[nginx] HTTP/2: implemented HPACK Huffman encoding for response ...
Valentin Bartenev
vbart at nginx.com
Thu Feb 11 16:30:23 UTC 2016
details: http://hg.nginx.org/nginx/rev/ba3c2ca21aa5
branches:
changeset: 6395:ba3c2ca21aa5
user: Valentin Bartenev <vbart at nginx.com>
date: Thu Feb 11 15:35:36 2016 +0300
description:
HTTP/2: implemented HPACK Huffman encoding for response headers.
This reduces the size of headers by over 30% on average.
Based on the patch by Vlad Krasnov:
http://mailman.nginx.org/pipermail/nginx-devel/2015-December/007682.html
diffstat:
auto/cc/conf | 10 +
src/http/v2/ngx_http_v2.h | 2 +
src/http/v2/ngx_http_v2_filter_module.c | 157 +++++++++++++-------
src/http/v2/ngx_http_v2_huff_encode.c | 240 ++++++++++++++++++++++++++++++++
4 files changed, 353 insertions(+), 56 deletions(-)
diffs (558 lines):
diff -r 5fe617f38222 -r ba3c2ca21aa5 auto/cc/conf
--- a/auto/cc/conf Thu Feb 11 18:46:46 2016 +0300
+++ b/auto/cc/conf Thu Feb 11 15:35:36 2016 +0300
@@ -225,6 +225,16 @@ if [ "$NGX_PLATFORM" != win32 ]; then
. auto/feature
+ ngx_feature="gcc builtin 64 bit byteswap"
+ ngx_feature_name="NGX_HAVE_GCC_BSWAP64"
+ ngx_feature_run=no
+ ngx_feature_incs=
+ ngx_feature_path=
+ ngx_feature_libs=
+ ngx_feature_test="__builtin_bswap64(0)"
+ . auto/feature
+
+
# ngx_feature="inline"
# ngx_feature_name=
# ngx_feature_run=no
diff -r 5fe617f38222 -r ba3c2ca21aa5 src/http/v2/ngx_http_v2.h
--- a/src/http/v2/ngx_http_v2.h Thu Feb 11 18:46:46 2016 +0300
+++ b/src/http/v2/ngx_http_v2.h Thu Feb 11 15:35:36 2016 +0300
@@ -274,6 +274,8 @@ ngx_int_t ngx_http_v2_table_size(ngx_htt
ngx_int_t ngx_http_v2_huff_decode(u_char *state, u_char *src, size_t len,
u_char **dst, ngx_uint_t last, ngx_log_t *log);
+size_t ngx_http_v2_huff_encode(u_char *src, size_t len, u_char *dst,
+ ngx_uint_t lower);
#define ngx_http_v2_prefix(bits) ((1 << (bits)) - 1)
diff -r 5fe617f38222 -r ba3c2ca21aa5 src/http/v2/ngx_http_v2_filter_module.c
--- a/src/http/v2/ngx_http_v2_filter_module.c Thu Feb 11 18:46:46 2016 +0300
+++ b/src/http/v2/ngx_http_v2_filter_module.c Thu Feb 11 15:35:36 2016 +0300
@@ -25,6 +25,11 @@
#define ngx_http_v2_indexed(i) (128 + (i))
#define ngx_http_v2_inc_indexed(i) (64 + (i))
+#define ngx_http_v2_write_name(dst, src, len, tmp) \
+ ngx_http_v2_string_encode(dst, src, len, tmp, 1)
+#define ngx_http_v2_write_value(dst, src, len, tmp) \
+ ngx_http_v2_string_encode(dst, src, len, tmp, 0)
+
#define NGX_HTTP_V2_ENCODE_RAW 0
#define NGX_HTTP_V2_ENCODE_HUFF 0x80
@@ -46,6 +51,8 @@
#define NGX_HTTP_V2_VARY_INDEX 59
+static u_char *ngx_http_v2_string_encode(u_char *dst, u_char *src, size_t len,
+ u_char *tmp, ngx_uint_t lower);
static u_char *ngx_http_v2_write_int(u_char *pos, ngx_uint_t prefix,
