feature: implement block and fields as Struct implementing (Try)From trait

This commit is contained in:
Florian Briand 2024-07-30 21:27:10 +02:00
parent 2ba548aa28
commit 2d24b78a67
Signed by: florian_briand
GPG Key ID: CC981B9E6B98E70B

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@ -4,141 +4,178 @@
// TODO : Est-ce qu'on pourrait/devrait définir un type custom pour représenter les tableaux de bytes ? // TODO : Est-ce qu'on pourrait/devrait définir un type custom pour représenter les tableaux de bytes ?
use std::convert::TryFrom;
#[derive(PartialEq, Debug)] #[derive(PartialEq, Debug)]
pub struct ElementSize { struct ElementSize {
pub size: usize, pub size: usize,
pub pad: usize, pub pad: usize,
} }
#[derive(PartialEq, Debug)] impl TryFrom<&[u8]> for ElementSize {
pub enum MemoryParsingError<'a> { type Error = &'static str;
MemoryIsEmpty(&'a str),
MemoryIsNotValid(&'a str),
}
pub fn read_element_size(bytes: &[u8]) -> Result<ElementSize, MemoryParsingError> { fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
/* Longueur: /* Longueur:
* - si le bit de poids fort du premier octet est à 0, la longueur est codée sur un octet * - si le bit de poids fort du premier octet est à 0, la longueur est codée sur un octet
* - si le bit de poids fort du premier octet est à 1, les 7 bits de poids faible codent le nombre d'octets utilisés pour coder la longueur * - si le bit de poids fort du premier octet est à 1, les 7 bits de poids faible codent le nombre d'octets utilisés pour coder la longueur
*/ */
if bytes.len() == 0 { if bytes.len() == 0 {
return Err(MemoryParsingError::MemoryIsEmpty("Empty bytes input")); return Err("Empty bytes input");
}
let mut element_size = ElementSize { size: 0, pad: 1 };
if bytes[0] & 0b1000_0000 == 0 {
// Size coded on 1 byte
element_size.size = bytes[0] as usize;
} else {
// Size coded on N bytes
// N are the 7 lower bits of the first byte
let size_bytes_len = (bytes[0] & 0b0111_1111) as usize;
if size_bytes_len > bytes.len() - 1 {
return Err(MemoryParsingError::MemoryIsNotValid(
"Invalid memory: not enough bytes to read the size",
));
} else if size_bytes_len > 4 {
return Err(MemoryParsingError::MemoryIsNotValid(
"Invalid memory: size is too big",
));
} }
let size_bytes = &bytes[1..1 + size_bytes_len];
// u32::from_be_bytes() requires a 4 bytes array let mut element_size = ElementSize { size: 0, pad: 1 };
let mut padded_bytes = [0u8; 4]; if bytes[0] & 0b1000_0000 == 0 {
padded_bytes[size_bytes_len..].copy_from_slice(&size_bytes); // Size coded on 1 byte
element_size.size = bytes[0] as usize;
} else {
// Size coded on N bytes
// N are the 7 lower bits of the first byte
let size_bytes_len = (bytes[0] & 0b0111_1111) as usize;
if size_bytes_len > bytes.len() - 1 {
return Err("Invalid memory: not enough bytes to read the size");
} else if size_bytes_len > 4 {
return Err("Invalid memory: size is too big");
}
let size_bytes = &bytes[1..1 + size_bytes_len];
element_size.size = u32::from_be_bytes(padded_bytes) as usize; // u32::from_be_bytes() requires a 4 bytes array
element_size.pad += size_bytes_len; let mut padded_bytes = [0u8; 4];
padded_bytes[size_bytes_len..].copy_from_slice(&size_bytes);
element_size.size = u32::from_be_bytes(padded_bytes) as usize;
element_size.pad += size_bytes_len;
}
Ok(element_size)
} }
Ok(element_size)
} }
pub struct Element { #[derive(Debug)]
pub pad: usize, pub struct Block<'a> {
pub contenu: Vec<u8>, pub id: u16,
pub size: usize,
pub content: Vec<Field<'a>>,
} }
pub fn read_element(bytes: &[u8]) -> Element { impl<'a> From<&'a [u8]> for Block<'a> {
let ElementSize { size, pad } = read_element_size(bytes).unwrap(); fn from(bytes: &'a [u8]) -> Self {
let contenu = bytes[pad..pad+size].to_vec(); let mut offset = 0;
Element { let id = u16::from_be_bytes(bytes[..2].try_into().unwrap());
