yasna/models/
der.rs

1// Copyright 2017 Fortanix, Inc.
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9use alloc::vec::Vec;
10use super::super::{PCBit, Tag};
11use super::super::tags::*;
12
13/// Container for a tag and arbitrary DER value.
14///
15/// When obtained by `BERReader::read_tagged_der` in DER mode,
16/// the reader verifies that the payload is actually valid DER.
17/// When constructed from bytes, the caller is responsible for
18/// providing valid DER.
19#[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
20pub struct TaggedDerValue {
21    tag: Tag,
22    pcbit: PCBit,
23    value: Vec<u8>,
24}
25
26impl TaggedDerValue {
27    /// Constructs a new `TaggedDerValue` as an octet string
28    pub fn from_octetstring(bytes: Vec<u8>) -> Self {
29        TaggedDerValue {
30            tag: TAG_OCTETSTRING,
31            pcbit: PCBit::Primitive,
32            value: bytes,
33        }
34    }
35
36    /// Constructs a new `TaggedDerValue` from its tag and content
37    pub fn from_tag_and_bytes(tag: Tag, bytes: Vec<u8>) -> Self {
38        let pcbit = match tag {
39            TAG_SEQUENCE | TAG_SET => PCBit::Constructed,
40            _ => PCBit::Primitive,
41        };
42        TaggedDerValue {
43            tag,
44            pcbit,
45            value: bytes,
46        }
47    }
48
49    /// Constructs a new `TaggedDerValue` from its tag,
50    /// primitive/constructed bit, and content
51    pub fn from_tag_pc_and_bytes(tag: Tag, pcbit: PCBit, bytes: Vec<u8>) -> Self {
52        TaggedDerValue {
53            tag,
54            pcbit,
55            value: bytes,
56        }
57    }
58
59    /// Returns the tag
60    pub fn tag(&self) -> Tag {
61        self.tag
62    }
63
64    /// Returns the primitive/constructed bit
65    pub fn pcbit(&self) -> PCBit {
66        self.pcbit
67    }
68
69    /// Returns the value
70    pub fn value(&self) -> &[u8] {
71        &self.value
72    }
73
74    /// If the value is something that contains raw bytes,
75    /// returns its content.
76    ///
77    /// # Examples
78    /// ```
79    /// use yasna::models::TaggedDerValue;
80    /// let value = TaggedDerValue::from_octetstring(vec![1, 2, 3, 4, 5, 6]);
81    /// assert!(value.as_bytes() == Some(&[1, 2, 3, 4, 5, 6]));
82    /// ```
83    pub fn as_bytes(&self) -> Option<&[u8]> {
84        match (self.tag, self.pcbit) {
85            (TAG_BITSTRING, PCBit::Primitive) => {
86                // First byte of bitstring value is number of unused bits.
87                // We only accept bitstrings that are multiples of bytes.
88                if let Some(&0) = self.value.first() {
89                    Some(&self.value[1..])
90                } else {
91                    None
92                }
93            },
94            (TAG_OCTETSTRING, PCBit::Primitive) => Some(&self.value),
95            _ => None
96        }
97    }
98
99    /// If the value is something string-like, returns it as string.
100    pub fn as_str(&self) -> Option<&str> {
101        use alloc::str::from_utf8;
102
103        match (self.tag, self.pcbit) {
104            (TAG_IA5STRING, PCBit::Primitive) => from_utf8(&self.value).ok(),
105            (TAG_PRINTABLESTRING, PCBit::Primitive) => from_utf8(&self.value).ok(),
106            (TAG_UTF8STRING, PCBit::Primitive) => from_utf8(&self.value).ok(),
107            _ => None
108        }
109    }
110}
yasna/models/der.rs

yasna/models/
der.rs
