Automatic determination of maximum PB-TNC batch and PA-TNC message size

5 files changed, 46 insertions, 12 deletions

diff --git a/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.c b/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.c
index ef0faf2c1..228c08255 100644
--- a/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.c
+++ b/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.c
@@ -16,6 +16,7 @@
 
 #include "pb_tnc_batch.h"
 #include "messages/ietf/pb_error_msg.h"
+#include "messages/ietf/pb_pa_msg.h"
 #include "state_machine/pb_tnc_state_machine.h"
 
 #include <tnc/tnccs/tnccs.h>
@@ -51,7 +52,6 @@ typedef struct private_pb_tnc_batch_t private_pb_tnc_batch_t;
 
 #define PB_TNC_BATCH_FLAG_NONE		0x00
 #define PB_TNC_BATCH_FLAG_D			(1<<7)
-#define PB_TNC_BATCH_HEADER_SIZE	8
 
 /**
  *   PB-TNC Message (see section 4.2 of RFC 5793)
@@ -71,7 +71,6 @@ typedef struct private_pb_tnc_batch_t private_pb_tnc_batch_t;
 
 #define PB_TNC_FLAG_NONE			0x00
 #define PB_TNC_FLAG_NOSKIP			(1<<7)
-#define PB_TNC_HEADER_SIZE			12
 
 #define PB_TNC_RESERVED_MSG_TYPE	0xffffffff
 
@@ -148,7 +147,7 @@ METHOD(pb_tnc_batch_t, add_msg, bool,
 
 	msg->build(msg);
 	msg_value = msg->get_encoding(msg);
-	msg_len = PB_TNC_HEADER_SIZE + msg_value.len;
+	msg_len = PB_TNC_MSG_HEADER_SIZE + msg_value.len;
 
 	if (this->batch_len + msg_len > this->max_batch_len)
 	{
@@ -201,7 +200,7 @@ METHOD(pb_tnc_batch_t, build, void,
 
 		/* build PB-TNC message */
 		msg_value = msg->get_encoding(msg);
-		msg_len = PB_TNC_HEADER_SIZE + msg_value.len;
+		msg_len = PB_TNC_MSG_HEADER_SIZE + msg_value.len;
 		msg_type = msg->get_type(msg);
 		switch (msg_type.vendor_id)
 		{
@@ -339,7 +338,7 @@ static status_t process_tnc_msg(private_pb_tnc_batch_t *this)
 
 	data = chunk_skip(this->encoding, this->offset);
 
-	if (data.len < PB_TNC_HEADER_SIZE)
+	if (data.len < PB_TNC_MSG_HEADER_SIZE)
 	{
 		DBG1(DBG_TNC, "%u bytes insufficient to parse PB-TNC message header",
 					  data.len);
@@ -403,7 +402,7 @@ static status_t process_tnc_msg(private_pb_tnc_batch_t *this)
 	}
 	else
 	{
-		if (msg_len < PB_TNC_HEADER_SIZE)
+		if (msg_len < PB_TNC_MSG_HEADER_SIZE)
 		{
 			DBG1(DBG_TNC, "%u bytes too small for PB-TNC message length",
 						   msg_len);
@@ -475,7 +474,7 @@ static status_t process_tnc_msg(private_pb_tnc_batch_t *this)
 	DBG2(DBG_TNC, "processing %N/%N message (%u bytes)", pen_names, vendor_id,
 		 msg_type_names, msg_type, msg_len);
 	data.len = msg_len;
-	msg_value = chunk_skip(data, PB_TNC_HEADER_SIZE);
+	msg_value = chunk_skip(data, PB_TNC_MSG_HEADER_SIZE);
 	msg_pen_type = pen_type_create(vendor_id, msg_type);
 	pb_tnc_msg = pb_tnc_msg_create_from_data(msg_pen_type, msg_value);
 
diff --git a/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.h b/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.h
index 60cef7735..106c5578c 100644
--- a/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.h
+++ b/src/libtnccs/plugins/tnccs_20/batch/pb_tnc_batch.h
@@ -29,6 +29,9 @@ typedef struct pb_tnc_batch_t pb_tnc_batch_t;
 
