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freebsd-skq/sys/netgraph/ng_l2tp.c
bz 3d1edadd15 Writing out the L2TP control packet requires 12 bytes of 
contiguous memory but in one path we did not always guarantee this,
thus do a m_pullup() there.

PR:			214385
Submitted by:		Joe Jones (joeknockando googlemail.com)
MFC after:		3 days
2016-11-17 14:03:44 +00:00

1623 lines
40 KiB
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/*-
* Copyright (c) 2001-2002 Packet Design, LLC.
* All rights reserved.
*
* Subject to the following obligations and disclaimer of warranty,
* use and redistribution of this software, in source or object code
* forms, with or without modifications are expressly permitted by
* Packet Design; provided, however, that:
*
* (i) Any and all reproductions of the source or object code
* must include the copyright notice above and the following
* disclaimer of warranties; and
* (ii) No rights are granted, in any manner or form, to use
* Packet Design trademarks, including the mark "PACKET DESIGN"
* on advertising, endorsements, or otherwise except as such
* appears in the above copyright notice or in the software.
*
* THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND
* TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
* REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING
* THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
* OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE,
* OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS
* OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
* RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE
* LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE
* OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL
* DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF
* USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
* THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*
* Author: Archie Cobbs <archie@freebsd.org>
*
* $FreeBSD$
*/
/*
* L2TP netgraph node type.
*
* This node type implements the lower layer of the
* L2TP protocol as specified in RFC 2661.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/time.h>
#include <sys/conf.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/errno.h>
#include <sys/libkern.h>
#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_parse.h>
#include <netgraph/ng_l2tp.h>
#ifdef NG_SEPARATE_MALLOC
static MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
#else
#define M_NETGRAPH_L2TP M_NETGRAPH
#endif
/* L2TP header format (first 2 bytes only) */
#define L2TP_HDR_CTRL 0x8000 /* control packet */
#define L2TP_HDR_LEN 0x4000 /* has length field */
#define L2TP_HDR_SEQ 0x0800 /* has ns, nr fields */
#define L2TP_HDR_OFF 0x0200 /* has offset field */
#define L2TP_HDR_PRIO 0x0100 /* give priority */
#define L2TP_HDR_VERS_MASK 0x000f /* version field mask */
#define L2TP_HDR_VERSION 0x0002 /* version field */
/* Bits that must be zero or one in first two bytes of header */
#define L2TP_CTRL_0BITS 0x030d /* ctrl: must be 0 */
#define L2TP_CTRL_1BITS 0xc802 /* ctrl: must be 1 */
#define L2TP_DATA_0BITS 0x800d /* data: must be 0 */
#define L2TP_DATA_1BITS 0x0002 /* data: must be 1 */
/* Standard xmit ctrl and data header bits */
#define L2TP_CTRL_HDR (L2TP_HDR_CTRL | L2TP_HDR_LEN \
| L2TP_HDR_SEQ | L2TP_HDR_VERSION)
#define L2TP_DATA_HDR (L2TP_HDR_VERSION) /* optional: len, seq */
/* Some hard coded values */
#define L2TP_MAX_XWIN 128 /* my max xmit window */
#define L2TP_MAX_REXMIT 5 /* default max rexmit */
#define L2TP_MAX_REXMIT_TO 30 /* default rexmit to */
#define L2TP_DELAYED_ACK ((hz + 19) / 20) /* delayed ack: 50 ms */
/* Default data sequence number configuration for new sessions */
#define L2TP_CONTROL_DSEQ 1 /* we are the lns */
#define L2TP_ENABLE_DSEQ 1 /* enable data seq # */
/* Compare sequence numbers using circular math */
#define L2TP_SEQ_DIFF(x, y) ((int16_t)((x) - (y)))
#define SESSHASHSIZE 0x0020
#define SESSHASH(x) (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
/* Hook private data (data session hooks only) */
struct ng_l2tp_hook_private {
struct ng_l2tp_sess_config conf; /* hook/session config */
struct ng_l2tp_session_stats stats; /* per sessions statistics */
hook_p hook; /* hook reference */
u_int16_t ns; /* data ns sequence number */
u_int16_t nr; /* data nr sequence number */
LIST_ENTRY(ng_l2tp_hook_private) sessions;
};
typedef struct ng_l2tp_hook_private *hookpriv_p;
/*
* Sequence number state
*
* Invariants:
* - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
* - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
* - The first (ns - rack) mbuf's in xwin[] array are copies of these
* unacknowledged packets; the remainder of xwin[] consists first of
* zero or more further untransmitted packets in the transmit queue
* - We try to keep the peer's receive window as full as possible.
* Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
* - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
* - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
* - xack_timer is running iff xack != nr (unack'd rec'd pkts)
*/
struct l2tp_seq {
u_int16_t ns; /* next xmit seq we send */
u_int16_t nr; /* next recv seq we expect */
u_int16_t inproc; /* packet is in processing */
u_int16_t rack; /* last 'nr' we rec'd */
u_int16_t xack; /* last 'nr' we sent */
u_int16_t wmax; /* peer's max recv window */
u_int16_t cwnd; /* current congestion window */
u_int16_t ssth; /* slow start threshold */
u_int16_t acks; /* # consecutive acks rec'd */
u_int16_t rexmits; /* # retransmits sent */
struct callout rack_timer; /* retransmit timer */
struct callout xack_timer; /* delayed ack timer */
struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
struct mtx mtx; /* seq mutex */
};
/* Node private data */
struct ng_l2tp_private {
node_p node; /* back pointer to node */
hook_p ctrl; /* hook to upper layers */
hook_p lower; /* hook to lower layers */
struct ng_l2tp_config conf; /* node configuration */
struct ng_l2tp_stats stats; /* node statistics */
struct l2tp_seq seq; /* ctrl sequence number state */
ng_ID_t ftarget; /* failure message target */
LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
};
typedef struct ng_l2tp_private *priv_p;
/* Netgraph node methods */
static ng_constructor_t ng_l2tp_constructor;
static ng_rcvmsg_t ng_l2tp_rcvmsg;
static ng_shutdown_t ng_l2tp_shutdown;
static ng_newhook_t ng_l2tp_newhook;
static ng_rcvdata_t ng_l2tp_rcvdata;
static ng_rcvdata_t ng_l2tp_rcvdata_lower;
static ng_rcvdata_t ng_l2tp_rcvdata_ctrl;
static ng_disconnect_t ng_l2tp_disconnect;
/* Internal functions */
static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
static void ng_l2tp_seq_init(priv_p priv);
static int ng_l2tp_seq_set(priv_p priv,
const struct ng_l2tp_seq_config *conf);
static int ng_l2tp_seq_adjust(priv_p priv,
const struct ng_l2tp_config *conf);
static void ng_l2tp_seq_reset(priv_p priv);
static void ng_l2tp_seq_failure(priv_p priv);
static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
static void ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
void *arg1, int arg2);
static void ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
void *arg1, int arg2);
static hookpriv_p ng_l2tp_find_session(priv_p privp, u_int16_t sid);
static ng_fn_eachhook ng_l2tp_reset_session;
#ifdef INVARIANTS
static void ng_l2tp_seq_check(struct l2tp_seq *seq);
#endif
/* Parse type for struct ng_l2tp_seq_config. */
static const struct ng_parse_struct_field
ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
static const struct ng_parse_type ng_l2tp_seq_config_type = {
&ng_parse_struct_type,
&ng_l2tp_seq_config_fields
};
/* Parse type for struct ng_l2tp_config */
static const struct ng_parse_struct_field
ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
static const struct ng_parse_type ng_l2tp_config_type = {
&ng_parse_struct_type,
&ng_l2tp_config_type_fields,
};
/* Parse type for struct ng_l2tp_sess_config */
static const struct ng_parse_struct_field
ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
static const struct ng_parse_type ng_l2tp_sess_config_type = {
&ng_parse_struct_type,
&ng_l2tp_sess_config_type_fields,
};
/* Parse type for struct ng_l2tp_stats */
static const struct ng_parse_struct_field
ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
static const struct ng_parse_type ng_l2tp_stats_type = {
&ng_parse_struct_type,
&ng_l2tp_stats_type_fields
};
/* Parse type for struct ng_l2tp_session_stats. */
static const struct ng_parse_struct_field
ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
static const struct ng_parse_type ng_l2tp_session_stats_type = {
&ng_parse_struct_type,
&ng_l2tp_session_stats_type_fields
};
/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
{
NGM_L2TP_COOKIE,
NGM_L2TP_SET_CONFIG,
"setconfig",
&ng_l2tp_config_type,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GET_CONFIG,
"getconfig",
NULL,
&ng_l2tp_config_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_SET_SESS_CONFIG,
"setsessconfig",
&ng_l2tp_sess_config_type,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GET_SESS_CONFIG,
"getsessconfig",
&ng_parse_hint16_type,
&ng_l2tp_sess_config_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GET_STATS,
"getstats",
NULL,
&ng_l2tp_stats_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_CLR_STATS,
"clrstats",
NULL,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GETCLR_STATS,
"getclrstats",
NULL,
&ng_l2tp_stats_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GET_SESSION_STATS,
"getsessstats",
&ng_parse_int16_type,
&ng_l2tp_session_stats_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_CLR_SESSION_STATS,
"clrsessstats",
&ng_parse_int16_type,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GETCLR_SESSION_STATS,
"getclrsessstats",
&ng_parse_int16_type,
&ng_l2tp_session_stats_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_ACK_FAILURE,
"ackfailure",
NULL,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_SET_SEQ,
"setsequence",
&ng_l2tp_seq_config_type,
NULL
},
{ 0 }
};
/* Node type descriptor */
static struct ng_type ng_l2tp_typestruct = {
.version = NG_ABI_VERSION,
.name = NG_L2TP_NODE_TYPE,
.constructor = ng_l2tp_constructor,
.rcvmsg = ng_l2tp_rcvmsg,
.shutdown = ng_l2tp_shutdown,
.newhook = ng_l2tp_newhook,
.rcvdata = ng_l2tp_rcvdata,
.disconnect = ng_l2tp_disconnect,
.cmdlist = ng_l2tp_cmdlist,
};
NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
/* Sequence number state sanity checking */
#ifdef INVARIANTS
#define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
#else
#define L2TP_SEQ_CHECK(x) do { } while (0)
#endif
/* Whether to use m_copypacket() or m_dup() */
#define L2TP_COPY_MBUF m_copypacket
#define ERROUT(x) do { error = (x); goto done; } while (0)
/************************************************************************
NETGRAPH NODE STUFF
************************************************************************/
/*
* Node type constructor
*/
static int
ng_l2tp_constructor(node_p node)
{
priv_p priv;
int i;
/* Allocate private structure */
priv = malloc(sizeof(*priv), M_NETGRAPH_L2TP, M_WAITOK | M_ZERO);
NG_NODE_SET_PRIVATE(node, priv);
priv->node = node;
/* Apply a semi-reasonable default configuration */
priv->conf.peer_win = 1;
priv->conf.rexmit_max = L2TP_MAX_REXMIT;
priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
/* Initialize sequence number state */
ng_l2tp_seq_init(priv);
for (i = 0; i < SESSHASHSIZE; i++)
LIST_INIT(&priv->sesshash[i]);
/* Done */
return (0);
}
/*
* Give our OK for a hook to be added.
