/* Authors: Simo Sorce <ssorce@redhat.com>
 *
 * Copyright (C) 2007  Red Hat
 * see file 'COPYING' for use and warranty information
 *
 * 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/>.
 */

#define _GNU_SOURCE

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <krb5.h>
#include <ldap.h>
#include <resolv.h>
#include <sasl/sasl.h>
#include <popt.h>
#include <ini_configobj.h>
#include <openssl/rand.h>

#include "config.h"

#include "ipa_krb5.h"
#include "ipa_asn1.h"
#include "ipa-client-common.h"
#include "ipa_ldap.h"


struct srvrec {
    char *host;
    uint16_t port;
    int priority, weight;
    struct srvrec *next;
};

static int
srvrec_priority_sort(const void *a, const void *b)
{
	const struct srvrec *sa, *sb;

	sa = a;
	sb = b;
	return sa->priority - sb->priority;
}

static int
srvrec_sort_weight(const void *a, const void *b)
{
	const struct srvrec *sa, *sb;

	sa = a;
	sb = b;
	return sa->weight - sb->weight;
}

/* Return a uniform random number between 0 and range */
static double
rand_inclusive(double range)
{
	long long r;

	if (range == 0) {
		return 0;
	}

	if (RAND_bytes((unsigned char *) &r, sizeof(r)) == -1) {
		return 0;
	}
	if (r < 0) {
		r = -r;
	}
	return ((double)r / (double)LLONG_MAX) * range;
}

static void
sort_prio_weight(struct srvrec *res, int len)
{
	int i, j;
	double tweight;
	struct srvrec tmp;
	double r;

	qsort(res, len, sizeof(res[0]), srvrec_sort_weight);
	for (i = 0; i < len - 1; i++) {
		tweight = 0;
		for (j = i; j < len; j++) {
            /* Give records with 0 weight a small chance */
			tweight += res[j].weight ? res[j].weight : 0.01;
		}
		r = rand_inclusive(tweight);
		tweight = 0;
		for (j = i; j < len; j++) {
			tweight += res[j].weight ? res[j].weight : 0.01;
			if (tweight >= r) {
				break;
			}
		}
		if (j >= len) {
			continue;
		}
		memcpy(&tmp, &res[i], sizeof(tmp));
		memcpy(&res[i], &res[j], sizeof(tmp));
		memcpy(&res[j], &tmp, sizeof(tmp));
	}
}

/* The caller is responsible for freeing the results */
static int
query_srv(const char *name, const char *domain, struct srvrec **results)
{
	int i, j, len;
	unsigned char *answer = NULL;
	size_t answer_len = NS_MAXMSG;
	struct srvrec *res = NULL;
	ns_msg msg;
	ns_rr rr;
	int rv = -1;

	*results = NULL;
	if ((name == NULL) || (strlen(name) == 0) ||
	    (domain == NULL) || (strlen(domain) == 0)) {
		return -1;
	}

	res_init();
	answer = malloc(answer_len + 1);
	if (answer == NULL) {
		return -1;
	}
	memset(answer, 0, answer_len + 1);
	i = res_querydomain(name, domain, C_IN, T_SRV, answer, answer_len);
	if (i == -1) {
		goto error;
	}
	answer_len = i;
	memset(&msg, 0, sizeof(msg));
	if (ns_initparse(answer, answer_len, &msg) != 0) {
		goto error;
	}
	memset(&rr, 0, sizeof(rr));
	for (i = 0; ns_parserr(&msg, ns_s_an, i, &rr) == 0; i++) {
		continue;
	}
	if (i == 0) {
		goto error;
	}
	len = i;
	res = malloc(sizeof(*res) * i);
	if (res == NULL) {
		goto error;
	}
	memset(res, 0, sizeof(*res) * i);
	for (i = 0, j = 0; i < len; i++) {
		if (ns_parserr(&msg, ns_s_an, i, &rr) != 0) {
			continue;
		}
		if (rr.rdlength < 6) {
			continue;
		}
		res[j].host = malloc(rr.rdlength - 6 + 1);
		if (res[j].host == NULL) {
			goto error;
		}
		res[j].priority = ntohs(*(uint16_t *)rr.rdata);
		res[j].weight = ntohs(*(uint16_t *)(rr.rdata + 2));
		res[j].port = ntohs(*(uint16_t *)(rr.rdata + 4));
		memcpy(res[j].host, rr.rdata + 6, rr.rdlength - 6);
		if (ns_name_ntop(rr.rdata + 6, res[j].host, rr.rdlength - 6) == -1) {
			continue;
		}
		res[j].host[rr.rdlength - 6] = '\0';
		j++;
	}
	len = j;
	qsort(res, len, sizeof(res[0]), srvrec_priority_sort);
	i = 0;
	while (i < len) {
		j = i + 1;
		while (j < len && (res[j].priority == res[i].priority)) {
			j++;
		}
		sort_prio_weight(res + i, j - i);
		i = j;
	}
	/* Fixup the linked-list pointers */
	for (i = 0; i < len - 1; i++) {
		res[i].next = &res[i + 1];
	}
	*results = res;
	rv = 0;

