diff options
Diffstat (limited to 'openbsc/src/libgb/gprs_ns_frgre.c')
-rw-r--r-- | openbsc/src/libgb/gprs_ns_frgre.c | 310 |
1 files changed, 310 insertions, 0 deletions
diff --git a/openbsc/src/libgb/gprs_ns_frgre.c b/openbsc/src/libgb/gprs_ns_frgre.c new file mode 100644 index 00000000..be5f0f6c --- /dev/null +++ b/openbsc/src/libgb/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; +} |