/** BEGIN COPYRIGHT BLOCK
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Additional permission under GPLv3 section 7:
 *
 * In the following paragraph, "GPL" means the GNU General Public
 * License, version 3 or any later version, and "Non-GPL Code" means
 * code that is governed neither by the GPL nor a license
 * compatible with the GPL.
 *
 * You may link the code of this Program with Non-GPL Code and convey
 * linked combinations including the two, provided that such Non-GPL
 * Code only links to the code of this Program through those well
 * defined interfaces identified in the file named EXCEPTION found in
 * the source code files (the "Approved Interfaces"). The files of
 * Non-GPL Code may instantiate templates or use macros or inline
 * functions from the Approved Interfaces without causing the resulting
 * work to be covered by the GPL. Only the copyright holders of this
 * Program may make changes or additions to the list of Approved
 * Interfaces.
 *
 * Authors:
 * Sumit Bose <sbose@redhat.com>
 *
 * Copyright (C) 2017 Red Hat, Inc.
 * All rights reserved.
 * END COPYRIGHT BLOCK **/

#include <errno.h>
//#include <krb5/certauth_plugin.h>
#include <syslog.h>
#include <sss_certmap.h>

#include "util/ipa_krb5.h"
#include "ipa_kdb.h"

#define IPA_OC_CERTMAP_RULE "ipaCertMapRule"
#define IPA_CERTMAP_MAPRULE "ipaCertMapMapRule"
#define IPA_CERTMAP_MATCHRULE "ipaCertMapMatchRule"
#define IPA_CERTMAP_PRIORITY "ipaCertMapPriority"
#define IPA_ENABLED_FLAG "ipaEnabledFlag"
#define IPA_TRUE_VALUE "TRUE"
#define IPA_ASSOCIATED_DOMAIN "associatedDomain"

#define OBJECTCLASS "objectClass"

#define CERTMAP_FILTER "(&("OBJECTCLASS"="IPA_OC_CERTMAP_RULE")" \
                              "("IPA_ENABLED_FLAG"="IPA_TRUE_VALUE"))"

#ifndef discard_const
#define discard_const(ptr) ((void *)((uintptr_t)(ptr)))
#endif


struct krb5_certauth_moddata_st {
    char *local_domain;
    struct sss_certmap_ctx *sss_certmap_ctx;
    struct ipadb_context *ipactx;
};

void ipa_certmap_debug(void *private,
                       const char *file, long line,
                       const char *function,
                       const char *format, ...)
{
    va_list ap;
    char str[255] = { 0 };

    va_start(ap, format);
    vsnprintf(str, sizeof(str)-1, format, ap);
    va_end(ap);
    krb5_klog_syslog(LOG_ERR, str);
}

void ipa_certauth_free_moddata(krb5_certauth_moddata *moddata)
{
    if (moddata == NULL || *moddata == NULL) {
        return;
    }

    free((*moddata)->local_domain);
    (*moddata)->local_domain = NULL;
    sss_certmap_free_ctx((*moddata)->sss_certmap_ctx);
    (*moddata)->sss_certmap_ctx = NULL;

    free(*moddata);

    return;
}

static krb5_error_code ipa_certauth_authorize(krb5_context context,
                                              krb5_certauth_moddata moddata,
                                              krb5_data cert,
                                              krb5_principal princ,
                                              void *db_entry,
                                              char ***authinds_out,
                                              krb5_boolean *status)
{
    char *cert_filter = NULL;
    char **domains = NULL;
    int ret;
    size_t c;
    char *principal = NULL;
    LDAPMessage *res = NULL;
    krb5_error_code kerr;
    LDAPMessage *lentry;

    if (status == NULL
            || moddata == NULL || moddata->sss_certmap_ctx == NULL) {
        return EINVAL;
    }

    ret = krb5_unparse_name(context, princ, &principal);
    if (ret != 0) {
        goto done;
    }
    krb5_klog_syslog(LOG_ERR, "Doing certauth authorize for [%s]", principal);

    ret = sss_certmap_get_search_filter(moddata->sss_certmap_ctx,
                                        (uint8_t *) cert.data, cert.length,
                                        &cert_filter, &domains);
    if (ret != 0) {
        if (ret == ENOENT) {
            ret = KRB5KDC_ERR_CERTIFICATE_MISMATCH;
        }
        goto done;
    }
    krb5_klog_syslog(LOG_ERR, "Got cert filter [%s]", cert_filter);

