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Handle b64 padding if needed

master
Benoît 2 years ago
parent
commit
9ec954cd3f
  1. 68
      set1/chal1/src/main.rs

68
set1/chal1/src/main.rs

@ -24,26 +24,23 @@ fn hex_to_char(s: &str) -> Result<char, std::num::ParseIntError> {
}
fn main() {
let mut input_str = String::new();
let args: Vec<String> = env::args().collect();
let input = &args[1];
let mut input_str = String::new();
let char_vec: Vec<char> = input.chars().collect();
let hex_char = &char_vec
.chunks(2)
.map(|chunk| chunk.iter().collect::<String>())
.collect::<Vec<_>>();
// Printing the string in Ascii format - for decoding example
print!("Input string in ASCII is : « ");
// Printing the string in Ascii format - for hexa to Ascii example
for (i, s) in hex_char.into_iter().enumerate() {
match hex_to_char(s) {
Ok(s) => input_str.push(s),
Err(e) => println!("\nError decoding char '{}' at index {}", e, i),
}
}
println!(" »");
// Convert hex_char : Vec<String> into Vec<u8>
// Warning: Panic if not base16
@ -54,39 +51,52 @@ fn main() {
.map(|i| u8::from_str_radix(i, 16).unwrap())
.collect();
println!(" Len is : {}, is it modulo 3-bytes ? {}",
&hex.len(),
if &hex.len()%3 == 0 { "true" } else { "false"}
);
print!("b64_encode({:?}) ==> ", &input_str);
// Ugly right ?
// TODO !
// TODO: Make not ugly and move to function b64_encode(Vec<u8>) -> str
// TODO !
let mut output = String::new();
for j in (0..hex.len()).step_by(3) {
let mut pad = 0;
let mut arr = [0u8;4];
// Must handle Padding here !
// Index will be out of bound
// Find a way in rust to detect that ? or just compute here.
// Si padding 1 = '=' + arr[3] = 0
// Si padding 2 = '==' + arr[3] & arr[4] = 0
arr[0] = 0;
for i in 0..3 {
arr[i+1] = hex[i+j];
if i+j == hex.len() {
arr[i+1] = 0;
pad = 1;
} else if i+j > hex.len() {
arr[i+1] = 0;
pad = 2;
} else {
arr[i+1] = hex[i+j];
}
}
let tmp = u32::from_be_bytes(arr);
let tmp1:usize = ((tmp>>18) & 0x3F).try_into().unwrap();
let tmp2:usize = ((tmp>>12) & 0x3F).try_into().unwrap();
// If this fail we need to PAD '=='
let tmp3:usize = ((tmp>>6) & 0x3F).try_into().unwrap();
// If this fail we need to PAD '='
let tmp4:usize = ((tmp) & 0x3F).try_into().unwrap();
output.push(BASE64_TABLE[tmp1]);
output.push(BASE64_TABLE[tmp2]);
if pad == 2 {
output.push_str("==");
break
} else {
let tmp3:usize = ((tmp>>6) & 0x3F).try_into().unwrap();
output.push(BASE64_TABLE[tmp3]);
}
print!("{}", BASE64_TABLE[tmp1]);
print!("{}", BASE64_TABLE[tmp2]);
print!("{}", BASE64_TABLE[tmp3]);
print!("{}", BASE64_TABLE[tmp4]);
if pad == 1 {
output.push_str("=");
break
} else {
let tmp4:usize = ((tmp) & 0x3F).try_into().unwrap();
output.push(BASE64_TABLE[tmp4]);
}
}
println!();
println!("Input string is '{}'", input);
println!("Hex String to ASCII '{}'", &input_str);
println!("Base64 encode '{}'", output);
}

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