stage

problems/p15/src/main.rs

@@ -0,0 +1,96 @@
+use anyhow::{Result, anyhow};
+
+fn pkcs7_unpadding(input: &[u8]) -> Result<Vec<u8>> {
+    if input.is_empty() {
+        return Err(anyhow!("Input cannot be empty"));
+    }
+    let padding_length = *input.last().unwrap();
+    if padding_length == 0 || padding_length > input.len() as u8 {
+        return Err(anyhow!("Invalid PKCS#7 padding"));
+    }
+    for &byte in input.iter().rev().take(padding_length as usize) {
+        if byte != padding_length {
+            return Err(anyhow!("Invalid PKCS#7 padding"));
+        }
+    }
+    Ok(input[..input.len() - padding_length as usize].to_vec())
+}
+
+fn main() {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_valid_padding() {
+        let padded = vec![1, 2, 3, 4, 4, 4, 4, 4];
+        let result = pkcs7_unpadding(&padded).unwrap();
+        assert_eq!(result, vec![1, 2, 3, 4]);
+    }
+
+    #[test]
+    fn test_single_byte_padding() {
+        let padded = vec![1, 2, 3, 4, 5, 1];
+        let result = pkcs7_unpadding(&padded).unwrap();
+        assert_eq!(result, vec![1, 2, 3, 4, 5]);
+    }
+
+    #[test]
+    fn test_full_block_padding() {
+        let padded = vec![8, 8, 8, 8, 8, 8, 8, 8];
+        let result = pkcs7_unpadding(&padded).unwrap();
+        assert_eq!(result, Vec::<u8>::new());
+    }
+
+    #[test]
+    fn test_empty_input() {
+        let result = pkcs7_unpadding(&[]);
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().to_string(), "Input cannot be empty");
+    }
+
+    #[test]
+    fn test_invalid_padding_value() {
+        let padded = vec![1, 2, 3, 4, 3, 4, 4];
+        let result = pkcs7_unpadding(&padded);
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().to_string(), "Invalid PKCS#7 padding");
+    }
+
+    #[test]
+    fn test_zero_padding() {
+        let padded = vec![1, 2, 3, 0];
+        let result = pkcs7_unpadding(&padded);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_padding_length_exceeds_data() {
+        let padded = vec![1, 2, 10];
+        let result = pkcs7_unpadding(&padded);
+        assert!(result.is_err());
+    }
+    #[test]
+    fn test_ice_ice_baby_valid() {
+        let padded = b"ICE ICE BABY\x04\x04\x04\x04".to_vec();
+        let result = pkcs7_unpadding(&padded).unwrap();
+        assert_eq!(result, b"ICE ICE BABY");
+    }
+
+    #[test]
+    fn test_ice_ice_baby_invalid_value() {
+        let padded = b"ICE ICE BABY\x05\x05\x05\x05".to_vec();
+        let result = pkcs7_unpadding(&padded);
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().to_string(), "Invalid PKCS#7 padding");
+    }
+
+    #[test]
+    fn test_ice_ice_baby_invalid_sequence() {
+        let padded = b"ICE ICE BABY\x01\x02\x03\x04".to_vec();
+        let result = pkcs7_unpadding(&padded);
+        assert!(result.is_err());
+        assert_eq!(result.unwrap_err().to_string(), "Invalid PKCS#7 padding");
+    }
+}