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f-stack/freebsd/netgraph/ng_nat.c

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/*-
* Copyright 2005, Gleb Smirnoff <glebius@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON 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 ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/ctype.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <machine/in_cksum.h>
#include <netinet/libalias/alias.h>
#include <netinet/libalias/alias_local.h>
#include <netgraph/ng_message.h>
#include <netgraph/ng_parse.h>
#include <netgraph/ng_nat.h>
#include <netgraph/netgraph.h>
static ng_constructor_t ng_nat_constructor;
static ng_rcvmsg_t ng_nat_rcvmsg;
static ng_shutdown_t ng_nat_shutdown;
static ng_newhook_t ng_nat_newhook;
static ng_rcvdata_t ng_nat_rcvdata;
static ng_disconnect_t ng_nat_disconnect;
static unsigned int ng_nat_translate_flags(unsigned int x);
/* Parse type for struct ng_nat_mode. */
static const struct ng_parse_struct_field ng_nat_mode_fields[]
= NG_NAT_MODE_INFO;
static const struct ng_parse_type ng_nat_mode_type = {
&ng_parse_struct_type,
&ng_nat_mode_fields
};
/* Parse type for 'description' field in structs. */
static const struct ng_parse_fixedstring_info ng_nat_description_info
= { NG_NAT_DESC_LENGTH };
static const struct ng_parse_type ng_nat_description_type = {
&ng_parse_fixedstring_type,
&ng_nat_description_info
};
/* Parse type for struct ng_nat_redirect_port. */
static const struct ng_parse_struct_field ng_nat_redirect_port_fields[]
= NG_NAT_REDIRECT_PORT_TYPE_INFO(&ng_nat_description_type);
static const struct ng_parse_type ng_nat_redirect_port_type = {
&ng_parse_struct_type,
&ng_nat_redirect_port_fields
};
/* Parse type for struct ng_nat_redirect_addr. */
static const struct ng_parse_struct_field ng_nat_redirect_addr_fields[]
= NG_NAT_REDIRECT_ADDR_TYPE_INFO(&ng_nat_description_type);
static const struct ng_parse_type ng_nat_redirect_addr_type = {
&ng_parse_struct_type,
&ng_nat_redirect_addr_fields
};
/* Parse type for struct ng_nat_redirect_proto. */
static const struct ng_parse_struct_field ng_nat_redirect_proto_fields[]
= NG_NAT_REDIRECT_PROTO_TYPE_INFO(&ng_nat_description_type);
static const struct ng_parse_type ng_nat_redirect_proto_type = {
&ng_parse_struct_type,
&ng_nat_redirect_proto_fields
};
/* Parse type for struct ng_nat_add_server. */
static const struct ng_parse_struct_field ng_nat_add_server_fields[]
= NG_NAT_ADD_SERVER_TYPE_INFO;
static const struct ng_parse_type ng_nat_add_server_type = {
&ng_parse_struct_type,
&ng_nat_add_server_fields
};
/* Parse type for one struct ng_nat_listrdrs_entry. */
static const struct ng_parse_struct_field ng_nat_listrdrs_entry_fields[]
= NG_NAT_LISTRDRS_ENTRY_TYPE_INFO(&ng_nat_description_type);
static const struct ng_parse_type ng_nat_listrdrs_entry_type = {
&ng_parse_struct_type,
&ng_nat_listrdrs_entry_fields
};
/* Parse type for 'redirects' array in struct ng_nat_list_redirects. */
static int
ng_nat_listrdrs_ary_getLength(const struct ng_parse_type *type,
const u_char *start, const u_char *buf)
{
const struct ng_nat_list_redirects *lr;
lr = (const struct ng_nat_list_redirects *)
(buf - offsetof(struct ng_nat_list_redirects, redirects));
return lr->total_count;
}
static const struct ng_parse_array_info ng_nat_listrdrs_ary_info = {
&ng_nat_listrdrs_entry_type,
&ng_nat_listrdrs_ary_getLength,
NULL
};
static const struct ng_parse_type ng_nat_listrdrs_ary_type = {
&ng_parse_array_type,
&ng_nat_listrdrs_ary_info
};
/* Parse type for struct ng_nat_list_redirects. */
