libads/cldap.c

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/* 
   Samba Unix/Linux SMB client library 
   net ads cldap functions 
   Copyright (C) 2001 Andrew Tridgell (tridge@samba.org)
   Copyright (C) 2003 Jim McDonough (jmcd@us.ibm.com)

   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
*/

#include "includes.h"

/*
  These seem to be strings as described in RFC1035 4.1.4 and can be:

   - a sequence of labels ending in a zero octet
   - a pointer
   - a sequence of labels ending with a pointer

  A label is a byte where the first two bits must be zero and the remaining
  bits represent the length of the label followed by the label itself.
  Therefore, the length of a label is at max 64 bytes.  Under RFC1035, a
  sequence of labels cannot exceed 255 bytes.

  A pointer consists of a 14 bit offset from the beginning of the data.

  struct ptr {
    unsigned ident:2; // must be 11
    unsigned offset:14; // from the beginning of data
  };

  This is used as a method to compress the packet by eliminated duplicate
  domain components.  Since a UDP packet should probably be < 512 bytes and a
  DNS name can be up to 255 bytes, this actually makes a lot of sense.
*/
static unsigned pull_netlogon_string(char *ret, const char *ptr,
                                     const char *data)
{
        char *pret = ret;
        int followed_ptr = 0;
        unsigned ret_len = 0;

        memset(pret, 0, MAX_DNS_LABEL);
        do {
                if ((*ptr & 0xc0) == 0xc0) {
                        uint16 len;

                        if (!followed_ptr) {
                                ret_len += 2;
                                followed_ptr = 1;
                        }
                        len = ((ptr[0] & 0x3f) << 8) | ptr[1];
                        ptr = data + len;
                } else if (*ptr) {
                        uint8 len = (uint8)*(ptr++);

                        if ((pret - ret + len + 1) >= MAX_DNS_LABEL) {
                                DEBUG(1,("DC returning too long DNS name\n"));
                                return 0;
                        }

                        if (pret != ret) {
                                *pret = '.';
                                pret++;
                        }
                        memcpy(pret, ptr, len);
                        pret += len;
                        ptr += len;

                        if (!followed_ptr) {
                                ret_len += (len + 1);
                        }
                }
        } while (*ptr);

        return followed_ptr ? ret_len : ret_len + 1;
}

/*
  do a cldap netlogon query
*/
static int send_cldap_netlogon(int sock, const char *domain, 
                               const char *hostname, unsigned ntversion)
{
        ASN1_DATA data;
        char ntver[4];
#ifdef CLDAP_USER_QUERY
        char aac[4];

        SIVAL(aac, 0, 0x00000180);
#endif
        SIVAL(ntver, 0, ntversion);

        memset(&data, 0, sizeof(data));

        asn1_push_tag(&data,ASN1_SEQUENCE(0));
        asn1_write_Integer(&data, 4);
        asn1_push_tag(&data, ASN1_APPLICATION(3));
        asn1_write_OctetString(&data, NULL, 0);
        asn1_write_enumerated(&data, 0);
        asn1_write_enumerated(&data, 0);
        asn1_write_Integer(&data, 0);
        asn1_write_Integer(&data, 0);
        asn1_write_BOOLEAN2(&data, False);
        asn1_push_tag(&data, ASN1_CONTEXT(0));

        if (domain) {
                asn1_push_tag(&data, ASN1_CONTEXT(3));
                asn1_write_OctetString(&data, "DnsDomain", 9);
                asn1_write_OctetString(&data, domain, strlen(domain));
                asn1_pop_tag(&data);
        }

        asn1_push_tag(&data, ASN1_CONTEXT(3));
        asn1_write_OctetString(&data, "Host", 4);
        asn1_write_OctetString(&data, hostname, strlen(hostname));
        asn1_pop_tag(&data);

#ifdef CLDAP_USER_QUERY
        asn1_push_tag(&data, ASN1_CONTEXT(3));
        asn1_write_OctetString(&data, "User", 4);
        asn1_write_OctetString(&data, "SAMBA$", 6);
        asn1_pop_tag(&data);

        asn1_push_tag(&data, ASN1_CONTEXT(3));
        asn1_write_OctetString(&data, "AAC", 4);
        asn1_write_OctetString(&data, aac, 4);
        asn1_pop_tag(&data);
#endif

        asn1_push_tag(&data, ASN1_CONTEXT(3));
        asn1_write_OctetString(&data, "NtVer", 5);
        asn1_write_OctetString(&data, ntver, 4);
        asn1_pop_tag(&data);

        asn1_pop_tag(&data);

        asn1_push_tag(&data,ASN1_SEQUENCE(0));
        asn1_write_OctetString(&data, "NetLogon", 8);
        asn1_pop_tag(&data);
        asn1_pop_tag(&data);
        asn1_pop_tag(&data);

        if (data.has_error) {
                DEBUG(2,("Failed to build cldap netlogon at offset %d\n", (int)data.ofs));
                asn1_free(&data);
                return -1;
        }

        if (write(sock, data.data, data.length) != (ssize_t)data.length) {
                DEBUG(2,("failed to send cldap query (%s)\n", strerror(errno)));
                asn1_free(&data);
                return -1;
        }

        asn1_free(&data);

        return 0;
}

static SIG_ATOMIC_T gotalarm;
                                                                                                                   
