# HG changeset patch
# User Vlad Krasnov <vlad@cloudflare.com>
# Date 1450274269 28800
# Wed Dec 16 05:57:49 2015 -0800
# Node ID d672e9c2b814710986683e050491536355c90f0d
# Parent def9c9c9ae05cfa7467b0ec96e76afa180c23dfb
HTTP/2: HPACK Huffman encoding

Implement HPACK Huffman encoding for HTTP/2.
This reduces the size of headers by over 30% on average.

diff -r def9c9c9ae05 -r d672e9c2b814 src/http/v2/ngx_http_v2.h
--- a/src/http/v2/ngx_http_v2.h Sat Dec 12 10:32:58 2015 +0300
+++ b/src/http/v2/ngx_http_v2.h Wed Dec 16 05:57:49 2015 -0800
@@ -51,6 +51,9 @@
#define NGX_HTTP_V2_PRIORITY_FLAG 0x20


+#define NGX_HTTP_V2_ENCODE_RAW 0
+#define NGX_HTTP_V2_ENCODE_HUFF 0x80
+
typedef struct ngx_http_v2_connection_s ngx_http_v2_connection_t;
typedef struct ngx_http_v2_node_s ngx_http_v2_node_t;
typedef struct ngx_http_v2_out_frame_s ngx_http_v2_out_frame_t;
@@ -255,6 +258,28 @@
}


+static ngx_inline u_char *
+ngx_http_v2_write_int(u_char *pos, ngx_uint_t prefix, ngx_uint_t value)
+{
+ if (value < prefix) {
+ *pos++ |= value;
+ return pos;
+ }
+
+ *pos++ |= prefix;
+ value -= prefix;
+
+ while (value >= 128) {
+ *pos++ = value % 128 + 128;
+ value /= 128;
+ }
+
+ *pos++ = (u_char) value;
+
+ return pos;
+}
+
+
void ngx_http_v2_init(ngx_event_t *rev);
void ngx_http_v2_request_headers_init(void);

@@ -275,7 +300,8 @@

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);
-
+u_char *ngx_http_v2_string_encode(u_char *src, size_t len, u_char *dst,
+ u_char *tmp, ngx_log_t *log, ngx_flag_t lower);

#define ngx_http_v2_prefix(bits) ((1 << (bits)) - 1)

diff -r def9c9c9ae05 -r d672e9c2b814 src/http/v2/ngx_http_v2_filter_module.c
--- a/src/http/v2/ngx_http_v2_filter_module.c Sat Dec 12 10:32:58 2015 +0300
+++ b/src/http/v2/ngx_http_v2_filter_module.c Wed Dec 16 05:57:49 2015 -0800
@@ -25,9 +25,6 @@
#define ngx_http_v2_indexed(i) (128 + (i))
#define ngx_http_v2_inc_indexed(i) (64 + (i))

-#define NGX_HTTP_V2_ENCODE_RAW 0
-#define NGX_HTTP_V2_ENCODE_HUFF 0x80
-
#define NGX_HTTP_V2_STATUS_INDEX 8
#define NGX_HTTP_V2_STATUS_200_INDEX 8
#define NGX_HTTP_V2_STATUS_204_INDEX 9
@@ -46,8 +43,9 @@
#define NGX_HTTP_V2_VARY_INDEX 59


-static u_char *ngx_http_v2_write_int(u_char *pos, ngx_uint_t prefix,
- ngx_uint_t value);
+#define ACCEPT_ENCODING "\x84\x84\x2d\x69\x5b\x05\x44\x3c\x86\xaa\x6f"
+
+
static ngx_http_v2_out_frame_t *ngx_http_v2_create_headers_frame(
ngx_http_request_t *r, u_char *pos, u_char *end);

@@ -119,8 +117,8 @@
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, *huff;
+ size_t len, hlen, nlen;
ngx_str_t host, location;
ngx_uint_t i, port;
ngx_list_part_t *part;
@@ -343,7 +341,7 @@
#if (NGX_HTTP_GZIP)
if (r->gzip_vary) {
if (clcf->gzip_vary) {
- len += 1 + ngx_http_v2_literal_size("Accept-Encoding");
+ len += 1 + ngx_http_v2_literal_size(ACCEPT_ENCODING);