    /* If there are no domains assigned the rule will apply to the local
     * domain only. */
    if (domains != NULL) {

        if (moddata->local_domain == NULL) {
        /* We don't know our own domain name, in general this should not
         * happen. But to be fault tolerant we allow matching rule which
         * do not have a domain assigned. */

            ret = KRB5KDC_ERR_CERTIFICATE_MISMATCH;
            goto done;
        }

        for (c = 0; domains[c] != NULL; c++) {
            if (strcasecmp(domains[c], moddata->local_domain) == 0) {
                break;
            }
        }

        /* Our domain was not in the list */
        if (domains[c] == NULL) {
            ret = KRB5KDC_ERR_CERTIFICATE_MISMATCH;
            goto done;
        }
    }

    kerr = ipadb_fetch_principals_with_extra_filter(moddata->ipactx,
                                                    KRB5_KDB_FLAG_ALIAS_OK,
                                                    principal,
                                                    cert_filter,
                                                    &res);
    if (kerr != 0) {
        krb5_klog_syslog(LOG_ERR, "Search failed [%d]", kerr);
        ret = kerr;
        goto done;
    }

    kerr = ipadb_find_principal(context, KRB5_KDB_FLAG_ALIAS_OK, res,
                                &principal, &lentry);
    if (kerr == KRB5_KDB_NOENTRY) {
        krb5_klog_syslog(LOG_ERR, "No matching entry found");
        ret = KRB5KDC_ERR_CERTIFICATE_MISMATCH;
        goto done;
    } else if (kerr != 0) {
        krb5_klog_syslog(LOG_ERR, "ipadb_find_principal failed [%d]", kerr);
        ret = kerr;
        goto done;
    }

    /* TODO: add more tests ? */

    ret = 0;
    *status = TRUE;

done:
    sss_certmap_free_filter_and_domains(cert_filter, domains);
    krb5_free_unparsed_name(context, principal);
    ldap_msgfree(res);

    return ret;
}

static krb5_error_code ipa_certauth_req_init(krb5_context kcontext, void *opts,
                                             krb5_certauth_moddata *moddata_out)
{
    int ret;
    struct sss_certmap_ctx *ctx = NULL;
    struct ipadb_context *ipactx;
    krb5_error_code kerr;
    char *basedn = NULL;
    LDAPMessage *result = NULL;
    LDAPMessage *le;
    LDAP *lc;
    size_t c;
    uint32_t prio;
    char *map_rule = NULL;
    char *match_rule = NULL;
    char **domains = NULL;

    const char *certmap_attrs[] = { OBJECTCLASS,
                                    IPA_CERTMAP_PRIORITY,
                                    IPA_CERTMAP_MATCHRULE,
                                    IPA_CERTMAP_MAPRULE,
                                    IPA_ASSOCIATED_DOMAIN,
                                    IPA_ENABLED_FLAG,
                                    NULL};


    krb5_klog_syslog(LOG_ERR, "IPA certauth plugin loaded.");

    ipactx = ipadb_get_context(kcontext);
    if (ipactx == NULL) {
        return KRB5_KDB_DBNOTINITED;
    }

    if (ipactx->certauth_moddata == NULL) {
        ret = asprintf(&basedn, "cn=certmap,%s", ipactx->base);
        if (ret == -1) {
            return ENOMEM;
        }

        kerr = ipadb_simple_search(ipactx,basedn, LDAP_SCOPE_SUBTREE,
                                   CERTMAP_FILTER, discard_const(certmap_attrs),
                                   &result);
        if (kerr != 0 && kerr != KRB5_KDB_NOENTRY) {
            goto done;
        }