/***************************************************************
 Signal function to tell us we timed out.
****************************************************************/
                                                                                                                   
static void gotalarm_sig(void)
{
        gotalarm = 1;
}
                                                                                                                   
/*
  receive a cldap netlogon reply
*/
static int recv_cldap_netlogon(int sock, struct cldap_netlogon_reply *reply)
{
        int ret;
        ASN1_DATA data;
        DATA_BLOB blob = data_blob(NULL, 0);
        DATA_BLOB os1 = data_blob(NULL, 0);
        DATA_BLOB os2 = data_blob(NULL, 0);
        DATA_BLOB os3 = data_blob(NULL, 0);
        int i1;
        /* half the time of a regular ldap timeout, not less than 3 seconds. */
        unsigned int al_secs = MAX(3,lp_ldap_timeout()/2);
        char *p;

        blob = data_blob(NULL, 8192);
        if (blob.data == NULL) {
                DEBUG(1, ("data_blob failed\n"));
                errno = ENOMEM;
                return -1;
        }

        /* Setup timeout */
        gotalarm = 0;
        CatchSignal(SIGALRM, SIGNAL_CAST gotalarm_sig);
        alarm(al_secs);
        /* End setup timeout. */
 
        ret = read(sock, blob.data, blob.length);

        /* Teardown timeout. */
        CatchSignal(SIGALRM, SIGNAL_CAST SIG_IGN);
        alarm(0);

        if (ret <= 0) {
                DEBUG(1,("no reply received to cldap netlogon\n"));
                data_blob_free(&blob);
                return -1;
        }
        blob.length = ret;

        asn1_load(&data, blob);
        asn1_start_tag(&data, ASN1_SEQUENCE(0));
        asn1_read_Integer(&data, &i1);
        asn1_start_tag(&data, ASN1_APPLICATION(4));
        asn1_read_OctetString(&data, &os1);
        asn1_start_tag(&data, ASN1_SEQUENCE(0));
        asn1_start_tag(&data, ASN1_SEQUENCE(0));
        asn1_read_OctetString(&data, &os2);
        asn1_start_tag(&data, ASN1_SET);
        asn1_read_OctetString(&data, &os3);
        asn1_end_tag(&data);
        asn1_end_tag(&data);
        asn1_end_tag(&data);
        asn1_end_tag(&data);
        asn1_end_tag(&data);

        if (data.has_error) {
                data_blob_free(&blob);
                data_blob_free(&os1);
                data_blob_free(&os2);
                data_blob_free(&os3);
                asn1_free(&data);
                DEBUG(1,("Failed to parse cldap reply\n"));
                return -1;
        }

        p = (char *)os3.data;

        reply->type = IVAL(p, 0); p += 4;
        reply->flags = IVAL(p, 0); p += 4;

        memcpy(&reply->guid.info, p, UUID_FLAT_SIZE);
        p += UUID_FLAT_SIZE;

        p += pull_netlogon_string(reply->forest, p, (const char *)os3.data);
        p += pull_netlogon_string(reply->domain, p, (const char *)os3.data);
        p += pull_netlogon_string(reply->hostname, p, (const char *)os3.data);
        p += pull_netlogon_string(reply->netbios_domain, p, (const char *)os3.data);
        p += pull_netlogon_string(reply->netbios_hostname, p, (const char *)os3.data);
        p += pull_netlogon_string(reply->unk, p, (const char *)os3.data);

        if (reply->type == SAMLOGON_AD_R) {
                p += pull_netlogon_string(reply->user_name, p, (const char *)os3.data);
        } else {
                *reply->user_name = 0;
        }

        p += pull_netlogon_string(reply->server_site_name, p, (const char *)os3.data);
        p += pull_netlogon_string(reply->client_site_name, p, (const char *)os3.data);

        reply->version = IVAL(p, 0);
        reply->lmnt_token = SVAL(p, 4);
        reply->lm20_token = SVAL(p, 6);

        data_blob_free(&os1);
        data_blob_free(&os2);
        data_blob_free(&os3);
        data_blob_free(&blob);
        
        asn1_free(&data);

        return 0;
}

/*******************************************************************
  do a cldap netlogon query.  Always 389/udp
*******************************************************************/

BOOL ads_cldap_netlogon(const char *server, const char *realm,  struct cldap_netlogon_reply *reply)
{
        int sock;
        int ret;

        sock = open_udp_socket(server, LDAP_PORT );
        if (sock == -1) {
                DEBUG(2,("ads_cldap_netlogon: Failed to open udp socket to %s\n", 
                         server));
                return False;
        }

        ret = send_cldap_netlogon(sock, realm, global_myname(), 6);
        if (ret != 0) {
                close(sock);
                return False;
        }
        ret = recv_cldap_netlogon(sock, reply);
        close(sock);

        if (ret == -1) {
                return False;
        }

        return True;
}

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