Gb: add a second NS implementation

Reimplement NS with FSM.

Change-Id: I3525beef205588dfab9d3880a34115f1a2676e48

1 files changed, 596 insertions, 0 deletions

diff --git a/src/gb/gprs_ns2_frgre.c b/src/gb/gprs_ns2_frgre.c
new file mode 100644
index 00000000..2b19157b
--- /dev/null
+++ b/src/gb/gprs_ns2_frgre.c
@@ -0,0 +1,596 @@
+/*! \file gprs_ns2_frgre.c
+ * NS-over-FR-over-GRE implementation.
+ * 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)
+ * as well as its successor 3GPP TS 48.016 */
+
+/* (C) 2009-2010,2014,2017 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2020 sysmocom - s.f.m.c. GmbH
+ * Author: Alexander Couzens <lynxis@fe80.eu>
+ *
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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 <netinet/ip6.h>
+#include <arpa/inet.h>
+
+#include <osmocom/core/byteswap.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/gprs/gprs_ns2.h>
+
+#include "gprs_ns2_internal.h"
+
+#define GRE_PTYPE_FR	0x6559
+#define GRE_PTYPE_IPv4	0x0800
+#define GRE_PTYPE_IPv6	0x86dd
+#define GRE_PTYPE_KAR	0x0000	/* keepalive response */
+
+#ifndef IPPROTO_GRE
+# define IPPROTO_GRE 47
+#endif
+
+struct gre_hdr {
+	uint16_t flags;
+	uint16_t ptype;
+} __attribute__ ((packed));
+
+#if defined(__FreeBSD__) || defined(__APPLE__) || defined(__CYGWIN__)
+/**
+ * On BSD the IPv4 struct is called struct ip and instead of iXX
+ * the members are called ip_XX. One could change this code to use
+ * struct ip but that would require to define _BSD_SOURCE and that
+ * might have other complications. Instead make sure struct iphdr
+ * is present on FreeBSD. The below is taken from GLIBC.
+ *
+ * The GNU C Library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ */
+struct iphdr
+  {
+#if BYTE_ORDER == LITTLE_ENDIAN
+    unsigned int ihl:4;
+    unsigned int version:4;
+#elif BYTE_ORDER == BIG_ENDIAN
+    unsigned int version:4;
+    unsigned int ihl:4;
+#endif
+    u_int8_t tos;
+    u_int16_t tot_len;
+    u_int16_t id;
+    u_int16_t frag_off;
+    u_int8_t ttl;
+    u_int8_t protocol;
+    u_int16_t check;
+    u_int32_t saddr;
+    u_int32_t daddr;
+    /*The options start here. */
+  };
+#endif
+
+
+static void free_bind(struct gprs_ns2_vc_bind *bind);
+static inline int frgre_sendmsg(struct gprs_ns2_vc_bind *bind,
+			       struct msgb *msg,
+			       struct osmo_sockaddr *dest);
+
+struct gprs_ns2_vc_driver vc_driver_frgre = {
+	.name = "GB frame relay over GRE",
+	.free_bind = free_bind,
+};
+
+struct priv_bind {
+	struct osmo_fd fd;
+	struct osmo_sockaddr addr;
+	uint16_t dlci;
+	int dscp;
+};
+
+struct priv_vc {
+	struct osmo_sockaddr remote;
+	uint16_t dlci;
+};
+
+static void free_vc(struct gprs_ns2_vc *nsvc)
+{
+	OSMO_ASSERT(nsvc);
+
+	if (!nsvc->priv)
+		return;
+
+	talloc_free(nsvc->priv);
+	nsvc->priv = NULL;
+}
+
+
+/*! clean up all private driver state. Should be only called by gprs_ns2_free_bind() */
+static void free_bind(struct gprs_ns2_vc_bind *bind)
+{
+	struct priv_bind *priv;
+
+	if (!bind)
+		return;
+
+	priv = bind->priv;
+
+	OSMO_ASSERT(llist_empty(&bind->nsvc));
+
+	osmo_fd_close(&priv->fd);
+	talloc_free(priv);
+}
+
+static struct priv_vc *frgre_alloc_vc(struct gprs_ns2_vc_bind *bind,