*/
static int
ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
{
const priv_p priv = NG_NODE_PRIVATE(node);
/* Check hook name */
if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
if (priv->ctrl != NULL)
return (EISCONN);
priv->ctrl = hook;
NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
} else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
if (priv->lower != NULL)
return (EISCONN);
priv->lower = hook;
NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
} else {
static const char hexdig[16] = "0123456789abcdef";
u_int16_t session_id;
hookpriv_p hpriv;
uint16_t hash;
const char *hex;
int i;
int j;
/* Parse hook name to get session ID */
if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
return (EINVAL);
hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
for (session_id = i = 0; i < 4; i++) {
for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
if (j == 16)
return (EINVAL);
session_id = (session_id << 4) | j;
}
if (hex[i] != '\0')
return (EINVAL);
/* Create hook private structure */
hpriv = malloc(sizeof(*hpriv),
M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
if (hpriv == NULL)
return (ENOMEM);
hpriv->conf.session_id = session_id;
hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
hpriv->hook = hook;
NG_HOOK_SET_PRIVATE(hook, hpriv);
hash = SESSHASH(hpriv->conf.session_id);
LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
}
/* Done */
return (0);
}
/*
* Receive a control message.
*/
static int
ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct ng_mesg *resp = NULL;
struct ng_mesg *msg;
int error = 0;
NGI_GET_MSG(item, msg);
switch (msg->header.typecookie) {
case NGM_L2TP_COOKIE:
switch (msg->header.cmd) {
case NGM_L2TP_SET_CONFIG:
{
struct ng_l2tp_config *const conf =
(struct ng_l2tp_config *)msg->data;
/* Check for invalid or illegal config */
if (msg->header.arglen != sizeof(*conf)) {
error = EINVAL;
break;
}
conf->enabled = !!conf->enabled;
conf->match_id = !!conf->match_id;
if (priv->conf.enabled
&& ((priv->conf.tunnel_id != 0
&& conf->tunnel_id != priv->conf.tunnel_id)
|| ((priv->conf.peer_id != 0
&& conf->peer_id != priv->conf.peer_id)))) {
error = EBUSY;
break;
}
/* Save calling node as failure target */
priv->ftarget = NGI_RETADDR(item);
/* Adjust sequence number state */
if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
break;
/* Update node's config */
priv->conf = *conf;
break;
}
case NGM_L2TP_GET_CONFIG:
{
struct ng_l2tp_config *conf;
NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
conf = (struct ng_l2tp_config *)resp->data;
*conf = priv->conf;
break;
}
case NGM_L2TP_SET_SESS_CONFIG:
{
struct ng_l2tp_sess_config *const conf =
(struct ng_l2tp_sess_config *)msg->data;
hookpriv_p hpriv;
/* Check for invalid or illegal config. */
if (msg->header.arglen != sizeof(*conf)) {
error = EINVAL;
break;
}
/* Find matching hook */
hpriv = ng_l2tp_find_session(priv, conf->session_id);
if (hpriv == NULL) {
error = ENOENT;
break;
}
/* Update hook's config */
hpriv->conf = *conf;
break;
}
case NGM_L2TP_GET_SESS_CONFIG:
{
struct ng_l2tp_sess_config *conf;
u_int16_t session_id;
hookpriv_p hpriv;
/* Get session ID */
if (msg->header.arglen != sizeof(session_id)) {
error = EINVAL;
break;
}
memcpy(&session_id, msg->data, 2);
/* Find matching hook */
hpriv = ng_l2tp_find_session(priv, session_id);
if (hpriv == NULL) {
error = ENOENT;
break;
}
/* Send response */
NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
conf = (struct ng_l2tp_sess_config *)resp->data;
*conf = hpriv->conf;
break;
}
case NGM_L2TP_GET_STATS:
