[mod_deflate] skip deflate if loadavg too high (fixes #1505)

[lighttpd.git] / src / mod_deflate.c

/* mod_deflate
 *
 *
 * bug fix on Robert Jakabosky from alphatrade.com's lighttp 1.4.10 mod_deflate patch
 *
 * Bug fix and new features:
 * 1) fix loop bug when content-length is bigger than work-block-size*k
 *
 * -------
 *
 * lighttpd-1.4.26.mod_deflate.patch from
 *   https://redmine.lighttpd.net/projects/1/wiki/Docs_ModDeflate
 *
 * -------
 *
 * Patch further modified in this incarnation.
 *
 * Note: this patch only handles completed responses (con->file_finished);
 *       this patch does not currently handle streaming dynamic responses,
 *       and therefore also does not worry about Transfer-Encoding: chunked
 *       (or having separate con->output_queue for chunked-encoded output)
 *       (or using separate buffers per connection instead of p->tmp_buf)
 *       (or handling interactions with block buffering and write timeouts)
 *
 * Bug fix:
 * - fixed major bug with compressing chunks with offset > 0
 *     x-ref:
 *       "Response breaking in mod_deflate"
 *       https://redmine.lighttpd.net/issues/986
 * - fix broken (in some cases) chunk accounting in deflate_compress_response()
 * - fix broken bzip2
 *     x-ref:
 *       "mod_deflate's bzip2 broken by default"
 *       https://redmine.lighttpd.net/issues/2035
 * - fix mismatch with current chunk interfaces
 *     x-ref:
 *       "Weird things in chunk.c (functions only handling specific cases, unexpected behaviour)"
 *       https://redmine.lighttpd.net/issues/1510
 *
 * Behavior changes from prior patch:
 * - deflate.mimetypes must now be configured to enable compression
 *     deflate.mimetypes = ( )          # compress nothing (disabled; default)
 *     deflate.mimetypes = ( "" )       # compress all mimetypes
 *     deflate.mimetypes = ( "text/" )  # compress text/... mimetypes
 *     x-ref:
 *       "mod_deflate enabled by default"
 *       https://redmine.lighttpd.net/issues/1394
 * - deflate.enabled directive removed (see new behavior of deflate.mimetypes)
 * - deflate.debug removed (was developer debug trace, not end-user debug)
 * - deflate.bzip2 replaced with deflate.allowed-encodings (like mod_compress)
 *     x-ref:
 *       "mod_deflate should allow limiting of compression algorithm from the configuration file"
 *       https://redmine.lighttpd.net/issues/996
 *       "mod_compress disabling methods"
 *       https://redmine.lighttpd.net/issues/1773
 * - deflate.nocompress-url removed since disabling compression for a URL
 *   can now easily be done by setting to a blank list either directive
 *   deflate.accept_encodings = () or deflate.mimetypes = () in a conditional
 *   block, e.g. $HTTP["url"] =~ "....." { deflate.mimetypes = ( ) }
 * - deflate.sync-flush removed; controlled by con->conf.stream_response_body
 *     (though streaming compression not currently implemented in mod_deflate)
 * - inactive directives in this patch (since con->file_finished required)
 *     deflate.work-block-size
 *     deflate.output-buffer-size
 * - remove weak file size check; SIGBUS is trapped, file that shrink will error
 *     x-ref:
 *       "mod_deflate: filesize check is too weak"
 *       https://redmine.lighttpd.net/issues/1512
 * - change default deflate.min-compress-size from 0 to now be 256
 *   http://webmasters.stackexchange.com/questions/31750/what-is-recommended-minimum-object-size-for-gzip-performance-benefits
 *   Apache 2.4 mod_deflate minimum is 68 bytes
 *   Akamai recommends minimum 860 bytes
 *   Google recommends minimum be somewhere in range between 150 and 1024 bytes
 * - deflate.max-compress-size new directive (in kb like compress.max_filesize)
 * - deflate.mem-level removed (too many knobs for little benefit)
 * - deflate.window-size removed (too many knobs for little benefit)
 *
 * Future:
 * - config directives may be changed, renamed, or removed
 *   e.g. A set of reasonable defaults might be chosen
 *        instead of making them configurable.
 *     deflate.min-compress-size
 * - might add deflate.mimetypes-exclude = ( ... ) for list of mimetypes
 *   to avoid compressing, even if a broader deflate.mimetypes matched,
 *   e.g. to compress all "text/" except "text/special".
 * - mod_compress and mod_deflate might merge overlapping feature sets
 *     (mod_compress.cache-dir does not yet have an equivalent in mod_deflate)
 *
 * Implementation notes:
 * - http_chunk_append_mem() used instead of http_chunk_append_buffer()
 *   so that p->tmp_buf can be large and re-used.  This results in an extra copy
 *   of compressed data before data is sent to network, though if the compressed
 *   size is larger than 64k, it ends up being sent to a temporary file on
 *   disk without suffering an extra copy in memory, and without extra chunk
 *   create and destroy.  If this is ever changed to give away buffers, then use
 *   a unique hctx->output buffer per hctx; do not reuse p->tmp_buf across
 *   multiple requests being handled in parallel.
 */
#include "first.h"

#include <sys/types.h>
#include <sys/stat.h>
#include "sys-mmap.h"

#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>

#include "base.h"
#include "log.h"
#include "buffer.h"
#include "etag.h"
#include "http_chunk.h"
#include "response.h"

#include "plugin.h"

#if defined HAVE_ZLIB_H && defined HAVE_LIBZ
# define USE_ZLIB
# include <zlib.h>
#endif
#ifndef Z_DEFAULT_COMPRESSION
#define Z_DEFAULT_COMPRESSION -1
#endif
#ifndef MAX_WBITS
#define MAX_WBITS 15
#endif

#if defined HAVE_BZLIB_H && defined HAVE_LIBBZ2
# define USE_BZ2LIB
/* we don't need stdio interface */
# define BZ_NO_STDIO
# include <bzlib.h>
#endif

#if defined HAVE_SYS_MMAN_H && defined HAVE_MMAP && defined ENABLE_MMAP
#define USE_MMAP