ngx_uint_t value);
static ngx_http_v2_out_frame_t *ngx_http_v2_create_headers_frame(
@@ -119,8 +126,8 @@ static ngx_http_output_header_filter_pt
static ngx_int_t
ngx_http_v2_header_filter(ngx_http_request_t *r)
{
- u_char status, *pos, *start, *p;
- size_t len;
+ u_char status, *pos, *start, *p, *tmp;
+ size_t len, tmp_len;
ngx_str_t host, location;
ngx_uint_t i, port;
ngx_list_part_t *part;
@@ -136,6 +143,14 @@ ngx_http_v2_header_filter(ngx_http_reque
#endif
u_char addr[NGX_SOCKADDR_STRLEN];
+ static const u_char nginx[5] = "\x84\xaa\x63\x55\xe7";
+#if (NGX_HTTP_GZIP)
+ static const u_char accept_encoding[12] =
+ "\x8b\x84\x84\x2d\x69\x5b\x05\x44\x3c\x86\xaa\x6f";
+#endif
+
+ static size_t nginx_ver_len = ngx_http_v2_literal_size(NGINX_VER);
+ static u_char nginx_ver[ngx_http_v2_literal_size(NGINX_VER)];
if (!r->stream) {
return ngx_http_next_header_filter(r);
@@ -215,8 +230,7 @@ ngx_http_v2_header_filter(ngx_http_reque
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
if (r->headers_out.server == NULL) {
- len += 1 + (clcf->server_tokens ? ngx_http_v2_literal_size(NGINX_VER)
- : ngx_http_v2_literal_size("nginx"));
+ len += 1 + (clcf->server_tokens ? nginx_ver_len : sizeof(nginx));
}
if (r->headers_out.date == NULL) {
@@ -340,10 +354,12 @@ ngx_http_v2_header_filter(ngx_http_reque
len += 1 + NGX_HTTP_V2_INT_OCTETS + r->headers_out.location->value.len;
}
+ tmp_len = len;
+
#if (NGX_HTTP_GZIP)
if (r->gzip_vary) {
if (clcf->gzip_vary) {
- len += 1 + ngx_http_v2_literal_size("Accept-Encoding");
+ len += 1 + sizeof(accept_encoding);
} else {
r->gzip_vary = 0;
@@ -386,10 +402,20 @@ ngx_http_v2_header_filter(ngx_http_reque
len += 1 + NGX_HTTP_V2_INT_OCTETS + header[i].key.len
+ NGX_HTTP_V2_INT_OCTETS + header[i].value.len;
+
+ if (header[i].key.len > tmp_len) {
+ tmp_len = header[i].key.len;
+ }
+
+ if (header[i].value.len > tmp_len) {
+ tmp_len = header[i].value.len;
+ }
}
- pos = ngx_palloc(r->pool, len);
- if (pos == NULL) {
+ tmp = ngx_palloc(r->pool, tmp_len);
+ pos = ngx_pnalloc(r->pool, len);
+
+ if (pos == NULL || tmp == NULL) {
return NGX_ERROR;
}
@@ -408,21 +434,23 @@ ngx_http_v2_header_filter(ngx_http_reque
*pos++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_SERVER_INDEX);
if (clcf->server_tokens) {
- *pos++ = NGX_HTTP_V2_ENCODE_RAW | (sizeof(NGINX_VER) - 1);
- pos = ngx_cpymem(pos, NGINX_VER, sizeof(NGINX_VER) - 1);
+ if (nginx_ver[0] == '\0') {
+ p = ngx_http_v2_write_value(nginx_ver, (u_char *) NGINX_VER,
+ sizeof(NGINX_VER) - 1, tmp);
+ nginx_ver_len = p - nginx_ver;
+ }
+
+ pos = ngx_cpymem(pos, nginx_ver, nginx_ver_len);
} else {
- *pos++ = NGX_HTTP_V2_ENCODE_RAW | (sizeof("nginx") - 1);
- pos = ngx_cpymem(pos, "nginx", sizeof("nginx") - 1);