error:
	free(answer);
	return rv;
}

static int check_sasl_mech(const char *mech)
{
    int i;
    int ret = 1;
    const char *supported_sasl_mechs[] = {
        LDAP_SASL_EXTERNAL,
        LDAP_SASL_GSSAPI,
        NULL
    };

    for (i=0; NULL != supported_sasl_mechs[i]; i++) {
        if (strcmp(mech, supported_sasl_mechs[i]) == 0) {
            return 0;
        }
    }
    return ret;
}

static int ldap_sasl_interact(LDAP *ld, unsigned flags, void *priv_data, void *sit)
{
	sasl_interact_t *in = NULL;
	int ret = LDAP_OTHER;
	krb5_principal princ = (krb5_principal)priv_data;
	krb5_context krbctx;
	char *outname = NULL;
	krb5_error_code krberr;

	if (!ld) return LDAP_PARAM_ERROR;

	for (in = sit; in && in->id != SASL_CB_LIST_END; in++) {
		switch(in->id) {
		case SASL_CB_USER:
			krberr = krb5_init_context(&krbctx);

			if (krberr) {
				fprintf(stderr, _("Kerberos context initialization failed: %1$s (%2$d)\n"),
                                error_message(krberr), krberr);
				in->result = NULL;
				in->len = 0;
				ret = LDAP_LOCAL_ERROR;
				break;
			}

			krberr = krb5_unparse_name(krbctx, princ, &outname);

			if (krberr) {
                fprintf(stderr, _("Unable to parse principal: %1$s (%2$d)\n"),
                                error_message(krberr), krberr);
				in->result = NULL;
				in->len = 0;
				ret = LDAP_LOCAL_ERROR;
				break;
			}

			in->result = outname;
			in->len = strlen(outname);
			ret = LDAP_SUCCESS;

			krb5_free_context(krbctx);

			break;
		case SASL_CB_GETREALM:
			in->result = princ->realm.data;
			in->len = princ->realm.length;
			ret = LDAP_SUCCESS;
			break;
		default:
			in->result = NULL;
			in->len = 0;
			ret = LDAP_OTHER;
		}
	}
	return ret;
}

static int filter_keys(krb5_context krbctx, struct keys_container *keys,
                ber_int_t *enctypes)
{
    struct krb_key_salt *ksdata;
    int i, j, n;

    n = keys->nkeys;
    ksdata = keys->ksdata;
    for (i = 0; i < n; i++) {
        if (ksdata[i].enctype == enctypes[i]) continue;
        if (enctypes[i] == 0) {
            /* remove unsupported one */
            krb5_free_keyblock_contents(krbctx, &ksdata[i].key);
            krb5_free_data_contents(krbctx, &ksdata[i].salt);
            for (j = i; j < n-1; j++) {
                ksdata[j] = ksdata[j + 1];
                enctypes[j] = enctypes[j + 1];
            }
            n--;
            /* new key has been moved to this position, make sure
             * we do not skip it, by neutralizing next i increment */
            i--;
        }
    }

    if (n == 0) {
        fprintf(stderr, _("No keys accepted by KDC\n"));
        return 0;
    }

    keys->nkeys = n;
    return n;
}

static int ipa_server_to_uri(const char *servername, const char *mech,
                             char **ldap_uri)
{
    char *url = NULL;
    int url_len = 0;
    int port = 389;

    url_len = asprintf(&url, "%s%s:%d", SCHEMA_LDAP, servername, port);

    if (url_len == -1) {
        fprintf(stderr, _("Out of memory \n"));
        return LDAP_NO_MEMORY;
    }
    *ldap_uri = url;
    return 0;
}

static int ipa_ldap_bind(const char *ldap_uri, krb5_principal bind_princ,
                         const char *bind_dn, const char *bind_pw,
                         const char *mech, const char *ca_cert_file,
                         LDAP **_ld)
{
    struct berval bv;
    LDAP *ld;
    int ret;

    /* TODO: support referrals ? */
    ret = ipa_ldap_init(&ld, ldap_uri);
    if (ret != LDAP_SUCCESS) {
        return ret;
    }

    if (ld == NULL) {
        fprintf(stderr, _("Unable to initialize ldap library!\n"));
        return LDAP_OPERATIONS_ERROR;
    }

    ret = ipa_tls_ssl_init(ld, ldap_uri, ca_cert_file);
    if (ret != LDAP_OPT_SUCCESS) {
        goto done;
    }

    if (bind_dn) {
        bv.bv_val = discard_const(bind_pw);
        bv.bv_len = strlen(bind_pw);

