Change in osmo-mgw[master]: generate shorter 'I:' conn IDs

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Neels Hofmeyr gerrit-no-reply at lists.osmocom.org
Wed Aug 29 00:39:26 UTC 2018


Neels Hofmeyr has uploaded this change for review. ( https://gerrit.osmocom.org/10676


Change subject: generate shorter 'I:' conn IDs
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generate shorter 'I:' conn IDs

Reduce the number of hex chars generated as Connection Identifier from 32 to 8.

According to RFC3435 2.1.3.2 "Names of Connections", the maximum length is
indeed 32 characters, but there isn't really a benefit of using IDs of that
size. That, and:

A specific SCCPlite MSC is seen to be able to store conn IDs of up to 8 hex
characters of length. If given more than that, it will later send 'ffffffff' as
ID, e.g. in the DLCX message, causing mismatches and rejected DLCX.

Conn IDs need to be unique only within the context of one endpoint, so
producing 32 characters of ID is far beyond overkill, especially if we
currently expect exactly two IDs per endpoint.

The nicer solution would be to make the length of generated ID configurable,
but it would also require some code refactoring to handle a variable length of
ID internally. We can safely and simply go with a fixed length of 8 chars.

Related: OS#3507
Change-Id: Ia290c22a91fca0e5aa44515fca6df00064aff100
---
M include/osmocom/mgcp/mgcp_common.h
M src/libosmo-mgcp/mgcp_conn.c
2 files changed, 2 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-mgw refs/changes/76/10676/1

diff --git a/include/osmocom/mgcp/mgcp_common.h b/include/osmocom/mgcp/mgcp_common.h
index b2c7370..0be227f 100644
--- a/include/osmocom/mgcp/mgcp_common.h
+++ b/include/osmocom/mgcp/mgcp_common.h
@@ -81,7 +81,7 @@
 
 /* String length of Connection Identifiers
  * (see also RFC3435 2.1.3.2 Names of Connections) */
-#define MGCP_CONN_ID_LENGTH 32+1
+#define MGCP_CONN_ID_LENGTH 8+1
 
 /* String length of Endpoint Identifiers.
 /  (see also RFC3435 section 3.2.1.3) */
diff --git a/src/libosmo-mgcp/mgcp_conn.c b/src/libosmo-mgcp/mgcp_conn.c
index 3a5db0f..8d855f2 100644
--- a/src/libosmo-mgcp/mgcp_conn.c
+++ b/src/libosmo-mgcp/mgcp_conn.c
@@ -58,7 +58,7 @@
 	int i;
 	int k;
 	int rc;
-	uint8_t id_bin[16];
+	uint8_t id_bin[4];
 	char *id_hex;
 
 	/* Generate a connection id that is unique for the current endpoint.

-- 
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Gerrit-Project: osmo-mgw
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Ia290c22a91fca0e5aa44515fca6df00064aff100
Gerrit-Change-Number: 10676
Gerrit-PatchSet: 1
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>
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