From f52584e7310ad9af414cdd22cbfad81d53417c22 Mon Sep 17 00:00:00 2001
From: Nikias Bassen
Date: Fri, 19 Jul 2019 00:06:38 +0700
Subject: OpenSSL: Use SSL_pending() to determine if we want a select() before
 SSL_read()

In order to obey the timeout in idevice_connection_receive_timeout(), we are
using select() via socket_check_fd(). However, the SSL bio might have buffered
more bytes than actually requested upon a call to SSL_read(), so in the next
call to idevice_connection_receive_timeout() a select() would not find the fd
being ready to read, and make it fail with an error, after the specified
timeout is reached.
With the help of SSL_pending() we can now skip calling select() so that
SSL_read() will directly be called again.
---
 src/idevice.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/idevice.c b/src/idevice.c
index 02d34cc..794af8b 100644
--- a/src/idevice.c
+++ b/src/idevice.c
@@ -453,19 +453,24 @@ LIBIMOBILEDEVICE_API idevice_error_t idevice_connection_receive_timeout(idevice_
 
 	if (connection->ssl_data) {
 		uint32_t received = 0;
+		int do_select = 1;
 
 		while (received < len) {
-
-			int conn_error = socket_check_fd((int)(long)connection->data, FDM_READ, timeout);
-			idevice_error_t error = socket_recv_to_idevice_error(conn_error, len, received);
-
-			switch (error) {
-				case IDEVICE_E_SUCCESS:
-					break;
-				case IDEVICE_E_UNKNOWN_ERROR:
-					debug_info("ERROR: socket_check_fd returned %d (%s)", conn_error, strerror(-conn_error));
-				default:
-					return error;
+#ifdef HAVE_OPENSSL
+			do_select = (SSL_pending(connection->ssl_data->session) == 0);
+#endif
+			if (do_select) {
+				int conn_error = socket_check_fd((int)(long)connection->data, FDM_READ, timeout);
+				idevice_error_t error = socket_recv_to_idevice_error(conn_error, len, received);
+
+				switch (error) {
+					case IDEVICE_E_SUCCESS:
+						break;
+					case IDEVICE_E_UNKNOWN_ERROR:
+						debug_info("ERROR: socket_check_fd returned %d (%s)", conn_error, strerror(-conn_error));
+					default:
+						return error;
+				}
 			}
 
 #ifdef HAVE_OPENSSL
-- 
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