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view src/http/v2/ngx_http_v2_huff_encode.c @ 6750:cb330cd39030 stable-1.10

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HTTP/2: implemented preread buffer for request body (closes #959). Previously, the stream's window was kept zero in order to prevent a client from sending the request body before it was requested (see 887cca40ba6a for details). Until such initial window was acknowledged all requests with data were rejected (see 0aa07850922f for details). That approach revealed a number of problems: 1. Some clients (notably MS IE/Edge, Safari, iOS applications) show an error or even crash if a stream is rejected; 2. This requires at least one RTT for every request with body before the client receives window update and able to send data. To overcome these problems the new directive "http2_body_preread_size" is introduced. It sets the initial window and configures a special per stream preread buffer that is used to save all incoming data before the body is requested and processed. If the directive's value is lower than the default initial window (65535), as previously, all streams with data will be rejected until the new window is acknowledged. Otherwise, no special processing is used and all requests with data are welcome right from the connection start. The default value is chosen to be 64k, which is bigger than the default initial window. Setting it to zero is fully complaint to the previous behavior.
author Valentin Bartenev <vbart@nginx.com>
date Tue, 24 May 2016 17:37:52 +0300
parents dcfe355dfda4
children
line wrap: on
line source


/*
 * Copyright (C) Nginx, Inc.
 * Copyright (C) Valentin V. Bartenev
 * Copyright (C) 2015 Vlad Krasnov
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


typedef struct {
    uint32_t  code;
    uint32_t  len;
} ngx_http_v2_huff_encode_code_t;


