    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
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245

    //! # Configs
    //!
    //! There isn't just one type of Base64; that would be too simple. You need to choose a character
    //! set (standard, URL-safe, etc) and padding suffix (yes/no).
    //! The `Config` struct encapsulates this info. There are some common configs included: `STANDARD`,
    //! `URL_SAFE`, etc. You can also make your own `Config` if needed.
    //!
    //! The functions that don't have `config` in the name (e.g. `encode()` and `decode()`) use the
    //! `STANDARD` config .
    //!
    //! The functions that write to a slice (the ones that end in `_slice`) are generally the fastest
    //! because they don't need to resize anything. If it fits in your workflow and you care about
    //! performance, keep using the same buffer (growing as need be) and use the `_slice` methods for
    //! the best performance.
    //!
    //! # Encoding
    //!
    //! Several different encoding functions are available to you depending on your desire for
    //! convenience vs performance.
    //!
    //! | Function                | Output                       | Allocates                      |
    //! | ----------------------- | ---------------------------- | ------------------------------ |
    //! | `encode`                | Returns a new `String`       | Always                         |
    //! | `encode_config`         | Returns a new `String`       | Always                         |
    //! | `encode_config_buf`     | Appends to provided `String` | Only if `String` needs to grow |
    //! | `encode_config_slice`   | Writes to provided `&[u8]`   | Never                          |
    //!
    //! All of the encoding functions that take a `Config` will pad as per the config.
    //!
    //! # Decoding
    //!
    //! Just as for encoding, there are different decoding functions available.
    //!
    //! | Function                | Output                        | Allocates                      |
    //! | ----------------------- | ----------------------------- | ------------------------------ |
    //! | `decode`                | Returns a new `Vec<u8>`       | Always                         |
    //! | `decode_config`         | Returns a new `Vec<u8>`       | Always                         |
    //! | `decode_config_buf`     | Appends to provided `Vec<u8>` | Only if `Vec` needs to grow    |
    //! | `decode_config_slice`   | Writes to provided `&[u8]`    | Never                          |
    //!
    //! Unlike encoding, where all possible input is valid, decoding can fail (see `DecodeError`).
    //!
    //! Input can be invalid because it has invalid characters or invalid padding. (No padding at all is
    //! valid, but excess padding is not.) Whitespace in the input is invalid.
    //!
    //! # `Read` and `Write`
    //!
    //! To map a `Read` of b64 bytes to the decoded bytes, wrap a reader (file, network socket, etc)
    //! with `base64::read::DecoderReader`. To write raw bytes and have them b64 encoded on the fly,
    //! wrap a writer with `base64::write::EncoderWriter`. There is some performance overhead (15% or
    //! so) because of the necessary buffer shuffling -- still fast enough that almost nobody cares.
    //! Also, these implementations do not heap allocate.
    //!
    //! # Panics
    //!
    //! If length calculations result in overflowing `usize`, a panic will result.
    //!
    //! The `_slice` flavors of encode or decode will panic if the provided output slice is too small,

    #![cfg_attr(feature = "cargo-clippy", allow(clippy::cast_lossless))]
    #![deny(
        missing_docs,
        trivial_casts,
        trivial_numeric_casts,
        unused_extern_crates,
        unused_import_braces,
        unused_results,
        variant_size_differences,
        warnings
    )]
    #![forbid(unsafe_code)]
    #![cfg_attr(not(any(feature = "std", test)), no_std)]

    #[cfg(all(feature = "alloc", not(any(feature = "std", test))))]
    extern crate alloc;
    #[cfg(any(feature = "std", test))]
    extern crate std as alloc;

    mod chunked_encoder;
    pub mod display;
    #[cfg(any(feature = "std", test))]
    pub mod read;
    mod tables;
    #[cfg(any(feature = "std", test))]
    pub mod write;

    mod encode;
    pub use crate::encode::encode_config_slice;
    #[cfg(any(feature = "alloc", feature = "std", test))]
    pub use crate::encode::{encode, encode_config, encode_config_buf};

    mod decode;
    #[cfg(any(feature = "alloc", feature = "std", test))]
    pub use crate::decode::{decode, decode_config, decode_config_buf};
    pub use crate::decode::{decode_config_slice, DecodeError};

    #[cfg(test)]
    mod tests;