} else {
r->gzip_vary = 0;
@@ -354,6 +352,8 @@
part = &r->headers_out.headers.part;
header = part->elts;

+ hlen = len;
+
for (i = 0; /* void */; i++) {

if (i >= part->nelts) {
@@ -384,11 +384,14 @@
return NGX_ERROR;
}

- len += 1 + NGX_HTTP_V2_INT_OCTETS + header[i].key.len
+ nlen = 1 + NGX_HTTP_V2_INT_OCTETS + header[i].key.len
+ NGX_HTTP_V2_INT_OCTETS + header[i].value.len;
+ len += nlen;
+ hlen = nlen > hlen ? nlen : hlen;
}

pos = ngx_palloc(r->pool, len);
+ huff = ngx_palloc(r->pool, hlen);
if (pos == NULL) {
return NGX_ERROR;
}
@@ -408,12 +411,15 @@
*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);
+ pos = ngx_http_v2_string_encode((u_char*)NGINX_VER,
+ sizeof(NGINX_VER) - 1, pos, huff,
+ r->connection->log, 0);

} else {
- *pos++ = NGX_HTTP_V2_ENCODE_RAW | (sizeof("nginx") - 1);
- pos = ngx_cpymem(pos, "nginx", sizeof("nginx") - 1);
+ pos = ngx_http_v2_string_encode((u_char*)"nginx",
+ sizeof("nginx") - 1, pos, huff,
+ r->connection->log, 0);
+
}
}

@@ -453,11 +459,9 @@
r->headers_out.content_type.data = p;

} 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_string_encode(r->headers_out.content_type.data,
+ r->headers_out.content_type.len,
+ pos, huff, r->connection->log, 0);
}
}

@@ -476,26 +480,27 @@
{
*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);
+ nlen = sizeof("Wed, 31 Dec 1986 18:00:00 GMT") - 1;
+ ngx_http_time(pos + 1, r->headers_out.last_modified_time);
+
+ pos = ngx_http_v2_string_encode(pos + 1, nlen, pos, huff,
+ r->connection->log, 0);
}

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_string_encode(r->headers_out.location->value.data,
+ r->headers_out.location->value.len,
+ pos, huff, r->connection->log, 0);
}

#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_HTTP_V2_ENCODE_HUFF | (sizeof(ACCEPT_ENCODING) - 1);
+ pos = ngx_cpymem(pos, ACCEPT_ENCODING, sizeof(ACCEPT_ENCODING) - 1);
}
#endif

@@ -520,16 +525,14 @@

*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_string_encode(header[i].key.data,
+ header[i].key.len,
+ pos, huff, r->connection->log, 1);

- *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_string_encode(header[i].value.data,
+ header[i].value.len,
+ pos, huff, r->connection->log, 0);
+
}

frame = ngx_http_v2_create_headers_frame(r, start, pos);
@@ -556,28 +559,6 @@
}


-static u_char *
-ngx_http_v2_write_int(u_char *pos, ngx_uint_t prefix, ngx_uint_t value)
-{
- if (value < prefix) {
- *pos++ |= value;
- return pos;
- }
-
- *pos++ |= prefix;
- value -= prefix;
-
- while (value >= 128) {
- *pos++ = value % 128 + 128;
- value /= 128;
- }
-
- *pos++ = (u_char) value;
-
- return pos;
-}
-
-
static ngx_http_v2_out_frame_t *
ngx_http_v2_create_headers_frame(ngx_http_request_t *r, u_char *pos,
u_char *end)
diff -r def9c9c9ae05 -r d672e9c2b814 src/http/v2/ngx_http_v2_huff_encode.c
--- a/src/http/v2/ngx_http_v2_huff_encode.c Sat Dec 12 10:32:58 2015 +0300
+++ b/src/http/v2/ngx_http_v2_huff_encode.c Wed Dec 16 05:57:49 2015 -0800
@@ -1,10 +1,296 @@