static ngx_http_v2_huff_encode_code_t  ngx_http_v2_huff_encode_table[256] =
{
    {0x00001ff8, 13}, {0x007fffd8, 23}, {0x0fffffe2, 28}, {0x0fffffe3, 28},
    {0x0fffffe4, 28}, {0x0fffffe5, 28}, {0x0fffffe6, 28}, {0x0fffffe7, 28},
    {0x0fffffe8, 28}, {0x00ffffea, 24}, {0x3ffffffc, 30}, {0x0fffffe9, 28},
    {0x0fffffea, 28}, {0x3ffffffd, 30}, {0x0fffffeb, 28}, {0x0fffffec, 28},
    {0x0fffffed, 28}, {0x0fffffee, 28}, {0x0fffffef, 28}, {0x0ffffff0, 28},
    {0x0ffffff1, 28}, {0x0ffffff2, 28}, {0x3ffffffe, 30}, {0x0ffffff3, 28},
    {0x0ffffff4, 28}, {0x0ffffff5, 28}, {0x0ffffff6, 28}, {0x0ffffff7, 28},
    {0x0ffffff8, 28}, {0x0ffffff9, 28}, {0x0ffffffa, 28}, {0x0ffffffb, 28},
    {0x00000014,  6}, {0x000003f8, 10}, {0x000003f9, 10}, {0x00000ffa, 12},
    {0x00001ff9, 13}, {0x00000015,  6}, {0x000000f8,  8}, {0x000007fa, 11},
    {0x000003fa, 10}, {0x000003fb, 10}, {0x000000f9,  8}, {0x000007fb, 11},
    {0x000000fa,  8}, {0x00000016,  6}, {0x00000017,  6}, {0x00000018,  6},
    {0x00000000,  5}, {0x00000001,  5}, {0x00000002,  5}, {0x00000019,  6},
    {0x0000001a,  6}, {0x0000001b,  6}, {0x0000001c,  6}, {0x0000001d,  6},
    {0x0000001e,  6}, {0x0000001f,  6}, {0x0000005c,  7}, {0x000000fb,  8},
    {0x00007ffc, 15}, {0x00000020,  6}, {0x00000ffb, 12}, {0x000003fc, 10},
    {0x00001ffa, 13}, {0x00000021,  6}, {0x0000005d,  7}, {0x0000005e,  7},
    {0x0000005f,  7}, {0x00000060,  7}, {0x00000061,  7}, {0x00000062,  7},
    {0x00000063,  7}, {0x00000064,  7}, {0x00000065,  7}, {0x00000066,  7},
    {0x00000067,  7}, {0x00000068,  7}, {0x00000069,  7}, {0x0000006a,  7},
    {0x0000006b,  7}, {0x0000006c,  7}, {0x0000006d,  7}, {0x0000006e,  7},
    {0x0000006f,  7}, {0x00000070,  7}, {0x00000071,  7}, {0x00000072,  7},
    {0x000000fc,  8}, {0x00000073,  7}, {0x000000fd,  8}, {0x00001ffb, 13},
    {0x0007fff0, 19}, {0x00001ffc, 13}, {0x00003ffc, 14}, {0x00000022,  6},
    {0x00007ffd, 15}, {0x00000003,  5}, {0x00000023,  6}, {0x00000004,  5},
    {0x00000024,  6}, {0x00000005,  5}, {0x00000025,  6}, {0x00000026,  6},
    {0x00000027,  6}, {0x00000006,  5}, {0x00000074,  7}, {0x00000075,  7},
    {0x00000028,  6}, {0x00000029,  6}, {0x0000002a,  6}, {0x00000007,  5},
    {0x0000002b,  6}, {0x00000076,  7}, {0x0000002c,  6}, {0x00000008,  5},
    {0x00000009,  5}, {0x0000002d,  6}, {0x00000077,  7}, {0x00000078,  7},
    {0x00000079,  7}, {0x0000007a,  7}, {0x0000007b,  7}, {0x00007ffe, 15},
    {0x000007fc, 11}, {0x00003ffd, 14}, {0x00001ffd, 13}, {0x0ffffffc, 28},
    {0x000fffe6, 20}, {0x003fffd2, 22}, {0x000fffe7, 20}, {0x000fffe8, 20},
    {0x003fffd3, 22}, {0x003fffd4, 22}, {0x003fffd5, 22}, {0x007fffd9, 23},
    {0x003fffd6, 22}, {0x007fffda, 23}, {0x007fffdb, 23}, {0x007fffdc, 23},
    {0x007fffdd, 23}, {0x007fffde, 23}, {0x00ffffeb, 24}, {0x007fffdf, 23},
    {0x00ffffec, 24}, {0x00ffffed, 24}, {0x003fffd7, 22}, {0x007fffe0, 23},
    {0x00ffffee, 24}, {0x007fffe1, 23}, {0x007fffe2, 23}, {0x007fffe3, 23},
    {0x007fffe4, 23}, {0x001fffdc, 21}, {0x003fffd8, 22}, {0x007fffe5, 23},
    {0x003fffd9, 22}, {0x007fffe6, 23}, {0x007fffe7, 23}, {0x00ffffef, 24},
    {0x003fffda, 22}, {0x001fffdd, 21}, {0x000fffe9, 20}, {0x003fffdb, 22},
    {0x003fffdc, 22}, {0x007fffe8, 23}, {0x007fffe9, 23}, {0x001fffde, 21},
    {0x007fffea, 23}, {0x003fffdd, 22}, {0x003fffde, 22}, {0x00fffff0, 24},
    {0x001fffdf, 21}, {0x003fffdf, 22}, {0x007fffeb, 23}, {0x007fffec, 23},
    {0x001fffe0, 21}, {0x001fffe1, 21}, {0x003fffe0, 22}, {0x001fffe2, 21},
    {0x007fffed, 23}, {0x003fffe1, 22}, {0x007fffee, 23}, {0x007fffef, 23},
    {0x000fffea, 20}, {0x003fffe2, 22}, {0x003fffe3, 22}, {0x003fffe4, 22},
    {0x007ffff0, 23}, {0x003fffe5, 22}, {0x003fffe6, 22}, {0x007ffff1, 23},
    {0x03ffffe0, 26}, {0x03ffffe1, 26}, {0x000fffeb, 20}, {0x0007fff1, 19},
    {0x003fffe7, 22}, {0x007ffff2, 23}, {0x003fffe8, 22}, {0x01ffffec, 25},
    {0x03ffffe2, 26}, {0x03ffffe3, 26}, {0x03ffffe4, 26}, {0x07ffffde, 27},
    {0x07ffffdf, 27}, {0x03ffffe5, 26}, {0x00fffff1, 24}, {0x01ffffed, 25},
    {0x0007fff2, 19}, {0x001fffe3, 21}, {0x03ffffe6, 26}, {0x07ffffe0, 27},
    {0x07ffffe1, 27}, {0x03ffffe7, 26}, {0x07ffffe2, 27}, {0x00fffff2, 24},
    {0x001fffe4, 21}, {0x001fffe5, 21}, {0x03ffffe8, 26}, {0x03ffffe9, 26},
    {0x0ffffffd, 28}, {0x07ffffe3, 27}, {0x07ffffe4, 27}, {0x07ffffe5, 27},
    {0x000fffec, 20}, {0x00fffff3, 24}, {0x000fffed, 20}, {0x001fffe6, 21},
    {0x003fffe9, 22}, {0x001fffe7, 21}, {0x001fffe8, 21}, {0x007ffff3, 23},
    {0x003fffea, 22}, {0x003fffeb, 22}, {0x01ffffee, 25}, {0x01ffffef, 25},
    {0x00fffff4, 24}, {0x00fffff5, 24}, {0x03ffffea, 26}, {0x007ffff4, 23},
    {0x03ffffeb, 26}, {0x07ffffe6, 27}, {0x03ffffec, 26}, {0x03ffffed, 26},
    {0x07ffffe7, 27}, {0x07ffffe8, 27}, {0x07ffffe9, 27}, {0x07ffffea, 27},
    {0x07ffffeb, 27}, {0x0ffffffe, 28}, {0x07ffffec, 27}, {0x07ffffed, 27},
    {0x07ffffee, 27}, {0x07ffffef, 27}, {0x07fffff0, 27}, {0x03ffffee, 26}
};


