| /* 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 <openbsc/socket.h> |
| #include <openbsc/debug.h> |
| #include <openbsc/gprs_ns.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 bsc_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 bsc_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 bsc_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 bsc_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)); |
| |
| talloc_free(msg); |
| |
| return rc; |
| } |
| |
| static int nsfrgre_fd_cb(struct bsc_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) |
| { |
| int rc; |
| |
| /* 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; |
| |
| rc = make_sock(&nsi->frgre.fd, IPPROTO_GRE, nsi->frgre.local_ip, |
| 0, 0, nsfrgre_fd_cb, NULL); |
| if (rc < 0) { |
| LOGP(DNS, LOGL_ERROR, "Error creating GRE socket (%s)\n", |
| strerror(errno)); |
| return rc; |
| } |
| nsi->frgre.fd.data = nsi; |
| |
| return rc; |
| } |