pad: pad+size, offset += 2;
contenu, let ElementSize { size: block_size, pad } = bytes[2..].try_into().unwrap();
offset += pad;
let raw_content = &bytes[offset..];
let mut field_offset = 0;
// While there is still content to read, parse Fields
let mut content = Vec::new();
while field_offset < block_size {
let field: Field<'a> = raw_content[field_offset..].into();
field_offset += field.size;
content.push(field);
}
Block {
id,
size: offset + block_size,
content,
}
} }
} }
#[derive(Debug)]
pub struct Field<'a> {
pub size: usize,
pub content: &'a [u8],
}
impl<'a> From<&'a [u8]> for Field<'a> {
fn from(bytes: &'a [u8]) -> Self {
let ElementSize { size, pad } = bytes.try_into().unwrap();
let contenu = &bytes[pad..pad+size];
Field {
size: pad+size,
content: contenu,
}
}
}
pub fn decode_ssv_memory(bytes: &[u8], size: usize) -> Vec<Block> {
let mut blocks: Vec<Block> = Vec::new();
let mut offset = 0;
while offset < size {
let block: Block = bytes[offset..].into();
offset += block.size;
blocks.push(block);
}
blocks
}
#[cfg(test)] #[cfg(test)]
mod test_read_element_size { mod test_element_size {
use super::*; use super::*;
#[test] #[test]
fn short_size() { fn short_size() {
let bytes = [0b_0000_0001_u8]; let bytes: &[u8] = &[0b_0000_0001_u8];
let element_size = read_element_size(&bytes).unwrap(); let element_size: ElementSize = bytes.try_into().unwrap();
assert_eq!(element_size.size, 1); assert_eq!(element_size.size, 1);
assert_eq!(element_size.pad, 1); assert_eq!(element_size.pad, 1);
let bytes = [0b_0100_0000_u8]; let bytes: &[u8] = &[0b_0100_0000_u8];
let element_size = read_element_size(&bytes).unwrap(); let element_size: ElementSize = bytes.try_into().unwrap();
assert_eq!(element_size.size, 64); assert_eq!(element_size.size, 64);
assert_eq!(element_size.pad, 1); assert_eq!(element_size.pad, 1);
} }
#[test] #[test]
fn long_size() { fn long_size() {
let bytes = [0b_1000_0010_u8, 0b_0000_0001_u8, 0b_0100_0000_u8]; let bytes: &[u8] = &[0b_1000_0010_u8, 0b_0000_0001_u8, 0b_0100_0000_u8];
let element_size = read_element_size(&bytes).unwrap(); let element_size: ElementSize = bytes.try_into().unwrap();
assert_eq!(element_size.size, 320); assert_eq!(element_size.size, 320);
assert_eq!(element_size.pad, 3); assert_eq!(element_size.pad, 3);
} }
#[test] #[test]
fn null_size() { fn null_size() {
let bytes = []; let bytes: &[u8] = &[];
let toto = "toto"; let result: Result<ElementSize, &str> = bytes.try_into();
// Expect an error
assert_eq!( assert_eq!(
read_element_size(&bytes), result,
Err(MemoryParsingError::MemoryIsEmpty("Empty bytes input")), Err("Empty bytes input"),
); );
} }
#[test] #[test]
fn invalid_memory() { fn invalid_memory() {
let bytes = [0b_1000_0001_u8]; let bytes: &[u8] = &[0b_1000_0001_u8];
let result: Result<ElementSize, &str> = bytes.try_into();
assert_eq!( assert_eq!(
read_element_size(&bytes), result,
Err(MemoryParsingError::MemoryIsNotValid( Err("Invalid memory: not enough bytes to read the size"),
"Invalid memory: not enough bytes to read the size"
)),
); );
let bytes = [0b_1000_0010_u8, 1]; let bytes: &[u8] = &[0b_1000_0010_u8, 1];
let result: Result<ElementSize, &str> = bytes.try_into();
assert_eq!( assert_eq!(
read_element_size(&bytes), result,
Err(MemoryParsingError::MemoryIsNotValid( Err("Invalid memory: not enough bytes to read the size"),
"Invalid memory: not enough bytes to read the size"
)),
); );
let bytes = [0b_1000_0101_u8, 1, 1, 1, 1, 1]; let bytes: &[u8] = &[0b_1000_0101_u8, 1, 1, 1, 1, 1];
let result: Result<ElementSize, &str> = bytes.try_into();
assert_eq!( assert_eq!(
read_element_size(&bytes), result,
Err(MemoryParsingError::MemoryIsNotValid( Err("Invalid memory: size is too big"),
"Invalid memory: size is too big"
)),
); );
} }
} }
#[cfg(test)] #[cfg(test)]