        ret = ldap_sasl_bind_s(ld, bind_dn, LDAP_SASL_SIMPLE,
                               &bv, NULL, NULL, NULL);
        if (ret != LDAP_SUCCESS) {
            ipa_ldap_error(ld, ret, _("Simple bind failed\n"));
            goto done;
        }
    } else {
        if (strcmp(mech, LDAP_SASL_EXTERNAL) == 0) {
            ret = ldap_sasl_bind_s(ld, NULL, LDAP_SASL_EXTERNAL,
                                   NULL, NULL, NULL, NULL);
        } else {
            ret = ldap_sasl_interactive_bind_s(ld, NULL, LDAP_SASL_GSSAPI,
                                               NULL, NULL, LDAP_SASL_QUIET,
                                               ldap_sasl_interact, bind_princ);
        }

        if (ret != LDAP_SUCCESS) {
            ipa_ldap_error(ld, ret, _("SASL Bind failed\n"));
            goto done;
        }
    }

    ret = LDAP_SUCCESS;

done:
    if (ret != LDAP_SUCCESS) {
        if (ld) ldap_unbind_ext(ld, NULL, NULL);
    } else {
        *_ld = ld;
    }
    return ret;
}

static int ipa_ldap_extended_op(LDAP *ld, const char *reqoid,
                                struct berval *control,
                                LDAPControl ***srvctrl)
{
    struct berval *retdata = NULL;
    LDAPMessage *res = NULL;
    char *retoid = NULL;
    struct timeval tv;
    char *err = NULL;
    int msgid;
    int ret, rc;

    ret = ldap_extended_operation(ld, reqoid, control,
                                  NULL, NULL, &msgid);
    if (ret != LDAP_SUCCESS) {
        fprintf(stderr, _("Operation failed: %s\n"), ldap_err2string(ret));
        return ret;
    }

    /* wait max 100 secs for the answer */
    tv.tv_sec = 100;
    tv.tv_usec = 0;
    ret = ldap_result(ld, msgid, 1, &tv, &res);
    if (ret == -1) {
        fprintf(stderr, _("Failed to get result: %s\n"), ldap_err2string(ret));
        goto done;
    }
    else if (res == NULL) {
        fprintf(stderr, _("Timeout exceeded."));
        goto done;
    }

    ret = ldap_parse_extended_result(ld, res, &retoid, &retdata, 0);
    if (ret != LDAP_SUCCESS) {
        fprintf(stderr, _("Failed to parse extended result: %s\n"),
                        ldap_err2string(ret));
        goto done;
    }

    ret = ldap_parse_result(ld, res, &rc, NULL, &err, NULL, srvctrl, 0);
    if (ret != LDAP_SUCCESS || rc != LDAP_SUCCESS) {
        fprintf(stderr, _("Failed to parse result: %s\n"),
                        err ? err : ldap_err2string(ret));
        if (ret == LDAP_SUCCESS) ret = rc;
        goto done;
    }

done:
    if (err) ldap_memfree(err);
    if (res) ldap_msgfree(res);
    return ret;
}

static int find_control_data(LDAPControl **list, const char *repoid,
                             struct berval *data)
{
    LDAPControl *control = NULL;
    int i;

    if (!list) {
        fprintf(stderr, _("Missing reply control list!\n"));
        return LDAP_OPERATIONS_ERROR;
    }

    for (i = 0; list[i]; i++) {
        if (strcmp(list[i]->ldctl_oid, repoid) == 0) {
            control = list[i];
        }
    }
    if (!control) {
        fprintf(stderr, _("Missing reply control!\n"));
        return LDAP_OPERATIONS_ERROR;
    }

    *data = control->ldctl_value;
    return LDAP_SUCCESS;
}

static BerElement *get_control_data(LDAPControl **list, const char *repoid)
{
    struct berval data;
    int ret;

    ret = find_control_data(list, repoid, &data);
    if (ret != LDAP_SUCCESS) return NULL;

    return ber_init(&data);
}

static int ldap_set_keytab(krb5_context krbctx,
			   const char *ldap_uri,
			   const char *principal_name,
			   krb5_principal princ,
			   const char *binddn,
			   const char *bindpw,
			   const char *mech,
			   const char *ca_cert_file,
			   struct keys_container *keys)
{
	LDAP *ld = NULL;
	BerElement *sctrl = NULL;
	struct berval *control = NULL;
	LDAPControl **srvctrl = NULL;
	ber_tag_t ret;
	int kvno, i;
	ber_tag_t rtag;
	ber_int_t *encs = NULL;
	int successful_keys = 0;

	/* cant' return more than nkeys, sometimes less */
	encs = calloc(keys->nkeys + 1, sizeof(ber_int_t));
	if (!encs) {
		fprintf(stderr, _("Out of Memory!\n"));
		return 0;
	}

	/* build password change control */
	control = create_key_control(keys, principal_name);
	if (!control) {
		fprintf(stderr, _("Failed to create control!\n"));
		goto error_out;
	}

    ret = ipa_ldap_bind(ldap_uri, princ, binddn, bindpw, mech, ca_cert_file, &ld);
    if (ret != LDAP_SUCCESS) {
        fprintf(stderr, _("Failed to bind to server!\n"));
        goto error_out;
    }

