llc: Move some more secrets from the TBF into the LLC

Introduce a method to append data to a TBF and then reset the
read pointer when the frame has been sent.

3 files changed, 57 insertions, 26 deletions

diff --git a/src/llc.cpp b/src/llc.cpp
index 1787daa6..3a50bc78 100644
--- a/src/llc.cpp
+++ b/src/llc.cpp
@@ -32,7 +32,7 @@ extern "C" {
 void gprs_llc::reset()
 {
 	index = 0;
-	length = 0;
+	m_length = 0;
 }
 
 void gprs_llc::reset_frame_space()
@@ -48,11 +48,15 @@ void gprs_llc::enqueue(struct msgb *llc_msg)
 void gprs_llc::put_frame(const uint8_t *data, size_t len)
 {
 	/* only put frames when we are empty */
-	OSMO_ASSERT(index == 0 && length == 0);
+	OSMO_ASSERT(index == 0 && m_length == 0);
+	append_frame(data, len);
+}
 
+void gprs_llc::append_frame(const uint8_t *data, size_t len)
+{
 	/* TODO: bounds check */
-	memcpy(frame, data, len);
-	length = len;
+	memcpy(frame + index, data, len);
+	m_length += len;
 }
 
 void gprs_llc::clear(BTS *bts)
diff --git a/src/llc.h b/src/llc.h
index d3b940ea..b22b1c20 100644
--- a/src/llc.h
+++ b/src/llc.h
@@ -37,20 +37,42 @@ struct gprs_llc {
 	struct msgb *dequeue();
 
 	void put_frame(const uint8_t *data, size_t len);
+	void append_frame(const uint8_t *data, size_t len);
+
+	void consume(size_t len);
 	void consume(uint8_t *data, size_t len);
 	void clear(BTS *bts);
 
 	uint16_t chunk_size() const;
+	uint16_t remaining_space() const;
+	uint16_t frame_length() const;
+
+	bool fits_in_current_frame(uint8_t size) const;
 
 	uint8_t frame[LLC_MAX_LEN]; /* current DL or UL frame */
 	uint16_t index; /* current write/read position of frame */
-	uint16_t length; /* len of current DL LLC_frame, 0 == no frame */
+	uint16_t m_length; /* len of current DL LLC_frame, 0 == no frame */
 	struct llist_head queue; /* queued LLC DL data */
 };
 
 inline uint16_t gprs_llc::chunk_size() const
 {
-	return length - index;
+	return m_length - index;
+}
+
+inline uint16_t gprs_llc::remaining_space() const
+{
+	return LLC_MAX_LEN - index;
+}
+
+inline uint16_t gprs_llc::frame_length() const
+{
+	return m_length;
+}
+
+inline void gprs_llc::consume(size_t len)
+{
+	index += len;
 }
 
 inline void gprs_llc::consume(uint8_t *data, size_t len)
@@ -59,3 +81,8 @@ inline void gprs_llc::consume(uint8_t *data, size_t len)
 	memcpy(data, frame + index, len);
 	index += len;
 }
+
+inline bool gprs_llc::fits_in_current_frame(uint8_t chunk_size) const
+{
+	return index + chunk_size <= LLC_MAX_LEN;
+}
diff --git a/src/tbf.cpp b/src/tbf.cpp
index aa0f2236..41a94bcd 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -98,7 +98,6 @@ int gprs_rlcmac_tbf::append_data(const uint8_t ms_class,
 		LOGP(DRLCMAC, LOGL_DEBUG,
 			"%s in WAIT RELEASE state "
 			"(T3193), so reuse TBF\n", tbf_name(this));
-#warning "verify that m_llc.index/length is 0... check the state change"
 		bts->tbf_reused();
 		m_llc.put_frame(data, len);
 		bts->llc_frame_sched();
@@ -849,21 +848,21 @@ int gprs_rlcmac_tbf::assemble_forward_llc(uint8_t *data, uint8_t len)
 			/* data until next frame */
 			chunk = frame_offset[i + 1] - frame_offset[i];
 		}
-		LOGP(DRLCMACUL, LOGL_DEBUG, "-- Appending chunk (len=%d) to "
-			"frame at %d.\n", chunk, m_llc.index);
-		if (m_llc.index + chunk > LLC_MAX_LEN) {
+		if (!m_llc.fits_in_current_frame(chunk)) {
 			LOGP(DRLCMACUL, LOGL_NOTICE, "%s LLC frame exceeds "
-				"maximum size.\n", tbf_name(this));
-			chunk = LLC_MAX_LEN - m_llc.index;
+				"maximum size %u.\n", tbf_name(this),
+				m_llc.remaining_space());
+			chunk = m_llc.remaining_space();
 		}
-		memcpy(m_llc.frame + m_llc.index, data + frame_offset[i], chunk);
-		m_llc.index += chunk;
+		m_llc.append_frame(data + frame_offset[i], chunk);
+		m_llc.consume(chunk);
 		/* not last frame. */
 		if (i != frames - 1) {
 			/* send frame to SGSN */
 			LOGP(DRLCMACUL, LOGL_INFO, "%s complete UL frame len=%d\n",
-				tbf_name(this) , m_llc.index);
+				tbf_name(this) , m_llc.frame_length());
 			snd_ul_ud();
+			m_llc.reset();
 		/* also check if CV==0, because the frame may fill up the
 		 * block precisely, then it is also complete. normally the
 		 * frame would be extended into the next block with a 0-length
@@ -872,8 +871,9 @@ int gprs_rlcmac_tbf::assemble_forward_llc(uint8_t *data, uint8_t len)
 			/* send frame to SGSN */
 			LOGP(DRLCMACUL, LOGL_INFO, "%s complete UL frame "
 				"that fits precisely in last block: "
-				"len=%d\n", tbf_name(this), m_llc.index);
+				"len=%d\n", tbf_name(this), m_llc.frame_length());
 			snd_ul_ud();
+			m_llc.reset();
 		}
 	}
 