case NGM_L2TP_CLR_STATS:
case NGM_L2TP_GETCLR_STATS:
{
if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
NG_MKRESPONSE(resp, msg,
sizeof(priv->stats), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
memcpy(resp->data,
&priv->stats, sizeof(priv->stats));
}
if (msg->header.cmd != NGM_L2TP_GET_STATS)
memset(&priv->stats, 0, sizeof(priv->stats));
break;
}
case NGM_L2TP_GET_SESSION_STATS:
case NGM_L2TP_CLR_SESSION_STATS:
case NGM_L2TP_GETCLR_SESSION_STATS:
{
uint16_t session_id;
hookpriv_p hpriv;
/* Get session ID. */
if (msg->header.arglen != sizeof(session_id)) {
error = EINVAL;
break;
}
bcopy(msg->data, &session_id, sizeof(uint16_t));
/* Find matching hook. */
hpriv = ng_l2tp_find_session(priv, session_id);
if (hpriv == NULL) {
error = ENOENT;
break;
}
if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
NG_MKRESPONSE(resp, msg,
sizeof(hpriv->stats), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
bcopy(&hpriv->stats, resp->data,
sizeof(hpriv->stats));
}
if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
bzero(&hpriv->stats, sizeof(hpriv->stats));
break;
}
case NGM_L2TP_SET_SEQ:
{
struct ng_l2tp_seq_config *const conf =
(struct ng_l2tp_seq_config *)msg->data;
/* Check for invalid or illegal seq config. */
if (msg->header.arglen != sizeof(*conf)) {
error = EINVAL;
break;
}
conf->ns = htons(conf->ns);
conf->nr = htons(conf->nr);
conf->rack = htons(conf->rack);
conf->xack = htons(conf->xack);
/* Set sequence numbers. */
error = ng_l2tp_seq_set(priv, conf);
break;
}
default:
error = EINVAL;
break;
}
break;
default:
error = EINVAL;
break;
}
/* Done */
NG_RESPOND_MSG(error, node, item, resp);
NG_FREE_MSG(msg);
return (error);
}
/*
* Destroy node
*/
static int
ng_l2tp_shutdown(node_p node)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
/* Sanity check */
L2TP_SEQ_CHECK(seq);
/* Reset sequence number state */
ng_l2tp_seq_reset(priv);
/* Free private data if neither timer is running */
ng_uncallout(&seq->rack_timer, node);
ng_uncallout(&seq->xack_timer, node);
mtx_destroy(&seq->mtx);
free(priv, M_NETGRAPH_L2TP);
/* Unref node */
NG_NODE_UNREF(node);
return (0);
}
/*
* Hook disconnection
*/
static int
ng_l2tp_disconnect(hook_p hook)
{
const node_p node = NG_HOOK_NODE(hook);
const priv_p priv = NG_NODE_PRIVATE(node);
/* Zero out hook pointer */
if (hook == priv->ctrl)
priv->ctrl = NULL;
else if (hook == priv->lower)
priv->lower = NULL;
else {
const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
LIST_REMOVE(hpriv, sessions);
free(hpriv, M_NETGRAPH_L2TP);
NG_HOOK_SET_PRIVATE(hook, NULL);
}
/* Go away if no longer connected to anything */
if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
ng_rmnode_self(node);
return (0);
}
/*************************************************************************
INTERNAL FUNCTIONS
*************************************************************************/
/*
* Find the hook with a given session ID.
*/
static hookpriv_p
ng_l2tp_find_session(priv_p privp, u_int16_t sid)
{
uint16_t hash = SESSHASH(sid);
hookpriv_p hpriv = NULL;
LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
if (hpriv->conf.session_id == sid)
break;
}
return (hpriv);
}
/*
* Reset a hook's session state.
*/
static int
ng_l2tp_reset_session(hook_p hook, void *arg)
{
const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
if (hpriv != NULL) {
hpriv->conf.control_dseq = 0;
hpriv->conf.enable_dseq = 0;
bzero(&hpriv->stats, sizeof(struct ng_l2tp_session_stats));
hpriv->nr = 0;
hpriv->ns = 0;
}
return (-1);
}
/*
* Handle an incoming frame from below.