#include "sys-mmap.h"
#include <setjmp.h>
#include <signal.h>

static volatile int sigbus_jmp_valid;
static sigjmp_buf sigbus_jmp;

static void sigbus_handler(int sig) {
        UNUSED(sig);
        if (sigbus_jmp_valid) siglongjmp(sigbus_jmp, 1);
        log_failed_assert(__FILE__, __LINE__, "SIGBUS");
}
#endif

/* request: accept-encoding */
#define HTTP_ACCEPT_ENCODING_IDENTITY BV(0)
#define HTTP_ACCEPT_ENCODING_GZIP     BV(1)
#define HTTP_ACCEPT_ENCODING_DEFLATE  BV(2)
#define HTTP_ACCEPT_ENCODING_COMPRESS BV(3)
#define HTTP_ACCEPT_ENCODING_BZIP2    BV(4)
#define HTTP_ACCEPT_ENCODING_X_GZIP   BV(5)
#define HTTP_ACCEPT_ENCODING_X_BZIP2  BV(6)

#define KByte * 1024
#define MByte * 1024 KByte
#define GByte * 1024 MByte

typedef struct {
        array           *mimetypes;
        int             allowed_encodings;
        unsigned int    max_compress_size;
        unsigned short  min_compress_size;
        unsigned short  output_buffer_size;
        unsigned short  work_block_size;
        unsigned short  sync_flush;
        short           compression_level;
        double          max_loadavg;
} plugin_config;

typedef struct {
        PLUGIN_DATA;
        buffer *tmp_buf;
        array *encodings;

        plugin_config **config_storage;
        plugin_config conf;
} plugin_data;

typedef struct {
        union {
              #ifdef USE_ZLIB
                z_stream z;
              #endif
              #ifdef USE_BZ2LIB
                bz_stream bz;
              #endif
                int dummy;
        } u;
        off_t bytes_in;
        off_t bytes_out;
        chunkqueue *in_queue;
        buffer *output;
        plugin_data *plugin_data;
        int compression_type;
} handler_ctx;

static handler_ctx *handler_ctx_init() {
        handler_ctx *hctx;

        hctx = calloc(1, sizeof(*hctx));
        hctx->in_queue = chunkqueue_init();

        return hctx;
}

static void handler_ctx_free(handler_ctx *hctx) {
      #if 0
        if (hctx->output != p->tmp_buf) {
                buffer_free(hctx->output);
        }
      #endif
        chunkqueue_free(hctx->in_queue);
        free(hctx);
}

INIT_FUNC(mod_deflate_init) {
        plugin_data *p;

        p = calloc(1, sizeof(*p));

        p->encodings = array_init();
        p->tmp_buf = buffer_init();
        buffer_string_prepare_copy(p->tmp_buf, 64 KByte);

        return p;
}

FREE_FUNC(mod_deflate_free) {
        plugin_data *p = p_d;

        UNUSED(srv);

        if (!p) return HANDLER_GO_ON;

        if (p->config_storage) {
                size_t i;
                for (i = 0; i < srv->config_context->used; i++) {
                        plugin_config *s = p->config_storage[i];

                        if (!s) continue;

                        array_free(s->mimetypes);
                        free(s);
                }
                free(p->config_storage);
        }

        buffer_free(p->tmp_buf);
        array_free(p->encodings);

        free(p);

        return HANDLER_GO_ON;
}

SETDEFAULTS_FUNC(mod_deflate_setdefaults) {
        plugin_data *p = p_d;
        size_t i = 0;

        config_values_t cv[] = {
                { "deflate.mimetypes",             NULL, T_CONFIG_ARRAY, T_CONFIG_SCOPE_CONNECTION },
                { "deflate.allowed-encodings",     NULL, T_CONFIG_ARRAY, T_CONFIG_SCOPE_CONNECTION },
                { "deflate.max-compress-size",     NULL, T_CONFIG_INT,   T_CONFIG_SCOPE_CONNECTION },
                { "deflate.min-compress-size",     NULL, T_CONFIG_SHORT, T_CONFIG_SCOPE_CONNECTION },
                { "deflate.compression-level",     NULL, T_CONFIG_SHORT, T_CONFIG_SCOPE_CONNECTION },
                { "deflate.output-buffer-size",    NULL, T_CONFIG_SHORT, T_CONFIG_SCOPE_CONNECTION },
                { "deflate.work-block-size",       NULL, T_CONFIG_SHORT, T_CONFIG_SCOPE_CONNECTION },
                { "deflate.max-loadavg",           NULL, T_CONFIG_STRING,T_CONFIG_SCOPE_CONNECTION },
                { NULL,                            NULL, T_CONFIG_UNSET, T_CONFIG_SCOPE_UNSET }
        };

        p->config_storage = calloc(1, srv->config_context->used * sizeof(plugin_config *));

        for (i = 0; i < srv->config_context->used; i++) {
                plugin_config *s;

                s = calloc(1, sizeof(plugin_config));
                s->mimetypes = array_init();
                s->allowed_encodings = 0;
                s->max_compress_size = 128*1024; /*(128 MB measured as num KB)*/
                s->min_compress_size = 256;
                s->output_buffer_size = 0;
                s->work_block_size = 2048;
                s->sync_flush = 0;
                s->compression_level = -1;
                s->max_loadavg = 0.0;

                array_reset(p->encodings); /* temp array for allowed encodings list */

                cv[0].destination = s->mimetypes;
                cv[1].destination = p->encodings;
                cv[2].destination = &(s->max_compress_size);
                cv[3].destination = &(s->min_compress_size);
                cv[4].destination = &(s->compression_level);
                cv[5].destination = &(s->output_buffer_size);
                cv[6].destination = &(s->work_block_size);
                cv[7].destination = p->tmp_buf;
                buffer_string_set_length(p->tmp_buf, 0);

                p->config_storage[i] = s;

                if (0 != config_insert_values_global(srv, ((data_config *)srv->config_context->data[i])->value, cv, i == 0 ? T_CONFIG_SCOPE_SERVER : T_CONFIG_SCOPE_CONNECTION)) {
                        return HANDLER_ERROR;
                }