mod test_read_element { mod test_field {
use super::*; use super::*;
#[test] #[test]
fn short_size() { fn short_size() {
let bytes = [51, let bytes: &[u8] = &[51,
1, 48, 1, 56, 11, 57, 57, 55, 48, 48, 1, 48, 1, 56, 11, 57, 57, 55, 48, 48,
53, 50, 52, 49, 57, 52, 1, 52, 2, 50, 53, 50, 52, 49, 57, 52, 1, 52, 2, 50,
50, 17, 80, 72, 65, 82, 77, 65, 67, 73, 50, 17, 80, 72, 65, 82, 77, 65, 67, 73,
@ -146,20 +183,142 @@ mod test_read_element {
70, 82, 65, 78, 67, 79, 73, 83, 69, 1, 70, 82, 65, 78, 67, 79, 73, 83, 69, 1,
84, 84,
]; ];
let element = read_element(&bytes); let element: Field = bytes.try_into().unwrap();
assert_eq!(element.pad, 52); assert_eq!(element.size, 52);
assert_eq!(element.contenu[..5], [1, 48, 1, 56, 11]); assert_eq!(element.content[..5], [1, 48, 1, 56, 11]);
} }
#[test] #[test]
fn long_size() { fn long_size() {
let mut bytes = vec![0b_1000_0010_u8, let mut bytes_vec = vec![0b_1000_0010_u8,
0b_0000_0001_u8, 0b_0000_0000_u8, // size = 256 0b_0000_0001_u8, 0b_0000_0000_u8, // size = 256
]; ];
// Add 256 bytes to the content // Add 256 bytes to the content
bytes.append(&mut vec![1; 256]); bytes_vec.append(&mut vec![1; 256]);
let element = read_element(&bytes); let bytes: &[u8] = &bytes_vec;
assert_eq!(element.pad, 259); let element: Field = bytes.try_into().unwrap();
assert_eq!(element.contenu.len(), 256); assert_eq!(element.size, 259);
assert_eq!(element.content.len(), 256);
}
}
#[cfg(test)]
mod test_block {
use super::*;
#[test]
fn test_francoise_pharmacien0052419_partial_block_1() {
let bytes: &[u8] = &[
1, 48,
1, 56,
11, 57, 57, 55, 48, 48, 53, 50, 52, 49, 57, 52,
];
let field1: Field = bytes.into();
assert_eq!(field1.size, 2);
assert_eq!(field1.content, &[48]);
let field2: Field = bytes[field1.size..].into();
assert_eq!(field2.size, 2);
assert_eq!(field2.content, &[56]);
let field3: Field = bytes[field1.size + field2.size..].into();
assert_eq!(field3.size, 12);
assert_eq!(field3.content, &[57, 57, 55, 48, 48, 53, 50, 52, 49, 57, 52]);
}
#[test]
fn test_francoise_pharmacien0052419() {
let bytes: &[u8] = &[
0, 1, 51, // 3
1, 48, // 2
1, 56, // 2
11, 57, 57, 55, 48, 48, 53, 50, 52, 49, 57, 52, // 12
1, 52, // 2
2, 50, 50, // 3
17, 80, 72, 65, 82, 77, 65, 67, 73, 69, 78, 48, 48, 53, 50, 52, 49, 57, // 18
9, 70, 82, 65, 78, 67, 79, 73, 83, 69, // 10
1, 84, // 2
// total: 54
0, 2, 83,
1, 1,
1, 48,
1, 49,
2, 56, 54,
1, 49,
9, 48, 66, 48, 50, 50, 49, 57, 53, 56,
1, 56,
24, 80, 72, 65, 82, 77, 65, 67, 73, 69, 32, 68, 85, 32, 67, 69, 78, 84, 82, 69, 50, 50, 49, 57, 53,
8, 48, 48, 50, 48, 50, 52, 49, 57,
1, 56,
0,
1, 48,
1, 49,
2, 53, 48,
2, 49, 48,
2, 48, 48,
1, 48,
1, 48,
1, 48,
1, 49,
1, 49,
];
let first_block: Block = bytes.into();
assert_eq!(first_block.id, 1);
assert_eq!(first_block.size, 54);
assert_eq!(first_block.content.len(), 8);
let second_block: Block = bytes[first_block.size..].into();
assert_eq!(second_block.id, 2);
assert_eq!(second_block.size, 86);
assert_eq!(second_block.content.len(), 21);
}
}
#[cfg(test)]
mod test_decode_ssv_memory {
use super::*;
#[test]
fn test_francoise_pharmacien0052419() {
let bytes: &[u8] = &[
0, 1, 51, // 3
1, 48, // 2
1, 56, // 2
11, 57, 57, 55, 48, 48, 53, 50, 52, 49, 57, 52, // 12
1, 52, // 2
2, 50, 50, // 3
17, 80, 72, 65, 82, 77, 65, 67, 73, 69, 78, 48, 48, 53, 50, 52, 49, 57, // 18
9, 70, 82, 65, 78, 67, 79, 73, 83, 69, // 10
1, 84, // 2
// total: 54
0, 2, 83,
1, 1,
1, 48,
1, 49,
2, 56, 54,
1, 49,
9, 48, 66, 48, 50, 50, 49, 57, 53, 56,
1, 56,
24, 80, 72, 65, 82, 77, 65, 67, 73, 69, 32, 68, 85, 32, 67, 69, 78, 84, 82, 69, 50, 50, 49, 57, 53,
8, 48, 48, 50, 48, 50, 52, 49, 57,
1, 56,
0,
1, 48,
1, 49,
2, 53, 48,
2, 49, 48,
2, 48, 48,
1, 48,
1, 48,
1, 48,
1, 49,
1, 49,
];
let blocks = decode_ssv_memory(&bytes, bytes.len());
assert_eq!(blocks.len(), 2);
} }
} }