static const struct ng_parse_struct_field ng_nat_list_redirects_fields[]
= NG_NAT_LIST_REDIRECTS_TYPE_INFO(&ng_nat_listrdrs_ary_type);
static const struct ng_parse_type ng_nat_list_redirects_type = {
&ng_parse_struct_type,
&ng_nat_list_redirects_fields
};
/* Parse type for struct ng_nat_libalias_info. */
static const struct ng_parse_struct_field ng_nat_libalias_info_fields[]
= NG_NAT_LIBALIAS_INFO;
static const struct ng_parse_type ng_nat_libalias_info_type = {
&ng_parse_struct_type,
&ng_nat_libalias_info_fields
};
/* List of commands and how to convert arguments to/from ASCII. */
static const struct ng_cmdlist ng_nat_cmdlist[] = {
{
NGM_NAT_COOKIE,
NGM_NAT_SET_IPADDR,
"setaliasaddr",
&ng_parse_ipaddr_type,
NULL
},
{
NGM_NAT_COOKIE,
NGM_NAT_SET_MODE,
"setmode",
&ng_nat_mode_type,
NULL
},
{
NGM_NAT_COOKIE,
NGM_NAT_SET_TARGET,
"settarget",
&ng_parse_ipaddr_type,
NULL
},
{
NGM_NAT_COOKIE,
NGM_NAT_REDIRECT_PORT,
"redirectport",
&ng_nat_redirect_port_type,
&ng_parse_uint32_type
},
{
NGM_NAT_COOKIE,
NGM_NAT_REDIRECT_ADDR,
"redirectaddr",
&ng_nat_redirect_addr_type,
&ng_parse_uint32_type
},
{
NGM_NAT_COOKIE,
NGM_NAT_REDIRECT_PROTO,
"redirectproto",
&ng_nat_redirect_proto_type,
&ng_parse_uint32_type
},
{
NGM_NAT_COOKIE,
NGM_NAT_REDIRECT_DYNAMIC,
"redirectdynamic",
&ng_parse_uint32_type,
NULL
},
{
NGM_NAT_COOKIE,
NGM_NAT_REDIRECT_DELETE,
"redirectdelete",
&ng_parse_uint32_type,
NULL
},
{
NGM_NAT_COOKIE,
NGM_NAT_ADD_SERVER,
"addserver",
&ng_nat_add_server_type,
NULL
},
{
NGM_NAT_COOKIE,
NGM_NAT_LIST_REDIRECTS,
"listredirects",
NULL,
&ng_nat_list_redirects_type
},
{
NGM_NAT_COOKIE,
NGM_NAT_PROXY_RULE,
"proxyrule",
&ng_parse_string_type,
NULL
},
{
NGM_NAT_COOKIE,
NGM_NAT_LIBALIAS_INFO,
"libaliasinfo",
NULL,
&ng_nat_libalias_info_type
},
{ 0 }
};
/* Netgraph node type descriptor. */
static struct ng_type typestruct = {
.version = NG_ABI_VERSION,
.name = NG_NAT_NODE_TYPE,
.constructor = ng_nat_constructor,
.rcvmsg = ng_nat_rcvmsg,
.shutdown = ng_nat_shutdown,
.newhook = ng_nat_newhook,
.rcvdata = ng_nat_rcvdata,
.disconnect = ng_nat_disconnect,
.cmdlist = ng_nat_cmdlist,
};
NETGRAPH_INIT(nat, &typestruct);
MODULE_DEPEND(ng_nat, libalias, 1, 1, 1);
/* Element for list of redirects. */
struct ng_nat_rdr_lst {
STAILQ_ENTRY(ng_nat_rdr_lst) entries;
struct alias_link *lnk;
struct ng_nat_listrdrs_entry rdr;
};
STAILQ_HEAD(rdrhead, ng_nat_rdr_lst);
/* Information we store for each node. */
struct ng_nat_priv {
node_p node; /* back pointer to node */
hook_p in; /* hook for demasquerading */
hook_p out; /* hook for masquerading */
struct libalias *lib; /* libalias handler */
uint32_t flags; /* status flags */
uint32_t rdrcount; /* number or redirects in list */
uint32_t nextid; /* for next in turn in list */
struct rdrhead redirhead; /* redirect list header */
};
typedef struct ng_nat_priv *priv_p;
/* Values of flags */
#define NGNAT_CONNECTED 0x1 /* We have both hooks connected */
#define NGNAT_ADDR_DEFINED 0x2 /* NGM_NAT_SET_IPADDR happened */
static int
ng_nat_constructor(node_p node)
{
priv_p priv;
/* Initialize private descriptor. */
priv = malloc(sizeof(*priv), M_NETGRAPH, M_WAITOK | M_ZERO);
/* Init aliasing engine. */
priv->lib = LibAliasInit(NULL);
/* Set same ports on. */
(void )LibAliasSetMode(priv->lib, PKT_ALIAS_SAME_PORTS,
PKT_ALIAS_SAME_PORTS);
/* Init redirects housekeeping. */
priv->rdrcount = 0;
priv->nextid = 1;
STAILQ_INIT(&priv->redirhead);
/* Link structs together. */
NG_NODE_SET_PRIVATE(node, priv);
priv->node = node;
/*
* libalias is not thread safe, so our node
* must be single threaded.
