                    *errcode = ERR_DER_UNSUPPORTED_STRING;
                goto issuer_dn_error;
        }

        if (strcmp(shortname,"CN")==0)
            separator = "/";
        if (it->next != NULL)
            strlcat(buffer, separator, length);
        it = it->next;
    }

    if (errcode)
        *errcode = 0;

    rc = 0;
issuer_dn_error:
    return rc;
}

int Asn1DerGetSubjectDN(const Asn1Generic *cert, char *buffer, uint32_t length, uint32_t *errcode)
{
    const Asn1Generic *node_oid;
    const Asn1Generic *node, *it;
    const Asn1Generic *node_set;
    const Asn1Generic *node_str;
    const char *shortname;
    int rc = -1;
    const char *separator = ", ";

    if (errcode)
        *errcode = ERR_DER_MISSING_ELEMENT;

    if (length < 10)
        goto subject_dn_error;
    buffer[0] = '\0';

    node = Asn1DerGet(cert, SEQ_IDX_SUBJECT, sizeof(SEQ_IDX_SUBJECT), errcode);

    if ((node == NULL) || node->type != ASN1_SEQUENCE)
        goto subject_dn_error;

    it = node;
    while (it != NULL) {
        if (it == NULL || it->data == NULL)
            goto subject_dn_error;
        node_set = it->data;
        if (node_set->type != ASN1_SET || node_set->data == NULL)
            goto subject_dn_error;
        node = node_set->data;
        if (node->type != ASN1_SEQUENCE || node->data == NULL)
            goto subject_dn_error;
        node_oid = node->data;
        if (node_oid->str == NULL || node_oid->type != ASN1_OID)
            goto subject_dn_error;
        shortname = Oid2ShortStr(node_oid->str);
        if (node->next == NULL)
            goto subject_dn_error;
        node = node->next;
        node_str = node->data;
        if (node_str == NULL || node_str->str == NULL)
            goto subject_dn_error;

        switch (node_str->type) {
            case ASN1_PRINTSTRING:
            case ASN1_IA5STRING:
            case ASN1_T61STRING:
            case ASN1_UTF8STRING:
            case ASN1_OCTETSTRING:
                strlcat(buffer, shortname, length);
                strlcat(buffer, "=", length);
                strlcat(buffer, node_str->str, length);
                break;
            default:
                if (errcode)
                    *errcode = ERR_DER_UNSUPPORTED_STRING;
                goto subject_dn_error;
        }

        if (strcmp(shortname,"CN")==0)
            separator = "/";
        if (it->next != NULL)
            strlcat(buffer, separator, length);
        it = it->next;
    }

    if (errcode)
        *errcode = 0;

    rc = 0;
subject_dn_error:
    return rc;
}

/* vim: set et ts=4 sw=4: */