 #include <library.h>
 
+#define PB_TNC_BATCH_HEADER_SIZE	 8
+#define PB_TNC_MSG_HEADER_SIZE		12
+
 /**
   * PB-TNC Batch Types as defined in section 4.1 of RFC 5793
  */
diff --git a/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.c b/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.c
index a9a097bd4..263af3224 100644
--- a/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.c
+++ b/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.c
@@ -117,7 +117,7 @@ METHOD(pb_tnc_msg_t, build, void,
 	}
 
 	/* build message header */
-	writer = bio_writer_create(64);
+	writer = bio_writer_create(PB_PA_MSG_HEADER_SIZE);
 	writer->write_uint8 (writer, this->excl ? PA_FLAG_EXCL : PA_FLAG_NONE);
 	writer->write_uint24(writer, this->subtype.vendor_id);
 	writer->write_uint32(writer, this->subtype.type);
diff --git a/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.h b/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.h
index 093bb45ae..f3b6b1518 100644
--- a/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.h
+++ b/src/libtnccs/plugins/tnccs_20/messages/ietf/pb_pa_msg.h
@@ -27,6 +27,8 @@ typedef struct pb_pa_msg_t pb_pa_msg_t;
 
 #include <pen/pen.h>
 
+#define PB_PA_MSG_HEADER_SIZE	12
+
 /**
  * Class representing the PB-PA message type.
  */
diff --git a/src/libtnccs/plugins/tnccs_20/tnccs_20.c b/src/libtnccs/plugins/tnccs_20/tnccs_20.c
index f78b85a68..b593f853f 100644
--- a/src/libtnccs/plugins/tnccs_20/tnccs_20.c
+++ b/src/libtnccs/plugins/tnccs_20/tnccs_20.c
@@ -1032,6 +1032,38 @@ tnccs_t* tnccs_20_create(bool is_server,
 						 tnc_ift_type_t transport, tnccs_cb_t cb)
 {
 	private_tnccs_20_t *this;
+	size_t max_batch_size, default_max_batch_size;
+	size_t max_message_size, default_max_message_size;
+
+	/* Determine the maximum PB-TNC batch size and PA-TNC message size */
+	switch (transport)
+	{
+		case TNC_IFT_TLS_2_0:
+		case TNC_IFT_TLS_1_0:
+			default_max_batch_size = 8 * TLS_MAX_FRAGMENT_LEN - 16;
+			break;
+		case TNC_IFT_EAP_2_0:
+		case TNC_IFT_EAP_1_1:
+		case TNC_IFT_EAP_1_0:
+		case TNC_IFT_UNKNOWN:
+		default:
+			default_max_batch_size = 4 * TLS_MAX_FRAGMENT_LEN - 14;
+			break;
+	}
+
+	max_batch_size = min(default_max_batch_size,
+						lib->settings->get_int(lib->settings,
+								"%s.plugins.tnccs-20.max_batch_size",
+								 default_max_batch_size, lib->ns));
+
+	default_max_message_size = max_batch_size - PB_TNC_BATCH_HEADER_SIZE
+											  - PB_TNC_MSG_HEADER_SIZE
+											  - PB_PA_MSG_HEADER_SIZE;
+
+	max_message_size = min(default_max_message_size,
+							lib->settings->get_int(lib->settings,
+								"%s.plugins.tnccs-20.max_message_size",
+								 default_max_message_size, lib->ns));
 
 	INIT(this,
 		.public = {
@@ -1062,10 +1094,8 @@ tnccs_t* tnccs_20_create(bool is_server,
 		.state_machine = pb_tnc_state_machine_create(is_server),
 		.mutex = mutex_create(MUTEX_TYPE_DEFAULT),
 		.messages = linked_list_create(),
-		.max_batch_len = lib->settings->get_int(lib->settings,
-						"%s.plugins.tnccs-20.max_batch_size", 65522, lib->ns),
-		.max_msg_len = lib->settings->get_int(lib->settings,
-						"%s.plugins.tnccs-20.max_message_size", 65490, lib->ns),
+		.max_batch_len = max_batch_size,
+		.max_msg_len = max_message_size,
 		.ref = 1,
 	);