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


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
+#if (__GNUC__)
+#include <byteswap.h>
+#endif
+
+
+typedef struct {
+ ngx_uint_t code;
+ ngx_uint_t len;
+} ngx_http_v2_huff_encode_code_t;
+
+
+static ngx_http_v2_huff_encode_code_t ngx_http_v2_huff_encode_codes[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 embedes to lower case transformations */
+static ngx_http_v2_huff_encode_code_t ngx_http_v2_huff_encode_codes_low[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_HAVE_LITTLE_ENDIAN)
+#if (__GNUC__)
+
+static void
+put64(u_char *dst, uint64_t val)
+{
+ *(uint64_t*)dst = __bswap_64(val);
+}
+
+#else /* !__GNUC__ */
+
+static void
+put64(u_char *dst, uint64_t val)
+{
+ dst[0] = val >> 56;
+ dst[1] = val >> 48;
+ dst[2] = val >> 40;
+ dst[3] = val >> 32;
+ dst[4] = val >> 24;
+ dst[5] = val >> 16;
+ dst[6] = val >> 8;
+ dst[7] = val;
+}
+#endif /* __GNUC__ */
+
+#else /* !NGX_HAVE_LITTLE_ENDIAN */
+
+static void
+put64(u_char *dst, uint64_t val)
+{
+ *(uint64_t*)dst = val;
+}
+
+#endif
+
+
+static ngx_int_t
+ngx_http_v2_huff_encode(u_char *src, size_t len, u_char *dst, ngx_log_t *log,
+ ngx_flag_t lower)
+{
+ ngx_uint_t inp, outp;
+ ngx_int_t pending;
+ uint64_t buf;
+ ngx_http_v2_huff_encode_code_t next;
+ ngx_http_v2_huff_encode_code_t *table;
+
+ if (!lower) {
+ table = ngx_http_v2_huff_encode_codes;
+
+ } else {
+ table = ngx_http_v2_huff_encode_codes_low;
+ }
+
+ inp = 0;
+ outp = 0;
+ pending = 0;
+ buf = 0;
+
+ while (inp < len) {
+ next = table[src[inp]];
+ /* Accumulate 64 bits */
+ if ((next.len + pending) < 64) {
+ buf ^= (uint64_t)next.code << (64 - pending - next.len);
+ pending += next.len;
+
+ } else {
+ /* If compressed result is longer than source, no point in using it */
+ if ((outp + 8) >= len) {
+ return NGX_ERROR;
+ }
+
+ buf ^= (uint64_t)next.code >> (next.len - (64 - pending));
+ put64(&dst[outp], buf);
+ outp += 8;
+ pending = (next.len - (64 - pending));
+
+ if (pending) {
+ buf = (uint64_t)next.code << (64 - pending);
+
+ } else {
+ buf = 0;
+ }
+ }
+
+ inp++;
+ }
+
+ buf ^= 0xffffffffffffffffUL >> pending;
+
+ while (pending > 0) {
+ dst[outp] = buf >> 56;
+ buf <<= 8;
+ pending -= 8;
+ outp++;
+
+ if (outp >= len) {
+ return NGX_ERROR;
+ }
+ }
+
+ ngx_log_debug2(NGX_LOG_DEBUG_HTTP, log, 0,
+ "http2 huffman encoding successful; "
+ "input len: %d, output len %d", len, outp);
+
+ return outp;
+}
+
+
+u_char *
+ngx_http_v2_string_encode(u_char *src, size_t len, u_char *dst, u_char *tmp,
+ ngx_log_t *log, ngx_flag_t lower)
+{
+ ngx_int_t hlen;
+
+ hlen = ngx_http_v2_huff_encode(src, len, tmp, log, lower);
+
+ if (hlen != NGX_ERROR) {
+ *dst = NGX_HTTP_V2_ENCODE_HUFF;
+ dst = ngx_http_v2_write_int(dst, ngx_http_v2_prefix(7), hlen);
+ dst = ngx_cpymem(dst, tmp, hlen);
+
+ } else {
+ *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);
+ dst += len;
+
+ } else {
+ dst = ngx_cpymem(dst, src, len);
+ }
+ }
+
+ return dst;
+}

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