llc: Move all direct accesses to the frame into the llc structure
Add some todo items where we could add assertions now that I see
the constraints and invariants of this code.
diff --git a/src/llc.cpp b/src/llc.cpp
index f5daa1e..a4fd7af 100644
--- a/src/llc.cpp
+++ b/src/llc.cpp
@@ -22,8 +22,6 @@
#include <tbf.h>
#include <bts.h>
-#include <string.h>
-
extern "C" {
#include <osmocom/core/msgb.h>
}
@@ -73,6 +71,7 @@
void gprs_llc::update_frame(struct msgb *msg)
{
+ /* TODO: assert that index is 0 now */
/* TODO: bounds check */
memcpy(frame, msg->data, msg->len);
length = msg->len;
diff --git a/src/llc.h b/src/llc.h
index 3144362..43c027e 100644
--- a/src/llc.h
+++ b/src/llc.h
@@ -19,6 +19,7 @@
#pragma once
#include <stdint.h>
+#include <string.h>
#define LLC_MAX_LEN 1543
@@ -35,11 +36,25 @@
void update_frame(struct msgb *msg);
void put_frame(const uint8_t *data, size_t len);
+ void consume(uint8_t *data, size_t len);
void clear(BTS *bts);
+ uint16_t chunk_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 */
struct llist_head queue; /* queued LLC DL data */
};
+inline uint16_t gprs_llc::chunk_size() const
+{
+ return length - index;
+}
+
+inline void gprs_llc::consume(uint8_t *data, size_t len)
+{
+ /* copy and increment index */
+ memcpy(data, frame + index, len);
+ index += len;
+}
diff --git a/src/tbf.cpp b/src/tbf.cpp
index 41aaf90..8803e54 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -1008,7 +1008,7 @@
delimiter = data; /* where next length header would be stored */
space = block_data - 3;
while (1) {
- chunk = m_llc.length - m_llc.index;
+ chunk = m_llc.chunk_size();
/* if chunk will exceed block limit */
if (chunk > space) {
LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
@@ -1018,9 +1018,7 @@
/* block is filled, so there is no extension */
*e_pointer |= 0x01;
/* fill only space */
- memcpy(data, m_llc.frame + m_llc.index, space);
- /* incement index */
- m_llc.index += space;
+ m_llc.consume(data, space);
/* return data block as message */
break;
}
@@ -1037,7 +1035,7 @@
/* block is filled, so there is no extension */
*e_pointer |= 0x01;
/* fill space */
- memcpy(data, m_llc.frame + m_llc.index, space);
+ m_llc.consume(data, space);
m_llc.reset();
/* final block */
rh->fbi = 1; /* we indicate final block */
@@ -1064,9 +1062,7 @@
li->li = 0; /* chunk fills the complete space */
// no need to set e_pointer nor increase delimiter
/* fill only space, which is 1 octet less than chunk */
- memcpy(data, m_llc.frame + m_llc.index, space);
- /* incement index */
- m_llc.index += space;
+ m_llc.consume(data, space);
/* return data block as message */
break;
}
@@ -1086,8 +1082,8 @@
li->li = chunk; /* length of chunk */
e_pointer = delimiter; /* points to E of current delimiter */
delimiter++;
- /* copy (rest of) LLC frame to space */
- memcpy(data, m_llc.frame + m_llc.index, chunk);
+ /* copy (rest of) LLC frame to space and reset later */
+ m_llc.consume(data, chunk);
data += chunk;
space -= chunk;
LOGP(DRLCMACDL, LOGL_INFO, "Complete DL frame for %s"