/*
 * $OpenBSD: util.c,v 1.5 2023/04/19 12:34:23 jsg Exp $
 * Copyright (c) 2002 Institute for Open Systems Technology Australia (IFOST)
 * Copyright (c) 2007 Michael Erdely <merdely@openbsd.org>
 * Copyright (c) 2019 Martijn van Duren <martijn@openbsd.org>
 *
 * 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.
 */

#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <netinet/in.h>

#include <ctype.h>
#include <grp.h>
#include <unistd.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <syslog.h>
#include <tls.h>
#include <netdb.h>
#include <login_cap.h>

#include "aldap.h"
#include "login_ldap.h"

int debug = 0;

static int getscope(char *);

void
dlog(int d, char *fmt, ...)
{
        va_list ap;

        /*
         * if debugging is on, print everything to stderr
         * otherwise, syslog it if d = 0. messing with
         * newlines means there wont be newlines in stuff
         * that goes to syslog.
         */

        va_start(ap, fmt);
        if (debug) {
                vfprintf(stderr, fmt, ap);
                fputc('\n', stderr);
        } else if (d == 0)
                vsyslog(LOG_WARNING, fmt, ap);

        va_end(ap);
}

const char *
ldap_resultcode(enum result_code code)
{
#define CODE(_X)        case _X:return (#_X)
        switch (code) {
        CODE(LDAP_SUCCESS);
        CODE(LDAP_OPERATIONS_ERROR);
        CODE(LDAP_PROTOCOL_ERROR);
        CODE(LDAP_TIMELIMIT_EXCEEDED);
        CODE(LDAP_SIZELIMIT_EXCEEDED);
        CODE(LDAP_COMPARE_FALSE);
        CODE(LDAP_COMPARE_TRUE);
        CODE(LDAP_STRONG_AUTH_NOT_SUPPORTED);
        CODE(LDAP_STRONG_AUTH_REQUIRED);
        CODE(LDAP_REFERRAL);
        CODE(LDAP_ADMINLIMIT_EXCEEDED);
        CODE(LDAP_UNAVAILABLE_CRITICAL_EXTENSION);
        CODE(LDAP_CONFIDENTIALITY_REQUIRED);
        CODE(LDAP_SASL_BIND_IN_PROGRESS);
        CODE(LDAP_NO_SUCH_ATTRIBUTE);
        CODE(LDAP_UNDEFINED_TYPE);
        CODE(LDAP_INAPPROPRIATE_MATCHING);
        CODE(LDAP_CONSTRAINT_VIOLATION);
        CODE(LDAP_TYPE_OR_VALUE_EXISTS);
        CODE(LDAP_INVALID_SYNTAX);
        CODE(LDAP_NO_SUCH_OBJECT);
        CODE(LDAP_ALIAS_PROBLEM);
        CODE(LDAP_INVALID_DN_SYNTAX);
        CODE(LDAP_ALIAS_DEREF_PROBLEM);
        CODE(LDAP_INAPPROPRIATE_AUTH);
        CODE(LDAP_INVALID_CREDENTIALS);
        CODE(LDAP_INSUFFICIENT_ACCESS);
        CODE(LDAP_BUSY);
        CODE(LDAP_UNAVAILABLE);
        CODE(LDAP_UNWILLING_TO_PERFORM);
        CODE(LDAP_LOOP_DETECT);
        CODE(LDAP_NAMING_VIOLATION);
        CODE(LDAP_OBJECT_CLASS_VIOLATION);
        CODE(LDAP_NOT_ALLOWED_ON_NONLEAF);
        CODE(LDAP_NOT_ALLOWED_ON_RDN);
        CODE(LDAP_ALREADY_EXISTS);
        CODE(LDAP_NO_OBJECT_CLASS_MODS);
        CODE(LDAP_AFFECTS_MULTIPLE_DSAS);
        CODE(LDAP_OTHER);
        }

        return ("UNKNOWN_ERROR");
};


static int
parse_server_line(char *buf, struct aldap_url *s)
{
        /**
         * host=[<protocol>://]<hostname>[:port]
         *
         * must have a hostname
         * protocol can be "ldap", "ldaps", "ldap+tls" or "ldapi"
         * for ldap and ldap+tls, port defaults to 389
         * for ldaps, port defaults to 636
         */