    /// Available encoding character sets
    #[derive(Clone, Copy, Debug)]
    pub enum CharacterSet {
        /// The standard character set (uses `+` and `/`).
        ///
        /// See [RFC 3548](https://tools.ietf.org/html/rfc3548#section-3).
        Standard,
        /// The URL safe character set (uses `-` and `_`).
        ///
        /// See [RFC 3548](https://tools.ietf.org/html/rfc3548#section-4).
        UrlSafe,
        /// The `crypt(3)` character set (uses `./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz`).
        ///
        /// Not standardized, but folk wisdom on the net asserts that this alphabet is what crypt uses.
        Crypt,
        /// The bcrypt character set (uses `./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789`).
        Bcrypt,
        /// The character set used in IMAP-modified UTF-7 (uses `+` and `,`).
        ///
        /// See [RFC 3501](https://tools.ietf.org/html/rfc3501#section-5.1.3)
        ImapMutf7,
        /// The character set used in BinHex 4.0 files.
        ///
        /// See [BinHex 4.0 Definition](http://files.stairways.com/other/binhex-40-specs-info.txt)
        BinHex,
    }

    impl CharacterSet {
        fn encode_table(self) -> &'static [u8; 64] {
            match self {
                CharacterSet::Standard => tables::STANDARD_ENCODE,
                CharacterSet::UrlSafe => tables::URL_SAFE_ENCODE,
                CharacterSet::Crypt => tables::CRYPT_ENCODE,
                CharacterSet::Bcrypt => tables::BCRYPT_ENCODE,
                CharacterSet::ImapMutf7 => tables::IMAP_MUTF7_ENCODE,
                CharacterSet::BinHex => tables::BINHEX_ENCODE,
            }
        }

        fn decode_table(self) -> &'static [u8; 256] {
            match self {
                CharacterSet::Standard => tables::STANDARD_DECODE,
                CharacterSet::UrlSafe => tables::URL_SAFE_DECODE,
                CharacterSet::Crypt => tables::CRYPT_DECODE,
                CharacterSet::Bcrypt => tables::BCRYPT_DECODE,
                CharacterSet::ImapMutf7 => tables::IMAP_MUTF7_DECODE,
                CharacterSet::BinHex => tables::BINHEX_DECODE,
            }
        }
    }

    /// Contains configuration parameters for base64 encoding
    #[derive(Clone, Copy, Debug)]
    pub struct Config {
        /// Character set to use
        char_set: CharacterSet,
        /// True to pad output with `=` characters
        pad: bool,
        /// True to ignore excess nonzero bits in the last few symbols, otherwise an error is returned.
        decode_allow_trailing_bits: bool,
    }

    impl Config {
        /// Create a new `Config`.
        pub const fn new(char_set: CharacterSet, pad: bool) -> Config {
            Config {
                char_set,
                pad,
                decode_allow_trailing_bits: false,
            }
        }

        /// Sets whether to pad output with `=` characters.
        pub const fn pad(self, pad: bool) -> Config {
            Config { pad, ..self }
        }

        /// Sets whether to emit errors for nonzero trailing bits.
        ///
        /// This is useful when implementing
        /// [forgiving-base64 decode](https://infra.spec.whatwg.org/#forgiving-base64-decode).
        pub const fn decode_allow_trailing_bits(self, allow: bool) -> Config {
            Config {
                decode_allow_trailing_bits: allow,
                ..self
            }
        }
    }

    /// Standard character set with padding.
    pub const STANDARD: Config = Config {
        char_set: CharacterSet::Standard,
        pad: true,
        decode_allow_trailing_bits: false,
    };

    /// Standard character set without padding.
    pub const STANDARD_NO_PAD: Config = Config {
        char_set: CharacterSet::Standard,
        pad: false,
        decode_allow_trailing_bits: false,
    };

    /// URL-safe character set with padding
    pub const URL_SAFE: Config = Config {
        char_set: CharacterSet::UrlSafe,
        pad: true,
        decode_allow_trailing_bits: false,
    };

    /// URL-safe character set without padding
    pub const URL_SAFE_NO_PAD: Config = Config {
        char_set: CharacterSet::UrlSafe,
        pad: false,
        decode_allow_trailing_bits: false,
    };

    /// As per `crypt(3)` requirements
    pub const CRYPT: Config = Config {
        char_set: CharacterSet::Crypt,
        pad: false,
        decode_allow_trailing_bits: false,
    };

    /// Bcrypt character set
    pub const BCRYPT: Config = Config {
        char_set: CharacterSet::Bcrypt,
        pad: false,
        decode_allow_trailing_bits: false,
    };

    /// IMAP modified UTF-7 requirements
    pub const IMAP_MUTF7: Config = Config {
        char_set: CharacterSet::ImapMutf7,
        pad: false,
        decode_allow_trailing_bits: false,
    };

    /// BinHex character set
    pub const BINHEX: Config = Config {
        char_set: CharacterSet::BinHex,
        pad: false,
        decode_allow_trailing_bits: false,
    };

    const PAD_BYTE: u8 = b'=';