    /* perform password change */
    ret = ipa_ldap_extended_op(ld, KEYTAB_SET_OID, control, &srvctrl);
    if (ret != LDAP_SUCCESS) {
        fprintf(stderr, _("Failed to get keytab!\n"));
        goto error_out;
    }

	ber_bvfree(control);
	control = NULL;

	sctrl = get_control_data(srvctrl, KEYTAB_RET_OID);
	if (!sctrl) {
		fprintf(stderr, _("ber_init() failed, Invalid control ?!\n"));
		goto error_out;
	}

	/* Format of response
	 *
	 * KeytabGetRequest ::= SEQUENCE {
	 * 	new_kvno	Int32
	 * 	SEQUENCE OF	KeyTypes
	 * }
	 *
	 * * List of accepted enctypes *
	 * KeyTypes ::= SEQUENCE {
	 * 	enctype		Int32
	 * }
	 */

	rtag = ber_scanf(sctrl, "{i{", &kvno);
	if (rtag == LBER_ERROR) {
		fprintf(stderr, _("ber_scanf() failed, unable to find kvno ?!\n"));
		goto error_out;
	}

	for (i = 0; i < keys->nkeys; i++) {
		ret = ber_scanf(sctrl, "{i}", &encs[i]);
		if (ret == LBER_ERROR) {
			char enc[79]; /* fit std terminal or truncate */
			krb5_error_code krberr;
			krberr = krb5_enctype_to_string(
				keys->ksdata[i].enctype, enc, 79);
			if (krberr) {
				fprintf(stderr, _("Failed to retrieve "
					"encryption type type #%d\n"),
					keys->ksdata[i].enctype);
			} else {
				fprintf(stderr, _("Failed to retrieve "
					"encryption type %1$s (#%2$d)\n"),
					enc, keys->ksdata[i].enctype);
			}
                } else {
			successful_keys++;
		}
	}

	if (successful_keys == 0) {
		fprintf(stderr, _("Failed to retrieve any keys"));
		goto error_out;
	}

	ret = filter_keys(krbctx, keys, encs);
	if (ret == 0) goto error_out;

	ber_free(sctrl, 1);
	ldap_controls_free(srvctrl);
	ldap_unbind_ext(ld, NULL, NULL);
	free(encs);
	return kvno;

error_out:
	if (sctrl) ber_free(sctrl, 1);
	if (srvctrl) ldap_controls_free(srvctrl);
	if (ld) ldap_unbind_ext(ld, NULL, NULL);
	if (control) ber_bvfree(control);
	free(encs);
	return -1;
}

/* use asn1c generated code to fill up control */
static struct berval *create_getkeytab_control(const char *svc_princ, bool gen,
                                               const char *password,
                                               struct krb_key_salt *encsalts,
                                               int num_encsalts)
{
    struct berval *result = NULL;
    void *buffer = NULL;
    size_t buflen;
    long ets[num_encsalts];
    bool ret;
    int i;

    if (gen) {
        for (i = 0; i < num_encsalts; i++) {
            ets[i] = encsalts[i].enctype;
        }
    }
    ret = ipaasn1_enc_getkt(gen, svc_princ,
                            password, ets, num_encsalts,
                            &buffer, &buflen);
    if (!ret) goto done;

    result = malloc(sizeof(struct berval));
    if (!result) goto done;

    result->bv_val = buffer;
    result->bv_len = buflen;

done:
    if (result == NULL) {
        if (buffer) {
            free(buffer);
        }
    }
    return result;
}

#define GK_REPLY_TAG (LBER_CLASS_CONTEXT | LBER_CONSTRUCTED | 2)
#define GKREP_KEY_TAG (LBER_CLASS_CONTEXT | LBER_CONSTRUCTED | 0)
#define GKREP_SALT_TAG (LBER_CLASS_CONTEXT | LBER_CONSTRUCTED | 1)

static int ldap_get_keytab(krb5_context krbctx, bool generate, char *password,
                           const char *enctypes, const char *ldap_uri,
                           const char *svc_princ, krb5_principal bind_princ,
                           const char *bind_dn, const char *bind_pw,
                           const char *mech,
                           const char *ca_cert_file,
                           struct keys_container *keys, int *kvno,
                           char **err_msg)
{
    struct krb_key_salt *es = NULL;
    int num_es = 0;
    struct berval *control = NULL;
    LDAP *ld = NULL;
    LDAPControl **srvctrl = NULL;
    struct berval data;
    bool res;
    int ret;

    *err_msg = NULL;

    if (enctypes) {
        ret = ipa_string_to_enctypes(enctypes, &es, &num_es, err_msg);
        if (ret || num_es == 0) {
            free(es);
            return LDAP_OPERATIONS_ERROR;
        }
    }

    control = create_getkeytab_control(svc_princ, generate,
                                       password, es, num_es);
    if (!control) {
        *err_msg = _("Failed to create control!\n");
        ret = LDAP_OPERATIONS_ERROR;
        goto done;
    }

    ret = ipa_ldap_bind(ldap_uri, bind_princ, bind_dn, bind_pw, mech,
                        ca_cert_file, &ld);
    if (ret != LDAP_SUCCESS) {
        *err_msg = _("Failed to bind to server!\n");
        goto done;
    }