/* same as above, but embeds lowercase transformation */
static ngx_http_v2_huff_encode_code_t  ngx_http_v2_huff_encode_table_lc[256] =
{
    {0x00001ff8, 13}, {0x007fffd8, 23}, {0x0fffffe2, 28}, {0x0fffffe3, 28},
    {0x0fffffe4, 28}, {0x0fffffe5, 28}, {0x0fffffe6, 28}, {0x0fffffe7, 28},
    {0x0fffffe8, 28}, {0x00ffffea, 24}, {0x3ffffffc, 30}, {0x0fffffe9, 28},
    {0x0fffffea, 28}, {0x3ffffffd, 30}, {0x0fffffeb, 28}, {0x0fffffec, 28},
    {0x0fffffed, 28}, {0x0fffffee, 28}, {0x0fffffef, 28}, {0x0ffffff0, 28},
    {0x0ffffff1, 28}, {0x0ffffff2, 28}, {0x3ffffffe, 30}, {0x0ffffff3, 28},
    {0x0ffffff4, 28}, {0x0ffffff5, 28}, {0x0ffffff6, 28}, {0x0ffffff7, 28},
    {0x0ffffff8, 28}, {0x0ffffff9, 28}, {0x0ffffffa, 28}, {0x0ffffffb, 28},
    {0x00000014,  6}, {0x000003f8, 10}, {0x000003f9, 10}, {0x00000ffa, 12},
    {0x00001ff9, 13}, {0x00000015,  6}, {0x000000f8,  8}, {0x000007fa, 11},
    {0x000003fa, 10}, {0x000003fb, 10}, {0x000000f9,  8}, {0x000007fb, 11},
    {0x000000fa,  8}, {0x00000016,  6}, {0x00000017,  6}, {0x00000018,  6},
    {0x00000000,  5}, {0x00000001,  5}, {0x00000002,  5}, {0x00000019,  6},
    {0x0000001a,  6}, {0x0000001b,  6}, {0x0000001c,  6}, {0x0000001d,  6},
    {0x0000001e,  6}, {0x0000001f,  6}, {0x0000005c,  7}, {0x000000fb,  8},
    {0x00007ffc, 15}, {0x00000020,  6}, {0x00000ffb, 12}, {0x000003fc, 10},
    {0x00001ffa, 13}, {0x00000003,  5}, {0x00000023,  6}, {0x00000004,  5},
    {0x00000024,  6}, {0x00000005,  5}, {0x00000025,  6}, {0x00000026,  6},
    {0x00000027,  6}, {0x00000006,  5}, {0x00000074,  7}, {0x00000075,  7},
    {0x00000028,  6}, {0x00000029,  6}, {0x0000002a,  6}, {0x00000007,  5},
    {0x0000002b,  6}, {0x00000076,  7}, {0x0000002c,  6}, {0x00000008,  5},
    {0x00000009,  5}, {0x0000002d,  6}, {0x00000077,  7}, {0x00000078,  7},
    {0x00000079,  7}, {0x0000007a,  7}, {0x0000007b,  7}, {0x00001ffb, 13},
    {0x0007fff0, 19}, {0x00001ffc, 13}, {0x00003ffc, 14}, {0x00000022,  6},
    {0x00007ffd, 15}, {0x00000003,  5}, {0x00000023,  6}, {0x00000004,  5},
    {0x00000024,  6}, {0x00000005,  5}, {0x00000025,  6}, {0x00000026,  6},
    {0x00000027,  6}, {0x00000006,  5}, {0x00000074,  7}, {0x00000075,  7},
    {0x00000028,  6}, {0x00000029,  6}, {0x0000002a,  6}, {0x00000007,  5},
    {0x0000002b,  6}, {0x00000076,  7}, {0x0000002c,  6}, {0x00000008,  5},
    {0x00000009,  5}, {0x0000002d,  6}, {0x00000077,  7}, {0x00000078,  7},
    {0x00000079,  7}, {0x0000007a,  7}, {0x0000007b,  7}, {0x00007ffe, 15},