*/
static int
ng_l2tp_rcvdata_lower(hook_p h, item_p item)
{
static const u_int16_t req_bits[2][2] = {
{ L2TP_DATA_0BITS, L2TP_DATA_1BITS },
{ L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
};
const node_p node = NG_HOOK_NODE(h);
const priv_p priv = NG_NODE_PRIVATE(node);
hookpriv_p hpriv = NULL;
hook_p hook = NULL;
struct mbuf *m;
u_int16_t tid, sid;
u_int16_t hdr;
u_int16_t ns, nr;
int is_ctrl;
int error;
int len, plen;
/* Sanity check */
L2TP_SEQ_CHECK(&priv->seq);
/* If not configured, reject */
if (!priv->conf.enabled) {
NG_FREE_ITEM(item);
ERROUT(ENXIO);
}
/* Grab mbuf */
NGI_GET_M(item, m);
/* Remember full packet length; needed for per session accounting. */
plen = m->m_pkthdr.len;
/* Update stats */
priv->stats.recvPackets++;
priv->stats.recvOctets += plen;
/* Get initial header */
if (m->m_pkthdr.len < 6) {
priv->stats.recvRunts++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(EINVAL);
}
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
ERROUT(EINVAL);
}
hdr = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1];
m_adj(m, 2);
/* Check required header bits and minimum length */
is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
if ((hdr & req_bits[is_ctrl][0]) != 0
|| (~hdr & req_bits[is_ctrl][1]) != 0) {
priv->stats.recvInvalid++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(EINVAL);
}
if (m->m_pkthdr.len < 4 /* tunnel, session id */
+ (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
+ (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
+ (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
priv->stats.recvRunts++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(EINVAL);
}
/* Get and validate length field if present */
if ((hdr & L2TP_HDR_LEN) != 0) {
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
ERROUT(EINVAL);
}
len = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1] - 4;
m_adj(m, 2);
if (len < 0 || len > m->m_pkthdr.len) {
priv->stats.recvInvalid++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(EINVAL);
}
if (len < m->m_pkthdr.len) /* trim extra bytes */
m_adj(m, -(m->m_pkthdr.len - len));
}
/* Get tunnel ID and session ID */
if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
ERROUT(EINVAL);
}
tid = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
sid = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
m_adj(m, 4);
/* Check tunnel ID */
if (tid != priv->conf.tunnel_id &&
(priv->conf.match_id || tid != 0)) {
priv->stats.recvWrongTunnel++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(EADDRNOTAVAIL);
}
/* Check session ID (for data packets only) */
if ((hdr & L2TP_HDR_CTRL) == 0) {
hpriv = ng_l2tp_find_session(priv, sid);
if (hpriv == NULL) {
priv->stats.recvUnknownSID++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(ENOTCONN);
}
hook = hpriv->hook;
}
/* Get Ns, Nr fields if present */
if ((hdr & L2TP_HDR_SEQ) != 0) {
if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
ERROUT(EINVAL);
}
ns = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
nr = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
m_adj(m, 4);
} else
ns = nr = 0;
/* Strip offset padding if present */
if ((hdr & L2TP_HDR_OFF) != 0) {
u_int16_t offset;
/* Get length of offset padding */
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
ERROUT(EINVAL);
}
offset = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
/* Trim offset padding */
if ((2+offset) > m->m_pkthdr.len) {
priv->stats.recvInvalid++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(EINVAL);
}
m_adj(m, 2+offset);
}
/* Handle control packets */
if ((hdr & L2TP_HDR_CTRL) != 0) {
struct l2tp_seq *const seq = &priv->seq;
/* Handle receive ack sequence number Nr */
ng_l2tp_seq_recv_nr(priv, nr);
/* Discard ZLB packets */
if (m->m_pkthdr.len == 0) {
priv->stats.recvZLBs++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(0);
}
mtx_lock(&seq->mtx);
/*
* If not what we expect or we are busy, drop packet and
* send an immediate ZLB ack.
*/
if (ns != seq->nr || seq->inproc) {
if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
priv->stats.recvDuplicates++;
else
priv->stats.recvOutOfOrder++;
mtx_unlock(&seq->mtx);
ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(0);
}
/*
* Until we deliver this packet we can't receive next one as
* we have no information for sending ack.
*/
seq->inproc = 1;
mtx_unlock(&seq->mtx);
/* Prepend session ID to packet. */
M_PREPEND(m, 2, M_NOWAIT);
if (m == NULL) {
seq->inproc = 0;
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
ERROUT(ENOBUFS);
}
mtod(m, u_int8_t *)[0] = sid >> 8;
mtod(m, u_int8_t *)[1] = sid & 0xff;
/* Deliver packet to upper layers */
NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
mtx_lock(&seq->mtx);
/* Ready to process next packet. */
seq->inproc = 0;
/* If packet was successfully delivered send ack. */
if (error == 0) {
/* Update recv sequence number */
seq->nr++;
/* Start receive ack timer, if not already running */
if (!callout_active(&seq->xack_timer)) {
ng_callout(&seq->xack_timer, priv->node, NULL,
L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
NULL, 0);
}
}
mtx_unlock(&seq->mtx);
ERROUT(error);
}
/* Per session packet, account it. */
hpriv->stats.recvPackets++;
hpriv->stats.recvOctets += plen;
/* Follow peer's lead in data sequencing, if configured to do so */
if (!hpriv->conf.control_dseq)
hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
/* Handle data sequence numbers if present and enabled */
if ((hdr & L2TP_HDR_SEQ) != 0) {
if (hpriv->conf.enable_dseq
&& L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
NG_FREE_ITEM(item); /* duplicate or out of order */
NG_FREE_M(m);
priv->stats.recvDataDrops++;
ERROUT(0);
}
hpriv->nr = ns + 1;
}
/* Drop empty data packets */
if (m->m_pkthdr.len == 0) {
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(0);
}
/* Deliver data */
NG_FWD_NEW_DATA(error, item, hook, m);
done:
/* Done */
L2TP_SEQ_CHECK(&priv->seq);
return (error);
}
/*
* Handle an outgoing control frame.
