1//! Base64 encoding support.
2use crate::error::ErrorStack;
3use crate::{cvt_n, LenType};
4use libc::c_int;
5use openssl_macros::corresponds;
6
7/// Encodes a slice of bytes to a base64 string.
8///
9/// # Panics
10///
11/// Panics if the input length or computed output length overflow a signed C integer.
12#[corresponds(EVP_EncodeBlock)]
13pub fn encode_block(src: &[u8]) -> String {
14 assert!(src.len() <= c_int::MAX as usize);
15 let src_len: i32 = src.len() as LenType;
16
17 let len: i32 = encoded_len(src_len).unwrap();
18 let mut out: Vec = Vec::with_capacity(len as usize);
19
20 // SAFETY: `encoded_len` ensures space for 4 output characters
21 // for every 3 input bytes including padding and nul terminator.
22 // `EVP_EncodeBlock` will write only single byte ASCII characters.
23 // `EVP_EncodeBlock` will only write to not read from `out`.
24 unsafe {
25 let out_len: i32 = ffi::EVP_EncodeBlock(dst:out.as_mut_ptr(), src.as_ptr(), src_len);
26 out.set_len(new_len:out_len as usize);
27 String::from_utf8_unchecked(bytes:out)
28 }
29}
30
31/// Decodes a base64-encoded string to bytes.
32///
33/// # Panics
34///
35/// Panics if the input length or computed output length overflow a signed C integer.
36#[corresponds(EVP_DecodeBlock)]
37pub fn decode_block(src: &str) -> Result<Vec<u8>, ErrorStack> {
38 let src = src.trim();
39
40 // https://github.com/openssl/openssl/issues/12143
41 if src.is_empty() {
42 return Ok(vec![]);
43 }
44
45 assert!(src.len() <= c_int::MAX as usize);
46 let src_len = src.len() as LenType;
47
48 let len = decoded_len(src_len).unwrap();
49 let mut out = Vec::with_capacity(len as usize);
50
51 // SAFETY: `decoded_len` ensures space for 3 output bytes
52 // for every 4 input characters including padding.
53 // `EVP_DecodeBlock` can write fewer bytes after stripping
54 // leading and trailing whitespace, but never more.
55 // `EVP_DecodeBlock` will only write to not read from `out`.
56 unsafe {
57 let out_len = cvt_n(ffi::EVP_DecodeBlock(
58 out.as_mut_ptr(),
59 src.as_ptr(),
60 src_len,
61 ))?;
62 out.set_len(out_len as usize);
63 }
64
65 if src.ends_with('=') {
66 out.pop();
67 if src.ends_with("==") {
68 out.pop();
69 }
70 }
71
72 Ok(out)
73}
74
75fn encoded_len(src_len: LenType) -> Option<LenType> {
76 let mut len: i32 = (src_len / 3).checked_mul(4)?;
77
78 if src_len % 3 != 0 {
79 len = len.checked_add(4)?;
80 }
81
82 len = len.checked_add(1)?;
83
84 Some(len)
85}
86
87fn decoded_len(src_len: LenType) -> Option<LenType> {
88 let mut len: i32 = (src_len / 4).checked_mul(3)?;
89
90 if src_len % 4 != 0 {
91 len = len.checked_add(3)?;
92 }
93
94 Some(len)
95}
96
97#[cfg(test)]
98mod tests {
99 use super::*;
100
101 #[test]
102 fn test_encode_block() {
103 assert_eq!("".to_string(), encode_block(b""));
104 assert_eq!("Zg==".to_string(), encode_block(b"f"));
105 assert_eq!("Zm8=".to_string(), encode_block(b"fo"));
106 assert_eq!("Zm9v".to_string(), encode_block(b"foo"));
107 assert_eq!("Zm9vYg==".to_string(), encode_block(b"foob"));
108 assert_eq!("Zm9vYmE=".to_string(), encode_block(b"fooba"));
109 assert_eq!("Zm9vYmFy".to_string(), encode_block(b"foobar"));
110 }
111
112 #[test]
113 fn test_decode_block() {
114 assert_eq!(b"".to_vec(), decode_block("").unwrap());
115 assert_eq!(b"f".to_vec(), decode_block("Zg==").unwrap());
116 assert_eq!(b"fo".to_vec(), decode_block("Zm8=").unwrap());
117 assert_eq!(b"foo".to_vec(), decode_block("Zm9v").unwrap());
118 assert_eq!(b"foob".to_vec(), decode_block("Zm9vYg==").unwrap());
119 assert_eq!(b"fooba".to_vec(), decode_block("Zm9vYmE=").unwrap());
120 assert_eq!(b"foobar".to_vec(), decode_block("Zm9vYmFy").unwrap());
121 }
122
123 #[test]
124 fn test_strip_whitespace() {
125 assert_eq!(b"foobar".to_vec(), decode_block(" Zm9vYmFy\n").unwrap());
126 assert_eq!(b"foob".to_vec(), decode_block(" Zm9vYg==\n").unwrap());
127 }
128}
129