    {0x000007fc, 11}, {0x00003ffd, 14}, {0x00001ffd, 13}, {0x0ffffffc, 28},
    {0x000fffe6, 20}, {0x003fffd2, 22}, {0x000fffe7, 20}, {0x000fffe8, 20},
    {0x003fffd3, 22}, {0x003fffd4, 22}, {0x003fffd5, 22}, {0x007fffd9, 23},
    {0x003fffd6, 22}, {0x007fffda, 23}, {0x007fffdb, 23}, {0x007fffdc, 23},
    {0x007fffdd, 23}, {0x007fffde, 23}, {0x00ffffeb, 24}, {0x007fffdf, 23},
    {0x00ffffec, 24}, {0x00ffffed, 24}, {0x003fffd7, 22}, {0x007fffe0, 23},
    {0x00ffffee, 24}, {0x007fffe1, 23}, {0x007fffe2, 23}, {0x007fffe3, 23},
    {0x007fffe4, 23}, {0x001fffdc, 21}, {0x003fffd8, 22}, {0x007fffe5, 23},
    {0x003fffd9, 22}, {0x007fffe6, 23}, {0x007fffe7, 23}, {0x00ffffef, 24},
    {0x003fffda, 22}, {0x001fffdd, 21}, {0x000fffe9, 20}, {0x003fffdb, 22},
    {0x003fffdc, 22}, {0x007fffe8, 23}, {0x007fffe9, 23}, {0x001fffde, 21},
    {0x007fffea, 23}, {0x003fffdd, 22}, {0x003fffde, 22}, {0x00fffff0, 24},
    {0x001fffdf, 21}, {0x003fffdf, 22}, {0x007fffeb, 23}, {0x007fffec, 23},
    {0x001fffe0, 21}, {0x001fffe1, 21}, {0x003fffe0, 22}, {0x001fffe2, 21},
    {0x007fffed, 23}, {0x003fffe1, 22}, {0x007fffee, 23}, {0x007fffef, 23},
    {0x000fffea, 20}, {0x003fffe2, 22}, {0x003fffe3, 22}, {0x003fffe4, 22},
    {0x007ffff0, 23}, {0x003fffe5, 22}, {0x003fffe6, 22}, {0x007ffff1, 23},
    {0x03ffffe0, 26}, {0x03ffffe1, 26}, {0x000fffeb, 20}, {0x0007fff1, 19},
    {0x003fffe7, 22}, {0x007ffff2, 23}, {0x003fffe8, 22}, {0x01ffffec, 25},
    {0x03ffffe2, 26}, {0x03ffffe3, 26}, {0x03ffffe4, 26}, {0x07ffffde, 27},
    {0x07ffffdf, 27}, {0x03ffffe5, 26}, {0x00fffff1, 24}, {0x01ffffed, 25},
    {0x0007fff2, 19}, {0x001fffe3, 21}, {0x03ffffe6, 26}, {0x07ffffe0, 27},
    {0x07ffffe1, 27}, {0x03ffffe7, 26}, {0x07ffffe2, 27}, {0x00fffff2, 24},
    {0x001fffe4, 21}, {0x001fffe5, 21}, {0x03ffffe8, 26}, {0x03ffffe9, 26},
    {0x0ffffffd, 28}, {0x07ffffe3, 27}, {0x07ffffe4, 27}, {0x07ffffe5, 27},
    {0x000fffec, 20}, {0x00fffff3, 24}, {0x000fffed, 20}, {0x001fffe6, 21},
    {0x003fffe9, 22}, {0x001fffe7, 21}, {0x001fffe8, 21}, {0x007ffff3, 23},
    {0x003fffea, 22}, {0x003fffeb, 22}, {0x01ffffee, 25}, {0x01ffffef, 25},
    {0x00fffff4, 24}, {0x00fffff5, 24}, {0x03ffffea, 26}, {0x007ffff4, 23},
    {0x03ffffeb, 26}, {0x07ffffe6, 27}, {0x03ffffec, 26}, {0x03ffffed, 26},
    {0x07ffffe7, 27}, {0x07ffffe8, 27}, {0x07ffffe9, 27}, {0x07ffffea, 27},
    {0x07ffffeb, 27}, {0x0ffffffe, 28}, {0x07ffffec, 27}, {0x07ffffed, 27},
    {0x07ffffee, 27}, {0x07ffffef, 27}, {0x07fffff0, 27}, {0x03ffffee, 26}
};