        ret = sss_certmap_init(NULL, ipa_certmap_debug, NULL, &ctx);
        if (ret != 0) {
            return ret;
        }

        if (kerr == KRB5_KDB_NOENTRY) {
            ret = sss_certmap_add_rule(ctx, SSS_CERTMAP_MIN_PRIO,
                                       NULL, NULL, NULL);
            if (ret != 0) {
                goto done;
            }
        } else {
            lc = ipactx->lcontext;

            for (le = ldap_first_entry(lc, result); le;
                                                 le = ldap_next_entry(lc, le)) {
                prio = SSS_CERTMAP_MIN_PRIO;
                ret = ipadb_ldap_attr_to_uint32(lc, le, IPA_CERTMAP_PRIORITY,
                                                &prio);
                if (ret != 0 && ret != ENOENT) {
                    goto done;
                }

                free(map_rule);
                map_rule = NULL;
                ret = ipadb_ldap_attr_to_str(lc, le, IPA_CERTMAP_MAPRULE,
                                             &map_rule);
                if (ret != 0 && ret != ENOENT) {
                    goto done;
                }

                free(match_rule);
                match_rule = NULL;
                ret = ipadb_ldap_attr_to_str(lc, le, IPA_CERTMAP_MATCHRULE,
                                             &match_rule);
                if (ret != 0 && ret != ENOENT) {
                    goto done;
                }

                if (domains != NULL) {
                    for (c = 0; domains[c] != NULL; c++) {
                        free(domains[c]);
                    }
                    free(domains);
                    domains = NULL;
                }
                ret = ipadb_ldap_attr_to_strlist(lc, le, IPA_ASSOCIATED_DOMAIN,
                                                 &domains);
                if (ret != 0 && ret != ENOENT) {
                    goto done;
                }

                ret = sss_certmap_add_rule(ctx, prio, match_rule, map_rule,
                                           (const char **) domains);
                if (ret != 0) {
                    goto done;
                }
            }
        }

        ipactx->certauth_moddata = calloc(1,
                                       sizeof(struct krb5_certauth_moddata_st));
        if (ipactx->certauth_moddata == NULL) {
            ret = ENOMEM;
            goto done;
        }

        if (ipactx->realm != NULL) {
            ipactx->certauth_moddata->local_domain = strdup(ipactx->realm);
            if (ipactx->certauth_moddata->local_domain == NULL) {
                free(ipactx->certauth_moddata);
                ipactx->certauth_moddata = NULL;
                ret = ENOMEM;
                goto done;
            }
        }

        ipactx->certauth_moddata->sss_certmap_ctx = ctx;
        ipactx->certauth_moddata->ipactx = ipactx;

    }

    *moddata_out = ipactx->certauth_moddata;

    ret = 0;

done:
    ldap_msgfree(result);
    free(basedn);
    free(map_rule);
    free(match_rule);
    if (domains != NULL) {
        for (c = 0; domains[c] != NULL; c++) {
            free(domains[c]);
        }
        free(domains);
        domains = NULL;
    }

    if (ret != 0) {
        sss_certmap_free_ctx(ctx);
    }

    return ret;
}

static void ipa_certauth_req_fini(krb5_context context,
                                  krb5_certauth_moddata *moddata_out)
{
    krb5_klog_syslog(LOG_ERR, "IPA certauth plugin un-loaded.");
    return;
}


krb5_error_code certauth_ipakdb_initvt(krb5_context context,
                                          int maj_ver, int min_ver,
                                          krb5_plugin_vtable vtable)
{
    krb5_certauth_vtable vt;

    if (maj_ver != 1) {
        return KRB5_PLUGIN_VER_NOTSUPP;
    }

    vt = (krb5_certauth_vtable) vtable;

    vt->name = "ipakdb";
    vt->authorize = ipa_certauth_authorize;
    vt->req_init = ipa_certauth_req_init;
    vt->req_fini = ipa_certauth_req_fini;
    return 0;
}