cbsp: Add osmo_cbsp_segmentation_cb for message segmentation
This call-back can for example be used as segmentation call-back
for libosmo-netif stream_cli/stream_srv or directly for osmo_io.
Related: OS#5755
Change-Id: I5e922c54b3431d759b38e81e55076125c5a34008
diff --git a/src/gsm/cbsp.c b/src/gsm/cbsp.c
index 28852f6..a5e58f4 100644
--- a/src/gsm/cbsp.c
+++ b/src/gsm/cbsp.c
@@ -1567,6 +1567,26 @@
return rc;
}
+/*! call-back function to segment the data at message boundaries.
+ * Returns the size of the next message. If it returns -EAGAIN or a value larger than msgb_length() (message
+ * is incomplete), the caller (e.g. osmo_io) has to wait for more data to be read. */
+int osmo_cbsp_segmentation_cb(struct msgb *msg)
+{
+ const struct cbsp_header *h;
+ int len;
+
+ if (msgb_length(msg) < sizeof(*h))
+ return -EAGAIN;
+
+ h = (const struct cbsp_header *) msg->data;
+ msg->l1h = msg->data;
+ msg->l2h = msg->data + sizeof(*h);
+ /* then read the length as specified in the header */
+ len = h->len[0] << 16 | h->len[1] << 8 | h->len[2];
+
+ return sizeof(*h) + len;
+}
+
/*! value_string[] for enum osmo_cbsp_cause. */
const struct value_string osmo_cbsp_cause_names[] = {
{ OSMO_CBSP_CAUSE_PARAM_NOT_RECOGNISED, "Parameter-not-recognised" },