*/
NG_NODE_FORCE_WRITER(node);
return (0);
}
static int
ng_nat_newhook(node_p node, hook_p hook, const char *name)
{
const priv_p priv = NG_NODE_PRIVATE(node);
if (strcmp(name, NG_NAT_HOOK_IN) == 0) {
priv->in = hook;
} else if (strcmp(name, NG_NAT_HOOK_OUT) == 0) {
priv->out = hook;
} else
return (EINVAL);
if (priv->out != NULL &&
priv->in != NULL)
priv->flags |= NGNAT_CONNECTED;
return(0);
}
static int
ng_nat_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_NAT_COOKIE:
switch (msg->header.cmd) {
case NGM_NAT_SET_IPADDR:
{
struct in_addr *const ia = (struct in_addr *)msg->data;
if (msg->header.arglen < sizeof(*ia)) {
error = EINVAL;
break;
}
LibAliasSetAddress(priv->lib, *ia);
priv->flags |= NGNAT_ADDR_DEFINED;
}
break;
case NGM_NAT_SET_MODE:
{
struct ng_nat_mode *const mode =
(struct ng_nat_mode *)msg->data;
if (msg->header.arglen < sizeof(*mode)) {
error = EINVAL;
break;
}
if (LibAliasSetMode(priv->lib,
ng_nat_translate_flags(mode->flags),
ng_nat_translate_flags(mode->mask)) < 0) {
error = ENOMEM;
break;
}
}
break;
case NGM_NAT_SET_TARGET:
{
struct in_addr *const ia = (struct in_addr *)msg->data;
if (msg->header.arglen < sizeof(*ia)) {
error = EINVAL;
break;
}
LibAliasSetTarget(priv->lib, *ia);
}
break;
case NGM_NAT_REDIRECT_PORT:
{
struct ng_nat_rdr_lst *entry;
struct ng_nat_redirect_port *const rp =
(struct ng_nat_redirect_port *)msg->data;
if (msg->header.arglen < sizeof(*rp)) {
error = EINVAL;
break;
}
if ((entry = malloc(sizeof(struct ng_nat_rdr_lst),
M_NETGRAPH, M_NOWAIT | M_ZERO)) == NULL) {
error = ENOMEM;
break;
}
/* Try actual redirect. */
entry->lnk = LibAliasRedirectPort(priv->lib,
rp->local_addr, htons(rp->local_port),
rp->remote_addr, htons(rp->remote_port),
rp->alias_addr, htons(rp->alias_port),
rp->proto);
if (entry->lnk == NULL) {
error = ENOMEM;
free(entry, M_NETGRAPH);
break;
}
/* Successful, save info in our internal list. */
entry->rdr.local_addr = rp->local_addr;
entry->rdr.alias_addr = rp->alias_addr;
entry->rdr.remote_addr = rp->remote_addr;
entry->rdr.local_port = rp->local_port;
entry->rdr.alias_port = rp->alias_port;
entry->rdr.remote_port = rp->remote_port;
entry->rdr.proto = rp->proto;
bcopy(rp->description, entry->rdr.description,
NG_NAT_DESC_LENGTH);
/* Safety precaution. */
entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
entry->rdr.id = priv->nextid++;
priv->rdrcount++;
/* Link to list of redirects. */
STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
/* Response with id of newly added entry. */
NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
}
break;
case NGM_NAT_REDIRECT_ADDR:
{
struct ng_nat_rdr_lst *entry;
struct ng_nat_redirect_addr *const ra =
(struct ng_nat_redirect_addr *)msg->data;
if (msg->header.arglen < sizeof(*ra)) {
error = EINVAL;
break;
}
if ((entry = malloc(sizeof(struct ng_nat_rdr_lst),
