From c16d55ccddd741057bf532bd946b2854dc208c65 Mon Sep 17 00:00:00 2001
From: mat <github@matdoes.dev>
Date: Wed, 8 Dec 2021 00:41:42 -0600
Subject: start adding minecraft-chat

---
 minecraft-protocol/src/mc_buf.rs | 48 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 43 insertions(+), 5 deletions(-)

(limited to 'minecraft-protocol/src/mc_buf.rs')

diff --git a/minecraft-protocol/src/mc_buf.rs b/minecraft-protocol/src/mc_buf.rs
index 1e6e5b08..a58905b7 100644
--- a/minecraft-protocol/src/mc_buf.rs
+++ b/minecraft-protocol/src/mc_buf.rs
@@ -33,14 +33,14 @@ pub fn write_bytes(buf: &mut Vec<u8>, bytes: &[u8]) {
 /// Read a single varint from the reader and return the value, along with the number of bytes read
 pub async fn read_varint<T: AsyncRead + std::marker::Unpin>(
     buf: &mut BufReader<T>,
-) -> Result<(u32, u8), String> {
+) -> Result<(i32, u8), String> {
     let mut buffer = [0];
     let mut ans = 0;
     for i in 0..4 {
         buf.read_exact(&mut buffer)
             .await
             .or_else(|_| Err("Invalid VarInt".to_string()))?;
-        ans |= ((buffer[0] & 0b0111_1111) as u32) << 7 * i;
+        ans |= ((buffer[0] & 0b0111_1111) as i32) << 7 * i;
         if buffer[0] & 0b1000_0000 == 0 {
             return Ok((ans, i + 1));
         }
@@ -48,14 +48,14 @@ pub async fn read_varint<T: AsyncRead + std::marker::Unpin>(
     Ok((ans, 5))
 }
 
-pub fn write_varint(buf: &mut Vec<u8>, mut value: u32) {
+pub fn write_varint(buf: &mut Vec<u8>, mut value: i32) {
     let mut buffer = [0];
     if value == 0 {
         buf.write(&buffer).unwrap();
     }
     while value != 0 {
         buffer[0] = (value & 0b0111_1111) as u8;
-        value = (value >> 7) & (u32::max_value() >> 6);
+        value = (value >> 7) & (i32::max_value() >> 6);
         if value != 0 {
             buffer[0] |= 0b1000_0000;
         }
@@ -104,10 +104,48 @@ pub fn write_utf_with_len(buf: &mut Vec<u8>, string: &String, len: usize) {
             len
         );
     }
-    write_varint(buf, string.len() as u32);
+    write_varint(buf, string.len() as i32);
     write_bytes(buf, string.as_bytes());
 }
 
+pub async fn read_utf<T: AsyncRead + std::marker::Unpin>(
+    buf: &mut BufReader<T>,
+    max_length: u32,
+) -> Result<String, String> {
+    let (length, length_varint_length) = read_varint(buf).await?;
+    // i don't know why it's multiplied by 4 but it's like that in mojang's code so
+    if length < 0 {
+        return Err(
+            "The received encoded string buffer length is less than zero! Weird string!"
+                .to_string(),
+        );
+    }
+    if length as u32 > max_length * 4 {
+        return Err(format!(
+            "The received encoded string buffer length is longer than maximum allowed ({} > {})",
+            length,
+            max_length * 4
+        ));
+    }
+
+    // this is probably quite inefficient, idk how to do it better
+    let mut string = String::new();
+    let mut buffer = vec![0; length as usize];
+    buf.read_exact(&mut buffer)
+        .await
+        .or_else(|_| Err("Invalid UTF-8".to_string()))?;
+
+    string.push_str(std::str::from_utf8(&buffer).unwrap());
+    if string.len() > length as usize {
+        return Err(format!(
+            "The received string length is longer than maximum allowed ({} > {})",
+            length, max_length
+        ));
+    }
+
+    Ok(string)
+}
+
 pub fn write_utf(buf: &mut Vec<u8>, string: &String) {
     write_utf_with_len(buf, string, MAX_STRING_LENGTH as usize);
 }
-- 
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