SecureSocket: fix non-blocking reads

OpenSSL says we should retry when a non-blocking read finds no data is
pending. But in that case we should not retry immediately, because the
operation should be non-blocking.

src/kits/network/libnetapi/SecureSocket.cpp

@@ -551,6 +551,12 @@ BSecureSocket::Read(void* buffer, size_t size)
 		bytesRead = SSL_read(fPrivate->fSSL, buffer, size);
 		if (bytesRead >= 0)
 			return bytesRead;
+		// Don't retry in cases of "no data available" for non-blocking sockets
+		int error = SSL_get_error(fPrivate->fSSL, bytesRead);
+		if (error == SSL_ERROR_WANT_READ || error == SSL_ERROR_WANT_WRITE)
+			return B_WOULD_BLOCK;
+		// Otherwise, check if we should retry (maybe we were interrupted by
+		// a signal, for example)
 		retry = BIO_should_retry(SSL_get_rbio(fPrivate->fSSL));
 	} while(retry != 0);