        if (buf == NULL) {
                dlog(1, "%s got NULL buf!", __func__);
                return 0;
        }

        dlog(1, "parse_server_line buf = %s", buf);

        memset(s, 0, sizeof(*s));

        if (aldap_parse_url(buf, s) == -1) {
                dlog(0, "failed to parse host %s", buf);
                return 0;
        }

        if (s->protocol == -1)
                s->protocol = LDAP;
        if (s->protocol != LDAPI && s->port == 0) {
                if (s->protocol == LDAPS)
                        s->port = 636;
                else
                        s->port = 389;
        }

        return 1;
}

int
parse_conf(struct auth_ctx *ctx, const char *path)
{
        FILE *cf;
        struct stat sb;
        struct group *grp;
        struct aldap_urlq *url;
        char *buf = NULL, *key, *value, *tail;
        const char *errstr;
        size_t buflen = 0;
        ssize_t linelen;

        dlog(1, "Parsing config file '%s'", path);

        if ((cf = fopen(path, "r")) == NULL) {
                dlog(0, "Can't open config file: %s", strerror(errno));
                return 0;
        }
        if (fstat(fileno(cf), &sb) == -1) {
                dlog(0, "Can't stat config file: %s", strerror(errno));
                return 0;
        }
        if ((grp = getgrnam("auth")) == NULL) {
                dlog(0, "Can't find group auth");
                return 0;
        }
        if (sb.st_uid != 0 ||
            sb.st_gid != grp->gr_gid ||
            (sb.st_mode & S_IRWXU) != (S_IRUSR | S_IWUSR) ||
            (sb.st_mode & S_IRWXG) != S_IRGRP ||
            (sb.st_mode & S_IRWXO) != 0) {
                dlog(0, "Wrong permissions for config file");
                return 0;
        }

        /* We need a default scope */
        ctx->gscope = ctx->scope = getscope(NULL);

        while ((linelen = getline(&buf, &buflen, cf)) != -1) {
                if (buf[linelen - 1] == '\n')
                        buf[linelen -1] = '\0';
                /* Allow leading spaces */
                for (key = buf; key[0] != '\0' && isspace(key[0]); key++)
                        continue;
                /* Comment or white lines */
                if (key[0] == '#' || key[0] == '\0')
                        continue;
                if ((tail = value = strchr(key, '=')) == NULL) {
                        dlog(0, "Missing value for option '%s'", key);
                        return 0;
                }
                value++;
                /* Don't fail over trailing key spaces */
                for (tail--; isspace(tail[0]); tail--)
                        continue;
                tail[1] = '\0';
                if (strcmp(key, "host") == 0) {
                        if ((url = calloc(1, sizeof(*url))) == NULL) {
                                dlog(0, "Failed to add %s: %s", value,
                                    strerror(errno));
                                continue;
                        }
                        if (parse_server_line(value, &(url->s)) == 0) {
                                free(url);
                                return 0;
                        }
                        TAILQ_INSERT_TAIL(&(ctx->s), url, entries);
                } else if (strcmp(key, "basedn") == 0) {
                        free(ctx->basedn);
                        if ((ctx->basedn = strdup(value)) == NULL) {
                                dlog(0, "%s", strerror(errno));
                                return 0;
                        }
                } else if (strcmp(key, "binddn") == 0) {
                        free(ctx->binddn);
                        if ((ctx->binddn = parse_filter(ctx, value)) == NULL)
                                return 0;
                } else if (strcmp(key, "bindpw") == 0) {
                        free(ctx->bindpw);
                        if ((ctx->bindpw = strdup(value)) == NULL) {
                                dlog(0, "%s", strerror(errno));
                                return 0;
                        }
                } else if (strcmp(key, "timeout") == 0) {
                        ctx->timeout = strtonum(value, 0, INT_MAX, &errstr);
                        if (ctx->timeout == 0 && errstr != NULL) {
                                dlog(0, "timeout %s", errstr);
                                return 0;
                        }
                } else if (strcmp(key, "filter") == 0) {
                        free(ctx->filter);
                        if ((ctx->filter = parse_filter(ctx, value)) == NULL)
                                return 0;
                } else if (strcmp(key, "scope") == 0) {
                        if ((ctx->scope = getscope(value)) == -1)
                                return 0;
                } else if (strcmp(key, "cacert") == 0) {
                        free(ctx->cacert);
                        if ((ctx->cacert = strdup(value)) == NULL) {
                                dlog(0, "%s", strerror(errno));
                                return 0;
                        }
                } else if (strcmp(key, "cacertdir") == 0) {
                        free(ctx->cacertdir);
                        if ((ctx->cacertdir = strdup(value)) == NULL) {
                                dlog(0, "%s", strerror(errno));
                                return 0;
                        }
                } else if (strcmp(key, "gbasedn") == 0) {
                        free(ctx->gbasedn);
                        if ((ctx->gbasedn = strdup(value)) == NULL) {
                                dlog(0, "%s", strerror(errno));
                                return 0;
                        }
                } else if (strcmp(key, "gfilter") == 0) {
                        free(ctx->gfilter);
                        if ((ctx->gfilter = strdup(value)) == NULL) {
                                dlog(0, "%s", strerror(errno));
                                return 0;
                        }
                } else if (strcmp(key, "gscope") == 0) {
                        if ((ctx->scope = getscope(value)) == -1)
                                return 0;
                } else {
                        dlog(0, "Unknown option '%s'", key);
                        return 0;
                }
        }
        if (ferror(cf)) {
                dlog(0, "Can't read config file: %s", strerror(errno));
                return 0;
        }
        if (TAILQ_EMPTY(&(ctx->s))) {
                dlog(0, "Missing host");
                return 0;
        }
        if (ctx->basedn == NULL && ctx->binddn == NULL) {
                dlog(0, "Missing basedn or binddn");
                return 0;
        }
        return 1;
}