                if ((s->compression_level < 1 || s->compression_level > 9) &&
                                s->compression_level != -1) {
                        log_error_write(srv, __FILE__, __LINE__, "sd",
                                "compression-level must be between 1 and 9:", s->compression_level);
                        return HANDLER_ERROR;
                }

                if (!buffer_string_is_empty(p->tmp_buf)) {
                        s->max_loadavg = strtod(p->tmp_buf->ptr, NULL);
                }

                if (p->encodings->used) {
                        size_t j = 0;
                        for (j = 0; j < p->encodings->used; j++) {
#if defined(USE_ZLIB) || defined(USE_BZ2LIB)
                                data_string *ds = (data_string *)p->encodings->data[j];
#endif
#ifdef USE_ZLIB
                                if (NULL != strstr(ds->value->ptr, "gzip"))
                                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_GZIP | HTTP_ACCEPT_ENCODING_X_GZIP;
                                if (NULL != strstr(ds->value->ptr, "x-gzip"))
                                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_X_GZIP;
                                if (NULL != strstr(ds->value->ptr, "deflate"))
                                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_DEFLATE;
                                /*
                                if (NULL != strstr(ds->value->ptr, "compress"))
                                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_COMPRESS;
                                */
#endif
#ifdef USE_BZ2LIB
                                if (NULL != strstr(ds->value->ptr, "bzip2"))
                                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_BZIP2 | HTTP_ACCEPT_ENCODING_X_BZIP2;
                                if (NULL != strstr(ds->value->ptr, "x-bzip2"))
                                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_X_BZIP2;
#endif
                        }
                } else {
                        /* default encodings */
#ifdef USE_ZLIB
                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_GZIP
                                             |  HTTP_ACCEPT_ENCODING_X_GZIP
                                             |  HTTP_ACCEPT_ENCODING_DEFLATE;
#endif
#ifdef USE_BZ2LIB
                        s->allowed_encodings |= HTTP_ACCEPT_ENCODING_BZIP2
                                             |  HTTP_ACCEPT_ENCODING_X_BZIP2;
#endif
                }

                /* mod_deflate matches mimetype as prefix of Content-Type
                 * so ignore '*' at end of mimetype for end-user flexibility
                 * in specifying trailing wildcard to grouping of mimetypes */
                for (size_t m = 0; m < s->mimetypes->used; ++m) {
                        buffer *mimetype = ((data_string *)s->mimetypes->data[m])->value;
                        size_t len = buffer_string_length(mimetype);
                        if (len > 2 && mimetype->ptr[len-1] == '*') {
                                buffer_string_set_length(mimetype, len-1);
                        }
                }
        }

        return HANDLER_GO_ON;

}


#if defined(USE_ZLIB) || defined(USE_BZ2LIB)
static int stream_http_chunk_append_mem(server *srv, connection *con, handler_ctx *hctx, size_t len) {
        /* future: might also write stream to hctx temporary file in compressed file cache */
        return http_chunk_append_mem(srv, con, hctx->output->ptr, len);
}
#endif


#ifdef USE_ZLIB

static int stream_deflate_init(handler_ctx *hctx) {
        z_stream * const z = &hctx->u.z;
        const plugin_data * const p = hctx->plugin_data;
        z->zalloc = Z_NULL;
        z->zfree = Z_NULL;
        z->opaque = Z_NULL;
        z->total_in = 0;
        z->total_out = 0;
        z->next_out = (unsigned char *)hctx->output->ptr;
        z->avail_out = hctx->output->size;

        if (Z_OK != deflateInit2(z,
                                 p->conf.compression_level > 0
                                  ? p->conf.compression_level
                                  : Z_DEFAULT_COMPRESSION,
                                 Z_DEFLATED,
                                 (hctx->compression_type == HTTP_ACCEPT_ENCODING_GZIP)
                                  ? (MAX_WBITS | 16) /*(0x10 flags gzip header, trailer)*/
                                  : -MAX_WBITS,      /*(negate to suppress zlib header)*/
                                 8, /* default memLevel */
                                 Z_DEFAULT_STRATEGY)) {
                return -1;
        }

        return 0;
}

static int stream_deflate_compress(server *srv, connection *con, handler_ctx *hctx, unsigned char *start, off_t st_size) {
        z_stream * const z = &(hctx->u.z);
        size_t len;

        z->next_in = start;
        z->avail_in = st_size;
        hctx->bytes_in += st_size;

        /* compress data */
        do {
                if (Z_OK != deflate(z, Z_NO_FLUSH)) return -1;

                if (z->avail_out == 0 || z->avail_in > 0) {
                        len = hctx->output->size - z->avail_out;
                        hctx->bytes_out += len;
                        stream_http_chunk_append_mem(srv, con, hctx, len);
                        z->next_out = (unsigned char *)hctx->output->ptr;
                        z->avail_out = hctx->output->size;
                }
        } while (z->avail_in > 0);

        return 0;
}

static int stream_deflate_flush(server *srv, connection *con, handler_ctx *hctx, int end) {
        z_stream * const z = &(hctx->u.z);
        const plugin_data *p = hctx->plugin_data;
        size_t len;
        int rc = 0;
        int done;

        /* compress data */
        do {
                done = 1;
                if (end) {
                        rc = deflate(z, Z_FINISH);
                        if (rc == Z_OK) {
                                done = 0;
                        } else if (rc != Z_STREAM_END) {
                                return -1;
                        }
                } else {
                        if (p->conf.sync_flush) {
                                rc = deflate(z, Z_SYNC_FLUSH);
                                if (rc != Z_OK) return -1;
                        } else if (z->avail_in > 0) {
                                rc = deflate(z, Z_NO_FLUSH);
                                if (rc != Z_OK) return -1;
                        }
                }

                len = hctx->output->size - z->avail_out;
                if (z->avail_out == 0 || (len > 0 && (end || p->conf.sync_flush))) {
                        hctx->bytes_out += len;
                        stream_http_chunk_append_mem(srv, con, hctx, len);
                        z->next_out = (unsigned char *)hctx->output->ptr;
                        z->avail_out = hctx->output->size;
                }
        } while (z->avail_in != 0 || !done);

        return 0;
}

static int stream_deflate_end(server *srv, handler_ctx *hctx) {
        z_stream * const z = &(hctx->u.z);
        int rc = deflateEnd(z);
        if (Z_OK == rc || Z_DATA_ERROR == rc) return 0;

        if (z->msg != NULL) {
                log_error_write(srv, __FILE__, __LINE__, "sdss",
                                "deflateEnd error ret=", rc, ", msg=", z->msg);
        } else {
                log_error_write(srv, __FILE__, __LINE__, "sd",
                                "deflateEnd error ret=", rc);
        }
        return -1;
}