+ pos = ngx_cpymem(pos, nginx, sizeof(nginx));
}
}
if (r->headers_out.date == NULL) {
*pos++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_DATE_INDEX);
- *pos++ = (u_char) ngx_cached_http_time.len;
-
- pos = ngx_cpymem(pos, ngx_cached_http_time.data,
- ngx_cached_http_time.len);
+ pos = ngx_http_v2_write_value(pos, ngx_cached_http_time.data,
+ ngx_cached_http_time.len, tmp);
}
if (r->headers_out.content_type.len) {
@@ -431,34 +459,30 @@ ngx_http_v2_header_filter(ngx_http_reque
if (r->headers_out.content_type_len == r->headers_out.content_type.len
&& r->headers_out.charset.len)
{
- *pos = NGX_HTTP_V2_ENCODE_RAW;
- pos = ngx_http_v2_write_int(pos, ngx_http_v2_prefix(7),
- r->headers_out.content_type.len
- + sizeof("; charset=") - 1
- + r->headers_out.charset.len);
+ len = r->headers_out.content_type.len + sizeof("; charset=") - 1
+ + r->headers_out.charset.len;
- p = pos;
+ p = ngx_pnalloc(r->pool, len);
+ if (p == NULL) {
+ return NGX_ERROR;
+ }
- pos = ngx_cpymem(pos, r->headers_out.content_type.data,
- r->headers_out.content_type.len);
+ p = ngx_cpymem(p, r->headers_out.content_type.data,
+ r->headers_out.content_type.len);
- pos = ngx_cpymem(pos, "; charset=", sizeof("; charset=") - 1);
+ p = ngx_cpymem(p, "; charset=", sizeof("; charset=") - 1);
- pos = ngx_cpymem(pos, r->headers_out.charset.data,
- r->headers_out.charset.len);
+ p = ngx_cpymem(p, r->headers_out.charset.data,
+ r->headers_out.charset.len);
- /* update r->headers_out.content_type for possible logging */
+ /* updated r->headers_out.content_type is also needed for logging */
- r->headers_out.content_type.len = pos - p;
- r->headers_out.content_type.data = p;
+ r->headers_out.content_type.len = len;
+ r->headers_out.content_type.data = p - len;
+ }
- } else {
- *pos = NGX_HTTP_V2_ENCODE_RAW;
- pos = ngx_http_v2_write_int(pos, ngx_http_v2_prefix(7),
- r->headers_out.content_type.len);
- pos = ngx_cpymem(pos, r->headers_out.content_type.data,
- r->headers_out.content_type.len);
- }
+ pos = ngx_http_v2_write_value(pos, r->headers_out.content_type.data,
+ r->headers_out.content_type.len, tmp);
}
if (r->headers_out.content_length == NULL
@@ -476,26 +500,26 @@ ngx_http_v2_header_filter(ngx_http_reque
{
*pos++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_LAST_MODIFIED_INDEX);
- *pos++ = NGX_HTTP_V2_ENCODE_RAW
- | (sizeof("Wed, 31 Dec 1986 18:00:00 GMT") - 1);
- pos = ngx_http_time(pos, r->headers_out.last_modified_time);
+ ngx_http_time(pos, r->headers_out.last_modified_time);
+ len = sizeof("Wed, 31 Dec 1986 18:00:00 GMT") - 1;
+
+ /*
+ * Date will always be encoded using huffman in the temporary buffer,
+ * so it's safe here to use src and dst pointing to the same address.