M_NETGRAPH, M_NOWAIT | M_ZERO)) == NULL) {
error = ENOMEM;
break;
}
/* Try actual redirect. */
entry->lnk = LibAliasRedirectAddr(priv->lib,
ra->local_addr, ra->alias_addr);
if (entry->lnk == NULL) {
error = ENOMEM;
free(entry, M_NETGRAPH);
break;
}
/* Successful, save info in our internal list. */
entry->rdr.local_addr = ra->local_addr;
entry->rdr.alias_addr = ra->alias_addr;
entry->rdr.proto = NG_NAT_REDIRPROTO_ADDR;
bcopy(ra->description, entry->rdr.description,
NG_NAT_DESC_LENGTH);
/* Safety precaution. */
entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
entry->rdr.id = priv->nextid++;
priv->rdrcount++;
/* Link to list of redirects. */
STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
/* Response with id of newly added entry. */
NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
}
break;
case NGM_NAT_REDIRECT_PROTO:
{
struct ng_nat_rdr_lst *entry;
struct ng_nat_redirect_proto *const rp =
(struct ng_nat_redirect_proto *)msg->data;
if (msg->header.arglen < sizeof(*rp)) {
error = EINVAL;
break;
}
if ((entry = malloc(sizeof(struct ng_nat_rdr_lst),
M_NETGRAPH, M_NOWAIT | M_ZERO)) == NULL) {
error = ENOMEM;
break;
}
/* Try actual redirect. */
entry->lnk = LibAliasRedirectProto(priv->lib,
rp->local_addr, rp->remote_addr,
rp->alias_addr, rp->proto);
if (entry->lnk == NULL) {
error = ENOMEM;
free(entry, M_NETGRAPH);
break;
}
/* Successful, save info in our internal list. */
entry->rdr.local_addr = rp->local_addr;
entry->rdr.alias_addr = rp->alias_addr;
entry->rdr.remote_addr = rp->remote_addr;
entry->rdr.proto = rp->proto;
bcopy(rp->description, entry->rdr.description,
NG_NAT_DESC_LENGTH);
/* Safety precaution. */
entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
entry->rdr.id = priv->nextid++;
priv->rdrcount++;
/* Link to list of redirects. */
STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
/* Response with id of newly added entry. */
NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
}
break;
case NGM_NAT_REDIRECT_DYNAMIC:
case NGM_NAT_REDIRECT_DELETE:
{
struct ng_nat_rdr_lst *entry;
uint32_t *const id = (uint32_t *)msg->data;
if (msg->header.arglen < sizeof(*id)) {
error = EINVAL;
break;
}
/* Find entry with supplied id. */
STAILQ_FOREACH(entry, &priv->redirhead, entries) {
if (entry->rdr.id == *id)
break;
}
/* Not found. */
if (entry == NULL) {
error = ENOENT;
break;
}
if (msg->header.cmd == NGM_NAT_REDIRECT_DYNAMIC) {
if (LibAliasRedirectDynamic(priv->lib,
entry->lnk) == -1) {
error = ENOTTY; /* XXX Something better? */
break;
}
} else { /* NGM_NAT_REDIRECT_DELETE */
LibAliasRedirectDelete(priv->lib, entry->lnk);
}
/* Delete entry from our internal list. */
priv->rdrcount--;
STAILQ_REMOVE(&priv->redirhead, entry, ng_nat_rdr_lst, entries);
free(entry, M_NETGRAPH);
}
break;
case NGM_NAT_ADD_SERVER:
{