#endif


#ifdef USE_BZ2LIB

static int stream_bzip2_init(handler_ctx *hctx) {
        bz_stream * const bz = &hctx->u.bz;
        const plugin_data * const p = hctx->plugin_data;
        bz->bzalloc = NULL;
        bz->bzfree = NULL;
        bz->opaque = NULL;
        bz->total_in_lo32 = 0;
        bz->total_in_hi32 = 0;
        bz->total_out_lo32 = 0;
        bz->total_out_hi32 = 0;
        bz->next_out = hctx->output->ptr;
        bz->avail_out = hctx->output->size;

        if (BZ_OK != BZ2_bzCompressInit(bz,
                                        p->conf.compression_level > 0
                                         ? p->conf.compression_level
                                         : 9, /* blocksize = 900k */
                                        0,    /* verbosity */
                                        0)) { /* workFactor: default */
                return -1;
        }

        return 0;
}

static int stream_bzip2_compress(server *srv, connection *con, handler_ctx *hctx, unsigned char *start, off_t st_size) {
        bz_stream * const bz = &(hctx->u.bz);
        size_t len;

        bz->next_in = (char *)start;
        bz->avail_in = st_size;
        hctx->bytes_in += st_size;

        /* compress data */
        do {
                if (BZ_RUN_OK != BZ2_bzCompress(bz, BZ_RUN)) return -1;

                if (bz->avail_out == 0 || bz->avail_in > 0) {
                        len = hctx->output->size - bz->avail_out;
                        hctx->bytes_out += len;
                        stream_http_chunk_append_mem(srv, con, hctx, len);
                        bz->next_out = hctx->output->ptr;
                        bz->avail_out = hctx->output->size;
                }
        } while (bz->avail_in > 0);

        return 0;
}

static int stream_bzip2_flush(server *srv, connection *con, handler_ctx *hctx, int end) {
        bz_stream * const bz = &(hctx->u.bz);
        const plugin_data *p = hctx->plugin_data;
        size_t len;
        int rc;
        int done;

        /* compress data */
        do {
                done = 1;
                if (end) {
                        rc = BZ2_bzCompress(bz, BZ_FINISH);
                        if (rc == BZ_FINISH_OK) {
                                done = 0;
                        } else if (rc != BZ_STREAM_END) {
                                return -1;
                        }
                } else if (bz->avail_in > 0) {
                        /* p->conf.sync_flush not implemented here,
                         * which would loop on BZ_FLUSH while BZ_FLUSH_OK
                         * until BZ_RUN_OK returned */
                        rc = BZ2_bzCompress(bz, BZ_RUN);
                        if (rc != BZ_RUN_OK) {
                                return -1;
                        }
                }

                len = hctx->output->size - bz->avail_out;
                if (bz->avail_out == 0 || (len > 0 && (end || p->conf.sync_flush))) {
                        hctx->bytes_out += len;
                        stream_http_chunk_append_mem(srv, con, hctx, len);
                        bz->next_out = hctx->output->ptr;
                        bz->avail_out = hctx->output->size;
                }
        } while (bz->avail_in != 0 || !done);

        return 0;
}

static int stream_bzip2_end(server *srv, handler_ctx *hctx) {
        bz_stream * const bz = &(hctx->u.bz);
        int rc = BZ2_bzCompressEnd(bz);
        if (BZ_OK == rc || BZ_DATA_ERROR == rc) return 0;

        log_error_write(srv, __FILE__, __LINE__, "sd",
                        "BZ2_bzCompressEnd error ret=", rc);
        return -1;
}

#endif


static int mod_deflate_stream_init(handler_ctx *hctx) {
        switch(hctx->compression_type) {
#ifdef USE_ZLIB
        case HTTP_ACCEPT_ENCODING_GZIP:
        case HTTP_ACCEPT_ENCODING_DEFLATE:
                return stream_deflate_init(hctx);
#endif
#ifdef USE_BZ2LIB
        case HTTP_ACCEPT_ENCODING_BZIP2:
                return stream_bzip2_init(hctx);
#endif
        default:
                return -1;
        }
}

static int mod_deflate_compress(server *srv, connection *con, handler_ctx *hctx, unsigned char *start, off_t st_size) {
        if (0 == st_size) return 0;
        switch(hctx->compression_type) {
#ifdef USE_ZLIB
        case HTTP_ACCEPT_ENCODING_GZIP:
        case HTTP_ACCEPT_ENCODING_DEFLATE:
                return stream_deflate_compress(srv, con, hctx, start, st_size);
#endif
#ifdef USE_BZ2LIB
        case HTTP_ACCEPT_ENCODING_BZIP2:
                return stream_bzip2_compress(srv, con, hctx, start, st_size);
#endif
        default:
                UNUSED(srv);
                UNUSED(con);
                UNUSED(start);
                return -1;
        }
}

static int mod_deflate_stream_flush(server *srv, connection *con, handler_ctx *hctx, int end) {
        if (0 == hctx->bytes_in) return 0;
        switch(hctx->compression_type) {
#ifdef USE_ZLIB
        case HTTP_ACCEPT_ENCODING_GZIP:
        case HTTP_ACCEPT_ENCODING_DEFLATE:
                return stream_deflate_flush(srv, con, hctx, end);
#endif
#ifdef USE_BZ2LIB
        case HTTP_ACCEPT_ENCODING_BZIP2:
                return stream_bzip2_flush(srv, con, hctx, end);
#endif
        default:
                UNUSED(srv);
                UNUSED(con);
                UNUSED(end);
                return -1;
        }
}