#if (NGX_PTR_SIZE == 8)

#if (NGX_HAVE_LITTLE_ENDIAN)

#if (NGX_HAVE_GCC_BSWAP64)
#define ngx_http_v2_huff_encode_buf(dst, buf)                                 \
    (*(uint64_t *) (dst) = __builtin_bswap64(buf))
#else
#define ngx_http_v2_huff_encode_buf(dst, buf)                                 \
    ((dst)[0] = (u_char) ((buf) >> 56),                                       \
     (dst)[1] = (u_char) ((buf) >> 48),                                       \
     (dst)[2] = (u_char) ((buf) >> 40),                                       \
     (dst)[3] = (u_char) ((buf) >> 32),                                       \
     (dst)[4] = (u_char) ((buf) >> 24),                                       \
     (dst)[5] = (u_char) ((buf) >> 16),                                       \
     (dst)[6] = (u_char) ((buf) >> 8),                                        \
     (dst)[7] = (u_char)  (buf))
#endif

#else /* !NGX_HAVE_LITTLE_ENDIAN */
#define ngx_http_v2_huff_encode_buf(dst, buf)                                 \
    (*(uint64_t *) (dst) = (buf))
#endif

#else /* NGX_PTR_SIZE == 4 */

#define ngx_http_v2_huff_encode_buf(dst, buf)                                 \
    (*(uint32_t *) (dst) = htonl(buf))

#endif


size_t
ngx_http_v2_huff_encode(u_char *src, size_t len, u_char *dst, ngx_uint_t lower)
{
    u_char                          *end;
    size_t                           hlen;
    ngx_uint_t                       buf, pending, code;
    ngx_http_v2_huff_encode_code_t  *table, *next;

    table = lower ? ngx_http_v2_huff_encode_table_lc
                  : ngx_http_v2_huff_encode_table;
    hlen = 0;
    buf = 0;
    pending = 0;

    end = src + len;

    while (src != end) {
        next = &table[*src++];

        code = next->code;
        pending += next->len;

        /* accumulate bits */
        if (pending < sizeof(buf) * 8) {
            buf |= code << (sizeof(buf) * 8 - pending);
            continue;
        }

        if (hlen + sizeof(buf) >= len) {
            return 0;
        }

        pending -= sizeof(buf) * 8;

        buf |= code >> pending;

        ngx_http_v2_huff_encode_buf(&dst[hlen], buf);

        hlen += sizeof(buf);

        buf = pending ? code << (sizeof(buf) * 8 - pending) : 0;
    }

    if (pending == 0) {
        return hlen;
    }

    buf |= (ngx_uint_t) -1 >> pending;

    pending = ngx_align(pending, 8);

    if (hlen + pending / 8 >= len) {
        return 0;
    }

    buf >>= sizeof(buf) * 8 - pending;

    do {
        pending -= 8;
        dst[hlen++] = (u_char) (buf >> pending);
    } while (pending);

    return hlen;
}