+				      struct gprs_ns2_vc *nsvc,
+				      struct osmo_sockaddr *remote,
+				      uint16_t dlci)
+{
+	struct priv_vc *priv = talloc_zero(bind, struct priv_vc);
+	if (!priv)
+		return NULL;
+
+	nsvc->priv = priv;
+	priv->remote = *remote;
+	priv->dlci = dlci;
+
+	return priv;
+}
+
+static int handle_rx_gre_ipv6(struct osmo_fd *bfd, struct msgb *msg,
+			      struct ip6_hdr *ip6hdr, struct gre_hdr *greh)
+{
+	/* RFC 7676 IPv6 Support for Generic Routing Encapsulation (GRE) */
+	struct gprs_ns2_vc_bind *bind = bfd->data;
+	struct priv_bind *priv = bind->priv;
+	int gre_payload_len;
+	struct ip6_hdr *inner_ip6h;
+	struct gre_hdr *inner_greh;
+	struct sockaddr_in6 daddr;
+	struct in6_addr ia6;
+
+	gre_payload_len = msg->len - (sizeof(*ip6hdr) + sizeof(*greh));
+
+	inner_ip6h = (struct ip6_hdr *) ((uint8_t *)greh + sizeof(*greh));
+
+	if (gre_payload_len < sizeof(*ip6hdr) + sizeof(*inner_greh)) {
+		LOGP(DLNS, LOGL_ERROR, "GRE keepalive too short\n");
+		return -EIO;
+	}
+
+	if (!memcmp(&inner_ip6h->ip6_src, &ip6hdr->ip6_src, sizeof(struct in6_addr)) ||
+	    !memcmp(&inner_ip6h->ip6_dst, &ip6hdr->ip6_dst, sizeof(struct in6_addr))) {
+		LOGP(DLNS, LOGL_ERROR,
+			"GRE keepalive with wrong tunnel addresses\n");
+		return -EIO;
+	}
+
+	/* Are IPv6 extensions header are allowed in the *inner*? In the outer they are */
+	if (inner_ip6h->ip6_ctlun.ip6_un1.ip6_un1_nxt != IPPROTO_GRE) {
+		LOGP(DLNS, LOGL_ERROR, "GRE keepalive with wrong protocol\n");
+		return -EIO;
+	}
+
+	inner_greh = (struct gre_hdr *) ((uint8_t *)inner_ip6h + sizeof(struct ip6_hdr));
+	if (inner_greh->ptype != osmo_htons(GRE_PTYPE_KAR)) {
+		LOGP(DLNS, LOGL_ERROR, "GRE keepalive inner GRE type != 0\n");
+		return -EIO;
+	}
+
+	/* Actually send the response back */
+
+	daddr.sin6_family = AF_INET6;
+	daddr.sin6_addr = inner_ip6h->ip6_dst;
+	daddr.sin6_port = IPPROTO_GRE;
+
+	ia6 = ip6hdr->ip6_src;
+	char ip6str[INET6_ADDRSTRLEN] = {};
+	inet_ntop(AF_INET6, &ia6, ip6str, INET6_ADDRSTRLEN);
+	LOGP(DLNS, LOGL_DEBUG, "GRE keepalive from %s, responding\n", ip6str);
+
+	/* why does it reduce the gre_payload_len by the ipv6 header?
+	 * make it similiar to ipv4 even this seems to be wrong */
+	return sendto(priv->fd.fd, inner_greh,
+		      gre_payload_len - sizeof(*inner_ip6h), 0,
+		      (struct sockaddr *)&daddr, sizeof(daddr));
+}
+
+/* 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_ns2_vc_bind *bind = bfd->data;
+	struct priv_bind *priv = bind->priv;
+	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(DLNS, LOGL_ERROR, "GRE keepalive too short\n");
+		return -EIO;
+	}
+
+	if (inner_iph->saddr != iph->daddr ||
+	    inner_iph->daddr != iph->saddr) {
+		LOGP(DLNS, LOGL_ERROR,
+			"GRE keepalive with wrong tunnel addresses\n");
+		return -EIO;
+	}
+
+	if (inner_iph->protocol != IPPROTO_GRE) {
+		LOGP(DLNS, 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 != osmo_htons(GRE_PTYPE_KAR)) {
+		LOGP(DLNS, 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(DLNS, LOGL_DEBUG, "GRE keepalive from %s, responding\n",
+		inet_ntoa(ia));
+
+	/* why does it reduce the gre_payload_len by the ipv4 header? */