static void mod_deflate_note_ratio(server *srv, connection *con, handler_ctx *hctx) {
    /* store compression ratio in con->environment
     * for possible logging by mod_accesslog
     * (late in response handling, so not seen by most other modules) */
    /*(should be called only at end of successful response compression)*/
    char ratio[LI_ITOSTRING_LENGTH];
    if (0 == hctx->bytes_in) return;
    li_itostrn(ratio, sizeof(ratio), hctx->bytes_out * 100 / hctx->bytes_in);
    array_set_key_value(con->environment,
                        CONST_STR_LEN("ratio"),
                        ratio, strlen(ratio));
    UNUSED(srv);
}

static int mod_deflate_stream_end(server *srv, handler_ctx *hctx) {
        switch(hctx->compression_type) {
#ifdef USE_ZLIB
        case HTTP_ACCEPT_ENCODING_GZIP:
        case HTTP_ACCEPT_ENCODING_DEFLATE:
                return stream_deflate_end(srv, hctx);
#endif
#ifdef USE_BZ2LIB
        case HTTP_ACCEPT_ENCODING_BZIP2:
                return stream_bzip2_end(srv, hctx);
#endif
        default:
                UNUSED(srv);
                return -1;
        }
}

static void deflate_compress_cleanup(server *srv, connection *con, handler_ctx *hctx) {
        const plugin_data *p = hctx->plugin_data;
        con->plugin_ctx[p->id] = NULL;

        if (0 != mod_deflate_stream_end(srv, hctx)) {
                log_error_write(srv, __FILE__, __LINE__, "s", "error closing stream");
        }

      #if 1 /* unnecessary if deflate.min-compress-size is set to a reasonable value */
        if (hctx->bytes_in < hctx->bytes_out) {
                log_error_write(srv, __FILE__, __LINE__, "sbsdsd",
                                "uri ", con->uri.path_raw, " in=", hctx->bytes_in, " smaller than out=", hctx->bytes_out);
        }
      #endif

        handler_ctx_free(hctx);
}


static int mod_deflate_file_chunk(server *srv, connection *con, handler_ctx *hctx, chunk *c, off_t st_size) {
        off_t abs_offset;
        off_t toSend = -1;
        char *start;
#ifdef USE_MMAP
        off_t we_want_to_mmap = 2 MByte;
        off_t we_want_to_send = st_size;
        volatile int mapped = 0;/* quiet warning: might be clobbered by 'longjmp' */
#else
        start = NULL;
#endif

        if (-1 == c->file.fd) {  /* open the file if not already open */
                if (-1 == (c->file.fd = fdevent_open_cloexec(c->file.name->ptr, O_RDONLY, 0))) {
                        log_error_write(srv, __FILE__, __LINE__, "sbs", "open failed for:", c->file.name, strerror(errno));

                        return -1;
                }
        }

        abs_offset = c->file.start + c->offset;

#ifdef USE_MMAP
        /* mmap the buffer
         * - first mmap
         * - new mmap as the we are at the end of the last one */
        if (c->file.mmap.start == MAP_FAILED ||
            abs_offset == (off_t)(c->file.mmap.offset + c->file.mmap.length)) {

                /* Optimizations for the future:
                 *
                 * adaptive mem-mapping
                 *   the problem:
                 *     we mmap() the whole file. If someone has alot large files and 32bit
                 *     machine the virtual address area will be unrun and we will have a failing
                 *     mmap() call.
                 *   solution:
                 *     only mmap 16M in one chunk and move the window as soon as we have finished
                 *     the first 8M
                 *
                 * read-ahead buffering
                 *   the problem:
                 *     sending out several large files in parallel trashes the read-ahead of the
                 *     kernel leading to long wait-for-seek times.
                 *   solutions: (increasing complexity)
                 *     1. use madvise
                 *     2. use a internal read-ahead buffer in the chunk-structure
                 *     3. use non-blocking IO for file-transfers
                 *   */

                /* all mmap()ed areas are 512kb expect the last which might be smaller */
                off_t to_mmap;

                /* this is a remap, move the mmap-offset */
                if (c->file.mmap.start != MAP_FAILED) {
                        munmap(c->file.mmap.start, c->file.mmap.length);
                        c->file.mmap.offset += we_want_to_mmap;
                } else {
                        /* in case the range-offset is after the first mmap()ed area we skip the area */
                        c->file.mmap.offset = 0;

                        while (c->file.mmap.offset + we_want_to_mmap < c->file.start) {
                                c->file.mmap.offset += we_want_to_mmap;
                        }
                }

                /* length is rel, c->offset too, assume there is no limit at the mmap-boundaries */
                to_mmap = (c->file.start + c->file.length) - c->file.mmap.offset;
                if (to_mmap > we_want_to_mmap) to_mmap = we_want_to_mmap;
                /* we have more to send than we can mmap() at once */
                if (we_want_to_send > to_mmap) we_want_to_send = to_mmap;

                if (MAP_FAILED == (c->file.mmap.start = mmap(0, (size_t)to_mmap, PROT_READ, MAP_SHARED, c->file.fd, c->file.mmap.offset))) {
                        /* close it here, otherwise we'd have to set FD_CLOEXEC */

                        log_error_write(srv, __FILE__, __LINE__, "ssbd", "mmap failed:",
                                        strerror(errno), c->file.name, c->file.fd);

                        return -1;
                }

                c->file.mmap.length = to_mmap;
#ifdef HAVE_MADVISE
                /* don't advise files < 64Kb */
                if (c->file.mmap.length > (64 KByte) &&
                    0 != madvise(c->file.mmap.start, c->file.mmap.length, MADV_WILLNEED)) {
                        log_error_write(srv, __FILE__, __LINE__, "ssbd", "madvise failed:",
                                        strerror(errno), c->file.name, c->file.fd);
                }
#endif

