msgb: Add msgb_hexdump() function

This function works like osmo_hexdump() and returns a static buffer
containing hex bytes along with markers for the layers.

Note that it uses osmo_hexdump() internally, thus a call to
msgb_hexdump() invalidates the buffer that has been returned by an
earlier call to osmo_hexdump(). In short: don't mix them in a single
call printf().

Sponsored-by: On-Waves ehf

2 files changed, 50 insertions, 0 deletions

diff --git a/include/osmocom/core/msgb.h b/include/osmocom/core/msgb.h
index fe2733b7..5d4bd84b 100644
--- a/include/osmocom/core/msgb.h
+++ b/include/osmocom/core/msgb.h
@@ -73,6 +73,7 @@ extern void msgb_enqueue(struct llist_head *queue, struct msgb *msg);
 extern struct msgb *msgb_dequeue(struct llist_head *queue);
 extern void msgb_reset(struct msgb *m);
 uint16_t msgb_length(const struct msgb *msg);
+extern const char *msgb_hexdump(const struct msgb *msg);
 
 #ifdef MSGB_DEBUG
 #include <osmocom/core/panic.h>
diff --git a/src/msgb.c b/src/msgb.c
index 359a545b..b2fe1d2c 100644
--- a/src/msgb.c
+++ b/src/msgb.c
@@ -153,4 +153,53 @@ void msgb_set_talloc_ctx(void *ctx)
 	tall_msgb_ctx = ctx;
 }
 
+/*! \brief Return a (static) buffer containing a hexdump of the msg
+ * \param[in] msg message buffer
+ * \returns a pointer to a static char array
+ */
+const char *msgb_hexdump(const struct msgb *msg)
+{
+	static char buf[4100];
+	int buf_offs = 0;
+	int nchars;
+	const unsigned char *start = msg->data;
+	const unsigned char *lxhs[4];
+	int i;
+
+	lxhs[0] = msg->l1h;
+	lxhs[1] = msg->l2h;
+	lxhs[2] = msg->l3h;
+	lxhs[3] = msg->l4h;
+
+	for (i = 0; i < ARRAY_SIZE(lxhs); i++) {
+		if (!lxhs[i])
+			continue;
+
+		if (lxhs[i] < msg->data)
+			goto out_of_range;
+		if (lxhs[i] > msg->tail)
+			goto out_of_range;
+		nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
+				  "%s[L%d]> ",
+				  osmo_hexdump(start, lxhs[i] - start),
+				  i+1);
+		if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
+			return "ERROR";
+
+		buf_offs += nchars;
+		start = lxhs[i];
+	}
+	nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
+			  "%s", osmo_hexdump(start, msg->tail - start));
+	if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
+		return "ERROR";
+
+	return buf;
+
+out_of_range:
+	nchars = snprintf(buf, sizeof(buf) - buf_offs,
+			  "!!! L%d out of range", i+1);
+	return buf;
+}
+
 /*! @} */