From 36b88c3ad77483b90537926871edf19f2ce3f199 Mon Sep 17 00:00:00 2001
From: Frank Morgner <frankmorgner@gmail.com>
Date: Fri, 6 Apr 2018 13:33:09 +0200
Subject: [PATCH] reader-pcsc: allow fixing the length of a PIN

fixes https://github.com/OpenSC/OpenSC/issues/1221
closes https://github.com/OpenSC/OpenSC/pull/1288
---
 etc/opensc.conf.in          |  6 ++++++
 src/libopensc/reader-pcsc.c | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/etc/opensc.conf.in b/etc/opensc.conf.in
index e5afe834..f553b58d 100644
--- a/etc/opensc.conf.in
+++ b/etc/opensc.conf.in
@@ -93,6 +93,12 @@ app default {
 		# Default: true
 		# enable_pinpad = false;
 		#
+		# Some pinpad readers can only handle one exact length of the PIN.
+		# fixed_pinlength sets this value so that OpenSC expands the padding to
+		# this length.
+		# Default: 0 (i.e. not fixed)
+		# fixed_pinlength = 6;
+		#
 		# Detect reader capabilities with escape commands (wrapped APDUs with
 		# CLA=0xFF as defined by PC/SC pt. 3 and BSI TR-03119, e.g. for getting
 		# the UID, escaped PIN commands and the reader's firmware version)
diff --git a/src/libopensc/reader-pcsc.c b/src/libopensc/reader-pcsc.c
index 95187790..18d97f0c 100644
--- a/src/libopensc/reader-pcsc.c
+++ b/src/libopensc/reader-pcsc.c
@@ -82,6 +82,7 @@ struct pcsc_global_private_data {
 	SCARDCONTEXT pcsc_ctx;
 	SCARDCONTEXT pcsc_wait_ctx;
 	int enable_pinpad;
+	int fixed_pinlength;
 	int enable_pace;
 	size_t force_max_recv_size;
 	size_t force_max_send_size;
@@ -766,6 +767,7 @@ static int pcsc_init(sc_context_t *ctx)
 	gpriv->transaction_end_action = SCARD_LEAVE_CARD;
 	gpriv->reconnect_action = SCARD_LEAVE_CARD;
 	gpriv->enable_pinpad = 1;
+	gpriv->fixed_pinlength = 0;
 	gpriv->enable_pace = 1;
 	gpriv->pcsc_ctx = -1;
 	gpriv->pcsc_wait_ctx = -1;
@@ -788,6 +790,8 @@ static int pcsc_init(sc_context_t *ctx)
 			pcsc_reset_action(scconf_get_str(conf_block, "reconnect_action", "leave"));
 		gpriv->enable_pinpad = scconf_get_bool(conf_block, "enable_pinpad",
 				gpriv->enable_pinpad);
+		gpriv->fixed_pinlength = scconf_get_bool(conf_block, "fixed_pinlength",
+				gpriv->fixed_pinlength);
 		gpriv->enable_pace = scconf_get_bool(conf_block, "enable_pace",
 				gpriv->enable_pace);
 		gpriv->force_max_send_size = scconf_get_int(conf_block,
@@ -1889,10 +1893,17 @@ part10_check_pin_min_max(sc_reader_t *reader, struct sc_pin_cmd_data *data)
 	unsigned char buffer[256];
 	size_t length = sizeof buffer;
 	struct pcsc_private_data *priv = reader->drv_data;
+	struct pcsc_global_private_data *gpriv = (struct pcsc_global_private_data *) reader->ctx->reader_drv_data;
 	struct sc_pin_cmd_pin *pin_ref =
 		data->flags & SC_PIN_CMD_IMPLICIT_CHANGE ?
 		&data->pin1 : &data->pin2;
 
+	if (gpriv->fixed_pinlength != 0) {
+		pin_ref->min_length = gpriv->fixed_pinlength;
+		pin_ref->max_length = gpriv->fixed_pinlength;
+		return 0;
+	}
+
 	if (!priv->get_tlv_properties)
 		return 0;