daniel has uploaded this change for review. (
https://gerrit.osmocom.org/c/libosmocore/+/33685 )
Change subject: osmo_io: Document expectation that segmentation_cb() can modify
msgb
......................................................................
osmo_io: Document expectation that segmentation_cb() can modify msgb
This is used for parsing e.g. the ipa header and setting msg->cb.
Guard against segmentation_cb changing msg->data in
iofd_handle_segmentation().
Change-Id: Idd2115baae98a7818aabb26232d4423d2d48fb5c
---
M include/osmocom/core/osmo_io.h
M src/core/osmo_io.c
2 files changed, 25 insertions(+), 4 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/85/33685/1
diff --git a/include/osmocom/core/osmo_io.h b/include/osmocom/core/osmo_io.h
index 932b909..81f13f2 100644
--- a/include/osmocom/core/osmo_io.h
+++ b/include/osmocom/core/osmo_io.h
@@ -46,7 +46,10 @@
* Needs to return the size of the next message. If it
returns
* -EAGAIN or a value larger than msgb_length()
(message is incomplete)
* osmo_io will wait for more data to be read. Other
negative values
- * cause the msg to be discarded. */
+ * cause the msg to be discarded. If a full message
was received the msgb
+ * will be trimmed to size and forwarded to the read
call-back. All parsing
+ * done to the msgb by the segmentation_cb() for that
message will be preserved
+ * (e.g. setting lxh or msgb->cb). */
int (*segmentation_cb)(struct msgb *msg);
};
diff --git a/src/core/osmo_io.c b/src/core/osmo_io.c
index fdb9e32..8217316 100644
--- a/src/core/osmo_io.c
+++ b/src/core/osmo_io.c
@@ -226,6 +226,9 @@
int extra_len, received_len;
struct msgb *msg_pending;
+ /* Save the start of message before segmentation_cb (which could change
it) */
+ uint8_t *data = msg->data;
+
received_len = msgb_length(msg);
if (!iofd->io_ops.segmentation_cb) {
@@ -258,12 +261,14 @@
/* msgb contains more than one segment */
/* Copy the trailing data over */
msg_pending = iofd_msgb_alloc(iofd);
- memcpy(msgb_data(msg_pending), msgb_data(msg) + expected_len,
extra_len);
+ memcpy(msgb_data(msg_pending), data + expected_len, extra_len);
msgb_put(msg_pending, extra_len);
*pending_out = msg_pending;
- /* Trim the original msgb to size */
- msgb_trim(msg, expected_len);
+ /* Trim the original msgb to size. Don't use msgb_trim because we need
to reference
+ * msg->data from before it might have been modified by the
segmentation_cb(). */
+ msg->len = expected_len;
+ msg->tail = data + expected_len;
return IOFD_SEG_ACT_HANDLE_MORE;
defer:
--
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Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Change-Id: Idd2115baae98a7818aabb26232d4423d2d48fb5c
Gerrit-Change-Number: 33685
Gerrit-PatchSet: 1
Gerrit-Owner: daniel <[email protected]>
Gerrit-MessageType: newchange