*/
static int
ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
{
const node_p node = NG_HOOK_NODE(hook);
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
struct mbuf *m;
int error;
int i;
u_int16_t ns;
/* Sanity check */
L2TP_SEQ_CHECK(&priv->seq);
/* If not configured, reject */
if (!priv->conf.enabled) {
NG_FREE_ITEM(item);
ERROUT(ENXIO);
}
/* Grab mbuf and discard other stuff XXX */
NGI_GET_M(item, m);
NG_FREE_ITEM(item);
/* Packet should have session ID prepended */
if (m->m_pkthdr.len < 2) {
priv->stats.xmitInvalid++;
m_freem(m);
ERROUT(EINVAL);
}
/* Check max length */
if (m->m_pkthdr.len >= 0x10000 - 14) {
priv->stats.xmitTooBig++;
m_freem(m);
ERROUT(EOVERFLOW);
}
mtx_lock(&seq->mtx);
/* Find next empty slot in transmit queue */
for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
if (i == L2TP_MAX_XWIN) {
mtx_unlock(&seq->mtx);
priv->stats.xmitDrops++;
m_freem(m);
ERROUT(ENOBUFS);
}
seq->xwin[i] = m;
/* If peer's receive window is already full, nothing else to do */
if (i >= seq->cwnd) {
mtx_unlock(&seq->mtx);
ERROUT(0);
}
/* Start retransmit timer if not already running */
if (!callout_active(&seq->rack_timer))
ng_callout(&seq->rack_timer, node, NULL,
hz, ng_l2tp_seq_rack_timeout, NULL, 0);
ns = seq->ns++;
mtx_unlock(&seq->mtx);
/* Copy packet */
if ((m = L2TP_COPY_MBUF(m, M_NOWAIT)) == NULL) {
priv->stats.memoryFailures++;
ERROUT(ENOBUFS);
}
/* Send packet and increment xmit sequence number */
error = ng_l2tp_xmit_ctrl(priv, m, ns);
done:
/* Done */
L2TP_SEQ_CHECK(&priv->seq);
return (error);
}
/*
* Handle an outgoing data frame.
*/
static int
ng_l2tp_rcvdata(hook_p hook, item_p item)
{
const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
struct mbuf *m;
uint8_t *p;
u_int16_t hdr;
int error;
int i = 2;
/* Sanity check */
L2TP_SEQ_CHECK(&priv->seq);
/* If not configured, reject */
if (!priv->conf.enabled) {
NG_FREE_ITEM(item);
ERROUT(ENXIO);
}
/* Get mbuf */
NGI_GET_M(item, m);
/* Check max length */
if (m->m_pkthdr.len >= 0x10000 - 12) {
priv->stats.xmitDataTooBig++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
ERROUT(EOVERFLOW);
}
/* Prepend L2TP header */
M_PREPEND(m, 6
+ (2 * (hpriv->conf.include_length != 0))
+ (4 * (hpriv->conf.enable_dseq != 0)),
M_NOWAIT);
if (m == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
ERROUT(ENOBUFS);
}
p = mtod(m, uint8_t *);
hdr = L2TP_DATA_HDR;
if (hpriv->conf.include_length) {
hdr |= L2TP_HDR_LEN;
p[i++] = m->m_pkthdr.len >> 8;
p[i++] = m->m_pkthdr.len & 0xff;
}
p[i++] = priv->conf.peer_id >> 8;
p[i++] = priv->conf.peer_id & 0xff;
p[i++] = hpriv->conf.peer_id >> 8;
p[i++] = hpriv->conf.peer_id & 0xff;
if (hpriv->conf.enable_dseq) {
hdr |= L2TP_HDR_SEQ;
p[i++] = hpriv->ns >> 8;
p[i++] = hpriv->ns & 0xff;
p[i++] = hpriv->nr >> 8;
p[i++] = hpriv->nr & 0xff;
hpriv->ns++;
}
p[0] = hdr >> 8;
p[1] = hdr & 0xff;
/* Update per session stats. */
hpriv->stats.xmitPackets++;
hpriv->stats.xmitOctets += m->m_pkthdr.len;
/* And the global one. */
priv->stats.xmitPackets++;
priv->stats.xmitOctets += m->m_pkthdr.len;
/* Send packet */
NG_FWD_NEW_DATA(error, item, priv->lower, m);
done:
/* Done */
L2TP_SEQ_CHECK(&priv->seq);
return (error);
}
/*
* Send a message to our controlling node that we've failed.
*/
static void
ng_l2tp_seq_failure(priv_p priv)
{
struct ng_mesg *msg;
int error;
NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
if (msg == NULL)
return;
NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
}
/************************************************************************
SEQUENCE NUMBER HANDLING
************************************************************************/
/*
* Initialize sequence number state.
*/
static void
ng_l2tp_seq_init(priv_p priv)
{
struct l2tp_seq *const seq = &priv->seq;
KASSERT(priv->conf.peer_win >= 1,
("%s: peer_win is zero", __func__));
memset(seq, 0, sizeof(*seq));
seq->cwnd = 1;
seq->wmax = priv->conf.peer_win;
if (seq->wmax > L2TP_MAX_XWIN)
seq->wmax = L2TP_MAX_XWIN;
seq->ssth = seq->wmax;
ng_callout_init(&seq->rack_timer);
ng_callout_init(&seq->xack_timer);
mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
L2TP_SEQ_CHECK(seq);
}
/*
* Set sequence number state as given from user.
