/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*
 *  glue routine gss_import_name
 *
 */

#include <mechglueP.h>
#include "gssapiP_generic.h"
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <string.h>
#include <errno.h>

extern int
get_der_length(unsigned char **, unsigned int, unsigned int *);

/* local function to import GSS_C_EXPORT_NAME names */
static OM_uint32 importExportName(OM_uint32 *, gss_union_name_t);

static OM_uint32
val_imp_name_args(
        OM_uint32 *minor_status,
        gss_buffer_t input_name_buffer,
        gss_name_t *output_name)
{

        /* Initialize outputs. */

        if (minor_status != NULL)
                *minor_status = 0;

        if (output_name != NULL)
                *output_name = GSS_C_NO_NAME;

        /* Validate arguments. */

        if (minor_status == NULL)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        if (output_name == NULL)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        if (input_name_buffer == GSS_C_NO_BUFFER)
                return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_BAD_NAME);

        if (GSS_EMPTY_BUFFER(input_name_buffer))
                return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_BAD_NAME);

        return (GSS_S_COMPLETE);
}

OM_uint32
gss_import_name(minor_status,
                input_name_buffer,
                input_name_type,
                output_name)

OM_uint32 *minor_status;
const gss_buffer_t input_name_buffer;
const gss_OID input_name_type;
gss_name_t *output_name;
{
        gss_union_name_t union_name;
        OM_uint32 major_status = GSS_S_FAILURE, tmp;

        major_status = val_imp_name_args(minor_status,
                                        input_name_buffer,
                                        output_name);
        if (major_status != GSS_S_COMPLETE)
                return (major_status);

        /*
         * First create the union name struct that will hold the external
         * name and the name type.
         */
        union_name = (gss_union_name_t)malloc(sizeof (gss_union_name_desc));
        if (!union_name)
                return (GSS_S_FAILURE);

        union_name->mech_type = 0;
        union_name->mech_name = 0;
        union_name->name_type = 0;
        union_name->external_name = 0;

        /*
         * All we do here is record the external name and name_type.
         * When the name is actually used, the underlying gss_import_name()
         * is called for the appropriate mechanism.  The exception to this
         * rule is when the name of GSS_C_NT_EXPORT_NAME type.  If that is
         * the case, then we make it MN in this call.
         */
        major_status = gssint_create_copy_buffer(input_name_buffer,
                                        &union_name->external_name, 0);
        if (major_status != GSS_S_COMPLETE) {
                free(union_name);
                return (major_status);
        }

        if (input_name_type != GSS_C_NULL_OID) {
                major_status = generic_gss_copy_oid(minor_status,
                                                input_name_type,
                                                &union_name->name_type);
                if (major_status != GSS_S_COMPLETE) {
                        map_errcode(minor_status);
                        goto allocation_failure;
                }
        }

        /*
         * In MIT Distribution the mechanism is determined from the nametype;
         * This is not a good idea - first mechanism that supports a given
         * name type is picked up; later on the caller can request a
         * different mechanism. So we don't determine the mechanism here. Now
         * the user level and kernel level import_name routine looks similar
         * except the kernel routine makes a copy of the nametype structure. We
         * do however make this an MN for names of GSS_C_NT_EXPORT_NAME type.
         */
        if (input_name_type != GSS_C_NULL_OID &&
            g_OID_equal(input_name_type, GSS_C_NT_EXPORT_NAME)) {
                major_status = importExportName(minor_status, union_name);
                if (major_status != GSS_S_COMPLETE)
                        goto allocation_failure;
        }

        *output_name = (gss_name_t)union_name;
        return (GSS_S_COMPLETE);

allocation_failure:
        if (union_name) {
                if (union_name->external_name) {
                        if (union_name->external_name->value)
                                free(union_name->external_name->value);
                        free(union_name->external_name);
                }
                if (union_name->name_type)
                        (void) generic_gss_release_oid(&tmp,
                                                    &union_name->name_type);
                if (union_name->mech_name)
                        (void) __gss_release_internal_name(minor_status,
                                                union_name->mech_type,
                                                &union_name->mech_name);
                if (union_name->mech_type)
                        (void) generic_gss_release_oid(&tmp,
                                                    &union_name->mech_type);
                free(union_name);
        }
        return (major_status);
}


/*
 * GSS export name constants
 */
static const char *expNameTokId = "\x04\x01";
static const int expNameTokIdLen = 2;
static const int mechOidLenLen = 2;
static const int nameTypeLenLen = 2;

static OM_uint32
importExportName(minor, unionName)
OM_uint32 *minor;
gss_union_name_t unionName;
{
        gss_OID_desc mechOid;
        gss_buffer_desc expName;
        unsigned char *buf;
        gss_mechanism mech;
        OM_uint32 major, mechOidLen, nameLen, curLength;
        unsigned int bytes;

        expName.value = unionName->external_name->value;
        expName.length = unionName->external_name->length;

        curLength = expNameTokIdLen + mechOidLenLen;
        if (expName.length < curLength)
                return (GSS_S_DEFECTIVE_TOKEN);

        buf = (unsigned char *)expName.value;
        if (memcmp(expNameTokId, buf, expNameTokIdLen) != 0)
                return (GSS_S_DEFECTIVE_TOKEN);

        buf += expNameTokIdLen;