struct ng_nat_rdr_lst *entry;
struct ng_nat_add_server *const as =
(struct ng_nat_add_server *)msg->data;
if (msg->header.arglen < sizeof(*as)) {
error = EINVAL;
break;
}
/* Find entry with supplied id. */
STAILQ_FOREACH(entry, &priv->redirhead, entries) {
if (entry->rdr.id == as->id)
break;
}
/* Not found. */
if (entry == NULL) {
error = ENOENT;
break;
}
if (LibAliasAddServer(priv->lib, entry->lnk,
as->addr, htons(as->port)) == -1) {
error = ENOMEM;
break;
}
entry->rdr.lsnat++;
}
break;
case NGM_NAT_LIST_REDIRECTS:
{
struct ng_nat_rdr_lst *entry;
struct ng_nat_list_redirects *ary;
int i = 0;
NG_MKRESPONSE(resp, msg, sizeof(*ary) +
(priv->rdrcount) * sizeof(*entry), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
ary = (struct ng_nat_list_redirects *)resp->data;
ary->total_count = priv->rdrcount;
STAILQ_FOREACH(entry, &priv->redirhead, entries) {
bcopy(&entry->rdr, &ary->redirects[i++],
sizeof(struct ng_nat_listrdrs_entry));
}
}
break;
case NGM_NAT_PROXY_RULE:
{
char *cmd = (char *)msg->data;
if (msg->header.arglen < 6) {
error = EINVAL;
break;
}
if (LibAliasProxyRule(priv->lib, cmd) != 0)
error = ENOMEM;
}
break;
case NGM_NAT_LIBALIAS_INFO:
{
struct ng_nat_libalias_info *i;
NG_MKRESPONSE(resp, msg,
sizeof(struct ng_nat_libalias_info), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
i = (struct ng_nat_libalias_info *)resp->data;
#define COPY(F) do { \
if (priv->lib->F >= 0 && priv->lib->F < UINT32_MAX) \
i->F = priv->lib->F; \
else \
i->F = UINT32_MAX; \
} while (0)
COPY(icmpLinkCount);
COPY(udpLinkCount);
COPY(tcpLinkCount);
COPY(pptpLinkCount);
COPY(sctpLinkCount);
COPY(protoLinkCount);
COPY(fragmentIdLinkCount);
COPY(fragmentPtrLinkCount);
COPY(sockCount);
#undef COPY
}
break;
default:
error = EINVAL; /* unknown command */
break;
}
break;
default:
error = EINVAL; /* unknown cookie type */
break;
}
NG_RESPOND_MSG(error, node, item, resp);
NG_FREE_MSG(msg);
return (error);
}
static int
ng_nat_rcvdata(hook_p hook, item_p item )
{
const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
struct mbuf *m;
struct ip *ip;
int rval, error = 0;
char *c;
/* We have no required hooks. */
if (!(priv->flags & NGNAT_CONNECTED)) {
NG_FREE_ITEM(item);
return (ENXIO);
}
/* We have no alias address yet to do anything. */
if (!(priv->flags & NGNAT_ADDR_DEFINED))
goto send;
m = NGI_M(item);
if ((m = m_megapullup(m, m->m_pkthdr.len)) == NULL) {
NGI_M(item) = NULL; /* avoid double free */
NG_FREE_ITEM(item);
return (ENOBUFS);
}
NGI_M(item) = m;
c = mtod(m, char *);
ip = mtod(m, struct ip *);
KASSERT(m->m_pkthdr.len == ntohs(ip->ip_len),
("ng_nat: ip_len != m_pkthdr.len"));
/*
* We drop packet when:
* 1. libalias returns PKT_ALIAS_ERROR;
* 2. For incoming packets:
* a) for unresolved fragments;
* b) libalias returns PKT_ALIAS_IGNORED and
* PKT_ALIAS_DENY_INCOMING flag is set.
