/* Provenance: openssl/openssl gid_cb (fixed).
 * repo: openssl/openssl
 * commit: 85977e013f32ceb96aa034c0e741adddc1a05e34
 * parent: 21d525dc846aed171fc886f3da614a6645948f13
 * commit_url: https://github.com/openssl/openssl/commit/85977e013f32ceb96aa034c0e741adddc1a05e34
 * cve: CVE-2026-2673
 * license: Apache-2.0
 * function: gid_cb
 * relpath: ssl/t1_lib.c
 */

static int gid_cb(const char *elem, int len, void *arg)
{
    gid_cb_st *garg = arg;
    size_t i, j, k;
    uint16_t gid = 0;
    int found_group = 0;
    char etmp[GROUP_NAME_BUFFER_LENGTH];
    int retval = 1; /* We assume success */
    const char *current_prefix;
    int ignore_unknown = 0;
    int add_keyshare = 0;
    int remove_group = 0;
    size_t restored_prefix_index = 0;
    char *restored_default_group_string;
    int continue_while_loop = 1;

    /* Sanity checks */
    if (garg == NULL || elem == NULL || len <= 0) {
        ERR_raise(ERR_LIB_SSL, SSL_R_UNSUPPORTED_CONFIG_VALUE);
        return 0;
    }

    /* Check the possible prefixes (remark: Leading and trailing spaces already cleared) */
    while (continue_while_loop && len > 0
        && ((current_prefix = strchr(prefixes, elem[0])) != NULL
            || OPENSSL_strncasecmp(current_prefix = (char *)DEFAULT_GROUPNAME_FIRST_CHARACTER, elem, 1) == 0)) {

        switch (*current_prefix) {
        case TUPLE_DELIMITER_CHARACTER:
            /* tuple delimiter not allowed here -> syntax error */
            return -1;
            break;
        case GROUP_DELIMITER_CHARACTER:
            return -1; /* Not a valid prefix for a single group name-> syntax error */
            break;
        case KEY_SHARE_INDICATOR_CHARACTER:
            if (add_keyshare)
                return -1; /* Only single key share prefix allowed -> syntax error */
            add_keyshare = 1;
            ++elem;
            --len;
            break;
        case REMOVE_GROUP_INDICATOR_CHARACTER:
            if (remove_group)
                return -1; /* Only single remove group prefix allowed -> syntax error */
            remove_group = 1;
            ++elem;
            --len;
            break;
        case IGNORE_UNKNOWN_GROUP_CHARACTER:
            if (ignore_unknown)
                return -1; /* Only single ? allowed -> syntax error */
            ignore_unknown = 1;
            ++elem;
            --len;
            break;
        default:
            /*
             * Check whether a DEFAULT[_XYZ] 'pseudo group' (= a built-in
             * list of groups) should be added
             */
            for (i = 0; i < OSSL_NELEM(default_group_strings); i++) {
                if ((size_t)len == (strlen(default_group_strings[i].list_name))
                    && OPENSSL_strncasecmp(default_group_strings[i].list_name, elem, len) == 0) {
                    int saved_first;

                    /*
                     * We're asked to insert an entire list of groups from a
                     * DEFAULT[_XYZ] 'pseudo group' which we do by
                     * recursively calling this function (indirectly via
                     * CONF_parse_list and tuple_cb); essentially, we treat a DEFAULT
                     * group string like a tuple which is appended to the current tuple
                     * rather then starting a new tuple.
                     */
                    if (ignore_unknown || remove_group)
                        return -1; /* removal or ignore not allowed here -> syntax error */

                    /*
                     * First, we restore any keyshare prefix in a new zero-terminated string
                     * (if not already present)
                     */
                    restored_default_group_string = OPENSSL_malloc((1 /* max prefix length */ + strlen(default_group_strings[i].group_string) + 1 /* \0 */) * sizeof(char));
                    if (restored_default_group_string == NULL)
                        return 0;
                    if (add_keyshare
                        /* Remark: we tolerate a duplicated keyshare indicator here */
                        && default_group_strings[i].group_string[0]
                            != KEY_SHARE_INDICATOR_CHARACTER)
                        restored_default_group_string[restored_prefix_index++] = KEY_SHARE_INDICATOR_CHARACTER;

                    memcpy(restored_default_group_string + restored_prefix_index,
                        default_group_strings[i].group_string,
                        strlen(default_group_strings[i].group_string));
                    restored_default_group_string[strlen(default_group_strings[i].group_string) + restored_prefix_index] = '\0';
                    /*
                     * Append first tuple of result to current tuple, and don't
                     * terminate the last tuple until we return to a top-level
                     * tuple_cb.
                     */
                    saved_first = garg->first;
                    garg->inner = garg->first = 1;
                    retval = CONF_parse_list(restored_default_group_string,
                        TUPLE_DELIMITER_CHARACTER, 1, tuple_cb, garg);
                    garg->inner = 0;
                    garg->first = saved_first;
                    /* We don't need the \0-terminated string anymore */
                    OPENSSL_free(restored_default_group_string);

                    return retval;
                }
            }
            /*
             * If we reached this point, a group name started with a 'd' or 'D', but no request
             * for a DEFAULT[_XYZ] 'pseudo group' was detected, hence processing of the group
             * name can continue as usual (= the while loop checking prefixes can end)
             */
            continue_while_loop = 0;
            break;
        }
    }

    if (len == 0)
        return -1; /* Seems we have prefxes without a group name -> syntax error */

