rlm_brotli.c

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/*
 *   This program is 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: ed081cc16421614c3c0c448d78b336a4b9d42c77 $
 * @file rlm_brotli.c
 * @brief Add support for brotli compression
 *
 * @copyright 2024 The FreeRADIUS server project
 * @copyright 2024 Arran Cudbard-Bell <a.cudbardb@freeradius.org>
 */
RCSID("$Id: ed081cc16421614c3c0c448d78b336a4b9d42c77 $")
 
#define LOG_PREFIX mctx->mi->name
 
#include <brotli/encode.h>
#include <brotli/decode.h>
 
#include <freeradius-devel/util/atexit.h>
#include <freeradius-devel/util/value.h>
 
#include <freeradius-devel/server/module_rlm.h>
 
#include <freeradius-devel/unlang/xlat.h>
#include <freeradius-devel/unlang/xlat_func.h>
 
static int quality_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule);
static int window_bits_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule);
static int block_bits_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule);
 
typedef struct {
        BrotliEncoderMode               mode;                   //!< Default mode to use when compressing data.
        int                             quality;                //!< Default quality to use when compressing data.
        int                             window_bits;            //!< Default window bits to use when compressing data.
        int                             block_bits;             //!< Default block bits to use when compressing data.
        bool                            block_bits_is_set;      //!< Whether block_bits has been set.
} rlm_brotli_compress_t;
 
typedef struct {
        size_t                          max_size;               //!< Maximum amount we attempt to decode
} rlm_brotli_decompress_t;
 
typedef struct {
        rlm_brotli_compress_t           compress;               //!< Compression settings
        rlm_brotli_decompress_t         decompress;             //!< Decompression settings
        bool                            large_window;           //!< non-standard "large", window size.
} rlm_brotli_t;
 
static fr_table_num_sorted_t const brotli_mode[] = {
        { L("font"),            BROTLI_MODE_FONT        },      //!< Probably not useful?
        { L("generic"),         BROTLI_MODE_GENERIC     },
        { L("text"),            BROTLI_MODE_TEXT        },
};
static size_t brotli_mode_len = NUM_ELEMENTS(brotli_mode);
 
static const conf_parser_t module_compress_config[] = {
        { FR_CONF_OFFSET("mode", rlm_brotli_compress_t, mode), .dflt = "generic",
                         .func = cf_table_parse_int, .uctx = &(cf_table_parse_ctx_t){ .table = brotli_mode, .len = &brotli_mode_len } },
        { FR_CONF_OFFSET("quality", rlm_brotli_compress_t, quality), .dflt = STRINGIFY(BROTLI_DEFAULT_QUALITY), .func = quality_parse },
        { FR_CONF_OFFSET("window_bits", rlm_brotli_compress_t, window_bits), .dflt = STRINGIFY(BROTLI_DEFAULT_WINDOW), .func = window_bits_parse },
        { FR_CONF_OFFSET_IS_SET("block_bits", FR_TYPE_INT32, 0, rlm_brotli_compress_t, block_bits), .dflt = STRINGIFY(BROTLI_MAX_INPUT_BLOCK_BITS), .func = block_bits_parse },
        CONF_PARSER_TERMINATOR
};
 
static const conf_parser_t module_decompress_config[] = {
        { FR_CONF_OFFSET_TYPE_FLAGS("max_size", FR_TYPE_SIZE, 0, rlm_brotli_decompress_t, max_size), .dflt = "10M" }, /* 10MB */
        CONF_PARSER_TERMINATOR
};
 
static const conf_parser_t module_config[] = {
        { FR_CONF_OFFSET_SUBSECTION("compress", 0, rlm_brotli_t, compress, module_compress_config) },
        { FR_CONF_OFFSET_SUBSECTION("decompress", 0, rlm_brotli_t, decompress, module_decompress_config) },
        { FR_CONF_OFFSET("large_window", rlm_brotli_t, large_window), .dflt = "no" },   /* For both compress and decompress */
 
        CONF_PARSER_TERMINATOR
};
 
static _Thread_local TALLOC_CTX *brotli_pool;   //!< Thread-local pool for brotli state
 
static inline CC_HINT(always_inline)
TALLOC_CTX *brotli_pool_get(void)
{
        if (unlikely(brotli_pool == NULL)) {
                TALLOC_CTX *pool;
 