+	return sendto(priv->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 osmo_sockaddr *saddr, uint16_t *dlci)
+{
+	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 = NULL;
+	struct ip6_hdr *ip6h = NULL;
+	size_t ip46hdr;
+	struct gre_hdr *greh;
+	uint8_t *frh;
+
+	if (!msg) {
+		*error = -ENOMEM;
+		return NULL;
+	}
+
+	ret = recvfrom(bfd->fd, msg->data, NS_ALLOC_SIZE, 0,
+			&saddr->u.sa, &saddr_len);
+	if (ret < 0) {
+		LOGP(DLNS, 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);
+
+	/* we've received a raw packet including the IPv4 or IPv6 header */
+	switch (saddr->u.sa.sa_family) {
+	case AF_INET:
+		ip46hdr = sizeof(struct iphdr);
+		break;
+	case AF_INET6:
+		ip46hdr = sizeof(struct ip6_hdr);
+	default:
+		*error = -EIO;
+		goto out_err;
+		break;
+	}
+
+	/* TODO: add support for the extension headers */
+	if (msg->len < ip46hdr + sizeof(*greh) + 2) {
+		LOGP(DLNS, LOGL_ERROR, "Short IP packet: %u bytes\n", msg->len);
+		*error = -EIO;
+		goto out_err;
+	}
+
+	switch (saddr->u.sa.sa_family) {
+	case AF_INET:
+		iph = (struct iphdr *) msg->data;
+		if (msg->len < (iph->ihl*4 + sizeof(*greh) + 2)) {
+			LOGP(DLNS, LOGL_ERROR, "Short IP packet: %u bytes\n", msg->len);
+			*error = -EIO;
+			goto out_err;
+		}
+		break;
+	case AF_INET6:
+		ip6h = (struct ip6_hdr *) msg->data;
+		break;
+	}
+
+	greh = (struct gre_hdr *) (msg->data + iph->ihl*4);
+	if (greh->flags) {
+		LOGP(DLNS, LOGL_NOTICE, "Unknown GRE flags 0x%04x\n",
+			osmo_ntohs(greh->flags));
+	}
+
+	switch (osmo_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_IPv6:
+		*error = handle_rx_gre_ipv6(bfd, msg, ip6h, greh);
+		goto out_err;
+		break;
+	case GRE_PTYPE_FR:
+		/* continue as usual */
+		break;
+	default:
+		LOGP(DLNS, LOGL_NOTICE, "Unknown GRE protocol 0x%04x != FR\n",
+			osmo_ntohs(greh->ptype));
+		*error = -EIO;
+		goto out_err;
+		break;
+	}
+
+	if (msg->len < sizeof(*greh) + 2) {
+		LOGP(DLNS, 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(DLNS, LOGL_NOTICE, "Unsupported single-byte FR address\n");
+		*error = -EIO;
+		goto out_err;
+	}
+	*dlci = ((frh[0] & 0xfc) << 2);
+	if ((frh[1] & 0x0f) != 0x01) {
+		LOGP(DLNS, LOGL_NOTICE, "Unknown second FR octet 0x%02x\n",
+			frh[1]);
+		*error = -EIO;
+		goto out_err;
+	}
+	*dlci |= (frh[1] >> 4);
+
+	msg->l2h = frh+2;
+
+	return msg;
+
+out_err:
+	msgb_free(msg);
+	return NULL;
+}
+
+static int gprs_ns2_find_vc_by_dlci(struct gprs_ns2_vc_bind *bind,
+				    uint16_t dlci,
+				    struct gprs_ns2_vc **result)
+{
+	struct gprs_ns2_vc *nsvc;
+	struct priv_vc *vcpriv;
+
+	if (!result)
+		return -EINVAL;
+
+	llist_for_each_entry(nsvc, &bind->nsvc, blist) {
+		vcpriv = nsvc->priv;
+		if (vcpriv->dlci != dlci) {
+			*result = nsvc;
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
+static int handle_nsfrgre_read(struct osmo_fd *bfd)
+{
+	int rc;
+	struct osmo_sockaddr saddr;
+	struct gprs_ns2_vc *nsvc;
+	struct gprs_ns2_vc_bind *bind = bfd->data;
+	struct msgb *msg;
+	struct msgb *reject;
+	uint16_t dlci;
+
+	msg = read_nsfrgre_msg(bfd, &rc, &saddr, &dlci);
+	if (!msg)
+		return rc;
+
+	if (dlci == 0 || dlci == 1023) {
+		LOGP(DLNS, LOGL_INFO, "Received FR on LMI DLCI %u - ignoring\n",
+			dlci);
+		rc = 0;
+		goto out;
