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-rw-r--r--src/gb/gprs_ns_frgre.c310
1 files changed, 310 insertions, 0 deletions
diff --git a/src/gb/gprs_ns_frgre.c b/src/gb/gprs_ns_frgre.c
new file mode 100644
index 0000000..be5f0f6
--- /dev/null
+++ b/src/gb/gprs_ns_frgre.c
@@ -0,0 +1,310 @@
+/* GPRS Networks Service (NS) messages on the Gb interface
+ * 3GPP TS 08.16 version 8.0.1 Release 1999 / ETSI TS 101 299 V8.0.1 (2002-05) */
+
+/* NS-over-FR-over-GRE implementation */
+
+/* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+
+#include <osmocom/core/select.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/gprs/gprs_ns.h>
+
+#include "common_vty.h"
+
+#define GRE_PTYPE_FR 0x6559
+#define GRE_PTYPE_IPv4 0x0800
+#define GRE_PTYPE_KAR 0x0000 /* keepalive response */
+
+struct gre_hdr {
+ uint16_t flags;
+ uint16_t ptype;
+} __attribute__ ((packed));
+
+/* IPv4 messages inside the GRE tunnel might be GRE keepalives */
+static int handle_rx_gre_ipv4(struct osmo_fd *bfd, struct msgb *msg,
+ struct iphdr *iph, struct gre_hdr *greh)
+{
+ struct gprs_ns_inst *nsi = bfd->data;
+ int gre_payload_len;
+ struct iphdr *inner_iph;
+ struct gre_hdr *inner_greh;
+ struct sockaddr_in daddr;
+ struct in_addr ia;
+
+ gre_payload_len = msg->len - (iph->ihl*4 + sizeof(*greh));
+
+ inner_iph = (struct iphdr *) ((uint8_t *)greh + sizeof(*greh));
+
+ if (gre_payload_len < inner_iph->ihl*4 + sizeof(*inner_greh)) {
+ LOGP(DNS, LOGL_ERROR, "GRE keepalive too short\n");
+ return -EIO;
+ }
+
+ if (inner_iph->saddr != iph->daddr ||
+ inner_iph->daddr != iph->saddr) {
+ LOGP(DNS, LOGL_ERROR,
+ "GRE keepalive with wrong tunnel addresses\n");
+ return -EIO;
+ }
+
+ if (inner_iph->protocol != IPPROTO_GRE) {
+ LOGP(DNS, LOGL_ERROR, "GRE keepalive with wrong protocol\n");
+ return -EIO;
+ }
+
+ inner_greh = (struct gre_hdr *) ((uint8_t *)inner_iph + iph->ihl*4);
+ if (inner_greh->ptype != htons(GRE_PTYPE_KAR)) {
+ LOGP(DNS, LOGL_ERROR, "GRE keepalive inner GRE type != 0\n");
+ return -EIO;
+ }
+
+ /* Actually send the response back */
+
+ daddr.sin_family = AF_INET;
+ daddr.sin_addr.s_addr = inner_iph->daddr;
+ daddr.sin_port = IPPROTO_GRE;
+
+ ia.s_addr = iph->saddr;
+ LOGP(DNS, LOGL_DEBUG, "GRE keepalive from %s, responding\n",
+ inet_ntoa(ia));
+
+ return sendto(nsi->frgre.fd.fd, inner_greh,
+ gre_payload_len - inner_iph->ihl*4, 0,
+ (struct sockaddr *)&daddr, sizeof(daddr));
+}
+
+static struct msgb *read_nsfrgre_msg(struct osmo_fd *bfd, int *error,
+ struct sockaddr_in *saddr)
+{
+ struct msgb *msg = msgb_alloc(NS_ALLOC_SIZE, "Gb/NS/FR/GRE Rx");
+ int ret = 0;
+ socklen_t saddr_len = sizeof(*saddr);
+ struct iphdr *iph;
+ struct gre_hdr *greh;
+ uint8_t *frh;
+ uint16_t dlci;
+
+ if (!msg) {
+ *error = -ENOMEM;
+ return NULL;
+ }
+
+ ret = recvfrom(bfd->fd, msg->data, NS_ALLOC_SIZE, 0,
+ (struct sockaddr *)saddr, &saddr_len);
+ if (ret < 0) {
+ LOGP(DNS, LOGL_ERROR, "recv error %s during NS-FR-GRE recv\n",
+ strerror(errno));
+ *error = ret;
+ goto out_err;
+ } else if (ret == 0) {
+ *error = ret;
+ goto out_err;
+ }
+
+ msgb_put(msg, ret);
+
+ if (msg->len < sizeof(*iph) + sizeof(*greh) + 2) {
+ LOGP(DNS, LOGL_ERROR, "Short IP packet: %u bytes\n", msg->len);
+ *error = -EIO;
+ goto out_err;
+ }
+
+ iph = (struct iphdr *) msg->data;
+ if (msg->len < (iph->ihl*4 + sizeof(*greh) + 2)) {
+ LOGP(DNS, LOGL_ERROR, "Short IP packet: %u bytes\n", msg->len);
+ *error = -EIO;
+ goto out_err;
+ }
+
+ greh = (struct gre_hdr *) (msg->data + iph->ihl*4);
+ if (greh->flags) {
+ LOGP(DNS, LOGL_NOTICE, "Unknown GRE flags 0x%04x\n",
