Rust中TcpStream缓冲区仅能读取multipart form data，其他POST请求内容丢失的问题求助

各位好，我现在在搭建一个本地Rust TCP服务器，用本地REST客户端发请求测试，目前只是把读取到的内容输出到控制台。但遇到了一个棘手的问题：只有multipart/form-data类型的POST请求能完整读取到内容，JSON或application/x-www-form-urlencoded格式的请求只能读到请求头，请求体完全拿不到。

我的处理连接的函数代码大概是这样的：

fn handle_connection(mut stream: TcpStream){
    let mut buf_reader = BufReader::with_capacity(16384, &mut stream);
    let mut request_lines = buf_reader.lines().peekable();

    let first_request_line = request_lines.next().unwrap().unwrap();
    let parts: Vec<&str> = first_request_line[..].split(" ").collect();

    if (parts[0] == "POST" && parts[2] == "HTTP/1.1") {
        let mut buffer_results = HashMap::new();
        let mut i = 0;

        while (request_lines.peek().is_some()){
            let newline = request_lines.next().unwrap().unwrap();
            let newline_copy = newline.clone();

            if newline_copy == "" {
                continue;
            } else if newline_copy.contains(":"){
                let newline_string = newline_copy.clone().to_string().to_owned();
                let newline_str = string_to_static_str(newline_string);
                let templine: Vec<&str> = (newline_str.split(":")).clone().collect();
                let key = templine[0];
                let value = templine[1..].join(":");
                buffer_results.insert(key, value.clone());
                println!("Continuing Stream {}:{}", key, value);
            } else {
                let newline_clone = newline_copy.clone().to_string().to_owned();
                let i_i = i32_to_static_str(i.clone());
                buffer_results.insert(i_i, newline_clone);
                println!("Continuing Stream {}:{:#?}", i.to_string(), newline_copy.to_string());
            }
            i += 1;
        }
        // ... 后续逻辑省略
    }
}

测试现象 #

• 当用RESTED客户端发送JSON或application/x-www-form-urlencoded格式的POST请求时，控制台只输出请求头内容，完全看不到请求体的数据：

POST CALL:[ "POST", "/", "HTTP/1.1", ]
Continuing Stream Host: 127.0.0.1:7878
Continuing Stream User-Agent: [[User-Agent]]
Continuing Stream Accept: HTTP/1.1
Continuing Stream Accept-Language: [[Language]],en;q=0.5
Continuing Stream Accept-Encoding: gzip, deflate, br, zstd
Continuing Stream content-type: application/x-www-form-urlencoded
Continuing Stream Content-Length: 27
Continuing Stream Origin: moz-extension://[[HASH]]
Continuing Stream Connection: keep-alive
Continuing Stream Sec-Fetch-Dest: empty
Continuing Stream Sec-Fetch-Mode: cors
Continuing Stream Sec-Fetch-Site: same-origin
Continuing Stream Priority: u=0

• 但切换成multipart/form-data格式时，能正常读取到包括表单数据在内的所有内容：

Continuing Stream content-type: multipart/form-data
Continuing Stream 13:"------[[hash]]"
Continuing Stream Content-Disposition: form-data; name="my_silly_request"
Continuing Stream 15:"void_angel"
Continuing Stream 16:"------[[hash]]--"

我尝试过的解决方法 #

• 把默认的BufReader::new()换成BufReader::with_capacity(16384, &mut stream)，增大缓冲区容量，没有效果
• 手动在循环后额外调用多次request_lines.next().unwrap().unwrap()，试图读取更多内容，还是拿不到请求体
• 试过直接调用buffer.read()，但报错说没有数据可读

我猜测是这几种POST请求的传输机制有什么我没注意到的差异，但实在想不通问题出在哪，有没有大佬能帮我分析下？

内容来源于stack exchange