                MEM(pool = talloc_pool(NULL, 4096));
                fr_atexit_thread_local(brotli_pool, fr_atexit_talloc_free, pool);
 
        }
        return brotli_pool;
}
 
static void *brotli_talloc_alloc(void *uctx, size_t size)
{
        void *ptr = talloc_size(uctx, size);
        return ptr;
}
 
static void brotli_talloc_free(UNUSED void *uctx, void *to_free)
{
        talloc_free(to_free);
}
 
static int quality_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule)
{
        int                     ret;
        int                     value;
 
        ret = cf_pair_parse_value(ctx, out, parent, ci, rule);
        if (ret < 0) return ret;
 
        value = *(int *) out;
        if ((value > BROTLI_MAX_QUALITY) || (value < BROTLI_MIN_QUALITY)) {
                cf_log_err(ci, "Allowed values are between %d-%d, got %d", BROTLI_MIN_QUALITY, BROTLI_MAX_QUALITY, value);
                return -1;
        }
 
        return 0;
}
 
static int window_bits_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule)
{
        int                     ret;
        int                     value;
 
        ret = cf_pair_parse_value(ctx, out, parent, ci, rule);
        if (ret < 0) return ret;
 
        value = *(int *) out;
        if ((value > BROTLI_MAX_WINDOW_BITS) || (value < BROTLI_MIN_WINDOW_BITS)) {
                cf_log_err(ci, "Allowed values are between %d-%d, got %d", BROTLI_MIN_WINDOW_BITS, BROTLI_MAX_WINDOW_BITS, value);
                return -1;
        }
 
        return 0;
}
 
static int block_bits_parse(TALLOC_CTX *ctx, void *out, void *parent, CONF_ITEM *ci, conf_parser_t const *rule)
{
        int                     ret;
        int                     value;
 
        ret = cf_pair_parse_value(ctx, out, parent, ci, rule);
        if (ret < 0) return ret;
 
        value = *(int *) out;
        if ((value > BROTLI_MAX_INPUT_BLOCK_BITS) || (value < BROTLI_MIN_INPUT_BLOCK_BITS)) {
                cf_log_err(ci, "Allowed values are between %d-%d, got %d", BROTLI_MIN_INPUT_BLOCK_BITS, BROTLI_MAX_INPUT_BLOCK_BITS, value);
                return -1;
        }
 
        return 0;
}
 
static xlat_arg_parser_t const brotli_xlat_compress_args[] = {
        { .required = true, .type = FR_TYPE_OCTETS },                   /* Input converted to raw binary data.  All inputs will be added to the same stream */
        XLAT_ARG_PARSER_TERMINATOR
};
 
/** Produce a brotli compressed string
 *
 * Example:
@verbatim
%brotli.compress(<input>) == <compressed data>
@endverbatim
 *
 * @ingroup xlat_functions
 */
static xlat_action_t brotli_xlat_compress(TALLOC_CTX *ctx, fr_dcursor_t *out,
                                          xlat_ctx_t const *xctx,
                                          request_t *request, fr_value_box_list_t *args)
{
        rlm_brotli_t const              *inst = talloc_get_type_abort_const(xctx->mctx->mi->data, rlm_brotli_t);
        fr_value_box_t const            *data_vb;
 
        BrotliEncoderState              *state;
        TALLOC_CTX                      *pool;
 
        size_t                          available_out = 0, total_out = 0, total_in = 0;
        fr_value_box_t                  *out_vb;
        uint8_t                         *out_buff;
 
        xlat_action_t                   ret = XLAT_ACTION_DONE;
 
        XLAT_ARGS(args, &data_vb);
 
        fr_assert(fr_type_is_group(data_vb->type));
 
        /*
         *      Calculate the maximum size of our output buffer
         *      and pre-allocate that.  We'll shrink it later.
         */
        fr_value_box_list_foreach(&data_vb->vb_group, vb) {
                total_in += vb->vb_length;
                available_out += BrotliEncoderMaxCompressedSize(vb->vb_length);
        }
 