    /* perform extedned opt to get keytab */
    ret = ipa_ldap_extended_op(ld, KEYTAB_GET_OID, control, &srvctrl);
    if (ret != LDAP_SUCCESS) {
        goto done;
    }

    ret = find_control_data(srvctrl, KEYTAB_GET_OID, &data);
    if (ret != LDAP_SUCCESS) goto done;

    res = ipaasn1_dec_getktreply(data.bv_val, data.bv_len, kvno, keys);
    if (!res) {
        *err_msg = _("Failed to decode control reply!\n");
        ret = LDAP_OPERATIONS_ERROR;
        goto done;
    }

    ret = LDAP_SUCCESS;

done:
    if (ld) ldap_unbind_ext(ld, NULL, NULL);
    if (control) ber_bvfree(control);
    free(es);
    if (ret) {
        free_keys_contents(krbctx, keys);
    }
    return ret;
}

/* Prompt for either a password.
 * This can be either asking for a new or existing password.
 *
 * To set a new password provide values for both prompt1 and prompt2 and
 * set match=true to enforce that the two entered passwords match.
 *
 * To prompt for an existing password provide prompt1 and set match=false.
 *
 * Implementation details:
 * krb5_prompter_posix() does not differentiate between too long entry or
 * an entry exactly the size of a buffer. Thus, allocate a bigger buffer
 * and do the check for a too long password afterwards.
 */
static char *ask_password(krb5_context krbctx, char *prompt1, char *prompt2,
                          bool match)
{
    krb5_prompt ap_prompts[2];
    krb5_data k5d_pw0;
    krb5_data k5d_pw1;
#define MAX(a,b) (((a)>(b))?(a):(b))
#define PWD_BUFFER_SIZE MAX((IPAPWD_PASSWORD_MAX_LEN + 2), 1024)
    char pw0[PWD_BUFFER_SIZE];
    char pw1[PWD_BUFFER_SIZE];
    char *password;
    int num_prompts = match ? 2:1;

    k5d_pw0.length = sizeof(pw0);
    k5d_pw0.data = pw0;
    ap_prompts[0].prompt = prompt1;
    ap_prompts[0].hidden = 1;
    ap_prompts[0].reply = &k5d_pw0;

    if (match) {
        k5d_pw1.length = sizeof(pw1);
        k5d_pw1.data = pw1;
        ap_prompts[1].prompt = prompt2;
        ap_prompts[1].hidden = 1;
        ap_prompts[1].reply = &k5d_pw1;
    }

    krb5_prompter_posix(krbctx, NULL,
                NULL, NULL,
                num_prompts, ap_prompts);

    if (match && (strcmp(pw0, pw1) != 0)) {
        fprintf(stderr, _("Passwords do not match!\n"));
        return NULL;
    }

    if (k5d_pw0.length > IPAPWD_PASSWORD_MAX_LEN) {
        fprintf(stderr, "%s\n", ipapwd_password_max_len_errmsg);
        return NULL;
    }

    password = malloc(k5d_pw0.length + 1);
    if (!password) return NULL;
    memcpy(password, pw0, k5d_pw0.length);
    password[k5d_pw0.length] = '\0';

    return password;
}

struct ipa_config {
    const char *server_name;
    const char *domain;
};

static int config_from_file(struct ini_cfgobj *cfgctx)
{
    struct ini_cfgfile *fctx = NULL;
    char **errors = NULL;
    int ret;

    ret = ini_config_file_open(IPACONFFILE, 0, &fctx);
    if (ret) {
        fprintf(stderr, _("Failed to open config file %s\n"), IPACONFFILE);
        return ret;
    }

    ret = ini_config_parse(fctx,
                           INI_STOP_ON_ANY,
                           INI_MS_MERGE | INI_MV1S_ALLOW | INI_MV2S_ALLOW,
                           INI_PARSE_NOWRAP,
                           cfgctx);
    if (ret) {
        fprintf(stderr, _("Failed to parse config file %s\n"), IPACONFFILE);
        if (ini_config_error_count(cfgctx)) {
            ini_config_get_errors(cfgctx, &errors);
            if (errors) {
                ini_config_print_errors(stderr, errors);
                ini_config_free_errors(errors);
            }
        }
        ini_config_file_destroy(fctx);
        return ret;
    }

    ini_config_file_destroy(fctx);
    return 0;
}

static int read_ipa_config(struct ipa_config **ipacfg)
{
    struct ini_cfgobj *cfgctx = NULL;
    struct value_obj *obj = NULL;
    int ret;