*/
static int
ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
{
struct l2tp_seq *const seq = &priv->seq;
/* If node is enabled, deny update to sequence numbers. */
if (priv->conf.enabled)
return (EBUSY);
/* We only can handle the simple cases. */
if (conf->xack != conf->nr || conf->ns != conf->rack)
return (EINVAL);
/* Set ns,nr,rack,xack parameters. */
seq->ns = conf->ns;
seq->nr = conf->nr;
seq->rack = conf->rack;
seq->xack = conf->xack;
return (0);
}
/*
* Adjust sequence number state accordingly after reconfiguration.
*/
static int
ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
{
struct l2tp_seq *const seq = &priv->seq;
u_int16_t new_wmax;
/* If disabling node, reset state sequence number */
if (!conf->enabled) {
ng_l2tp_seq_reset(priv);
return (0);
}
/* Adjust peer's max recv window; it can only increase */
new_wmax = conf->peer_win;
if (new_wmax > L2TP_MAX_XWIN)
new_wmax = L2TP_MAX_XWIN;
if (new_wmax == 0)
return (EINVAL);
if (new_wmax < seq->wmax)
return (EBUSY);
seq->wmax = new_wmax;
/* Done */
return (0);
}
/*
* Reset sequence number state.
*/
static void
ng_l2tp_seq_reset(priv_p priv)
{
struct l2tp_seq *const seq = &priv->seq;
hook_p hook;
int i;
/* Sanity check */
L2TP_SEQ_CHECK(seq);
/* Stop timers */
ng_uncallout(&seq->rack_timer, priv->node);
ng_uncallout(&seq->xack_timer, priv->node);
/* Free retransmit queue */
for (i = 0; i < L2TP_MAX_XWIN; i++) {
if (seq->xwin[i] == NULL)
break;
m_freem(seq->xwin[i]);
}
/* Reset session hooks' sequence number states */
NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
/* Reset node's sequence number state */
seq->ns = 0;
seq->nr = 0;
seq->rack = 0;
seq->xack = 0;
seq->wmax = L2TP_MAX_XWIN;
seq->cwnd = 1;
seq->ssth = seq->wmax;
seq->acks = 0;
seq->rexmits = 0;
bzero(seq->xwin, sizeof(seq->xwin));
/* Done */
L2TP_SEQ_CHECK(seq);
}
/*
* Handle receipt of an acknowledgement value (Nr) from peer.
*/
static void
ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
{
struct l2tp_seq *const seq = &priv->seq;
struct mbuf *xwin[L2TP_MAX_XWIN]; /* partial local copy */
int nack;
int i, j;
uint16_t ns;
mtx_lock(&seq->mtx);
/* Verify peer's ACK is in range */
if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
mtx_unlock(&seq->mtx);
return; /* duplicate ack */
}
if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
mtx_unlock(&seq->mtx);
priv->stats.recvBadAcks++; /* ack for packet not sent */
return;
}
KASSERT(nack <= L2TP_MAX_XWIN,
("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
/* Update receive ack stats */
seq->rack = nr;
seq->rexmits = 0;
/* Free acknowledged packets and shift up packets in the xmit queue */
for (i = 0; i < nack; i++)
m_freem(seq->xwin[i]);
memmove(seq->xwin, seq->xwin + nack,
(L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
nack * sizeof(*seq->xwin));
/*
* Do slow-start/congestion avoidance windowing algorithm described
* in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
* ACK had arrived separately.
*/
if (seq->cwnd < seq->wmax) {
/* Handle slow start phase */
if (seq->cwnd < seq->ssth) {
seq->cwnd += nack;
nack = 0;
if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
nack = seq->cwnd - seq->ssth;
seq->cwnd = seq->ssth;
}
}
/* Handle congestion avoidance phase */
if (seq->cwnd >= seq->ssth) {
seq->acks += nack;
while (seq->acks >= seq->cwnd) {
seq->acks -= seq->cwnd;
if (seq->cwnd < seq->wmax)
seq->cwnd++;
}
}
}
/* Stop xmit timer */
if (callout_active(&seq->rack_timer))
ng_uncallout(&seq->rack_timer, priv->node);
/* If transmit queue is empty, we're done for now */
if (seq->xwin[0] == NULL) {
mtx_unlock(&seq->mtx);
return;
}
/* Start restransmit timer again */
ng_callout(&seq->rack_timer, priv->node, NULL,
hz, ng_l2tp_seq_rack_timeout, NULL, 0);
/*
* Send more packets, trying to keep peer's receive window full.
* Make copy of everything we need before lock release.
*/
ns = seq->ns;
j = 0;
while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
&& seq->xwin[i] != NULL) {
xwin[j++] = seq->xwin[i];
seq->ns++;
}
mtx_unlock(&seq->mtx);
/*
* Send prepared.
* If there is a memory error, pretend packet was sent, as it
* will get retransmitted later anyway.
*/
for (i = 0; i < j; i++) {
struct mbuf *m;
if ((m = L2TP_COPY_MBUF(xwin[i], M_NOWAIT)) == NULL)
priv->stats.memoryFailures++;
else
ng_l2tp_xmit_ctrl(priv, m, ns);
ns++;
}
}
/*
* Handle an ack timeout. We have an outstanding ack that we
* were hoping to piggy-back, but haven't, so send a ZLB.