+ */
+ pos = ngx_http_v2_write_value(pos, pos, len, tmp);
}
if (r->headers_out.location && r->headers_out.location->value.len) {
*pos++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_LOCATION_INDEX);
-
- *pos = NGX_HTTP_V2_ENCODE_RAW;
- pos = ngx_http_v2_write_int(pos, ngx_http_v2_prefix(7),
- r->headers_out.location->value.len);
- pos = ngx_cpymem(pos, r->headers_out.location->value.data,
- r->headers_out.location->value.len);
+ pos = ngx_http_v2_write_value(pos, r->headers_out.location->value.data,
+ r->headers_out.location->value.len, tmp);
}
#if (NGX_HTTP_GZIP)
if (r->gzip_vary) {
*pos++ = ngx_http_v2_inc_indexed(NGX_HTTP_V2_VARY_INDEX);
- *pos++ = NGX_HTTP_V2_ENCODE_RAW | (sizeof("Accept-Encoding") - 1);
- pos = ngx_cpymem(pos, "Accept-Encoding", sizeof("Accept-Encoding") - 1);
+ pos = ngx_cpymem(pos, accept_encoding, sizeof(accept_encoding));
}
#endif
@@ -520,16 +544,11 @@ ngx_http_v2_header_filter(ngx_http_reque
*pos++ = 0;
- *pos = NGX_HTTP_V2_ENCODE_RAW;
- pos = ngx_http_v2_write_int(pos, ngx_http_v2_prefix(7),
- header[i].key.len);
- ngx_strlow(pos, header[i].key.data, header[i].key.len);
- pos += header[i].key.len;
+ pos = ngx_http_v2_write_name(pos, header[i].key.data,
+ header[i].key.len, tmp);
- *pos = NGX_HTTP_V2_ENCODE_RAW;
- pos = ngx_http_v2_write_int(pos, ngx_http_v2_prefix(7),
- header[i].value.len);
- pos = ngx_cpymem(pos, header[i].value.data, header[i].value.len);
+ pos = ngx_http_v2_write_value(pos, header[i].value.data,
+ header[i].value.len, tmp);
}
frame = ngx_http_v2_create_headers_frame(r, start, pos);
@@ -557,6 +576,32 @@ ngx_http_v2_header_filter(ngx_http_reque
static u_char *
+ngx_http_v2_string_encode(u_char *dst, u_char *src, size_t len, u_char *tmp,
+ ngx_uint_t lower)
+{
+ size_t hlen;
+
+ hlen = ngx_http_v2_huff_encode(src, len, tmp, lower);
+
+ if (hlen > 0) {
+ *dst = NGX_HTTP_V2_ENCODE_HUFF;
+ dst = ngx_http_v2_write_int(dst, ngx_http_v2_prefix(7), hlen);
+ return ngx_cpymem(dst, tmp, hlen);
+ }
+
+ *dst = NGX_HTTP_V2_ENCODE_RAW;
+ dst = ngx_http_v2_write_int(dst, ngx_http_v2_prefix(7), len);
+
+ if (lower) {
+ ngx_strlow(dst, src, len);
+ return dst + len;
+ }
+
+ return ngx_cpymem(dst, src, len);
+}
+
+
+static u_char *
ngx_http_v2_write_int(u_char *pos, ngx_uint_t prefix, ngx_uint_t value)
{
if (value < prefix) {
diff -r 5fe617f38222 -r ba3c2ca21aa5 src/http/v2/ngx_http_v2_huff_encode.c
--- a/src/http/v2/ngx_http_v2_huff_encode.c Thu Feb 11 18:46:46 2016 +0300
+++ b/src/http/v2/ngx_http_v2_huff_encode.c Thu Feb 11 15:35:36 2016 +0300
@@ -2,9 +2,249 @@
/*
* 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;
+ }
+
+ buf |= (ngx_uint_t) -1 >> pending;
+
+ pending = ngx_align(pending, 8);
+
+ if (hlen + pending / 8 >= len) {
+ return 0;
+ }
+
+ buf >>= sizeof(buf) * 8 - pending;
+
+ while (pending) {
+ pending -= 8;
+ dst[hlen++] = (u_char) (buf >> pending);
+ }
+
+ return hlen;
+}
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