                /* chunk_reset() or chunk_free() will cleanup for us */
        }

        /* to_send = abs_mmap_end - abs_offset */
        toSend = (c->file.mmap.offset + c->file.mmap.length) - abs_offset;
        if (toSend > we_want_to_send) toSend = we_want_to_send;

        if (toSend < 0) {
                log_error_write(srv, __FILE__, __LINE__, "soooo",
                                "toSend is negative:",
                                toSend,
                                c->file.mmap.length,
                                abs_offset,
                                c->file.mmap.offset);
                force_assert(toSend < 0);
        }

        start = c->file.mmap.start;
        mapped = 1;
#endif

        if (MAP_FAILED == c->file.mmap.start) {
                toSend = st_size;
                if (toSend > 2 MByte) toSend = 2 MByte;
                if (NULL == (start = malloc((size_t)toSend)) || -1 == lseek(c->file.fd, abs_offset, SEEK_SET) || toSend != read(c->file.fd, start, (size_t)toSend)) {
                        log_error_write(srv, __FILE__, __LINE__, "sbss", "reading", c->file.name, "failed:", strerror(errno));

                        free(start);
                        return -1;
                }
        }

#ifdef USE_MMAP
        if (mapped) {
                signal(SIGBUS, sigbus_handler);
                sigbus_jmp_valid = 1;
                if (0 != sigsetjmp(sigbus_jmp, 1)) {
                        sigbus_jmp_valid = 0;

                        log_error_write(srv, __FILE__, __LINE__, "sbd", "SIGBUS in mmap:",
                                c->file.name, c->file.fd);
                        return -1;
                }
        }
#endif

        if (mod_deflate_compress(srv, con, hctx,
                                (unsigned char *)start + (abs_offset - c->file.mmap.offset), toSend) < 0) {
                log_error_write(srv, __FILE__, __LINE__, "s",
                                "compress failed.");
                toSend = -1;
        }

#ifdef USE_MMAP
        if (mapped)
                sigbus_jmp_valid = 0;
        else
#endif
                free(start);

        return toSend;
}


static handler_t deflate_compress_response(server *srv, connection *con, handler_ctx *hctx) {
        off_t len, max;
        int close_stream;

        /* move all chunk from write_queue into our in_queue, then adjust
         * counters since con->write_queue is reused for compressed output */
        len = chunkqueue_length(con->write_queue);
        chunkqueue_remove_finished_chunks(con->write_queue);
        chunkqueue_append_chunkqueue(hctx->in_queue, con->write_queue);
        con->write_queue->bytes_in  -= len;
        con->write_queue->bytes_out -= len;

        max = chunkqueue_length(hctx->in_queue);
      #if 0
        /* calculate max bytes to compress for this call */
        if (p->conf.sync_flush && max > (len = p->conf.work_block_size << 10)) {
                max = len;
        }
      #endif

        /* Compress chunks from in_queue into chunks for write_queue */
        while (max) {
                chunk *c = hctx->in_queue->first;

                switch(c->type) {
                case MEM_CHUNK:
                        len = buffer_string_length(c->mem) - c->offset;
                        if (len > max) len = max;
                        if (mod_deflate_compress(srv, con, hctx, (unsigned char *)c->mem->ptr+c->offset, len) < 0) {
                                log_error_write(srv, __FILE__, __LINE__, "s",
                                                "compress failed.");
                                return HANDLER_ERROR;
                        }
                        break;
                case FILE_CHUNK:
                        len = c->file.length - c->offset;
                        if (len > max) len = max;
                        if ((len = mod_deflate_file_chunk(srv, con, hctx, c, len)) < 0) {
                                log_error_write(srv, __FILE__, __LINE__, "s",
                                                "compress file chunk failed.");
                                return HANDLER_ERROR;
                        }
                        break;
                default:
                        log_error_write(srv, __FILE__, __LINE__, "ds", c, "type not known");
                        return HANDLER_ERROR;
                }

                max -= len;
                chunkqueue_mark_written(hctx->in_queue, len);
        }

        /*(currently should always be true)*/
        /*(current implementation requires response be complete)*/
        close_stream = (con->file_finished && chunkqueue_is_empty(hctx->in_queue));
        if (mod_deflate_stream_flush(srv, con, hctx, close_stream) < 0) {
                log_error_write(srv, __FILE__, __LINE__, "s", "flush error");
                return HANDLER_ERROR;
        }

        return close_stream ? HANDLER_FINISHED : HANDLER_GO_ON;
}


#define PATCH(x) \
        p->conf.x = s->x;
static int mod_deflate_patch_connection(server *srv, connection *con, plugin_data *p) {
        size_t i, j;
        plugin_config *s = p->config_storage[0];

        PATCH(mimetypes);
        PATCH(allowed_encodings);
        PATCH(max_compress_size);
        PATCH(min_compress_size);
        PATCH(compression_level);
        PATCH(output_buffer_size);
        PATCH(work_block_size);
        PATCH(max_loadavg);

        /* skip the first, the global context */
        for (i = 1; i < srv->config_context->used; i++) {
                data_config *dc = (data_config *)srv->config_context->data[i];
                s = p->config_storage[i];

                /* condition didn't match */
                if (!config_check_cond(srv, con, dc)) continue;

                /* merge config */
                for (j = 0; j < dc->value->used; j++) {
                        data_unset *du = dc->value->data[j];

                        if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.mimetypes"))) {
                                PATCH(mimetypes);
                        } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.allowed-encodings"))) {
                                PATCH(allowed_encodings);
                        } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.max-compress-size"))) {
                                PATCH(max_compress_size);
                        } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.min-compress-size"))) {
                                PATCH(min_compress_size);
                        } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.compression-level"))) {
                                PATCH(compression_level);
                        } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.output-buffer-size"))) {
                                PATCH(output_buffer_size);
                        } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.work-block-size"))) {
                                PATCH(work_block_size);
                        } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("deflate.max-loadavg"))) {
                                PATCH(max_loadavg);
                        }
                }
        }