    *ipacfg = calloc(1, sizeof(struct ipa_config));
    if (!*ipacfg) {
        return ENOMEM;
    }

    ret = ini_config_create(&cfgctx);
    if (ret) {
        return ENOENT;
    }

    ret = config_from_file(cfgctx);
    if (ret) {
        ini_config_destroy(cfgctx);
        return EINVAL;
    }

    ret = ini_get_config_valueobj("global", "server", cfgctx,
                                  INI_GET_LAST_VALUE, &obj);
    if (ret != 0 || obj == NULL) {
        /* if called on an IPA server we need to look for 'host' instead */
        ret = ini_get_config_valueobj("global", "host", cfgctx,
                                      INI_GET_LAST_VALUE, &obj);
    }

    if (ret == 0 && obj != NULL) {
        (*ipacfg)->server_name = ini_get_string_config_value(obj, &ret);
    }
    ret = ini_get_config_valueobj("global", "domain", cfgctx,
                                  INI_GET_LAST_VALUE, &obj);
    if (ret == 0 && obj != NULL) {
        (*ipacfg)->domain = ini_get_string_config_value(obj, &ret);
    }

    return 0;
}

static int resolve_ktname(const char *keytab, char **ktname, char **err_msg)
{
	char keytab_resolved[PATH_MAX + 1];
	struct stat st;
	struct stat lst;
	int ret;

	*err_msg = NULL;

    /* Resolve keytab symlink to support dangling symlinks, see
     * https://pagure.io/freeipa/issue/4607. To prevent symlink attacks,
     * the symlink is only resolved owned by the current user or by
     * root. For simplicity, only one level if indirection is resolved.
     */
    if ((stat(keytab, &st) == -1) &&
            (errno == ENOENT) &&
            (lstat(keytab, &lst) == 0) &&
            (S_ISLNK(lst.st_mode))) {
        /* keytab is a dangling symlink. */
        if (((lst.st_uid == 0) && (lst.st_gid == 0)) ||
                ((lst.st_uid == geteuid()) && (lst.st_gid == getegid()))) {
            /* Either root or current user owns symlink, resolve symlink and
             * return the resolved symlink. */
            ret = readlink(keytab, keytab_resolved, PATH_MAX + 1);
            if ((ret == -1) || (ret > PATH_MAX)) {
                *err_msg = _("Failed to resolve symlink to keytab.\n");
                return ENOENT;
            }
            keytab_resolved[ret] = '\0';
            ret = asprintf(ktname, "WRFILE:%s", keytab_resolved);
            if (ret == -1) {
                *err_msg = strerror(errno);
                return ENOMEM;
            }
            return 0;
        } else {
            *err_msg = _("keytab is a dangling symlink and owned by another "
                         "user.\n");
            return EINVAL;
        }
    } else {
        ret = asprintf(ktname, "WRFILE:%s", keytab);
        if (ret == -1) {
            *err_msg = strerror(errno);
            return ENOMEM;
        }
        return 0;
    }
}

int main(int argc, const char *argv[])
{
	static const char *server = NULL;
	static const char *principal = NULL;
	static const char *keytab = NULL;
	static const char *enctypes_string = NULL;
	static const char *binddn = NULL;
	static const char *bindpw = NULL;
	char *ldap_uri = NULL;
	static const char *sasl_mech = NULL;
	static const char *ca_cert_file = NULL;
	int quiet = 0;
	int verbose = 0;
	int askpass = 0;
	int askbindpw = 0;
	int permitted_enctypes = 0;
	int retrieve = 0;
        struct poptOption options[] = {
            { "quiet", 'q', POPT_ARG_NONE, &quiet, 0,
              _("Print as little as possible"), _("Output only on errors")},
            { "verbose", 'v', POPT_ARG_NONE, &verbose, 0,
              _("Print debugging information"), _("Output debug info")},
            { "server", 's', POPT_ARG_STRING, &server, 0,
              _("Contact this specific KDC Server"),
              _("Server Name") },
            { "principal", 'p', POPT_ARG_STRING, &principal, 0,
              _("The principal to get a keytab for (ex: ftp/ftp.example.com@EXAMPLE.COM)"),
              _("Kerberos Service Principal Name") },
            { "keytab", 'k', POPT_ARG_STRING, &keytab, 0,
              _("The keytab file to append the new key to (will be "
                "created if it does not exist)."),
              _("Keytab File Name") },
	    { "enctypes", 'e', POPT_ARG_STRING, &enctypes_string, 0,
              _("Encryption types to request"),
              _("Comma separated encryption types list") },
	    { "permitted-enctypes", 0, POPT_ARG_NONE, &permitted_enctypes, 0,
              _("Show the list of permitted encryption types and exit"),
              _("Permitted Encryption Types") },
	    { "password", 'P', POPT_ARG_NONE, &askpass, 0,
              _("Asks for a non-random password to use for the principal"), NULL },
	    { "binddn", 'D', POPT_ARG_STRING, &binddn, 0,
              _("LDAP DN"), _("DN to bind as if not using kerberos") },
	    { "bindpw", 'w', POPT_ARG_STRING, &bindpw, 0,
              _("LDAP password"), _("password to use if not using kerberos") },
	    { NULL, 'W', POPT_ARG_NONE, &askbindpw, 0,
              _("Prompt for LDAP password"), NULL },
	    { "cacert", 0, POPT_ARG_STRING, &ca_cert_file, 0,
              _("Path to the IPA CA certificate"), _("IPA CA certificate")},
	    { "ldapuri", 'H', POPT_ARG_STRING, &ldap_uri, 0,
              _("LDAP uri to connect to. Mutually exclusive with --server"),
              _("url")},
	    { "mech", 'Y', POPT_ARG_STRING, &sasl_mech, 0,
              _("LDAP SASL bind mechanism if no bindd/bindpw"),
              _("GSSAPI|EXTERNAL") },
	    { "retrieve", 'r', POPT_ARG_NONE, &retrieve, 0,
              _("Retrieve current keys without changing them"), NULL },
            POPT_AUTOHELP
            POPT_TABLEEND
	};
	poptContext pc;
	char *ktname;
	char *password = NULL;
	krb5_context krbctx;
	krb5_ccache ccache;
	krb5_principal uprinc = NULL;
	krb5_principal sprinc;
	krb5_error_code krberr;
	struct keys_container keys = { 0 };
	krb5_keytab kt;
	int kvno;
	int i, ret;
	char *err_msg;