*/
if (hook == priv->in) {
rval = LibAliasIn(priv->lib, c, m->m_len + M_TRAILINGSPACE(m));
if (rval == PKT_ALIAS_ERROR ||
rval == PKT_ALIAS_UNRESOLVED_FRAGMENT ||
(rval == PKT_ALIAS_IGNORED &&
(priv->lib->packetAliasMode &
PKT_ALIAS_DENY_INCOMING) != 0)) {
NG_FREE_ITEM(item);
return (EINVAL);
}
} else if (hook == priv->out) {
rval = LibAliasOut(priv->lib, c, m->m_len + M_TRAILINGSPACE(m));
if (rval == PKT_ALIAS_ERROR) {
NG_FREE_ITEM(item);
return (EINVAL);
}
} else
panic("ng_nat: unknown hook!\n");
if (rval == PKT_ALIAS_RESPOND)
m->m_flags |= M_SKIP_FIREWALL;
m->m_pkthdr.len = m->m_len = ntohs(ip->ip_len);
if ((ip->ip_off & htons(IP_OFFMASK)) == 0 &&
ip->ip_p == IPPROTO_TCP) {
struct tcphdr *th = (struct tcphdr *)((caddr_t)ip +
(ip->ip_hl << 2));
/*
* Here is our terrible HACK.
*
* Sometimes LibAlias edits contents of TCP packet.
* In this case it needs to recompute full TCP
* checksum. However, the problem is that LibAlias
* doesn't have any idea about checksum offloading
* in kernel. To workaround this, we do not do
* checksumming in LibAlias, but only mark the
* packets in th_x2 field. If we receive a marked
* packet, we calculate correct checksum for it
* aware of offloading.
*
* Why do I do such a terrible hack instead of
* recalculating checksum for each packet?
* Because the previous checksum was not checked!
* Recalculating checksums for EVERY packet will
* hide ALL transmission errors. Yes, marked packets
* still suffer from this problem. But, sigh, natd(8)
* has this problem, too.
*/
if (th->th_x2) {
uint16_t ip_len = ntohs(ip->ip_len);
th->th_x2 = 0;
th->th_sum = in_pseudo(ip->ip_src.s_addr,
ip->ip_dst.s_addr, htons(IPPROTO_TCP +
ip_len - (ip->ip_hl << 2)));
if ((m->m_pkthdr.csum_flags & CSUM_TCP) == 0) {
m->m_pkthdr.csum_data = offsetof(struct tcphdr,
th_sum);
in_delayed_cksum(m);
}
}
}
send:
if (hook == priv->in)
NG_FWD_ITEM_HOOK(error, item, priv->out);
else
NG_FWD_ITEM_HOOK(error, item, priv->in);
return (error);
}
static int
ng_nat_shutdown(node_p node)
{
const priv_p priv = NG_NODE_PRIVATE(node);
NG_NODE_SET_PRIVATE(node, NULL);
NG_NODE_UNREF(node);
/* Free redirects list. */
while (!STAILQ_EMPTY(&priv->redirhead)) {
struct ng_nat_rdr_lst *entry = STAILQ_FIRST(&priv->redirhead);
STAILQ_REMOVE_HEAD(&priv->redirhead, entries);
free(entry, M_NETGRAPH);
}
/* Final free. */
LibAliasUninit(priv->lib);
free(priv, M_NETGRAPH);
return (0);
}
static int
ng_nat_disconnect(hook_p hook)
{
const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
priv->flags &= ~NGNAT_CONNECTED;
if (hook == priv->out)
priv->out = NULL;
if (hook == priv->in)
priv->in = NULL;
if (priv->out == NULL && priv->in == NULL)
ng_rmnode_self(NG_HOOK_NODE(hook));
return (0);
}
static unsigned int
ng_nat_translate_flags(unsigned int x)
{
unsigned int res = 0;
if (x & NG_NAT_LOG)
res |= PKT_ALIAS_LOG;
if (x & NG_NAT_DENY_INCOMING)
res |= PKT_ALIAS_DENY_INCOMING;
if (x & NG_NAT_SAME_PORTS)
res |= PKT_ALIAS_SAME_PORTS;
if (x & NG_NAT_UNREGISTERED_ONLY)
res |= PKT_ALIAS_UNREGISTERED_ONLY;
if (x & NG_NAT_RESET_ON_ADDR_CHANGE)
res |= PKT_ALIAS_RESET_ON_ADDR_CHANGE;
if (x & NG_NAT_PROXY_ONLY)
res |= PKT_ALIAS_PROXY_ONLY;
if (x & NG_NAT_REVERSE)
res |= PKT_ALIAS_REVERSE;
return (res);
}
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