encode.c

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/*
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   This library 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
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: 2a61464a5cd138dabce07297168318e2f3bdfaa0 $
 *
 * Because what we need is yet *ANOTHER* serialisation scheme.
 *
 * @file protocols/internal/encode.c
 * @brief Functions to encode data in our internal structure.
 *
 * @copyright 2020 The FreeRADIUS server project
 * @copyright 2020 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
#include <freeradius-devel/internal/internal.h>
#include <freeradius-devel/io/pair.h>
#include <freeradius-devel/io/test_point.h>
#include <freeradius-devel/util/net.h>
#include <freeradius-devel/util/proto.h>
 
 
static fr_internal_encode_ctx_t default_encode_ctx = { };
 
/** We use the same header for all types
 *
 */
 
/** Encode the value of the value pair the cursor currently points at.
 *
 * @param dbuff         data buffer to place the encoded data in
 * @param da_stack      da stack corresponding to the value pair
 * @param depth         in da_stack
 * @param cursor        cursor whose current value is the one to be encoded
 * @param encode_ctx    encoder context
 *
 * @return      either a negative number, indicating an error
 *              or the number of bytes used to encode the value
 */
static ssize_t internal_encode(fr_dbuff_t *dbuff,
                               fr_da_stack_t *da_stack, unsigned int depth,
                               fr_dcursor_t *cursor, void *encode_ctx)
{
        fr_dbuff_t                      work_dbuff = FR_DBUFF(dbuff);
        fr_dbuff_marker_t               enc_field, len_field, value_field;
        fr_dbuff_t                      value_dbuff;
        fr_dict_attr_t const            *da = da_stack->da[depth];
        fr_pair_t                       *vp = fr_dcursor_current(cursor);
        bool                            unknown = false, internal = false;
 
        ssize_t                         slen;
        size_t                          flen, vlen, mlen;
 
        uint8_t                         buff[sizeof(uint64_t)];
        uint8_t                         enc_byte = 0;
        fr_internal_encode_ctx_t        *our_encode_ctx = encode_ctx;
 
        if (!our_encode_ctx) our_encode_ctx = &default_encode_ctx;
 
        /*
         *      Silently skip name only attributes if we're writing
         *      to a database or cache.
         */
        if (!our_encode_ctx->allow_name_only && vp->da->flags.name_only) {
                fr_dcursor_next(cursor);
                return 0;
        }
 
        FR_PROTO_STACK_PRINT(da_stack, depth);
 
        fr_dbuff_marker(&enc_field, &work_dbuff);
 
        /*
         *      Advance past first encoding byte
         */
        FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, 0x00);
 
        switch (vp->vp_type) {
        /*
         *      Only leaf attributes can be tainted
         */
        case FR_TYPE_LEAF:
                if (vp->vp_tainted) enc_byte |= FR_INTERNAL_FLAG_TAINTED;
                break;
 
        default:
                break;
        }
 
        /*
         *      Need to use the second encoding byte
         *
         *      0                   1
         *      0 1 2 3 4 5 6 7 8 9 0
         *      +-+-+-+-+-+-+-+-+-+-+
         *      |u|i|-|-|-|-|-|e|
         *      +-+-+-+-+-+-+-+-+-+-+
         */
        if ((unknown = da->flags.is_unknown) ||
            (internal = (da->parent == fr_dict_root(fr_dict_internal())))) {
                enc_byte |= FR_INTERNAL_FLAG_EXTENDED;
                FR_DBUFF_IN_BYTES_RETURN(&work_dbuff,
                                         (unknown * FR_INTERNAL_FLAG_UNKNOWN) |
                                         (internal * FR_INTERNAL_FLAG_INTERNAL));
        }
 
        /*
         *      Encode the type and write the width of the
         *      integer to the encoding byte.
         */
        flen = fr_dbuff_in_uint64v(&work_dbuff, da->attr);
        if (flen <= 0) return flen;
        enc_byte |= ((flen - 1) << 5);
 
        /*
         *      Leave one byte in hopes that the length will fit
         *      so we needn't move the encoded data.
         */
        fr_dbuff_marker(&len_field, &work_dbuff);
        FR_DBUFF_ADVANCE_RETURN(&work_dbuff, 1);
 
        /*
         *      Create dbuff to hold encoded data--the fr_dbuff_move() done
         *      if the length field needs more than one byte will guard
         *      against insufficient space.
         */
        value_dbuff = FR_DBUFF_BIND_CURRENT(&work_dbuff);
        fr_dbuff_marker(&value_field, &value_dbuff);
 
        switch (da->type) {
        case FR_TYPE_LEAF:
                slen = fr_value_box_to_network(&value_dbuff, &vp->data);
                if (slen < 0) return PAIR_ENCODE_FATAL_ERROR;
                fr_dcursor_next(cursor);
                break;
 
        /*
         *      This is the vendor container.
         *      For RADIUS it'd be something like attr 26.
         *
         *      Inside the VSA you then have the vendor
         *      which is just encoded as another TLVish
         *      type attribute.
         *
         *      For small vendor PENs <= 255 this
         *      encoding is 6 bytes, the same as RADIUS.
         *
         *      For larger vendor PENs it's more bytes
         *      but we really don't care.
         */
        case FR_TYPE_VSA:
        case FR_TYPE_VENDOR:
 
        /*
         *      Children of TLVs are encoded in the context
         *      of the TLV.
         *
         *      STRUCTs are encoded as TLVs, because the struct
         *      packing only applies to the original protocol, and not
         *      to our internal encoding.
         */
        case FR_TYPE_TLV:
        case FR_TYPE_STRUCT:
                /*
                 *      We've done the complete stack.
                 *      Hopefully this TLV has some
                 *      children to encode...
                 */
                if (da == vp->da) {
                        fr_dcursor_t    children;
                        fr_pair_t       *child;
 
