From 9ec954cd3ff2875970ad07e82b58ee53283866c2 Mon Sep 17 00:00:00 2001
From: beneth <bmauduit@beneth.fr>
Date: Sun, 12 Apr 2020 23:57:45 +0200
Subject: [PATCH] Handle b64 padding if needed

---
 set1/chal1/src/main.rs | 68 ++++++++++++++++++++++++------------------
 1 file changed, 39 insertions(+), 29 deletions(-)

diff --git a/set1/chal1/src/main.rs b/set1/chal1/src/main.rs
index 686174b..04fb6a3 100644
--- a/set1/chal1/src/main.rs
+++ b/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]);
 
-    print!("{}", BASE64_TABLE[tmp1]);
-    print!("{}", BASE64_TABLE[tmp2]);
-    print!("{}", BASE64_TABLE[tmp3]);
-    print!("{}", BASE64_TABLE[tmp4]);
+    if pad == 2 {
+      output.push_str("==");
+      break
+    } else {
+      let tmp3:usize = ((tmp>>6) & 0x3F).try_into().unwrap();
+      output.push(BASE64_TABLE[tmp3]);
+    }
+
+    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);
 }