    /* Memory management in case more groups are present compared to initial allocation */
    if (garg->gidcnt == garg->gidmax) {
        uint16_t *tmp = OPENSSL_realloc(garg->gid_arr,
            (garg->gidmax + GROUPLIST_INCREMENT) * sizeof(*garg->gid_arr));

        if (tmp == NULL)
            return 0;

        garg->gidmax += GROUPLIST_INCREMENT;
        garg->gid_arr = tmp;
    }
    /* Memory management for key share groups */
    if (garg->ksidcnt == garg->ksidmax) {
        uint16_t *tmp = OPENSSL_realloc(garg->ksid_arr,
            (garg->ksidmax + GROUPLIST_INCREMENT) * sizeof(*garg->ksid_arr));

        if (tmp == NULL)
            return 0;
        garg->ksidmax += GROUPLIST_INCREMENT;
        garg->ksid_arr = tmp;
    }

    if (len > (int)(sizeof(etmp) - 1))
        return -1; /* group name to long  -> syntax error */

    /*
     * Prepare addition or removal of a single group by converting
     * a group name into its groupID equivalent
     */

    /* Create a \0-terminated string and get the gid for this group if possible */
    memcpy(etmp, elem, len);
    etmp[len] = 0;

    /* Get the groupID */
    gid = tls1_group_name2id(garg->ctx, etmp);
    /*
     * Handle the case where no valid groupID was returned
     * e.g. for an unknown group, which we'd ignore (only) if relevant prefix was set
     */
    if (gid == 0) {
        /* Is it one of the GOST groups ? */
        for (i = 0; i < OSSL_NELEM(name2id_arr); i++) {
            if (OPENSSL_strcasecmp(etmp, name2id_arr[i].group_name) == 0) {
                gid = name2id_arr[i].groupID;
                break;
            }
        }
        if (gid == 0) { /* still not found */
            /* Unknown group - ignore if ignore_unknown; trigger error otherwise */
            retval = ignore_unknown;
            goto done;
        }
    }

    /* Make sure that at least one provider is supporting this groupID */
    found_group = 0;
    for (j = 0; j < garg->ctx->group_list_len; j++)
        if (garg->ctx->group_list[j].group_id == gid) {
            found_group = 1;
            break;
        }

    /*
     * No provider supports this group - ignore if
     * ignore_unknown; trigger error otherwise
     */
    if (found_group == 0) {
        retval = ignore_unknown;
        goto done;
    }
    /* Remove group (and keyshare) from anywhere in the list if present, ignore if not present */
    if (remove_group) {
        /* Is the current group specified anywhere in the entire list so far? */
        found_group = 0;
        for (i = 0; i < garg->gidcnt; i++)
            if (garg->gid_arr[i] == gid) {
                found_group = 1;
                break;
            }
        /* The group to remove is at position i in the list of (zero indexed) groups */
        if (found_group) {
            /* We remove that group from its position (which is at i)... */
            for (j = i; j < (garg->gidcnt - 1); j++)
                garg->gid_arr[j] = garg->gid_arr[j + 1]; /* ...shift remaining groups left ... */
            garg->gidcnt--; /* ..and update the book keeping for the number of groups */

            /*
             * We also must update the number of groups either in a previous tuple (which we
             * must identify and check whether it becomes empty due to the deletion) or in
             * the current tuple, pending where the deleted group resides
             */
            k = 0;
            for (j = 0; j < garg->tplcnt; j++) {
                k += garg->tuplcnt_arr[j];
                /* Remark: i is zero-indexed, k is one-indexed */
                if (k > i) { /* remove from one of the previous tuples */
                    garg->tuplcnt_arr[j]--;
                    break; /* We took care not to have group duplicates, hence we can stop here */
                }
            }
            if (k <= i) /* remove from current tuple */
                garg->tuplcnt_arr[j]--;

            /* We also remove the group from the list of keyshares (if present) */
            found_group = 0;
            for (i = 0; i < garg->ksidcnt; i++)
                if (garg->ksid_arr[i] == gid) {
                    found_group = 1;
                    break;
                }
            if (found_group) {
                /* Found, hence we remove that keyshare from its position (which is at i)... */
                for (j = i; j < (garg->ksidcnt - 1); j++)
                    garg->ksid_arr[j] = garg->ksid_arr[j + 1]; /* shift remaining key shares */
                /* ... and update the book keeping */
                garg->ksidcnt--;
            }
        }
    } else { /* Processing addition of a single new group */

        /* Check for duplicates */
        for (i = 0; i < garg->gidcnt; i++)
            if (garg->gid_arr[i] == gid) {
                /* Duplicate group anywhere in the list of groups - ignore */
                goto done;
            }

        /* Add the current group to the 'flat' list of groups */
        garg->gid_arr[garg->gidcnt++] = gid;
        /* and update the book keeping for the number of groups in current tuple */
        garg->tuplcnt_arr[garg->tplcnt]++;

        /* We want to add a key share for the current group */
        if (add_keyshare)
            garg->ksid_arr[garg->ksidcnt++] = gid;
    }

done:
    return retval;
}