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authorHolger Hans Peter Freyther <holger@moiji-mobile.com>2015-06-08 16:28:15 +0200
committerHolger Hans Peter Freyther <holger@moiji-mobile.com>2015-07-01 08:16:40 +0200
commit9705671025eba34b70d73e9d4e78813e4f2d31da (patch)
tree8bd643348c44f9d19f6e719b6197f33f121aa9a5 /openbsc/src/osmo-bsc_nat
parentfce6971fe3673e8269414188fda0ce3b28b5cf03 (diff)
nat: Send 16 bytes of rand to the BSC and remember it
Generate 16 byte of random data to be used for A3A8 by the BSC in the response. We can't know which BSC it is at this point and I don't want to send another message once the token has been received so always send the data with an undefined code. The old BSCs don't parse the message and will happily ignore the RAND. /dev/urandom can give short reads on Linux so loop around it until the bytes have been read from the kernel.
Diffstat (limited to 'openbsc/src/osmo-bsc_nat')
-rw-r--r--openbsc/src/osmo-bsc_nat/bsc_nat.c40
1 files changed, 37 insertions, 3 deletions
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 82562ba..254ea42 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -188,9 +188,9 @@ static void send_id_ack(struct bsc_connection *bsc)
bsc_send_data(bsc, id_ack, sizeof(id_ack), IPAC_PROTO_IPACCESS);
}
-static void send_id_req(struct bsc_connection *bsc)
+static void send_id_req(struct bsc_nat *nat, struct bsc_connection *bsc)
{
- static const uint8_t id_req[] = {
+ static const uint8_t s_id_req[] = {
IPAC_MSGT_ID_GET,
0x01, IPAC_IDTAG_UNIT,
0x01, IPAC_IDTAG_MACADDR,
@@ -202,7 +202,41 @@ static void send_id_req(struct bsc_connection *bsc)
0x01, IPAC_IDTAG_SERNR,
};
+ int toread, rounds;
+ uint8_t *mrand, *randoff;
+ uint8_t id_req[sizeof(s_id_req) + (2+16)];
+ uint8_t *buf = &id_req[sizeof(s_id_req)];
+
+ /* copy the static data */
+ memcpy(id_req, s_id_req, sizeof(s_id_req));
+
+ /* put the RAND with length, tag, value */
+ buf = v_put(buf, 0x11);
+ buf = v_put(buf, 0x23);
+ mrand = bsc->last_rand;
+ randoff = mrand;
+ memset(randoff, 0, 16);
+
+ for (toread = 16, rounds = 0; rounds < 5 && toread > 0; ++rounds) {
+ int rc = read(nat->random_fd, randoff, toread);
+ if (rc <= 0)
+ goto failed_random;
+ toread -= rc;
+ randoff += rc;
+ }
+
+ if (toread != 0)
+ goto failed_random;
+ memcpy(buf, mrand, 16);
+ buf += 16;
+
bsc_send_data(bsc, id_req, sizeof(id_req), IPAC_PROTO_IPACCESS);
+ return;
+
+failed_random:
+ /* the timeout will trigger and close this connection */
+ LOGP(DNAT, LOGL_ERROR, "Failed to read from urandom.\n");
+ return;
}
static struct msgb *nat_create_rlsd(struct nat_sccp_connection *conn)
@@ -1362,7 +1396,7 @@ static int ipaccess_listen_bsc_cb(struct osmo_fd *bfd, unsigned int what)
bsc->last_id = 0;
send_id_ack(bsc);
- send_id_req(bsc);
+ send_id_req(nat, bsc);
send_mgcp_reset(bsc);
/*