examples: Add extension header octet to example

Mainly to make data/packets look (pseudo-)correct in Wireshark.

Also: Add helper for allocating message buffers with extended headroom for IPA.

Change-Id: I962b9edcba65cdc98da00d2f8753dc5acd481502

3 files changed, 10 insertions, 2 deletions

diff --git a/examples/ipa-stream-client.c b/examples/ipa-stream-client.c
index b66d93a..10eb786 100644
--- a/examples/ipa-stream-client.c
+++ b/examples/ipa-stream-client.c
@@ -74,7 +74,7 @@ static int connect_cb(struct osmo_stream_cli *conn)
 		char *ptr;
 		int x;
 
-		msg = osmo_ipa_msg_alloc(0);
+		msg = osmo_ipa_ext_msg_alloc(0);
 		if (msg == NULL) {
 			LOGP(DLINP, LOGL_ERROR, "cannot alloc msg\n");
 			return -1;
@@ -93,6 +93,7 @@ static int connect_cb(struct osmo_stream_cli *conn)
 		msg_sent->num = i;
 		llist_add(&msg_sent->head, &msg_sent_list);
 
+		ipa_prepend_header_ext(msg, IPAC_PROTO_EXT_MGCP);
 		osmo_ipa_msg_push_header(msg, IPAC_PROTO_OSMO);
 
 		osmo_stream_cli_send(conn, msg);
@@ -115,7 +116,7 @@ static int read_cb(struct osmo_stream_cli *conn, struct msgb *msg)
 	int num;
 	struct msg_sent *cur, *tmp, *found = NULL;
 
-	num = ntohl(*((int *)(msg->data + sizeof(struct ipa_head))));
+	num = ntohl(*((int *)(msg->data + sizeof(struct ipa_head) + sizeof(struct ipa_head_ext))));
 	LOGP(DLINP, LOGL_DEBUG, "received msg number %d\n", num);
 
 	llist_for_each_entry_safe(cur, tmp, &msg_sent_list, head) {
diff --git a/include/osmocom/netif/ipa.h b/include/osmocom/netif/ipa.h
index 0d1085f..7494d8d 100644
--- a/include/osmocom/netif/ipa.h
+++ b/include/osmocom/netif/ipa.h
@@ -19,6 +19,8 @@ struct ipa_head_ext {
 } __attribute__ ((packed));
 
 struct msgb *osmo_ipa_msg_alloc(int headroom);
+struct msgb *osmo_ipa_ext_msg_alloc(size_t headroom);
+
 void osmo_ipa_msg_push_header(struct msgb *msg, uint8_t proto);
 
 int osmo_ipa_process_msg(struct msgb *msg);
diff --git a/src/ipa.c b/src/ipa.c
index 197a47f..5f62e88 100644
--- a/src/ipa.c
+++ b/src/ipa.c
@@ -97,6 +97,11 @@ struct msgb *osmo_ipa_msg_alloc(int headroom)
 	return msg;
 }
 
+struct msgb *osmo_ipa_ext_msg_alloc(size_t headroom)
+{
+	return osmo_ipa_msg_alloc(sizeof(struct ipa_head_ext) + headroom);
+}
+
 void osmo_ipa_msg_push_header(struct msgb *msg, uint8_t proto)
 {
 	struct ipa_head *hh;