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Willy Tarreau1be4f3d2017-09-21 14:35:57 +02001/*
2 * HPACK compressor (RFC7541)
3 *
4 * Copyright (C) 2014-2017 Willy Tarreau <willy@haproxy.org>
5 * Copyright (C) 2017 HAProxy Technologies
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining
8 * a copy of this software and associated documentation files (the
9 * "Software"), to deal in the Software without restriction, including
10 * without limitation the rights to use, copy, modify, merge, publish,
11 * distribute, sublicense, and/or sell copies of the Software, and to
12 * permit persons to whom the Software is furnished to do so, subject to
13 * the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be
16 * included in all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
20 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
22 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
23 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
24 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
25 * OTHER DEALINGS IN THE SOFTWARE.
26 */
27
28#ifndef _COMMON_HPACK_ENC_H
29#define _COMMON_HPACK_ENC_H
30
31#include <stdint.h>
Willy Tarreaubd5659b2018-12-11 07:44:19 +010032#include <string.h>
Willy Tarreau2df026f2018-12-11 09:03:07 +010033#include <common/buf.h>
Willy Tarreau1be4f3d2017-09-21 14:35:57 +020034#include <common/config.h>
Willy Tarreau39c80eb2018-12-10 18:24:19 +010035#include <common/http.h>
Willy Tarreau1be4f3d2017-09-21 14:35:57 +020036#include <common/ist.h>
37
Willy Tarreau83061a82018-07-13 11:56:34 +020038int hpack_encode_header(struct buffer *out, const struct ist n,
39 const struct ist v);
Willy Tarreau1be4f3d2017-09-21 14:35:57 +020040
Willy Tarreaubad0a382018-12-11 07:44:00 +010041/* Returns the number of bytes required to encode the string length <len>. The
42 * number of usable bits is an integral multiple of 7 plus 6 for the last byte.
43 * The maximum number of bytes returned is 4 (2097279 max length). Larger values
44 * return 0.
45 */
46static inline int hpack_len_to_bytes(size_t len)
47{
48 ssize_t slen = len;
49
50 slen -= 127;
51 if (__builtin_expect(slen < 0, 1))
52 return 1;
53 if (slen < (1 << 14)) {
54 if (__builtin_expect(slen < (1 << 7), 1))
55 return 2;
56 else
57 return 3;
58 }
59 if (slen < (1 << 21))
60 return 4;
61 return 0;
62}
63
64/* Encodes <len> into <out>+<pos> and return the new position. The caller is
65 * responsible for checking for available room using hpack_len_to_bytes()
66 * first.
67 */
68static inline int hpack_encode_len(char *out, int pos, int len)
69{
70 int code = len - 127;
71
72 if (code < 0) {
73 out[pos++] = len;
74 } else {
75 out[pos++] = 127;
76 for (; code >= 128; code >>= 7)
77 out[pos++] = code | 128;
78 out[pos++] = code;
79 }
80 return pos;
81}
82
Willy Tarreau30eb8092018-12-11 06:16:45 +010083/* Tries to encode header field index <idx> with short value <val> into the
84 * aligned buffer <out>. Returns non-zero on success, 0 on failure (buffer
85 * full). The caller is responsible for ensuring that the length of <val> is
86 * strictly lower than 127, and that <idx> is lower than 64 (static list only),
87 * and that the buffer is aligned (head==0).
88 */
89static inline int hpack_encode_short_idx(struct buffer *out, int idx, struct ist val)
90{
91 if (out->data + 2 + val.len > out->size)
92 return 0;
93
94 /* literal header field with incremental indexing */
95 out->area[out->data++] = idx | 0x40;
96 out->area[out->data++] = val.len;
97 ist2bin(&out->area[out->data], val);
98 out->data += val.len;
99 return 1;
100}
101
Willy Tarreaubd5659b2018-12-11 07:44:19 +0100102/* Tries to encode header field index <idx> with long value <val> into the
103 * aligned buffer <out>. Returns non-zero on success, 0 on failure (buffer
104 * full). The caller is responsible for ensuring <idx> is lower than 64 (static
105 * list only), and that the buffer is aligned (head==0).
106 */
107static inline int hpack_encode_long_idx(struct buffer *out, int idx, struct ist val)
108{
109 int len = out->data;
110
111 if (!hpack_len_to_bytes(val.len) ||
112 1 + len + hpack_len_to_bytes(val.len) + val.len > out->size)
113 return 0;
114
115 /* emit literal with indexing (7541#6.2.1) :
116 * [ 0 | 1 | Index (6+) ]
117 */
118 out->area[len++] = idx | 0x40;
119 len = hpack_encode_len(out->area, len, val.len);
120 memcpy(out->area + len, val.ptr, val.len);
121 len += val.len;
122
123 out->data = len;
124 return 1;
125}
126
Willy Tarreau88953672018-12-10 18:04:42 +0100127/* Tries to encode a :status pseudo-header with the integer status <status>
128 * into the aligned buffer <out>. Returns non-zero on success, 0 on failure
129 * (buffer full). The caller is responsible for ensuring that the status is
130 * comprised between 100 and 999 inclusive and that the buffer is aligned. It's
131 * inlined because it's easily optimizable by the compiler.
132 */
133static inline int hpack_encode_int_status(struct buffer *out, unsigned int status)
134{
135 int len = out->data;
136 int size = out->size;
137 unsigned char c = 0;
138
139 /* try to emit a single byte code */
140 len++;
141 if (__builtin_expect(len > size, 0))
142 goto fail;
143
144 c = (status <= 304) ?
145 (status <= 204) ?
