Fix parser of AVRCP continuing messages

If packet_type is not START or SINGLE, we have to continue where we
stopped from previous packet. Therefore we must store where we left on
previous packet due to packet size limit. We store both the number of
attributes missing and the lenght of the last attribute that is missing.

An example interaction for this implementation, obtained with PTS test
TC_TG_MDI_BV_04_C (I reduced the MTU in order to reproduce it here and
values between brackets I added now):

> AVCTP: Command : pt 0x00 transaction 2 pid 0x110e
    AV/C: Status: address 0x48 opcode 0x00
      Subunit: Panel
      Opcode: Vendor Dependent
      Company ID: 0x001958
      AVRCP: GetElementAttributes: pt Single len 0x0009
        Identifier: 0x0 (PLAYING)
        AttributeCount: 0x00
< AVCTP: Response : pt 0x00 transaction 2 pid 0x110e
    AV/C: Stable: address 0x48 opcode 0x00
      Subunit: Panel
      Opcode: Vendor Dependent
      Company ID: 0x001958
      AVRCP: GetElementAttributes: pt Start len 0x0118
        AttributeCount: 0x04
        Attribute: 0x00000001 (Title)
        CharsetID: 0x006a (UTF-8)
        AttributeValueLength: 0x001b
        AttributeValue: isso eh um titulo mei longo
        Attribute: 0x00000003 (Album)
        CharsetID: 0x006a (UTF-8)
        AttributeValueLength: 0x00fe
	AttributeValue: super-long-album-name super-long-album-name
	super-long-album-name super-long-album-name super-long-album
	super-long-album-name [... snip... ] super-long-album-name-1234
> AVCTP: Command : pt 0x00 transaction 2 pid 0x110e
    AV/C: Control: address 0x48 opcode 0x00
      Subunit: Panel
      Opcode: Vendor Dependent
      Company ID: 0x001958
      AVRCP: RequestContinuingResponse: pt Single len 0x0001
< AVCTP: Response : pt 0x00 transaction 2 pid 0x110e
    AV/C: Stable: address 0x48 opcode 0x00
      Subunit: Panel
      Opcode: Vendor Dependent
      Company ID: 0x001958
      AVRCP: GetElementAttributes: pt End len 0x002a
        ContinuingAttributeValue: 678900000000000000
        Attribute: 0x00000005 (Track Total)
        CharsetID: 0x006a (UTF-8)
        AttributeValueLength: 0x0002
        AttributeValue: 30
        Attribute: 0x00000006 (Genre)
        CharsetID: 0x006a (UTF-8)
        AttributeValueLength: 0x0006
        AttributeValue: Gospel

1 files changed, 79 insertions, 15 deletions

diff --git a/parser/avrcp.c b/parser/avrcp.c
index bb2effa..643e494 100644
--- a/parser/avrcp.c
+++ b/parser/avrcp.c
@@ -84,6 +84,12 @@
 #define AVC_PANEL_FORWARD		0x4b
 #define AVC_PANEL_BACKWARD		0x4c
 
+/* Packet types */
+#define AVRCP_PACKET_TYPE_SINGLE	0x00
+#define AVRCP_PACKET_TYPE_START		0x01
+#define AVRCP_PACKET_TYPE_CONTINUING	0x02
+#define AVRCP_PACKET_TYPE_END		0x03
+
 /* pdu ids */
 #define AVRCP_GET_CAPABILITIES		0x10
 #define AVRCP_LIST_PLAYER_ATTRIBUTES	0x11
@@ -173,6 +179,11 @@
 #define AVRCP_PLAY_STATUS_REV_SEEK	0x04
 #define AVRCP_PLAY_STATUS_ERROR		0xFF
 
+static struct avrcp_continuing {
+	uint16_t num;
+	uint16_t size;
+} avrcp_continuing;
+
 static const char *ctype2str(uint8_t ctype)
 {
 	switch (ctype & 0x0f) {
@@ -221,6 +232,22 @@ static const char *opcode2str(uint8_t opcode)
 	}
 }
 