int
do_conn(struct auth_ctx *ctx, struct aldap_url *url)
{
        struct addrinfo          ai, *res, *res0;
        struct sockaddr_un       un;
        struct aldap_message    *m;
        struct tls_config       *tls_config;
        const char              *errstr;
        char                     port[6];
        int                      fd, code;

        dlog(1, "host %s, port %d", url->host, url->port);

        if (url->protocol == LDAPI) {
                memset(&un, 0, sizeof(un));
                un.sun_family = AF_UNIX;
                if (strlcpy(un.sun_path, url->host,
                    sizeof(un.sun_path)) >= sizeof(un.sun_path)) {
                        dlog(0, "socket '%s' too long", url->host);
                        return 0;
                }
                if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1 ||
                    connect(fd, (struct sockaddr *)&un, sizeof(un)) == -1) {
                        dlog(0, "can't create socket '%s'", url->host);
                        return 0;
                }
        } else {
                memset(&ai, 0, sizeof(ai));
                ai.ai_family = AF_UNSPEC;
                ai.ai_socktype = SOCK_STREAM;
                ai.ai_protocol = IPPROTO_TCP;
                (void)snprintf(port, sizeof(port), "%u", url->port);
                if ((code = getaddrinfo(url->host, port,
                    &ai, &res0)) != 0) {
                        dlog(0, "%s", gai_strerror(code));
                        return 0;
                }
                for (res = res0; res; res = res->ai_next, fd = -1) {
                        if ((fd = socket(res->ai_family, res->ai_socktype,
                            res->ai_protocol)) == -1)
                                continue;

                        if (connect(fd, res->ai_addr, res->ai_addrlen) >= 0)
                                break;

                        close(fd);
                }
                freeaddrinfo(res0);
                if (fd == -1)
                        return 0;
        }

        ctx->ld = aldap_init(fd);
        if (ctx->ld == NULL) {
                dlog(0, "aldap_open(%s:%hd) failed", url->host, url->port);
                return 0;
        }

        dlog(1, "connect success!");

        if (url->protocol == LDAPTLS) {
                dlog(1, "starttls!");
                if (aldap_req_starttls(ctx->ld) == -1) {
                        dlog(0, "failed to request STARTTLS");
                        goto fail;
                }

                if ((m = aldap_parse(ctx->ld)) == NULL) {
                        dlog(0, "failed to parse STARTTLS response");
                        goto fail;
                }