        return 0;
}
#undef PATCH

static int mod_deflate_choose_encoding (const char *value, plugin_data *p, const char **label) {
        /* get client side support encodings */
        int accept_encoding = 0;
#if !defined(USE_ZLIB) && !defined(USE_BZ2LIB)
        UNUSED(value);
#endif
#ifdef USE_ZLIB
        if (NULL != strstr(value, "gzip")) accept_encoding |= HTTP_ACCEPT_ENCODING_GZIP;
        else if (NULL != strstr(value, "x-gzip")) accept_encoding |= HTTP_ACCEPT_ENCODING_X_GZIP;
        if (NULL != strstr(value, "deflate")) accept_encoding |= HTTP_ACCEPT_ENCODING_DEFLATE;
#endif
        /* if (NULL != strstr(value, "compress")) accept_encoding |= HTTP_ACCEPT_ENCODING_COMPRESS; */
#ifdef USE_BZ2LIB
        if (p->conf.allowed_encodings & (HTTP_ACCEPT_ENCODING_BZIP2 | HTTP_ACCEPT_ENCODING_X_BZIP2)) {
                if (NULL != strstr(value, "bzip2")) accept_encoding |= HTTP_ACCEPT_ENCODING_BZIP2;
                else if (NULL != strstr(value, "x-bzip2")) accept_encoding |= HTTP_ACCEPT_ENCODING_X_BZIP2;
        }
#endif
        /* if (NULL != strstr(value, "identity")) accept_encoding |= HTTP_ACCEPT_ENCODING_IDENTITY; */

        /* mask to limit to allowed_encodings */
        accept_encoding &= p->conf.allowed_encodings;

        /* select best matching encoding */
#ifdef USE_BZ2LIB
        if (accept_encoding & HTTP_ACCEPT_ENCODING_BZIP2) {
                *label = "bzip2";
                return HTTP_ACCEPT_ENCODING_BZIP2;
        } else if (accept_encoding & HTTP_ACCEPT_ENCODING_X_BZIP2) {
                *label = "x-bzip2";
                return HTTP_ACCEPT_ENCODING_BZIP2;
        } else
#endif
        if (accept_encoding & HTTP_ACCEPT_ENCODING_GZIP) {
                *label = "gzip";
                return HTTP_ACCEPT_ENCODING_GZIP;
        } else if (accept_encoding & HTTP_ACCEPT_ENCODING_X_GZIP) {
                *label = "x-gzip";
                return HTTP_ACCEPT_ENCODING_GZIP;
        } else if (accept_encoding & HTTP_ACCEPT_ENCODING_DEFLATE) {
                *label = "deflate";
                return HTTP_ACCEPT_ENCODING_DEFLATE;
        } else {
                return 0;
        }
}

CONNECTION_FUNC(mod_deflate_handle_response_start) {
        plugin_data *p = p_d;
        data_string *ds;
        handler_ctx *hctx;
        const char *label;
        off_t len;
        size_t etaglen = 0;
        int compression_type;
        handler_t rc;

        /*(current implementation requires response be complete)*/
        if (!con->file_finished) return HANDLER_GO_ON;
        if (con->request.http_method == HTTP_METHOD_HEAD) return HANDLER_GO_ON;
        if (con->parsed_response & HTTP_TRANSFER_ENCODING_CHUNKED) return HANDLER_GO_ON;

        /* disable compression for some http status types. */
        switch(con->http_status) {
        case 100:
        case 101:
        case 204:
        case 205:
        case 304:
                /* disable compression as we have no response entity */
                return HANDLER_GO_ON;
        default:
                break;
        }

        mod_deflate_patch_connection(srv, con, p);

        /* check if deflate configured for any mimetypes */
        if (!p->conf.mimetypes->used) return HANDLER_GO_ON;

        /* check if size of response is below min-compress-size or exceeds max*/
        /* (con->file_finished checked at top of routine) */
        len = chunkqueue_length(con->write_queue);
        if (len <= (off_t)p->conf.min_compress_size) return HANDLER_GO_ON;
        if (p->conf.max_compress_size /*(max_compress_size in KB)*/
            && len > ((off_t)p->conf.max_compress_size << 10)) {
                return HANDLER_GO_ON;
        }

        /* Check if response has a Content-Encoding. */
        ds = (data_string *)array_get_element(con->response.headers, "Content-Encoding");
        if (NULL != ds) return HANDLER_GO_ON;

        /* Check Accept-Encoding for supported encoding. */
        ds = (data_string *)array_get_element(con->request.headers, "Accept-Encoding");
        if (NULL == ds) return HANDLER_GO_ON;

        /* find matching encodings */
        compression_type = mod_deflate_choose_encoding(ds->value->ptr, p, &label);
        if (!compression_type) return HANDLER_GO_ON;

        /* Check mimetype in response header "Content-Type" */
        if (NULL != (ds = (data_string *)array_get_element(con->response.headers, "Content-Type"))) {
                int found = 0;
                size_t m;
                for (m = 0; m < p->conf.mimetypes->used; ++m) {
                        data_string *mimetype = (data_string *)p->conf.mimetypes->data[m];
                        if (0 == strncmp(mimetype->value->ptr, ds->value->ptr, buffer_string_length(mimetype->value))) {
                                /* mimetype found */
                                found = 1;
                                break;
                        }
                }
                if (!found) return HANDLER_GO_ON;

#if 0
                if (0 == strncasecmp(ds->value->ptr, "application/x-javascript", 24)) {
                        /*reset compress type to deflate for javascript
                         * prevent buggy IE6 SP1 doesn't work for js in IFrame
                         */
                        compression_type = HTTP_ACCEPT_ENCODING_DEFLATE;
                }
#endif
        } else {
                /* If no Content-Type set, compress only if first p->conf.mimetypes value is "" */
                data_string *mimetype = (data_string *)p->conf.mimetypes->data[0];
                if (!buffer_string_is_empty(mimetype->value)) return HANDLER_GO_ON;
        }

        /* Vary: Accept-Encoding (response might change according to request Accept-Encoding) */
        if (NULL != (ds = (data_string *)array_get_element(con->response.headers, "Vary"))) {
                if (NULL == strstr(ds->value->ptr, "Accept-Encoding")) {
                        buffer_append_string_len(ds->value, CONST_STR_LEN(",Accept-Encoding"));
                }
        } else {
                response_header_insert(srv, con, CONST_STR_LEN("Vary"),
                                CONST_STR_LEN("Accept-Encoding"));
        }