    ret = init_gettext();
    if (ret) {
        fprintf(stderr, "Failed to load translations\n");
    }

	krberr = krb5_init_context(&krbctx);
	if (krberr) {
		fprintf(stderr, _("Kerberos context initialization failed\n"));
		exit(1);
	}

	pc = poptGetContext("ipa-getkeytab", argc, (const char **)argv, options, 0);
	ret = poptGetNextOpt(pc);
	if (ret == -1 && permitted_enctypes &&
	    !(server || principal || keytab || quiet)) {
		krb5_enctype *ktypes;
		char enc[79]; /* fit std terminal or truncate */

		krberr = krb5_get_permitted_enctypes(krbctx, &ktypes);
		if (krberr) {
			fprintf(stderr, _("No system preferred enctypes ?!\n"));
			exit(1);
		}
		fprintf(stdout, _("Supported encryption types:\n"));
		for (i = 0; ktypes[i]; i++) {
			krberr = krb5_enctype_to_string(ktypes[i], enc, 79);
			if (krberr) {
				fprintf(stderr, _("Warning: "
                                        "failed to convert type (#%d)\n"), i);
				continue;
			}
			fprintf(stdout, "%s\n", enc);
		}
		ipa_krb5_free_ktypes(krbctx, ktypes);
		exit (0);
	}

	if (ret != -1 || !principal || !keytab || permitted_enctypes) {
		if (!quiet) {
			poptPrintUsage(pc, stderr, 0);
		}
		exit(2);
	}

    if (askbindpw && bindpw != NULL) {
		fprintf(stderr, _("Bind password already provided (-w).\n"));
		if (!quiet) {
			poptPrintUsage(pc, stderr, 0);
		}
		exit(2);
    }

    if (askbindpw) {
		bindpw = ask_password(krbctx, _("Enter LDAP password"), NULL, false);
		if (!bindpw) {
			exit(2);
		}
    }

	if (NULL!=binddn && NULL==bindpw) {
		fprintf(stderr,
                        _("Bind password required when using a bind DN (-w or -W).\n"));
		if (!quiet)
			poptPrintUsage(pc, stderr, 0);
		exit(10);
	}

    if (NULL != binddn && NULL != sasl_mech) {
        fprintf(stderr, _("Cannot specify both SASL mechanism "
                          "and bind DN simultaneously.\n"));
        if (!quiet)
            poptPrintUsage(pc, stderr, 0);
        exit(2);
    }

    if (sasl_mech && check_sasl_mech(sasl_mech)) {
        fprintf(stderr, _("Invalid SASL bind mechanism\n"));
        if (!quiet)
            poptPrintUsage(pc, stderr, 0);
        exit(2);
    }

    if (!binddn && !sasl_mech) {
        sasl_mech = LDAP_SASL_GSSAPI;
    }

    if (server && ldap_uri) {
        fprintf(stderr, _("Cannot specify server and LDAP uri "
                          "simultaneously.\n"));
        if (!quiet)
            poptPrintUsage(pc, stderr, 0);
        exit(2);
    }

    if (server && (strcasecmp(server, "_srv_") == 0)) {
        struct srvrec *srvrecs, *srv;
        struct ipa_config *ipacfg = NULL;

        ret = read_ipa_config(&ipacfg);
        if (ret == 0 && ipacfg->domain && verbose) {
            fprintf(stderr, _("DNS discovery for domain %s\n"), ipacfg->domain);
        }
        if (query_srv("_ldap._tcp", ipacfg->domain, &srvrecs) == 0) {
            for (srv = srvrecs; (srv != NULL); srv = srv->next) {
				if (verbose) {
            	    fprintf(stderr, _("Discovered server %s\n"), srv->host);
                }
            }
            for (srv = srvrecs; (srv != NULL); srv = srv->next) {
                server = strdup(srv->host);
				if (verbose) {
            		fprintf(stderr, _("Using discovered server %s\n"), server);
				}
                break;
            }
            for (srv = srvrecs; (srv != NULL); srv = srv->next) {
				free(srv->host);
            }
        } else {
			if (verbose) {
           		fprintf(stderr, _("DNS Discovery failed\n"));
			}
        }
        if (strcasecmp(server, "_srv_") == 0) {
            /* Discovery failed, fall through to option methods */
            server = NULL;
        }
    }