                if (ctx->ld->msgid != m->msgid ||
                    (code = aldap_get_resultcode(m)) != LDAP_SUCCESS) {
                        dlog(0, "STARTTLS failed: %s(%d)",
                            ldap_resultcode(code), code);
                        aldap_freemsg(m);
                        goto fail;
                }
                aldap_freemsg(m);
        }
        if (url->protocol == LDAPTLS || url->protocol == LDAPS) {
                dlog(1, "%s: starting TLS", __func__);

                if ((tls_config = tls_config_new()) == NULL) {
                        dlog(0, "TLS config failed");
                        goto fail;
                }

                if (ctx->cacert != NULL &&
                    tls_config_set_ca_file(tls_config, ctx->cacert) == -1) {
                        dlog(0, "Failed to set ca file %s", ctx->cacert);
                        goto fail;
                }
                if (ctx->cacertdir != NULL &&
                    tls_config_set_ca_path(tls_config, ctx->cacertdir) == -1) {
                        dlog(0, "Failed to set ca dir %s", ctx->cacertdir);
                        goto fail;
                }

                if (aldap_tls(ctx->ld, tls_config, url->host) < 0) {
                        aldap_get_errno(ctx->ld, &errstr);
                        dlog(0, "TLS failed: %s", errstr);
                        goto fail;
                }
        }
        return 1;
fail:
        aldap_close(ctx->ld);
        return 0;
}

int
conn(struct auth_ctx *ctx)
{
        struct aldap_urlq *url;

        TAILQ_FOREACH(url, &(ctx->s), entries) {
                if (do_conn(ctx, &(url->s)))
                        return 1;
        }

        /* all the urls have failed */
        return 0;
}

static int
getscope(char *scope)
{
        if (scope == NULL || scope[0] == '\0')
                return LDAP_SCOPE_SUBTREE;

        if (strcmp(scope, "base") == 0)
                return LDAP_SCOPE_BASE;
        else if (strcmp(scope, "one") == 0)
                return LDAP_SCOPE_ONELEVEL;
        else if (strcmp(scope, "sub") == 0)
                return LDAP_SCOPE_SUBTREE;

        dlog(0, "Invalid scope");
        return -1;
}

/*
 * Convert format specifiers from the filter in login.conf to their
 * real values. return the new filter in the filter argument.
 */
char *
parse_filter(struct auth_ctx *ctx, const char *str)
{
        char tmp[PATH_MAX];
        char hostname[HOST_NAME_MAX+1];
        const char *p;
        char *q;

        if (str == NULL)
                return NULL;

        /*
         * copy over from str to q, if we hit a %, substitute the real value,
         * if we hit a NULL, its the end of the filter string
         */
        for (p = str, q = tmp; p[0] != '\0' &&
            ((size_t)(q - tmp) < sizeof(tmp)); p++) {
                if (p[0] == '%') {
                        p++;

                        /* Make sure we can find the end of tmp for strlcat */
                        q[0] = '\0';

                        /*
                         * Don't need to check strcat for truncation, since we
                         * will bail on the next iteration
                         */
                        switch (p[0]) {
                        case 'u': /* username */
                                q = tmp + strlcat(tmp, ctx->user, sizeof(tmp));
                                break;
                        case 'h': /* hostname */
                                if (gethostname(hostname, sizeof(hostname)) ==
                                    -1) {
                                        dlog(0, "couldn't get host name for "
                                            "%%h %s", strerror(errno));
                                        return NULL;
                                }
                                q = tmp + strlcat(tmp, hostname, sizeof(tmp));
                                break;
                        case 'd': /* user dn */
                                if (ctx->userdn == NULL) {
                                        dlog(0, "no userdn has been recorded");
                                        return 0;
                                }
                                q = tmp + strlcat(tmp, ctx->userdn,
                                    sizeof(tmp));
                                break;
                        case '%': /* literal % */
                                q[0] = p[0];
                                q++;
                                break;
                        default:
                                dlog(0, "%s: invalid filter specifier",
                                    __func__);
                                return NULL;
                        }
                } else {
                        q[0] = p[0];
                        q++;
                }
        }
        if ((size_t) (q - tmp) >= sizeof(tmp)) {
                dlog(0, "filter string too large, unable to process: %s", str);
                return NULL;
        }

        q[0] = '\0';
        q = strdup(tmp);
        if (q == NULL) {
                dlog(0, "%s", strerror(errno));
                return NULL;
        }

        return q;
}