From 224a6dda02a2fcf11f70ac25abe9c780167649bf Mon Sep 17 00:00:00 2001 From: Philipp Maier Date: Tue, 17 Oct 2017 15:23:53 +0200 Subject: gb: optionally allow nsip packets only from a specific host When listening for nsip connections is enabled, then every remote host may send packets. This is useful for an SGSN that serves multiple PCUs, but contraproductive for a PCU that awaits packets from a single SGSN. Add struct members remote_ip, and remote_port to struct gprs_ns_inst, when set, then the listening end uses connect() to ensure that only the expected host may send packets. Related: OS#2401 Change-Id: Ifeb201d9006eec275a46708007ff342cdfc14e45 --- src/gb/gprs_ns.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) (limited to 'src/gb/gprs_ns.c') diff --git a/src/gb/gprs_ns.c b/src/gb/gprs_ns.c index 7443a8ba..fd465b4b 100644 --- a/src/gb/gprs_ns.c +++ b/src/gb/gprs_ns.c @@ -1561,15 +1561,37 @@ static int nsip_fd_cb(struct osmo_fd *bfd, unsigned int what) int gprs_ns_nsip_listen(struct gprs_ns_inst *nsi) { struct in_addr in; + struct in_addr remote; + char remote_str[INET_ADDRSTRLEN]; int ret; in.s_addr = osmo_htonl(nsi->nsip.local_ip); + remote.s_addr = osmo_htonl(nsi->nsip.remote_ip); nsi->nsip.fd.cb = nsip_fd_cb; nsi->nsip.fd.data = nsi; - ret = osmo_sock_init_ofd(&nsi->nsip.fd, AF_INET, SOCK_DGRAM, - IPPROTO_UDP, inet_ntoa(in), - nsi->nsip.local_port, OSMO_SOCK_F_BIND); + + if (nsi->nsip.remote_ip && nsi->nsip.remote_port) { + /* connect to ensure only we only accept packets from the + * configured remote end/peer */ + snprintf(remote_str, sizeof(remote_str), "%s", inet_ntoa(remote)); + ret = + osmo_sock_init2_ofd(&nsi->nsip.fd, AF_INET, SOCK_DGRAM, + IPPROTO_UDP, inet_ntoa(in), + nsi->nsip.local_port, remote_str, + nsi->nsip.remote_port, OSMO_SOCK_F_BIND | OSMO_SOCK_F_CONNECT); + + LOGP(DNS, LOGL_NOTICE, + "Listening for nsip packets from %s:%u on %s:%u\n", + remote_str, nsi->nsip.remote_port, inet_ntoa(in), nsi->nsip.local_port); + } else { + /* Accept UDP packets from any source IP/Port */ + ret = osmo_sock_init_ofd(&nsi->nsip.fd, AF_INET, SOCK_DGRAM, + IPPROTO_UDP, inet_ntoa(in), nsi->nsip.local_port, OSMO_SOCK_F_BIND); + + LOGP(DNS, LOGL_NOTICE, "Listening for nsip packets on %s:%u\n", inet_ntoa(in), nsi->nsip.local_port); + } + if (ret < 0) return ret; -- cgit v1.2.3