+	}
+
+	rc = gprs_ns2_find_vc_by_dlci(bind, dlci, &nsvc);
+	if (rc) {
+		/* VC not found */
+		rc = ns2_create_vc(bind, msg, "newconnection", &reject, &nsvc);
+		switch (rc) {
+		case GPRS_NS2_CS_FOUND:
+			rc = ns2_recv_vc(bind->nsi, nsvc, msg);
+			break;
+		case GPRS_NS2_CS_ERROR:
+		case GPRS_NS2_CS_SKIPPED:
+			rc = 0;
+			break;
+		case GPRS_NS2_CS_REJECTED:
+			/* nsip_sendmsg will free reject */
+			frgre_sendmsg(bind, reject, &saddr);
+			return 0;
+		case GPRS_NS2_CS_CREATED:
+			frgre_alloc_vc(bind, nsvc, &saddr, dlci);
+			gprs_ns2_vc_fsm_start(nsvc);
+			rc = ns2_recv_vc(bind->nsi, nsvc, msg);
+			break;
+		}
+	} else {
+		/* VC found */
+		rc = ns2_recv_vc(bind->nsi, nsvc, msg);
+	}
+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;
+}
+
+static inline int frgre_sendmsg(struct gprs_ns2_vc_bind *bind,
+			       struct msgb *msg,
+			       struct osmo_sockaddr *dest)
+{
+	int rc;
+	struct priv_bind *priv = bind->priv;
+
+	rc = sendto(priv->fd.fd, msg->data, msg->len, 0,
+		    &dest->u.sa, sizeof(*dest));
+
+	msgb_free(msg);
+
+	return rc;
+}
+
+static int frgre_vc_sendmsg(struct gprs_ns2_vc *nsvc, struct msgb *msg)
+{
+	struct gprs_ns2_vc_bind *bind = nsvc->bind;
+	struct priv_vc *vcpriv = nsvc->priv;
+	struct priv_bind *bindpriv = bind->priv;
+
+	uint16_t dlci = osmo_htons(bindpriv->dlci);
+	uint8_t *frh;
+	struct gre_hdr *greh;
+
+	/* 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 = osmo_htons(GRE_PTYPE_FR);
+
+	return frgre_sendmsg(bind, msg, &vcpriv->remote);
+}
+
+static int frgre_fd_cb(struct osmo_fd *bfd, unsigned int what)
+{
+	int rc = 0;
+
+	if (what & OSMO_FD_READ)
+		rc = handle_nsfrgre_read(bfd);
+	if (what & OSMO_FD_WRITE)
+		rc = handle_nsfrgre_write(bfd);
+
+	return rc;
+}
+
+int gprs_ns2_is_frgre_bind(struct gprs_ns2_vc_bind *bind)
+{
+	return (bind->driver == &vc_driver_frgre);
+}
+
+int gprs_ns2_frgre_bind(struct gprs_ns2_inst *nsi,
+			struct osmo_sockaddr *local,
+			int dscp,
+			struct gprs_ns2_vc_bind **result)
+{
+	struct gprs_ns2_vc_bind *bind = talloc_zero(nsi, struct gprs_ns2_vc_bind);
+	struct priv_bind *priv;
+	int rc;
+
+	if (!bind)
+		return -ENOSPC;
+
+	if (local->u.sa.sa_family != AF_INET && local->u.sa.sa_family != AF_INET6) {
+		talloc_free(bind);
+		return -EINVAL;
+	}
+
+	bind->driver = &vc_driver_frgre;
+	bind->send_vc = frgre_vc_sendmsg;
+	bind->free_vc = free_vc;
+	bind->nsi = nsi;
+
+	priv = bind->priv = talloc_zero(bind, struct priv_bind);
+	if (!priv) {
+		talloc_free(bind);
+		return -ENOSPC;
+	}
+	priv->fd.cb = frgre_fd_cb;
+	priv->fd.data = bind;
+	priv->addr = *local;
+	INIT_LLIST_HEAD(&bind->nsvc);
+
+	llist_add(&bind->list, &nsi->binding);
+
+	rc = osmo_sock_init_osa_ofd(&priv->fd, SOCK_RAW, IPPROTO_GRE,
+				 local, NULL,
+				 OSMO_SOCK_F_BIND);
+	if (rc < 0) {
+		talloc_free(priv);
+		talloc_free(bind);
+		return rc;
+	}
+
+	if (dscp > 0) {
+		priv->dscp = dscp;
+
+		rc = setsockopt(priv->fd.fd, IPPROTO_IP, IP_TOS,
+				&dscp, sizeof(dscp));
+		if (rc < 0)
+			LOGP(DLNS, LOGL_ERROR,
+				"Failed to set the DSCP to %d with ret(%d) errno(%d)\n",
+				dscp, rc, errno);
+	}
+
+	ns2_vty_bind_apply(bind);
+
+	if (result)
+		*result = bind;
+
+	return rc;
+}