/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 * Copyright 1993 by OpenVision Technologies, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appears in all copies and
 * that both that copyright notice and this permission notice appear in
 * supporting documentation, and that the name of OpenVision not be used
 * in advertising or publicity pertaining to distribution of the software
 * without specific, written prior permission. OpenVision makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Copyright (C) 1998 by the FundsXpress, INC.
 *
 * All rights reserved.
 *
 * Export of this software from the United States of America may require
 * a specific license from the United States Government.  It is the
 * responsibility of any person or organization contemplating export to
 * obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of FundsXpress. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  FundsXpress makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include "gssapiP_krb5.h"

#include <assert.h>

static krb5_error_code
make_seal_token_v1 (krb5_context context,
                    krb5_key enc,
                    krb5_key seq,
                    uint64_t *seqnum,
                    int direction,
                    gss_buffer_t text,
                    gss_buffer_t token,
                    int signalg,
                    size_t cksum_size,
                    int sealalg,
                    int do_encrypt,
                    int toktype,
                    gss_OID oid)
{
    krb5_error_code code;
    size_t sumlen;
    char *data_ptr;
    krb5_data plaind;
    krb5_checksum md5cksum;
    /* msglen contains the message length
     * we are signing/encrypting.  tmsglen
     * contains the length of the message
     * we plan to write out to the token.
     * tlen is the length of the token
     * including header. */
    unsigned int conflen=0, tmsglen, tlen, msglen;
    unsigned char *t, *metadata, *checksum, *payload;
    unsigned char *plain;
    unsigned char pad;
    krb5_keyusage sign_usage = KG_USAGE_SIGN;
    struct k5buf buf;

    assert((!do_encrypt) || (toktype == KG_TOK_SEAL_MSG));
    /* create the token buffer */
    /* Do we need confounder? */
    if (do_encrypt || toktype == KG_TOK_SEAL_MSG)
        conflen = kg_confounder_size(context, enc->keyblock.enctype);
    else conflen = 0;

    if (toktype == KG_TOK_SEAL_MSG) {
        switch (sealalg) {
        case SEAL_ALG_MICROSOFT_RC4:
            msglen = conflen + text->length+1;
            pad = 1;
            break;
        default:
            /* XXX knows that des block size is 8 */
            msglen = (conflen+text->length+8)&(~7);
            pad = 8-(text->length%8);
        }
        tmsglen = msglen;
    } else {
        tmsglen = 0;
        msglen = text->length;
        pad = 0;
    }

    tlen = g_token_size(oid, 14 + cksum_size + tmsglen);
    t = gssalloc_malloc(tlen);
    if (t == NULL)
        return(ENOMEM);
    k5_buf_init_fixed(&buf, t, tlen);

    /*** fill in the token */

    g_make_token_header(&buf, oid, 14 + cksum_size + tmsglen, toktype);
    metadata = k5_buf_get_space(&buf, 14);
    checksum = k5_buf_get_space(&buf, cksum_size);
    payload = k5_buf_get_space(&buf, tmsglen);
    assert(metadata != NULL && checksum != NULL && payload != NULL);
    assert(buf.len == tlen);

    /* 0..1 SIGN_ALG */
    store_16_le(signalg, &metadata[0]);

    /* 2..3 SEAL_ALG or Filler */
    if ((toktype == KG_TOK_SEAL_MSG) && do_encrypt) {
        store_16_le(sealalg, &metadata[2]);
    } else {
        /* No seal */
        metadata[2] = 0xFF;
        metadata[3] = 0xFF;
    }

    /* 4..5 Filler */
    metadata[4] = 0xFF;
    metadata[5] = 0xFF;

    /* pad the plaintext, encrypt if needed, and stick it in the token */

    /* initialize the the checksum */
    switch (signalg) {
    case SGN_ALG_HMAC_SHA1_DES3_KD:
        md5cksum.checksum_type = CKSUMTYPE_HMAC_SHA1_DES3;
        break;
    case SGN_ALG_HMAC_MD5:
        md5cksum.checksum_type = CKSUMTYPE_HMAC_MD5_ARCFOUR;
        if (toktype != KG_TOK_SEAL_MSG)
            sign_usage = 15;
        break;
    default:
        abort ();
    }

    code = krb5_c_checksum_length(context, md5cksum.checksum_type, &sumlen);
    if (code) {
        gssalloc_free(t);
        return(code);
    }
    md5cksum.length = sumlen;


    if ((plain = (unsigned char *) xmalloc(msglen ? msglen : 1)) == NULL) {
        gssalloc_free(t);
        return(ENOMEM);
    }

    if (conflen) {
        if ((code = kg_make_confounder(context, enc->keyblock.enctype,
                                       plain))) {
            xfree(plain);
            gssalloc_free(t);
            return(code);
        }
    }

    memcpy(plain+conflen, text->value, text->length);
    if (pad) memset(plain+conflen+text->length, pad, pad);