*/
static void
ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
/* Make sure callout is still active before doing anything */
if (callout_pending(&seq->xack_timer) ||
(!callout_active(&seq->xack_timer)))
return;
/* Sanity check */
L2TP_SEQ_CHECK(seq);
/* Send a ZLB */
ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
/* callout_deactivate() is not needed here
as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
/* Sanity check */
L2TP_SEQ_CHECK(seq);
}
/*
* Handle a transmit timeout. The peer has failed to respond
* with an ack for our packet, so retransmit it.
*/
static void
ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
struct mbuf *m;
u_int delay;
/* Make sure callout is still active before doing anything */
if (callout_pending(&seq->rack_timer) ||
(!callout_active(&seq->rack_timer)))
return;
/* Sanity check */
L2TP_SEQ_CHECK(seq);
priv->stats.xmitRetransmits++;
/* Have we reached the retransmit limit? If so, notify owner. */
if (seq->rexmits++ >= priv->conf.rexmit_max)
ng_l2tp_seq_failure(priv);
/* Restart timer, this time with an increased delay */
delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
if (delay > priv->conf.rexmit_max_to)
delay = priv->conf.rexmit_max_to;
ng_callout(&seq->rack_timer, node, NULL,
hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
/* Do slow-start/congestion algorithm windowing algorithm */
seq->ns = seq->rack;
seq->ssth = (seq->cwnd + 1) / 2;
seq->cwnd = 1;
seq->acks = 0;
/* Retransmit oldest unack'd packet */
if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT)) == NULL)
priv->stats.memoryFailures++;
else
ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
/* callout_deactivate() is not needed here
as ng_callout() is getting called each time */
/* Sanity check */
L2TP_SEQ_CHECK(seq);
}
/*
* Transmit a control stream packet, payload optional.
* The transmit sequence number is not incremented.
*/
static int
ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
{
struct l2tp_seq *const seq = &priv->seq;
uint8_t *p;
u_int16_t session_id = 0;
int error;
mtx_lock(&seq->mtx);
/* Stop ack timer: we're sending an ack with this packet.
Doing this before to keep state predictable after error. */
if (callout_active(&seq->xack_timer))
ng_uncallout(&seq->xack_timer, priv->node);
seq->xack = seq->nr;
mtx_unlock(&seq->mtx);
/* If no mbuf passed, send an empty packet (ZLB) */
if (m == NULL) {
/* Create a new mbuf for ZLB packet */
MGETHDR(m, M_NOWAIT, MT_DATA);
if (m == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
m->m_len = m->m_pkthdr.len = 12;
m->m_pkthdr.rcvif = NULL;
priv->stats.xmitZLBs++;
} else {
/* Strip off session ID */
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
session_id = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
/* Make room for L2TP header */
M_PREPEND(m, 10, M_NOWAIT); /* - 2 + 12 = 10 */
if (m == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
/*
* The below requires 12 contiguous bytes for the L2TP header
* to be written into.
*/
m = m_pullup(m, 12);
if (m == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
}
/* Fill in L2TP header */
p = mtod(m, u_int8_t *);
p[0] = L2TP_CTRL_HDR >> 8;
p[1] = L2TP_CTRL_HDR & 0xff;
p[2] = m->m_pkthdr.len >> 8;
p[3] = m->m_pkthdr.len & 0xff;
p[4] = priv->conf.peer_id >> 8;
p[5] = priv->conf.peer_id & 0xff;
p[6] = session_id >> 8;
p[7] = session_id & 0xff;
p[8] = ns >> 8;
p[9] = ns & 0xff;
p[10] = seq->nr >> 8;
p[11] = seq->nr & 0xff;
/* Update sequence number info and stats */
priv->stats.xmitPackets++;
priv->stats.xmitOctets += m->m_pkthdr.len;
/* Send packet */
NG_SEND_DATA_ONLY(error, priv->lower, m);
return (error);
}
#ifdef INVARIANTS
/*
* Sanity check sequence number state.
*/
static void
ng_l2tp_seq_check(struct l2tp_seq *seq)
{
int self_unack, peer_unack;
int i;
#define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p))
mtx_lock(&seq->mtx);
self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
CHECK(seq->wmax <= L2TP_MAX_XWIN);
CHECK(seq->cwnd >= 1);
CHECK(seq->cwnd <= seq->wmax);
CHECK(seq->ssth >= 1);
CHECK(seq->ssth <= seq->wmax);
if (seq->cwnd < seq->ssth)
CHECK(seq->acks == 0);
else
CHECK(seq->acks <= seq->cwnd);
CHECK(self_unack >= 0);
CHECK(peer_unack >= 0);
CHECK(peer_unack <= seq->wmax);
CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
for (i = 0; i < peer_unack; i++)
CHECK(seq->xwin[i] != NULL);
for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
CHECK(seq->xwin[i] == NULL);
mtx_unlock(&seq->mtx);
#undef CHECK
}
#endif /* INVARIANTS */
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