146 (status == 204) ? 0x89 :
147 (status == 200) ? 0x88 :
148 0: /* > 204 */
149 (status == 304) ? 0x8b :
150 (status == 206) ? 0x8a :
151 0:
152 (status <= 404) ?
153 (status == 404) ? 0x8d :
154 (status == 400) ? 0x8c :
155 0: /* > 404 */
156 (status == 500) ? 0x8e :
157 0;
158
159 if (c)
160 goto last;
161
162 /* fall back to literal */
163 len += 4;
164 if (__builtin_expect(len > size, 0))
165 goto fail;
166
167 /* basic encoding of the status code */
168 out->area[len - 5] = 0x48; // indexed name -- name=":status" (idx 8)
169 out->area[len - 4] = 0x03; // 3 bytes status
170 out->area[len - 3] = '0' + status / 100;
171 out->area[len - 2] = '0' + status / 10 % 10;
172 c = '0' + status % 10;
173 last:
174 out->area[len - 1] = c;
175 out->data = len;
176 return 1;
177 fail:
178 return 0;
179}
180
181/* Tries to encode a :status pseudo-header with the integer status <status>
182 * also represented by <str> into the aligned buffer <out>. Returns non-zero
183 * on success or 0 on failure (buffer full). The caller is responsible for
184 * ensuring that the status is comprised between 100 and 999 inclusive, that
185 * <str> contains a valid representation of the numerical value, and that the
186 * buffer is aligned. This version is preferred when the caller already knows
187 * a string representation of the status because it avoids the computation in
188 * the uncompressed case. It's inlined because it's easily optimizable.
189 */
190static inline int hpack_encode_str_status(struct buffer *out, unsigned int status, struct ist str)
191{
192 /* don't try too hard, we already have the ASCII value for less common cases */
193 if (status == 200 || status == 304) {
194 if (out->data >= out->size)
195 return 0;
196 out->area[out->data] = (status == 304) ? 0x8b : 0x88;
197 out->data++;
198 return 1;
199 }
200 return hpack_encode_short_idx(out, 8, str); // name=":status" (idx 8)
201}
202
Willy Tarreau39c80eb2018-12-10 18:24:19 +0100203/* Tries to encode a :method pseudo-header with the method in <meth>, which
204 * also exists as a string in <str>, into the aligned buffer <out>. Returns
205 * non-zero on success or 0 on failure (buffer full). The caller is responsible
206 * for ensuring that the string matches <meth>, that it's smaller than 127
207 * bytes, and that the buffer is aligned. If <meth> is unknown then using
208 * HTTP_METH_OTHER will lead to the string being encoded as a literal. It's
209 * inlined because it's easily optimizable.
210 */
211static inline int hpack_encode_method(struct buffer *out, enum http_meth_t meth, struct ist str)
212{
213 if (out->data < out->size && meth == HTTP_METH_GET)
214 out->area[out->data++] = 0x82; // indexed field : idx[02]=(":method", "GET")
215 else if (out->data < out->size && meth == HTTP_METH_POST)
216 out->area[out->data++] = 0x83; // indexed field : idx[03]=(":method", "POST")
217 else
218 return hpack_encode_short_idx(out, 2, str); // name=":method" (idx 2)
219 return 1;
220}
221
Willy Tarreau820b3912018-12-10 19:16:20 +0100222/* Tries to encode a :scheme pseudo-header with the scheme in <scheme>, into
223 * the aligned buffer <out>. Returns non-zero on success or 0 on failure
224 * (buffer full). Only "http" and "https" are recognized and handled as indexed
225 * values, others are turned into short literals. The caller is responsible for
226 * ensuring that the scheme is smaller than 127 bytes, and that the buffer is
227 * aligned. Normally the compiler will detect constant strings in the comparison
228 * if the code remains inlined.
229 */
230static inline int hpack_encode_scheme(struct buffer *out, struct ist scheme)
231{
232 if (out->data < out->size && isteq(scheme, ist("https")))
233 out->area[out->data++] = 0x87; // indexed field : idx[07]=(":scheme", "https")
234 else if (out->data < out->size && isteq(scheme, ist("http")))
235 out->area[out->data++] = 0x86; // indexed field : idx[06]=(":scheme", "http")
236 else
237 return hpack_encode_short_idx(out, 6, scheme); // name=":scheme" (idx 6)
238 return 1;
239}
Willy Tarreau39c80eb2018-12-10 18:24:19 +0100240
Willy Tarreaueaeeb682018-12-10 19:26:51 +0100241/* Tries to encode a :path pseudo-header with the path in <path>, into the
242 * aligned buffer <out>. Returns non-zero on success or 0 on failure (buffer
243 * full). The well-known values "/" and "/index.html" are recognized, and other
244 * ones are handled as literals. The caller is responsible for ensuring that
245 * the buffer is aligned. Normally the compiler will detect constant strings
246 * in the comparison if the code remains inlined.
247 */
248static inline int hpack_encode_path(struct buffer *out, struct ist path)
249{
250 if (out->data < out->size && isteq(path, ist("/")))
251 out->area[out->data++] = 0x84; // indexed field : idx[04]=(":path", "/")
252 else if (out->data < out->size && isteq(path, ist("/index.html")))
253 out->area[out->data++] = 0x85; // indexed field : idx[05]=(":path", "/index.html")
254 else if (path.len < 127)
255 return hpack_encode_short_idx(out, 4, path); // name=":path" (idx 4)
256 else
257 return hpack_encode_long_idx(out, 4, path); // name=":path" (idx 4)
258 return 1;
259}
260
261
Willy Tarreau1be4f3d2017-09-21 14:35:57 +0200262#endif /* _COMMON_HPACK_ENC_H */