Willy Tarreau | 1be4f3d | 2017-09-21 14:35:57 +0200 | [diff] [blame] | 1 | /* |
| 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 Tarreau | 2df026f | 2018-12-11 09:03:07 +0100 | [diff] [blame] | 32 | #include <common/buf.h> |
Willy Tarreau | 1be4f3d | 2017-09-21 14:35:57 +0200 | [diff] [blame] | 33 | #include <common/config.h> |
| 34 | #include <common/ist.h> |
| 35 | |
Willy Tarreau | 83061a8 | 2018-07-13 11:56:34 +0200 | [diff] [blame] | 36 | int hpack_encode_header(struct buffer *out, const struct ist n, |
| 37 | const struct ist v); |
Willy Tarreau | 1be4f3d | 2017-09-21 14:35:57 +0200 | [diff] [blame] | 38 | |
Willy Tarreau | bad0a38 | 2018-12-11 07:44:00 +0100 | [diff] [blame^] | 39 | /* Returns the number of bytes required to encode the string length <len>. The |
| 40 | * number of usable bits is an integral multiple of 7 plus 6 for the last byte. |
| 41 | * The maximum number of bytes returned is 4 (2097279 max length). Larger values |
| 42 | * return 0. |
| 43 | */ |
| 44 | static inline int hpack_len_to_bytes(size_t len) |
| 45 | { |
| 46 | ssize_t slen = len; |
| 47 | |
| 48 | slen -= 127; |
| 49 | if (__builtin_expect(slen < 0, 1)) |
| 50 | return 1; |
| 51 | if (slen < (1 << 14)) { |
| 52 | if (__builtin_expect(slen < (1 << 7), 1)) |
| 53 | return 2; |
| 54 | else |
| 55 | return 3; |
| 56 | } |
| 57 | if (slen < (1 << 21)) |
| 58 | return 4; |
| 59 | return 0; |
| 60 | } |
| 61 | |
| 62 | /* Encodes <len> into <out>+<pos> and return the new position. The caller is |
| 63 | * responsible for checking for available room using hpack_len_to_bytes() |
| 64 | * first. |
| 65 | */ |
| 66 | static inline int hpack_encode_len(char *out, int pos, int len) |
| 67 | { |
| 68 | int code = len - 127; |
| 69 | |
| 70 | if (code < 0) { |
| 71 | out[pos++] = len; |
| 72 | } else { |
| 73 | out[pos++] = 127; |
| 74 | for (; code >= 128; code >>= 7) |
| 75 | out[pos++] = code | 128; |
| 76 | out[pos++] = code; |
| 77 | } |
| 78 | return pos; |
| 79 | } |
| 80 | |
Willy Tarreau | 1be4f3d | 2017-09-21 14:35:57 +0200 | [diff] [blame] | 81 | #endif /* _COMMON_HPACK_ENC_H */ |