    /* compute the checksum */

    /* 8 = head of token body as specified by mech spec */
    if (! (data_ptr = xmalloc(8 + msglen))) {
        xfree(plain);
        gssalloc_free(t);
        return(ENOMEM);
    }
    /* Checksum over the token ID, metadata bytes, and plaintext. */
    memcpy(data_ptr, metadata - 2, 8);
    memcpy(data_ptr + 8, plain, msglen);
    plaind.length = 8 + msglen;
    plaind.data = data_ptr;
    code = krb5_k_make_checksum(context, md5cksum.checksum_type, seq,
                                sign_usage, &plaind, &md5cksum);
    xfree(data_ptr);

    if (code) {
        xfree(plain);
        gssalloc_free(t);
        return(code);
    }
    switch(signalg) {
    case SGN_ALG_HMAC_SHA1_DES3_KD:
        /*
         * Using key derivation, the call to krb5_c_make_checksum
         * already dealt with encrypting.
         */
        if (md5cksum.length != cksum_size)
            abort ();
        memcpy(checksum, md5cksum.contents, md5cksum.length);
        break;
    case SGN_ALG_HMAC_MD5:
        memcpy(checksum, md5cksum.contents, cksum_size);
        break;
    }

    krb5_free_checksum_contents(context, &md5cksum);

    /* create the seq_num */

    code = kg_make_seq_num(context, seq, direction?0:0xff,
                           (krb5_ui_4)*seqnum, checksum, metadata + 6);
    if (code) {
        xfree (plain);
        gssalloc_free(t);
        return(code);
    }

    if (do_encrypt) {
        switch(sealalg) {
        case SEAL_ALG_MICROSOFT_RC4:
        {
            unsigned char bigend_seqnum[4];
            krb5_keyblock *enc_key;
            int i;
            store_32_be(*seqnum, bigend_seqnum);
            code = krb5_k_key_keyblock(context, enc, &enc_key);
            if (code)
            {
                xfree(plain);
                gssalloc_free(t);
                return(code);
            }
            assert (enc_key->length == 16);
            for (i = 0; i <= 15; i++)
                ((char *) enc_key->contents)[i] ^=0xf0;
            code = kg_arcfour_docrypt(enc_key, 0, bigend_seqnum, 4, plain,
                                      tmsglen, payload);
            krb5_free_keyblock (context, enc_key);
            if (code)
            {
                xfree(plain);
                gssalloc_free(t);
                return(code);
            }
        }
        break;
        default:
            code = kg_encrypt(context, enc, KG_USAGE_SEAL, NULL,  plain,
                              payload, tmsglen);
            if (code) {
                xfree(plain);
                gssalloc_free(t);
                return(code);
            }
        }
    }else {
        if (tmsglen)
            memcpy(payload, plain, tmsglen);
    }
    xfree(plain);


    /* that's it.  return the token */

    (*seqnum)++;
    *seqnum &= 0xffffffffL;

    token->length = tlen;
    token->value = (void *) t;

    return(0);
}

/* if signonly is true, ignore conf_req, conf_state,
   and do not encode the ENC_TYPE, MSG_LENGTH, or MSG_TEXT fields */

OM_uint32
kg_seal(OM_uint32 *minor_status, gss_ctx_id_t context_handle,
        int conf_req_flag, gss_qop_t qop_req,
        gss_buffer_t input_message_buffer, int *conf_state,
        gss_buffer_t output_message_buffer, int toktype)
{
    krb5_gss_ctx_id_rec *ctx;
    krb5_error_code code;
    krb5_context context;

    output_message_buffer->length = 0;
    output_message_buffer->value = NULL;

    /* Only default qop or matching established cryptosystem is allowed.

       There are NO EXTENSIONS to this set for AES and friends!  The
       new spec says "just use 0".  The old spec plus extensions would
       actually allow for certain non-zero values.  Fix this to handle
       them later.  */
    if (qop_req != 0) {
        *minor_status = (OM_uint32) G_UNKNOWN_QOP;
        return GSS_S_BAD_QOP;
    }

    ctx = (krb5_gss_ctx_id_rec *) context_handle;

    if (ctx->terminated || !ctx->established) {
        *minor_status = KG_CTX_INCOMPLETE;
        return(GSS_S_NO_CONTEXT);
    }

    context = ctx->k5_context;
    switch (ctx->proto)
    {
    case 0:
        code = make_seal_token_v1(context, ctx->enc, ctx->seq,
                                  &ctx->seq_send, ctx->initiate,
                                  input_message_buffer, output_message_buffer,
                                  ctx->signalg, ctx->cksum_size, ctx->sealalg,
                                  conf_req_flag, toktype, ctx->mech_used);
        break;
    case 1:
        code = gss_krb5int_make_seal_token_v3(context, ctx,
                                              input_message_buffer,
                                              output_message_buffer,
                                              conf_req_flag, toktype);
        break;
    default:
        code = G_UNKNOWN_QOP;   /* XXX */
        break;
    }

    if (code) {
        *minor_status = code;
        save_error_info(*minor_status, context);
        return(GSS_S_FAILURE);
    }

    if (conf_state)
        *conf_state = conf_req_flag;

    *minor_status = 0;
    return(GSS_S_COMPLETE);
}

OM_uint32 KRB5_CALLCONV
krb5_gss_wrap(OM_uint32 *minor_status, gss_ctx_id_t context_handle,
              int conf_req_flag, gss_qop_t qop_req,
              gss_buffer_t input_message_buffer, int *conf_state,
              gss_buffer_t output_message_buffer)
{
    return(kg_seal(minor_status, context_handle, conf_req_flag,
                   qop_req, input_message_buffer, conf_state,
                   output_message_buffer, KG_TOK_WRAP_MSG));
}

OM_uint32 KRB5_CALLCONV
krb5_gss_get_mic(OM_uint32 *minor_status, gss_ctx_id_t context_handle,
                 gss_qop_t qop_req, gss_buffer_t message_buffer,
                 gss_buffer_t message_token)
{
    return(kg_seal(minor_status, context_handle, 0,
                   qop_req, message_buffer, NULL,
                   message_token, KG_TOK_MIC_MSG));
}