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Gb Proxy: Proper msgb memory management 

The old idea was to take a msgb from gbprox_rcvmsg() and then
modify it and finally send it all the way down to nsip_sendmsg()
to the remote peer.

However, this introduces memory management difficulties, as we then
have to distinguish three cases:
 * msgb was sent to a remote peer
 * we sent some error message and need to free the msgb
 * we need to make n-1 copies in case of a BSSVC-RESET from the SGSN

So instead we now simply always copy the message if we pass it on.

All messages received by gbprox_rcvmsg() are msgb_free()d in the very
same routine

All messages allocated by tx2peer() or tx2sgsn() are freed after
nsip_sendmsg()
This commit is contained in:
Harald Welte 2010-05-12 18:10:25 +00:00
parent ea4647d264
commit 39d0bb5f7c
1 changed files with 31 additions and 2 deletions
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33
openbsc/src/gprs/gb_proxy.c
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@ -119,6 +119,23 @@ static void peer_free(struct gbprox_peer *peer)
talloc_free(peer);
}
/* FIXME: this needs to go to libosmocore/msgb.c */
static struct msgb *msgb_copy(const struct msgb *msg, const char *name)
{
struct msgb *new_msg;
new_msg = msgb_alloc(msg->data_len, name);
if (!new_msg)
return NULL;
/* copy header */
memcpy(new_msg, msg, sizeof(*new_msg));
/* copy data */
memcpy(new_msg->data, msg->data, new_msg->data_len);
return new_msg;
}
/* strip off the NS header */
static void strip_ns_hdr(struct msgb *msg)
{
@ -127,8 +144,12 @@ static void strip_ns_hdr(struct msgb *msg)
}
/* feed a message down the NS-VC associated with the specified peer */
static int gbprox_relay2sgsn(struct msgb *msg, uint16_t ns_bvci)
static int gbprox_relay2sgsn(struct msgb *old_msg, uint16_t ns_bvci)
{
/* create a copy of the message so the old one can
* be free()d safely when we return from gbprox_rcvmsg() */
struct msgb *msg = msgb_copy(old_msg, "msgb_relay2sgsn");
DEBUGP(DGPRS, "NSEI=%u proxying BTS->SGSN (NS_BVCI=%u, NSEI=%u)\n",
msgb_nsei(msg), ns_bvci, gbcfg.nsip_sgsn_nsei);
@ -141,9 +162,13 @@ static int gbprox_relay2sgsn(struct msgb *msg, uint16_t ns_bvci)
}
/* feed a message down the NS-VC associated with the specified peer */
static int gbprox_relay2peer(struct msgb *msg, struct gbprox_peer *peer,
static int gbprox_relay2peer(struct msgb *old_msg, struct gbprox_peer *peer,
uint16_t ns_bvci)
{
/* create a copy of the message so the old one can
* be free()d safely when we return from gbprox_rcvmsg() */
struct msgb *msg = msgb_copy(old_msg, "msgb_relay2peer");
DEBUGP(DGPRS, "NSEI=%u proxying to SGSN->BSS (NS_BVCI=%u, NSEI=%u)\n",
msgb_nsei(msg), ns_bvci, peer->nsvc->nsei);
@ -466,6 +491,10 @@ int gbprox_rcvmsg(struct msgb *msg, struct gprs_nsvc *nsvc, uint16_t ns_bvci)
}
}
/* We free the original message here, as we will have created a
* copy in case it is forwarded to another peer */
msgb_free(msg);
return rc;
}