1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
//! HTTP header types
//!
//! The module provides [`HeaderName`], [`HeaderMap`], and a number of types
//! used for interacting with `HeaderMap`. These types allow representing both
//! HTTP/1 and HTTP/2 headers.
//!
//! # `HeaderName`
//!
//! The `HeaderName` type represents both standard header names as well as
//! custom header names. The type handles the case insensitive nature of header
//! names and is used as the key portion of `HeaderMap`. Header names are
//! normalized to lower case. In other words, when creating a `HeaderName` with
//! a string, even if upper case characters are included, when getting a string
//! representation of the `HeaderName`, it will be all lower case. This allows
//! for faster `HeaderMap` comparison operations.
//!
//! The internal representation is optimized to efficiently handle the cases
//! most commonly encountered when working with HTTP. Standard header names are
//! special cased and are represented internally as an enum. Short custom
//! headers will be stored directly in the `HeaderName` struct and will not
//! incur any allocation overhead, however longer strings will require an
//! allocation for storage.
//!
//! ## Limitations
//!
//! `HeaderName` has a max length of 32,768 for header names. Attempting to
//! parse longer names will result in a panic.
//!
//! # `HeaderMap`
//!
//! `HeaderMap` is a map structure of header names highly optimized for use
//! cases common with HTTP. It is a [multimap] structure, where each header name
//! may have multiple associated header values. Given this, some of the APIs
//! diverge from [`HashMap`].
//!
//! ## Overview
//!
//! Just like `HashMap` in Rust's stdlib, `HeaderMap` is based on [Robin Hood
//! hashing]. This algorithm tends to reduce the worst case search times in the
//! table and enables high load factors without seriously affecting performance.
//! Internally, keys and values are stored in vectors. As such, each insertion
//! will not incur allocation overhead. However, once the underlying vector
//! storage is full, a larger vector must be allocated and all values copied.
//!
//! ## Deterministic ordering
//!
//! Unlike Rust's `HashMap`, values in `HeaderMap` are deterministically
//! ordered. Roughly, values are ordered by insertion. This means that a
//! function that deterministically operates on a header map can rely on the
//! iteration order to remain consistent across processes and platforms.
//!
//! ## Adaptive hashing
//!
//! `HeaderMap` uses an adaptive hashing strategy in order to efficiently handle
//! most common cases. All standard headers have statically computed hash values
//! which removes the need to perform any hashing of these headers at runtime.
//! The default hash function emphasizes performance over robustness. However,
//! `HeaderMap` detects high collision rates and switches to a secure hash
//! function in those events. The threshold is set such that only denial of
//! service attacks should trigger it.
//!
//! ## Limitations
//!
//! `HeaderMap` can store a maximum of 32,768 headers (header name / value
//! pairs). Attempting to insert more will result in a panic.
//!
//! [`HeaderName`]: struct.HeaderName.html
//! [`HeaderMap`]: struct.HeaderMap.html
//! [multimap]: https://en.wikipedia.org/wiki/Multimap
//! [`HashMap`]: https://doc.rust-lang.org/std/collections/struct.HashMap.html
//! [Robin Hood hashing]: https://en.wikipedia.org/wiki/Hash_table#Robin_Hood_hashing
mod map;
mod name;
mod value;
pub use self::map::{
AsHeaderName, Drain, Entry, GetAll, HeaderMap, IntoHeaderName, IntoIter, Iter, IterMut, Keys,
OccupiedEntry, VacantEntry, ValueDrain, ValueIter, ValueIterMut, Values, ValuesMut,
};
pub use self::name::{HeaderName, InvalidHeaderName};
pub use self::value::{HeaderValue, InvalidHeaderValue, ToStrError};
// Use header name constants
pub use self::name::{
ACCEPT,
ACCEPT_CHARSET,
ACCEPT_ENCODING,
ACCEPT_LANGUAGE,
ACCEPT_RANGES,
ACCESS_CONTROL_ALLOW_CREDENTIALS,
ACCESS_CONTROL_ALLOW_HEADERS,
ACCESS_CONTROL_ALLOW_METHODS,
ACCESS_CONTROL_ALLOW_ORIGIN,
ACCESS_CONTROL_EXPOSE_HEADERS,
ACCESS_CONTROL_MAX_AGE,
ACCESS_CONTROL_REQUEST_HEADERS,
ACCESS_CONTROL_REQUEST_METHOD,
AGE,
ALLOW,
ALT_SVC,
AUTHORIZATION,
CACHE_CONTROL,
CACHE_STATUS,
CDN_CACHE_CONTROL,
CONNECTION,
CONTENT_DISPOSITION,
CONTENT_ENCODING,
CONTENT_LANGUAGE,
CONTENT_LENGTH,
CONTENT_LOCATION,
CONTENT_RANGE,
CONTENT_SECURITY_POLICY,
CONTENT_SECURITY_POLICY_REPORT_ONLY,
CONTENT_TYPE,
COOKIE,
DNT,
DATE,
ETAG,
EXPECT,
EXPIRES,
FORWARDED,
FROM,
HOST,
IF_MATCH,
IF_MODIFIED_SINCE,
IF_NONE_MATCH,
IF_RANGE,
IF_UNMODIFIED_SINCE,
LAST_MODIFIED,
LINK,
LOCATION,
MAX_FORWARDS,
ORIGIN,
PRAGMA,
PROXY_AUTHENTICATE,
PROXY_AUTHORIZATION,
PUBLIC_KEY_PINS,
PUBLIC_KEY_PINS_REPORT_ONLY,
RANGE,
REFERER,
REFERRER_POLICY,
REFRESH,
RETRY_AFTER,
SEC_WEBSOCKET_ACCEPT,
SEC_WEBSOCKET_EXTENSIONS,
SEC_WEBSOCKET_KEY,
SEC_WEBSOCKET_PROTOCOL,
SEC_WEBSOCKET_VERSION,
SERVER,
SET_COOKIE,
STRICT_TRANSPORT_SECURITY,
TE,
TRAILER,
TRANSFER_ENCODING,
UPGRADE,
UPGRADE_INSECURE_REQUESTS,
USER_AGENT,
VARY,
VIA,
WARNING,
WWW_AUTHENTICATE,
X_CONTENT_TYPE_OPTIONS,
X_DNS_PREFETCH_CONTROL,
X_FRAME_OPTIONS,
X_XSS_PROTECTION,
};
/// Maximum length of a header name
///
/// Generally, 64kb for a header name is WAY too much than would ever be needed
/// in practice. Restricting it to this size enables using `u16` values to
/// represent offsets when dealing with header names.
const MAX_HEADER_NAME_LEN: usize = (1 << 16) - 1;
|