@@ -1019,8 +1019,8 @@ do_resend:
 				"header, and we are done\n", chunk, space);
 			LOGP(DRLCMACDL, LOGL_INFO, "Complete DL frame for "
 				"%s that fits precisely in last block: "
-				"len=%d\n", tbf_name(this), m_llc.length);
-			gprs_rlcmac_dl_bw(this, m_llc.length);
+				"len=%d\n", tbf_name(this), m_llc.frame_length());
+			gprs_rlcmac_dl_bw(this, m_llc.frame_length());
 			/* block is filled, so there is no extension */
 			*e_pointer |= 0x01;
 			/* fill space */
@@ -1076,8 +1076,8 @@ do_resend:
 		data += chunk;
 		space -= chunk;
 		LOGP(DRLCMACDL, LOGL_INFO, "Complete DL frame for %s"
-			"len=%d\n", tbf_name(this), m_llc.length);
-		gprs_rlcmac_dl_bw(this, m_llc.length);
+			"len=%d\n", tbf_name(this), m_llc.frame_length());
+		gprs_rlcmac_dl_bw(this, m_llc.frame_length());
 		m_llc.reset();
 		/* dequeue next LLC frame, if any */
 		msg = llc_dequeue(gprs_bssgp_pcu_current_bctx());
@@ -1089,12 +1089,12 @@ do_resend:
 			msgb_free(msg);
 		}
 		/* if we have more data and we have space left */
-		if (space > 0 && m_llc.length) {
+		if (space > 0 && m_llc.frame_length()) {
 			li->m = 1; /* we indicate more frames to follow */
 			continue;
 		}
 		/* if we don't have more LLC frames */
-		if (!m_llc.length) {
+		if (!m_llc.frame_length()) {
 			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Final block, so we "
 				"done.\n");
 			li->e = 1; /* we cannot extend */
@@ -1822,10 +1822,10 @@ int gprs_rlcmac_tbf::snd_ul_ud()
 {
 	uint8_t qos_profile[3];
 	struct msgb *llc_pdu;
-	unsigned msg_len = NS_HDR_LEN + BSSGP_HDR_LEN + m_llc.index;
+	unsigned msg_len = NS_HDR_LEN + BSSGP_HDR_LEN + m_llc.frame_length();
 	struct bssgp_bvc_ctx *bctx = gprs_bssgp_pcu_current_bctx();
 
-	LOGP(DBSSGP, LOGL_INFO, "LLC [PCU -> SGSN] %s len=%d\n", tbf_name(this), m_llc.index);
+	LOGP(DBSSGP, LOGL_INFO, "LLC [PCU -> SGSN] %s len=%d\n", tbf_name(this), m_llc.frame_length());
 	if (!bctx) {
 		LOGP(DBSSGP, LOGL_ERROR, "No bctx\n");
 		m_llc.reset_frame_space();
@@ -1833,8 +1833,8 @@ int gprs_rlcmac_tbf::snd_ul_ud()
 	}
 	
 	llc_pdu = msgb_alloc_headroom(msg_len, msg_len,"llc_pdu");
-	uint8_t *buf = msgb_push(llc_pdu, TL16V_GROSS_LEN(sizeof(uint8_t)*m_llc.index));
-	tl16v_put(buf, BSSGP_IE_LLC_PDU, sizeof(uint8_t)*m_llc.index, m_llc.frame);
+	uint8_t *buf = msgb_push(llc_pdu, TL16V_GROSS_LEN(sizeof(uint8_t)*m_llc.frame_length()));
+	tl16v_put(buf, BSSGP_IE_LLC_PDU, sizeof(uint8_t)*m_llc.frame_length(), m_llc.frame);
 	qos_profile[0] = QOS_PROFILE >> 16;
 	qos_profile[1] = QOS_PROFILE >> 8;
 	qos_profile[2] = QOS_PROFILE;