+static const char *pt2str(uint8_t pt)
+{
+	switch (pt) {
+	case AVRCP_PACKET_TYPE_SINGLE:
+		return "Single";
+	case AVRCP_PACKET_TYPE_START:
+		return "Start";
+	case AVRCP_PACKET_TYPE_CONTINUING:
+		return "Continuing";
+	case AVRCP_PACKET_TYPE_END:
+		return "End";
+	default:
+		return "Unknown";
+	}
+}
+
 static const char *pdu2str(uint8_t pduid)
 {
 	switch (pduid) {
@@ -914,7 +941,8 @@ static const char *mediattr2str(uint32_t attr)
 }
 
 static void avrcp_get_element_attributes_dump(int level, struct frame *frm,
-						uint8_t ctype, uint16_t len)
+						uint8_t ctype, uint16_t len,
+						uint8_t pt)
 {
 	uint64_t id;
 	uint8_t num;
@@ -950,18 +978,45 @@ static void avrcp_get_element_attributes_dump(int level, struct frame *frm,
 	return;
 
 response:
-	if (len < 1) {
-		printf("PDU Malformed\n");
-		raw_dump(level, frm);
-		return;
-	}
+	if (pt == AVRCP_PACKET_TYPE_SINGLE || pt == AVRCP_PACKET_TYPE_START) {
+		if (len < 1) {
+			printf("PDU Malformed\n");
+			raw_dump(level, frm);
+			return;
+		}
 
-	num = get_u8(frm);
-	printf("AttributeCount: 0x%02x\n", num);
+		num = get_u8(frm);
+		avrcp_continuing.num = num;
+		printf("AttributeCount: 0x%02x\n", num);
+		len--;
+	} else {
+		num = avrcp_continuing.num;
+
+		if (avrcp_continuing.size > 0) {
+			uint16_t size;
+
+			if (avrcp_continuing.size > len) {
+				size = len;
+				avrcp_continuing.size -= len;
+			} else {
+				size = avrcp_continuing.size;
+				avrcp_continuing.size = 0;
+			}
+
+			printf("ContinuingAttributeValue: ");
+			for (; size > 0; size--) {
+				uint8_t c = get_u8(frm);
+				printf("%1c", isprint(c) ? c : '.');
+			}
+			printf("\n");
 
-	for (; num > 0; num--) {
+			len -= size;
+		}
+	}
+
+	while (num > 0 && len > 0) {
 		uint32_t attr;
-		uint16_t charset, len;
+		uint16_t charset, attrlen;
 
 		p_indent(level, frm);
 
@@ -975,19 +1030,26 @@ response:
 							charset2str(charset));
 
 		p_indent(level, frm);
+		attrlen = get_u16(frm);
+		printf("AttributeValueLength: 0x%04x\n", attrlen);
 
-		len = get_u16(frm);
-		printf("AttributeValueLength: 0x%04x\n", len);
+		len -= sizeof(attr) + sizeof(charset) + sizeof(attrlen);
+		num--;
 
 		p_indent(level, frm);
 
 		printf("AttributeValue: ");
-		for (; len > 0; len--) {
+		for (; attrlen > 0 && len > 0; attrlen--, len--) {
 			uint8_t c = get_u8(frm);
 			printf("%1c", isprint(c) ? c : '.');
 		}
 		printf("\n");
+
+		if (attrlen > 0)
+			avrcp_continuing.size = attrlen;
 	}
+
+	avrcp_continuing.num = num;
 }
 
 static const char *playstatus2str(uint8_t status)
@@ -1150,7 +1212,8 @@ static void avrcp_pdu_dump(int level, struct frame *frm, uint8_t ctype)
 	pt = get_u8(frm);
 	len = get_u16(frm);
 
-	printf("AVRCP: %s: pt 0x%02x len 0x%04x\n", pdu2str(pduid), pt, len);
+	printf("AVRCP: %s: pt %s len 0x%04x\n", pdu2str(pduid),
+							pt2str(pt), len);
 
 	if (len != frm->len) {
 		p_indent(level, frm);
@@ -1195,7 +1258,8 @@ static void avrcp_pdu_dump(int level, struct frame *frm, uint8_t ctype)
 		avrcp_ct_battery_status_dump(level + 1, frm, ctype, len);
 		break;
 	case AVRCP_GET_ELEMENT_ATTRIBUTES:
-		avrcp_get_element_attributes_dump(level + 1, frm, ctype, len);
+		avrcp_get_element_attributes_dump(level + 1, frm, ctype, len,
+									pt);
 		break;
 	case AVRCP_GET_PLAY_STATUS:
 		avrcp_get_play_status_dump(level + 1, frm, ctype, len);