        /* check ETag as is done in http_response_handle_cachable()
         * (slightly imperfect (close enough?) match of ETag "000000" to "000000-gzip") */
        ds = (data_string *)array_get_element(con->response.headers, "ETag");
        if (NULL != ds) {
                etaglen = buffer_string_length(ds->value);
                if (etaglen
                    && con->http_status < 300 /*(want 2xx only)*/
                    && con->request.http_if_none_match
                    && 0 == strncmp(con->request.http_if_none_match, ds->value->ptr, etaglen-1)
                    && con->request.http_if_none_match[etaglen-1] == '-'
                    && 0 == strncmp(con->request.http_if_none_match+etaglen, label, strlen(label))) {

                        if (   HTTP_METHOD_GET  == con->request.http_method
                            || HTTP_METHOD_HEAD == con->request.http_method) {
                                /* modify ETag response header in-place to remove '"' and append '-label"' */
                                ds->value->ptr[etaglen-1] = '-'; /*(overwrite end '"')*/
                                buffer_append_string(ds->value, label);
                                buffer_append_string_len(ds->value, CONST_STR_LEN("\""));
                                /*buffer_copy_buffer(con->physical.etag, ds->value);*//*(keep in sync?)*/
                                con->http_status = 304;
                        } else {
                                con->http_status = 412;
                        }

                        /* response_start hook occurs after error docs have been handled.
                         * For now, send back empty response body.
                         * In the future, might extract the error doc code so that it
                         * might be run again if response_start hooks return with
                         * changed http_status and con->mode = DIRECT */
                        con->response.transfer_encoding &= ~HTTP_TRANSFER_ENCODING_CHUNKED;
                        con->parsed_response &= ~HTTP_CONTENT_LENGTH;
                        chunkqueue_reset(con->write_queue);
                        con->file_finished = 1;

                        con->mode = DIRECT;
                        return HANDLER_GO_ON;
                }
        }

        if (0.0 < p->conf.max_loadavg && p->conf.max_loadavg < srv->srvconf.loadavg[0]) {
                return HANDLER_GO_ON;
        }

        /* update ETag, if ETag response header is set */
        if (etaglen) {
                /* modify ETag response header in-place to remove '"' and append '-label"' */
                ds->value->ptr[etaglen-1] = '-'; /*(overwrite end '"')*/
                buffer_append_string(ds->value, label);
                buffer_append_string_len(ds->value, CONST_STR_LEN("\""));
                /*buffer_copy_buffer(con->physical.etag, ds->value);*//*(keep in sync?)*/
        }

        /* set Content-Encoding to show selected compression type */
        response_header_overwrite(srv, con, CONST_STR_LEN("Content-Encoding"), label, strlen(label));

        /* clear Content-Length and con->write_queue if HTTP HEAD request
         * (alternatively, could return original Content-Length with HEAD
         *  request if ETag not modified and Content-Encoding not added) */
        if (HTTP_METHOD_HEAD == con->request.http_method) {
                /* ensure that uncompressed Content-Length is not sent in HEAD response */
                chunkqueue_reset(con->write_queue);
                if (con->parsed_response & HTTP_CONTENT_LENGTH) {
                        con->parsed_response &= ~HTTP_CONTENT_LENGTH;
                        if (NULL != (ds = (data_string*) array_get_element(con->response.headers, "Content-Length"))) {
                                buffer_reset(ds->value); /* headers with empty values are ignored for output */
                        }
                }
                return HANDLER_GO_ON;
        }

        /* future: might use ETag to check if compressed content is in compressed file cache */
        /*if (etaglen) { ... } *//* return if in file cache after updating con->write_queue */

        /* enable compression */
        p->conf.sync_flush =
          (con->conf.stream_response_body && 0 == p->conf.output_buffer_size);
        hctx = handler_ctx_init();
        hctx->plugin_data = p;
        hctx->compression_type = compression_type;
        /* setup output buffer */
        buffer_string_set_length(p->tmp_buf, 0);
        hctx->output = p->tmp_buf;
        if (0 != mod_deflate_stream_init(hctx)) {
                /*(should not happen unless ENOMEM)*/
                handler_ctx_free(hctx);
                log_error_write(srv, __FILE__, __LINE__, "ss",
                                "Failed to initialize compression", label);
                /* restore prior Etag and unset Content-Encoding */
                if (etaglen) {
                        ds->value->ptr[etaglen-1] = '"'; /*(overwrite '-')*/
                        buffer_string_set_length(ds->value, etaglen);
                }
                ds = (data_string *)array_get_element(con->response.headers, "Content-Encoding");
                if (ds) buffer_reset(ds->value); /* headers with empty values are ignored for output */
                return HANDLER_GO_ON;
        }

        con->parsed_response &= ~HTTP_CONTENT_LENGTH;
        con->plugin_ctx[p->id] = hctx;

        rc = deflate_compress_response(srv, con, hctx);
        if (HANDLER_GO_ON != rc) {
                if (HANDLER_FINISHED == rc) {
                        mod_deflate_note_ratio(srv, con, hctx);
                }
                deflate_compress_cleanup(srv, con, hctx);
                if (HANDLER_ERROR == rc) return HANDLER_ERROR;
        }

        return HANDLER_GO_ON;
}

static handler_t mod_deflate_cleanup(server *srv, connection *con, void *p_d) {
        plugin_data *p = p_d;
        handler_ctx *hctx = con->plugin_ctx[p->id];

        if (NULL != hctx) deflate_compress_cleanup(srv, con, hctx);

        return HANDLER_GO_ON;
}

int mod_deflate_plugin_init(plugin *p);
int mod_deflate_plugin_init(plugin *p) {
        p->version     = LIGHTTPD_VERSION_ID;
        p->name        = buffer_init_string("deflate");

        p->init         = mod_deflate_init;
        p->cleanup      = mod_deflate_free;
        p->set_defaults = mod_deflate_setdefaults;
        p->connection_reset     = mod_deflate_cleanup;
        p->handle_connection_close      = mod_deflate_cleanup;
        p->handle_response_start        = mod_deflate_handle_response_start;

        p->data        = NULL;

        return 0;
}