        MEM(out_vb = fr_value_box_alloc(ctx, FR_TYPE_OCTETS, NULL));
        MEM(fr_value_box_mem_alloc(out_vb, &out_buff, out_vb, NULL, available_out, false) == 0);
 
        pool = brotli_pool_get();
        MEM(state = BrotliEncoderCreateInstance(brotli_talloc_alloc, brotli_talloc_free, pool));
 
        BrotliEncoderSetParameter(state, BROTLI_PARAM_MODE, inst->compress.mode);
        BrotliEncoderSetParameter(state, BROTLI_PARAM_QUALITY, inst->compress.quality);
        BrotliEncoderSetParameter(state, BROTLI_PARAM_LGWIN, inst->compress.window_bits);
        if (inst->compress.block_bits_is_set) BrotliEncoderSetParameter(state, BROTLI_PARAM_LGBLOCK, inst->compress.block_bits);
        BrotliEncoderSetParameter(state, BROTLI_PARAM_LARGE_WINDOW, inst->large_window ? BROTLI_TRUE : BROTLI_FALSE);
        BrotliEncoderSetParameter(state, BROTLI_PARAM_SIZE_HINT, total_in);
        /*
         *      Loop over all the input data and ingest it into brotli
         *      which will add it to an internal buffer (hopefully
         *      allocated, in our thread local pool).
         */
        {
                fr_value_box_list_foreach(&data_vb->vb_group, vb) {
                        size_t available_in = vb->vb_length;
                        const uint8_t *next_in = vb->vb_octets;
                        bool more = fr_value_box_list_next(&data_vb->vb_group, vb) != NULL;
 
                        /*
                         *      In reality this loop is probably unnecessary,
                         *      but the brotli docs state:
                         *
                         *      "client should repeat BROTLI_OPERATION_FINISH operation until available_in becomes 0,
                         *       and BrotliEncoderHasMoreOutput returns BROTLI_FALSE"
                         */
                        do {
                                BROTLI_BOOL bret;
 
                                bret = BrotliEncoderCompressStream(state,
                                                                   more ? BROTLI_OPERATION_PROCESS : BROTLI_OPERATION_FINISH,
                                                                   &available_in, &next_in, &available_out, &out_buff, &total_out);
                                if (bret == BROTLI_FALSE) {
                                        fr_assert_msg(0, "BrotliEncoderCompressStream returned false, this shouldn't happen");
                                        RERROR("BrotliEncoderCompressStream failed");
                                        ret = XLAT_ACTION_FAIL;
                                        goto finish;
                                }
                        } while (more && (available_in > 0) && (BrotliEncoderHasMoreOutput(state) == BROTLI_FALSE));
 
                        /*
                         *      There's no reason brotli wouldn't consume the complete
                         *      buffer on BROTLI_OPERATION_PROCESS.
                         */
                        fr_assert(available_in == 0);
                }
        }
 
        /*
         *      Realloc to the correct size if necessary
         */
        if (available_out != 0) MEM(fr_value_box_mem_realloc(out_vb, NULL, out_vb, total_out) == 0);
 
        fr_dcursor_insert(out, out_vb);
 
finish:
        BrotliEncoderDestroyInstance(state);
        talloc_free_children(pool);
 
        return ret;
}
 
static xlat_arg_parser_t const brotli_xlat_decompress_args[] = {
        { .required = true, .single = true, .type = FR_TYPE_OCTETS },
        XLAT_ARG_PARSER_TERMINATOR
};
 
/** Decompress a brotli string
 *
 * Example:
@verbatim
%brotli.decompress(<input>) == <decompressed data>
@endverbatim
 *
 * @ingroup xlat_functions
 */
static xlat_action_t brotli_xlat_decompress(TALLOC_CTX *ctx, fr_dcursor_t *out,
                                            xlat_ctx_t const *xctx,
                                            request_t *request, fr_value_box_list_t *args)
{
        rlm_brotli_t const              *inst = talloc_get_type_abort_const(xctx->mctx->mi->data, rlm_brotli_t);
        fr_value_box_t const            *data_vb;
 
        BrotliDecoderState              *state;
        TALLOC_CTX                      *pool;
 
        fr_value_box_t                  *out_vb;
 
        size_t                          total_in;
        size_t                          available_out;
        size_t                          total_out = 0;
 
        uint8_t const                   *in_buff;
        uint8_t                         *out_buff;
 
        xlat_action_t                   ret = XLAT_ACTION_DONE;
 