        /* extract the mechanism oid length */
        mechOidLen = (*buf++ << 8);
        mechOidLen |= (*buf++);
        curLength += mechOidLen;
        if (expName.length < curLength)
                return (GSS_S_DEFECTIVE_TOKEN);
        /*
         * The mechOid itself is encoded in DER format, OID Tag (0x06)
         * length and the value of mech_OID
         */
        if (*buf++ != 0x06)
                return (GSS_S_DEFECTIVE_TOKEN);

        /*
         * mechoid Length is encoded twice; once in 2 bytes as
         * explained in RFC2743 (under mechanism independent exported
         * name object format) and once using DER encoding
         *
         * We verify both lengths.
         */

        mechOid.length = get_der_length(&buf,
                                (expName.length - curLength), &bytes);
        mechOid.elements = (void *)buf;

        /*
         * 'bytes' is the length of the DER length, '1' is for the DER
         * tag for OID
         */
        if ((bytes + mechOid.length + 1) != mechOidLen)
                return (GSS_S_DEFECTIVE_TOKEN);

        buf += mechOid.length;
        if ((mech = __gss_get_mechanism(&mechOid)) == NULL)
                return (GSS_S_BAD_MECH);

        if (mech->gss_import_name == NULL)
                return (GSS_S_UNAVAILABLE);

        /*
         * we must now determine if we should unwrap the name ourselves
         * or make the mechanism do it - we should only unwrap it
         * if we create it; so if mech->gss_export_name == NULL, we must
         * have created it.
         */
        if (mech->gss_export_name) {
                major = mech->gss_import_name(mech->context, minor,
                                            &expName,
                                            (gss_OID)GSS_C_NT_EXPORT_NAME,
                                            &unionName->mech_name);
                if (major != GSS_S_COMPLETE)
                        map_error(minor, mech);
                else {
                        major = generic_gss_copy_oid(minor, &mechOid,
                                                    &unionName->mech_type);
                        if (major != GSS_S_COMPLETE)
                                map_errcode(minor);
                }
                return (major);
        }
        /*
         * we must have exported the name - so we now need to reconstruct it
         * and call the mechanism to create it
         *
         * WARNING:     Older versions of __gss_export_internal_name() did
         *              not export names correctly, but now it does.  In
         *              order to stay compatible with existing exported
         *              names we must support names exported the broken
         *              way.
         *
         * Specifically, __gss_export_internal_name() used to include
         * the name type OID in the encoding of the exported MN.
         * Additionally, the Kerberos V mech used to make display names
         * that included a null terminator which was counted in the
         * display name gss_buffer_desc.
         */
        curLength += 4;         /* 4 bytes for name len */
        if (expName.length < curLength)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* next 4 bytes in the name are the name length */
        nameLen = (*buf++) << 24;
        nameLen |= (*buf++ << 16);
        nameLen |= (*buf++ << 8);
        nameLen |= (*buf++);

        /*
         * we use < here because bad code in rpcsec_gss rounds up exported
         * name token lengths and pads with nulls, otherwise != would be
         * appropriate
         */
        curLength += nameLen;   /* this is the total length */
        if (expName.length < curLength)
                return (GSS_S_DEFECTIVE_TOKEN);

        /*
         * We detect broken exported names here: they always start with
         * a two-octet network-byte order OID length, which is always
         * less than 256 bytes, so the first octet of the length is
         * always '\0', which is not allowed in GSS-API display names
         * (or never occurs in them anyways).  Of course, the OID
         * shouldn't be there, but it is.  After the OID (sans DER tag
         * and length) there's the name itself, though null-terminated;
         * this null terminator should also not be there, but it is.
         */
        if (nameLen > 0 && *buf == '\0') {
                OM_uint32 nameTypeLen;
                /* next two bytes are the name oid */
                if (nameLen < nameTypeLenLen)
                        return (GSS_S_DEFECTIVE_TOKEN);

                nameLen -= nameTypeLenLen;

                nameTypeLen = (*buf++) << 8;
                nameTypeLen |= (*buf++);

                if (nameLen < nameTypeLen)
                        return (GSS_S_DEFECTIVE_TOKEN);

                buf += nameTypeLen;
                nameLen -= nameTypeLen;

                /*
                 * adjust for expected null terminator that should
                 * really not be there
                 */
                if (nameLen > 0 && *(buf + nameLen - 1) == '\0')
                        nameLen--;
        }

        /*
         * Can a name be null?  Let the mech decide.
         *
         * NOTE: We use GSS_C_NULL_OID as the name type when importing
         *       the unwrapped name.  Presumably the exported name had,
         *       prior to being exported been obtained in such a way
         *       that it has been properly perpared ("canonicalized," in
         *       GSS-API terms) accroding to some name type; we cannot
         *       tell what that name type was now, but the name should
         *       need no further preparation other than the lowest
         *       common denominator afforded by the mech to names
         *       imported with GSS_C_NULL_OID.  For the Kerberos V mech
         *       this means doing less busywork too (particularly once
         *       IDN is thrown in with Kerberos V extensions).
         */
        expName.length = nameLen;
        expName.value = nameLen ? (void *)buf : NULL;
        major = mech->gss_import_name(mech->context, minor, &expName,
                            GSS_C_NULL_OID, &unionName->mech_name);
        if (major != GSS_S_COMPLETE) {
                map_error(minor, mech);
                return (major);
        }

        major = generic_gss_copy_oid(minor, &mechOid, &unionName->mech_type);
        if (major != GSS_S_COMPLETE) {
                map_errcode(minor);
        }
        return (major);
} /* importExportName */