    if (!server && !ldap_uri) {
        struct ipa_config *ipacfg = NULL;

        ret = read_ipa_config(&ipacfg);
        if (ret == 0) {
            server = ipacfg->server_name;
            ipacfg->server_name = NULL;
        }
        free(ipacfg);
		if (verbose && server) {
            fprintf(stderr, _("Using server from config %s\n"), server);
        }
        if (!server) {
            fprintf(stderr, _("Server name not provided and unavailable\n"));
            exit(2);
        }
    } else {
        if (verbose) {
            fprintf(stderr, _("Using provided server %s\n"), server);
        }
    }
    if (server) {
        ret = ipa_server_to_uri(server, sasl_mech, &ldap_uri);
        if (ret) {
            exit(ret);
        }
    }

    if (!ca_cert_file) {
        ca_cert_file = DEFAULT_CA_CERT_FILE;
    }

    if (askpass && retrieve) {
        fprintf(stderr, _("Incompatible options provided (-r and -P)\n"));
        exit(2);
    }

        if (askpass) {
		password = ask_password(krbctx, _("New Principal Password"),
               	                _("Verify Principal Password"), true);
		if (!password) {
			exit(2);
		}
	} else if (enctypes_string && strchr(enctypes_string, ':')) {
		if (!quiet) {
			fprintf(stderr, _("Warning: salt types are not honored"
                                " with randomized passwords (see opt. -P)\n"));
		}
	}

	krberr = krb5_parse_name(krbctx, principal, &sprinc);
	if (krberr) {
		fprintf(stderr, _("Invalid Service Principal Name\n"));
		exit(4);
	}

	if (NULL == bindpw && strcmp(sasl_mech, LDAP_SASL_GSSAPI) == 0) {
		krberr = krb5_cc_default(krbctx, &ccache);
		if (krberr) {
			fprintf(stderr,
                                _("Kerberos Credential Cache not found. "
				  "Do you have a Kerberos Ticket?\n"));
			exit(5);
		}

		krberr = krb5_cc_get_principal(krbctx, ccache, &uprinc);
		if (krberr) {
			fprintf(stderr,
                                _("Kerberos User Principal not found. "
				  "Do you have a valid Credential Cache?\n"));
			exit(6);
		}
	}

	ret = resolve_ktname(keytab, &ktname, &err_msg);
	if (krberr) {
		fprintf(stderr, "%s", err_msg);
		exit(ret);
	}

	krberr = krb5_kt_resolve(krbctx, ktname, &kt);
	if (krberr) {
		fprintf(stderr, _("Failed to open Keytab\n"));
		exit(7);
	}

    kvno = -1;
    ret = ldap_get_keytab(krbctx, (retrieve == 0), password, enctypes_string,
                          ldap_uri, principal, uprinc, binddn, bindpw,
                          sasl_mech, ca_cert_file,
                          &keys, &kvno, &err_msg);
    if (ret) {
        if (!quiet && err_msg != NULL) {
            fprintf(stderr, "%s", err_msg);
        }
    }

    if (retrieve == 0 && kvno == -1) {
        if (!quiet) {
            fprintf(stderr,
                    _("Retrying with pre-4.0 keytab retrieval method...\n"));
        }

        /* create key material */
        ret = create_keys(krbctx, sprinc, password, enctypes_string, &keys, &err_msg);
        if (!ret) {
            if (err_msg != NULL) {
                fprintf(stderr, "%s", err_msg);
            }

            fprintf(stderr, _("Failed to create key material\n"));
            free_keys_contents(krbctx, &keys);
            exit(8);
        }

        kvno = ldap_set_keytab(krbctx, ldap_uri, principal, uprinc, binddn,
                               bindpw, sasl_mech, ca_cert_file, &keys);
    }

    if (kvno == -1) {
        fprintf(stderr, _("Failed to get keytab\n"));
        exit(9);
    }

	for (i = 0; i < keys.nkeys; i++) {
		krb5_keytab_entry kt_entry;
		memset((char *)&kt_entry, 0, sizeof(kt_entry));
		kt_entry.principal = sprinc;
		kt_entry.key = keys.ksdata[i].key;
		kt_entry.vno = kvno;

		krberr = krb5_kt_add_entry(krbctx, kt, &kt_entry);
		if (krberr) {
			fprintf(stderr,
                                _("Failed to add key to the keytab\n"));
			exit (11);
		}
	}

	free_keys_contents(krbctx, &keys);

	krberr = krb5_kt_close(krbctx, kt);
	if (krberr) {
		fprintf(stderr, _("Failed to close the keytab\n"));
		exit (12);
	}

	if (!quiet) {
		fprintf(stderr,
			_("Keytab successfully retrieved and stored in: %s\n"),
			keytab);
	}
	exit(0);
}