        XLAT_ARGS(args, &data_vb);
 
        MEM(out_vb = fr_value_box_alloc(ctx, FR_TYPE_OCTETS, NULL));
        available_out = (data_vb->vb_length * 2);
        MEM(fr_value_box_mem_alloc(out_vb, &out_buff, out_vb, NULL, available_out, false) == 0);
 
        pool = brotli_pool_get();
        MEM(state = BrotliDecoderCreateInstance(brotli_talloc_alloc, brotli_talloc_free, pool));
 
        BrotliDecoderSetParameter(state, BROTLI_DECODER_PARAM_LARGE_WINDOW, inst->large_window ? BROTLI_TRUE : BROTLI_FALSE);
 
        total_in = data_vb->vb_length;
        in_buff = data_vb->vb_octets;
 
        for (;;) {
                switch (BrotliDecoderDecompressStream(state, &total_in, &in_buff, &available_out, &out_buff, &total_out)) {
                default:
                case BROTLI_DECODER_RESULT_ERROR:
                {
                        BrotliDecoderErrorCode error = BrotliDecoderGetErrorCode(state);
                        REDEBUG("Decompressing brotli data failed - %s", BrotliDecoderErrorString(error));
                        ret = XLAT_ACTION_FAIL;
                        goto finish;
                }
 
                case BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT:
                        REDEBUG("Incomplete or truncated brotli data provided.  Decompressor wants more input...");
                        ret = XLAT_ACTION_FAIL;
                        goto finish;
 
                case BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT:
                {
                        size_t extra = out_vb->vb_length;
 
                        /*
                         *      Stop runaway brotli decodings...
                         */
                        if ((out_vb->vb_length + extra) > inst->decompress.max_size) {
                                RERROR("Decompressed data exceeds maximum size of %zu", inst->decompress.max_size);
                                ret = XLAT_ACTION_FAIL;
                                goto finish;
                        }
 
                        MEM(fr_value_box_mem_realloc(out_vb, &out_buff, out_vb, out_vb->vb_length + extra) == 0);
                        available_out += extra;
                }
                        continue;       /* Again! */
 
                case BROTLI_DECODER_RESULT_SUCCESS:
                        if (BrotliDecoderIsFinished(state) == BROTLI_TRUE) {
                                MEM(fr_value_box_mem_realloc(out_vb, &out_buff, out_vb, total_out) == 0);
                                fr_dcursor_insert(out, out_vb);
                                goto finish;
                        }
                        continue;       /* Again! */
                }
        }
 
finish:
        BrotliDecoderDestroyInstance(state);
        talloc_free_children(pool);
 
        return ret;
}
 
static int mod_bootstrap(module_inst_ctx_t const *mctx)
{
        xlat_t  *xlat;
 
        if (unlikely((xlat = module_rlm_xlat_register(mctx->mi->boot, mctx, "compress", brotli_xlat_compress,
                                                       FR_TYPE_OCTETS)) == NULL)) return -1;
        xlat_func_args_set(xlat, brotli_xlat_compress_args);
 
        if (unlikely((xlat = module_rlm_xlat_register(mctx->mi->boot, mctx, "decompress", brotli_xlat_decompress,
                                                       FR_TYPE_OCTETS)) == NULL)) return -1;
        xlat_func_args_set(xlat, brotli_xlat_decompress_args);
 
        return 0;
}
 
/*
 *      The module name should be the only globally exported symbol.
 *      That is, everything else should be 'static'.
 *
 *      If the module needs to temporarily modify it's instantiation
 *      data, the type should be changed to MODULE_TYPE_THREAD_UNSAFE.
 *      The server will then take care of ensuring that the module
 *      is single-threaded.
 */
extern module_rlm_t rlm_brotli;
module_rlm_t rlm_brotli = {
        .common = {
                .magic                  = MODULE_MAGIC_INIT,
                .name                   = "brotli",
                .inst_size              = sizeof(rlm_brotli_t),
                .bootstrap              = mod_bootstrap,
                .config                 = module_config
        }
};