+ ntohs(greh->flags));
+ }
+
+ switch (ntohs(greh->ptype)) {
+ case GRE_PTYPE_IPv4:
+ /* IPv4 messages might be GRE keepalives */
+ *error = handle_rx_gre_ipv4(bfd, msg, iph, greh);
+ goto out_err;
+ break;
+ case GRE_PTYPE_FR:
+ /* continue as usual */
+ break;
+ default:
+ LOGP(DNS, LOGL_NOTICE, "Unknown GRE protocol 0x%04x != FR\n",
+ ntohs(greh->ptype));
+ *error = -EIO;
+ goto out_err;
+ break;
+ }
+
+ if (msg->len < sizeof(*greh) + 2) {
+ LOGP(DNS, LOGL_ERROR, "Short FR header: %u bytes\n", msg->len);
+ *error = -EIO;
+ goto out_err;
+ }
+
+ frh = (uint8_t *)greh + sizeof(*greh);
+ if (frh[0] & 0x01) {
+ LOGP(DNS, LOGL_NOTICE, "Unsupported single-byte FR address\n");
+ *error = -EIO;
+ goto out_err;
+ }
+ dlci = ((frh[0] & 0xfc) << 2);
+ if ((frh[1] & 0x0f) != 0x01) {
+ LOGP(DNS, LOGL_NOTICE, "Unknown second FR octet 0x%02x\n",
+ frh[1]);
+ *error = -EIO;
+ goto out_err;
+ }
+ dlci |= (frh[1] >> 4);
+
+ msg->l2h = frh+2;
+
+ /* Store DLCI in NETWORK BYTEORDER in sockaddr port member */
+ saddr->sin_port = htons(dlci);
+
+ return msg;
+
+out_err:
+ msgb_free(msg);
+ return NULL;
+}
+
+int gprs_ns_rcvmsg(struct gprs_ns_inst *nsi, struct msgb *msg,
+ struct sockaddr_in *saddr, enum gprs_ns_ll ll);
+
+static int handle_nsfrgre_read(struct osmo_fd *bfd)
+{
+ int rc;
+ struct sockaddr_in saddr;
+ struct gprs_ns_inst *nsi = bfd->data;
+ struct msgb *msg;
+ uint16_t dlci;
+
+ msg = read_nsfrgre_msg(bfd, &rc, &saddr);
+ if (!msg)
+ return rc;
+
+ dlci = ntohs(saddr.sin_port);
+ if (dlci == 0 || dlci == 1023) {
+ LOGP(DNS, LOGL_INFO, "Received FR on LMI DLCI %u - ignoring\n",
+ dlci);
+ rc = 0;
+ goto out;
+ }
+
+ rc = gprs_ns_rcvmsg(nsi, msg, &saddr, GPRS_NS_LL_FR_GRE);
+out:
+ msgb_free(msg);
+
+ return rc;
+}
+
+static int handle_nsfrgre_write(struct osmo_fd *bfd)
+{
+ /* FIXME: actually send the data here instead of nsip_sendmsg() */
+ return -EIO;
+}
+
+int gprs_ns_frgre_sendmsg(struct gprs_nsvc *nsvc, struct msgb *msg)
+{
+ int rc;
+ struct gprs_ns_inst *nsi = nsvc->nsi;
+ struct sockaddr_in daddr;
+ uint16_t dlci = ntohs(nsvc->frgre.bts_addr.sin_port);
+ uint8_t *frh;
+ struct gre_hdr *greh;
+
+ /* Build socket address for the packet destionation */
+ daddr.sin_family = AF_INET;
+ daddr.sin_addr = nsvc->frgre.bts_addr.sin_addr;
+ daddr.sin_port = IPPROTO_GRE;
+
+ /* Prepend the FR header */
+ frh = msgb_push(msg, 2);
+ frh[0] = (dlci >> 2) & 0xfc;
+ frh[1] = ((dlci & 0xf)<<4) | 0x01;
+
+ /* Prepend the GRE header */
+ greh = (struct gre_hdr *) msgb_push(msg, sizeof(*greh));
+ greh->flags = 0;
+ greh->ptype = htons(GRE_PTYPE_FR);
+
+ rc = sendto(nsi->frgre.fd.fd, msg->data, msg->len, 0,
+ (struct sockaddr *)&daddr, sizeof(daddr));
+
+ msgb_free(msg);
+
+ return rc;
+}
+
+static int nsfrgre_fd_cb(struct osmo_fd *bfd, unsigned int what)
+{
+ int rc = 0;
+
+ if (what & BSC_FD_READ)
+ rc = handle_nsfrgre_read(bfd);
+ if (what & BSC_FD_WRITE)
+ rc = handle_nsfrgre_write(bfd);
+
+ return rc;
+}
+
+int gprs_ns_frgre_listen(struct gprs_ns_inst *nsi)
+{
+ struct in_addr in;
+ int rc;
+
+ in.s_addr = htonl(nsi->frgre.local_ip);
+
+ /* Make sure we close any existing socket before changing it */
+ if (nsi->frgre.fd.fd)
+ close(nsi->frgre.fd.fd);
+
+ if (!nsi->frgre.enabled)
+ return 0;
+
+ nsi->frgre.fd.cb = nsfrgre_fd_cb;
+ nsi->frgre.fd.data = nsi;
+ rc = osmo_sock_init_ofd(&nsi->frgre.fd, AF_INET, SOCK_RAW,
+ IPPROTO_GRE, inet_ntoa(in), 0,
+ OSMO_SOCK_F_BIND);
+ if (rc < 0) {
+ LOGP(DNS, LOGL_ERROR, "Error creating GRE socket (%s)\n",
+ strerror(errno));
+ return rc;
+ }
+ nsi->frgre.fd.data = nsi;
+
+ return rc;
+}