[RFC 2/2] Fix gatt_read_char() to work with long attributes

[Brian Gix <bgix@codeaurora.org>]

Fix gatt_read_char() so that it can correctly read an attribute longer
 	than (MTU-1) octets long. This is intended to be the first
 	use of the compound (multi-step) GATT Procedure mechanism
 	g_attrib_send_seq(), which will run the GATT procedure to completion
 	before executing any additional GATT Procedures. Functionaly, it
 	will check the result length of the original READ_REQ, and if
 	it is equal to the DEAFULT_MTU (23) octets long, it will make
 	a series of READ_BLOB_REQs until the entire remote attribute has
 	been read, after which it returns the result to the original
 	caller as if the data had been retrieved in a single ATT resp.

---
 attrib/gatt.c |  134 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 132 insertions(+), 2 deletions(-)

diff --git a/attrib/gatt.c b/attrib/gatt.c
index bca8b49..3a89b30 100644
--- a/attrib/gatt.c
+++ b/attrib/gatt.c
@@ -97,15 +97,145 @@ guint gatt_read_char_by_uuid(GAttrib *attrib, uint16_t start, uint16_t end,
 					pdu, plen, func, user_data, NULL);
 }
 
+struct read_long_data {
+	GAttrib *attrib;
+	GAttribResultFunc func;
+	gpointer user_data;
+	guint8 *buffer;
+	guint16 size;
+	guint16 handle;
+	guint id;
+	guint8 ref;
+};
+
+static void read_long_destroy(gpointer user_data)
+{
+	struct read_long_data *long_read = user_data;
+
+	if (--long_read->ref)
+		return;
+
+	if (long_read->buffer != NULL)
+		g_free(long_read->buffer);
+
+	g_free(long_read);
+}
+
+static void read_blob_helper(guint8 status, const guint8 *rpdu, guint16 rlen,
+							gpointer user_data)
+{
+	struct read_long_data *long_read = user_data;
+	uint8_t pdu[ATT_DEFAULT_MTU];
+	guint8 *tmp;
+	guint16 plen;
+	guint id;
+
+	if (status == ATT_ECODE_ATTR_NOT_LONG ||
+					status == ATT_ECODE_INVALID_OFFSET) {
+		status = 0;
+		goto done;
+	}
+
+	if (status != 0 || rlen == 1)
+		goto done;
+
+	tmp = g_try_realloc(long_read->buffer, long_read->size + rlen - 1);
+
+	if (tmp == NULL) {
+		status = ATT_ECODE_INSUFF_RESOURCES;
+		goto done;
+	}
+
+	memcpy(&tmp[long_read->size], &rpdu[1], rlen - 1);
+	long_read->buffer = tmp;
+	long_read->size += rlen - 1;
+
+	if (rlen < ATT_DEFAULT_MTU)
+		goto done;
+
+	plen = enc_read_blob_req(long_read->handle, long_read->size - 1,
+							pdu, sizeof(pdu));
+	id = g_attrib_send_seq(long_read->attrib, TRUE, long_read->id,
+				ATT_OP_READ_BLOB_REQ, pdu, plen,
+				read_blob_helper, long_read, read_long_destroy);
+
+	if (id != 0) {
+		long_read->ref++;
+		return;
+	}
+
+	status = ATT_ECODE_IO;
+
+done:
+	long_read->func(status, long_read->buffer, long_read->size,
+							long_read->user_data);
+}
+
+static void read_char_helper(guint8 status, const guint8 *rpdu,
+					guint16 rlen, gpointer user_data)
+{
+	struct read_long_data *long_read = user_data;
+	uint8_t pdu[ATT_DEFAULT_MTU];
+	guint16 plen;
+	guint id;
+
+	if (status != 0 || rlen < ATT_DEFAULT_MTU)
+		goto done;
+
+	long_read->buffer = g_malloc(rlen);
+
+	if (long_read->buffer == NULL)
+		goto done;
+
+	memcpy(long_read->buffer, rpdu, rlen);
+	long_read->size = rlen;
+
+	plen = enc_read_blob_req(long_read->handle, rlen - 1, pdu, sizeof(pdu));
+	id = g_attrib_send_seq(long_read->attrib, TRUE, long_read->id,
+			ATT_OP_READ_BLOB_REQ, pdu, plen, read_blob_helper,
+			long_read, read_long_destroy);
+
+	if (id != 0) {
+		long_read->ref++;
+		return;
+	}
+
+	status = ATT_ECODE_IO;
+
+done:
+	long_read->func(status, rpdu, rlen, long_read->user_data);
+}
+
 guint gatt_read_char(GAttrib *attrib, uint16_t handle, GAttribResultFunc func,
 							gpointer user_data)
 {
 	uint8_t pdu[ATT_DEFAULT_MTU];
 	guint16 plen;
+	guint id;
+	struct read_long_data *long_read;
+
+	long_read = g_try_new0(struct read_long_data, 1);
+
+	if (long_read == NULL)
+		return 0;
+
+	long_read->attrib = attrib;
+	long_read->func = func;
+	long_read->user_data = user_data;
+	long_read->handle = handle;
 
 	plen = enc_read_req(handle, pdu, sizeof(pdu));
-	return g_attrib_send(attrib, ATT_OP_READ_REQ, pdu, plen, func,
-							user_data, NULL);
+	id = g_attrib_send_seq(attrib, TRUE, 0, ATT_OP_READ_REQ, pdu, plen,
+				read_char_helper, long_read, read_long_destroy);
+
+	if (id == 0)
+		g_free(long_read);
+	else {
+		long_read->ref++;
+		long_read->id = id;
+	}
+
+	return id;
 }
 
 guint gatt_write_char(GAttrib *attrib, uint16_t handle, uint8_t *value,
-- 
1.7.2.2