Commit 8e01f8d2 authored by Alex Crichton's avatar Alex Crichton
Browse files

Handle zero-length reads/writes 

This commit adds some short-circuits for zero-length reads/writes to
`SslStream`. Because OpenSSL returns 0 on error, then we could mistakenly
confuse a 0-length success as an actual error, so we avoid writing or reading 0
bytes by returning quickly with a success.
parent 3cfcf138

openssl/src/ssl/mod.rs

+14 −0
Original line number Diff line number Diff line
@@ -1506,6 +1506,15 @@ impl<S: Read + Write> SslStream<S> { 
    /// This is particularly useful with a nonblocking socket, where the error

    /// value will identify if OpenSSL is waiting on read or write readiness.

    pub fn ssl_read(&mut self, buf: &mut [u8]) -> Result<usize, Error> {

        // The intepretation of the return code here is a little odd with a

        // zero-length write. OpenSSL will likely correctly report back to us

        // that it read zero bytes, but zero is also the sentinel for "error".

        // To avoid that confusion short-circuit that logic and return quickly

        // if `buf` has a length of zero.

        if buf.len() == 0 {

            return Ok(0)

        }



        let ret = self.ssl.read(buf);

        if ret > 0 {

            Ok(ret as usize)
@@ -1523,6 +1532,11 @@ impl<S: Read + Write> SslStream<S> { 
    /// This is particularly useful with a nonblocking socket, where the error

    /// value will identify if OpenSSL is waiting on read or write readiness.

    pub fn ssl_write(&mut self, buf: &[u8]) -> Result<usize, Error> {

        // See above for why we short-circuit on zero-length buffers

        if buf.len() == 0 {

            return Ok(0)

        }



        let ret = self.ssl.write(buf);

        if ret > 0 {

            Ok(ret as usize)

openssl/src/ssl/tests/mod.rs

+10 −0
Original line number Diff line number Diff line
@@ -421,6 +421,16 @@ fn test_write() { 
    stream.flush().unwrap();

}



#[test]

fn zero_length_buffers() {

    let (_s, stream) = Server::new();

    let ctx = SslContext::builder(SslMethod::tls()).unwrap();

    let mut stream = Ssl::new(&ctx.build()).unwrap().connect(stream).unwrap();



    assert_eq!(stream.write(b"").unwrap(), 0);

    assert_eq!(stream.read(&mut []).unwrap(), 0);

}



run_test!(get_peer_certificate, |method, stream| {

    let ctx = SslContext::builder(method).unwrap();

    let stream = Ssl::new(&ctx.build()).unwrap().connect(stream).unwrap();