                        for (child = fr_pair_dcursor_init(&children, &vp->vp_group);
                             child;
                             child = fr_dcursor_current(&children)) {
 
                                FR_PROTO_TRACE("encode ctx changed %s -> %s", da->name, child->da->name);
 
                                fr_proto_da_stack_build_partial(da_stack, da_stack->da[depth], child->da);
                                FR_PROTO_STACK_PRINT(da_stack, depth);
 
                                slen = internal_encode(&value_dbuff, da_stack, depth + 1, &children, encode_ctx);
                                if (slen < 0) return slen;
                        }
                        fr_dcursor_next(cursor);
                        break;
                }
 
                /*
                 *      Still encoding intermediary TLVs...
                 */
                slen = internal_encode(&value_dbuff, da_stack, depth + 1, cursor, encode_ctx);
                if (slen < 0) return slen;
                break;
 
        /*
         *      Each child of a group encodes from the
         *      dictionary root to the leaf da.
         *
         *      Re-enter the encoder at the start.
         *      We do this, because the child may
         *      have a completely different da_stack.
         */
        case FR_TYPE_GROUP:
        {
                fr_dcursor_t    children;
                fr_pair_t       *child;
 
                for (child = fr_pair_dcursor_init(&children, &vp->vp_group);
                     child;
                     child = fr_dcursor_current(&children)) {
                        FR_PROTO_TRACE("encode ctx changed %s -> %s", da->name, child->da->name);
 
                        slen = fr_internal_encode_pair(&value_dbuff, &children, encode_ctx);
                        if (slen < 0) return slen;
                }
                fr_dcursor_next(cursor);
        }
                break;
 
        default:
                fr_strerror_printf("%s: Unexpected attribute type \"%s\"",
                                   __FUNCTION__, fr_type_to_str(da->type));
                return PAIR_ENCODE_FATAL_ERROR;
        }
 
        /*
         *      Encode the total length, and write the width
         *      of the integer to the encoding byte.
         *
         *      Already did length checks at the start of
         *      the function.
         */
        vlen = fr_dbuff_used(&value_dbuff);
        flen = (ssize_t) fr_nbo_from_uint64v(buff, vlen);
 
        /*
         *      Ugh, it's a long one, need to move the data.
         */
        if (flen > 1) {
                fr_dbuff_advance(&value_field, flen - 1);
                fr_dbuff_set_to_start(&value_dbuff);
                mlen = fr_dbuff_move(&value_field, &value_dbuff, vlen);
                if (mlen < vlen) return -(vlen - mlen);
        }
 
        FR_DBUFF_IN_MEMCPY_RETURN(&len_field, buff, flen);
        enc_byte |= ((flen - 1) << 2);
        FR_DBUFF_IN_RETURN(&enc_field, enc_byte);
 
        FR_PROTO_HEX_DUMP(fr_dbuff_start(&work_dbuff), fr_dbuff_used(&work_dbuff) - vlen, "header");
 
        FR_PROTO_HEX_DUMP(fr_dbuff_start(&value_dbuff), vlen, "value %s",
                          fr_type_to_str(vp->vp_type));
 
        return fr_dbuff_set(dbuff, &work_dbuff);
}
 
/** Encode a data structure into an internal attribute
 *
 * @param[in,out] dbuff         Where to write encoded data and how much one can write.
 * @param[in] cursor            Specifying attribute to encode.
 * @param[in] encode_ctx        Additional data such as the shared secret to use.
 * @return
 *      - >0 The number of bytes written to out.
 *      - 0 Nothing to encode (or attribute skipped).
 *      - <0 an error occurred.
 */
ssize_t fr_internal_encode_pair(fr_dbuff_t *dbuff, fr_dcursor_t *cursor, void *encode_ctx)
{
        fr_pair_t               *vp;
        fr_da_stack_t           da_stack;
 
        vp = fr_dcursor_current(cursor);
        if (!vp) return 0;
 
        fr_proto_da_stack_build(&da_stack, vp->da);
 
        return internal_encode(dbuff, &da_stack, 0, cursor, encode_ctx);
}
 
/** Encode a list of pairs using the internal encoder
 *
 * @param[out] dbuff            Where to write encoded data.
 * @param[in] list              List of attributes to encode.
 * @param[in] encode_ctx        Additional data to be used by the encoder.
 * @return
 *      - length of encoded data on success
 *      - < 0 on failure
 */
ssize_t fr_internal_encode_list(fr_dbuff_t *dbuff, fr_pair_list_t const *list, void *encode_ctx)
{
        fr_pair_t               *vp;
        fr_dcursor_t            dcursor;
        ssize_t                 ret = 0, len = 0;
        fr_da_stack_t           da_stack;
 
        for (vp = fr_pair_dcursor_init(&dcursor, list);
             vp;
             vp = fr_dcursor_current(&dcursor)) {
                fr_proto_da_stack_build(&da_stack, vp->da);
                ret = internal_encode(dbuff, &da_stack, 0, &dcursor, encode_ctx);
                if (ret < 0) return ret;
                len += ret;
        }
 
        return len;
}
 
/*
 *      Test points
 */
extern fr_test_point_pair_encode_t internal_tp_encode_pair;
fr_test_point_pair_encode_t internal_tp_encode_pair = {
        .test_ctx       = NULL,
        .func           = fr_internal_encode_pair
};