ref: 172dc0005aa16dea8451bf2bcef7f3eb04df2c04
dir: /sys/src/9/ip/gre.c/
/*
* Generic Routing Encapsulation over IPv4, rfc1702
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "ip.h"
enum {
GRE_IPONLY = 12, /* size of ip header */
GRE_IPPLUSGRE = 12, /* minimum size of GRE header */
IP_GREPROTO = 47,
GRErxms = 200,
GREtickms = 100,
GREmaxxmit = 10,
K = 1024,
GREqlen = 256 * K,
GRE_cksum = 0x8000,
GRE_routing = 0x4000,
GRE_key = 0x2000,
GRE_seq = 0x1000,
Nring = 1 << 10, /* power of two, please */
Ringmask = Nring - 1,
GREctlraw = 0,
GREctlcooked,
GREctlretunnel,
GREctlreport,
GREctldlsuspend,
GREctlulsuspend,
GREctldlresume,
GREctlulresume,
GREctlforward,
GREctlulkey,
Ncmds,
};
typedef struct GREhdr GREhdr;
struct GREhdr{
/* ip header */
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar len[2]; /* packet length (including headers) */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
uchar ttl;
uchar proto; /* Protocol */
uchar cksum[2]; /* checksum */
uchar src[4]; /* Ip source */
uchar dst[4]; /* Ip destination */
/* gre header */
uchar flags[2];
uchar eproto[2]; /* encapsulation protocol */
};
typedef struct GREpriv GREpriv;
struct GREpriv{
/* non-MIB stats */
uvlong lenerr; /* short packet */
};
typedef struct Bring Bring;
struct Bring{
Block *ring[Nring];
long produced;
long consumed;
};
typedef struct GREconv GREconv;
struct GREconv{
int raw;
/* Retunnelling information. v4 only */
uchar north[4]; /* HA */
uchar south[4]; /* Base station */
uchar hoa[4]; /* Home address */
uchar coa[4]; /* Careof address */
ulong seq; /* Current sequence # */
int dlsusp; /* Downlink suspended? */
int ulsusp; /* Uplink suspended? */
ulong ulkey; /* GRE key */
QLock lock; /* Lock for rings */
Bring dlpending; /* Ring of pending packets */
Bring dlbuffered; /* Received while suspended */
Bring ulbuffered; /* Received while suspended */
};
typedef struct Metablock Metablock;
struct Metablock{
uchar *rp;
ulong seq;
};
static char *grectlcooked(Conv *, int, char **);
static char *grectldlresume(Conv *, int, char **);
static char *grectldlsuspend(Conv *, int, char **);
static char *grectlforward(Conv *, int, char **);
static char *grectlraw(Conv *, int, char **);
static char *grectlreport(Conv *, int, char **);
static char *grectlretunnel(Conv *, int, char **);
static char *grectlulkey(Conv *, int, char **);
static char *grectlulresume(Conv *, int, char **);
static char *grectlulsuspend(Conv *, int, char **);
static struct{
char *cmd;
int argc;
char *(*f)(Conv *, int, char **);
} grectls[Ncmds] = {
[GREctlraw] = { "raw", 1, grectlraw, },
[GREctlcooked] = { "cooked", 1, grectlcooked, },
[GREctlretunnel]= { "retunnel", 5, grectlretunnel, },
[GREctlreport] = { "report", 2, grectlreport, },
[GREctldlsuspend]= { "dlsuspend", 1, grectldlsuspend,},
[GREctlulsuspend]= { "ulsuspend", 1, grectlulsuspend,},
[GREctldlresume]= { "dlresume", 1, grectldlresume, },
[GREctlulresume]= { "ulresume", 1, grectlulresume, },
[GREctlforward] = { "forward", 2, grectlforward, },
[GREctlulkey] = { "ulkey", 2, grectlulkey, },
};
static uchar nulladdr[4];
static char *sessend = "session end";
static void grekick(void *x, Block *bp);
static char *gresetup(Conv *, char *, char *, char *);
uvlong grepdin, grepdout, grebdin, grebdout;
uvlong grepuin, grepuout, grebuin, grebuout;
static Block *
getring(Bring *r)
{
Block *bp;
if(r->consumed == r->produced)
return nil;
bp = r->ring[r->consumed & Ringmask];
r->ring[r->consumed & Ringmask] = nil;
r->consumed++;
return bp;
}
static void
addring(Bring *r, Block *bp)
{
Block *tbp;
if(r->produced - r->consumed > Ringmask){
/* Full! */
tbp = r->ring[r->produced & Ringmask];
assert(tbp);
freeb(tbp);
r->consumed++;
}
r->ring[r->produced & Ringmask] = bp;
r->produced++;
}
static char *
greconnect(Conv *c, char **argv, int argc)
{
Proto *p;
char *err;
Conv *tc, **cp, **ecp;
err = Fsstdconnect(c, argv, argc);
if(err != nil)
return err;
/* make sure noone's already connected to this other sys */
p = c->p;
qlock(p);
ecp = &p->conv[p->nc];
for(cp = p->conv; cp < ecp; cp++){
tc = *cp;
if(tc == nil)
break;
if(tc == c)
continue;
if(tc->rport == c->rport && ipcmp(tc->raddr, c->raddr) == 0){
err = "already connected to that addr/proto";
ipmove(c->laddr, IPnoaddr);
ipmove(c->raddr, IPnoaddr);
break;
}
}
qunlock(p);
if(err != nil)
return err;
Fsconnected(c, nil);
return nil;
}
static void
grecreate(Conv *c)
{
c->rq = qopen(GREqlen, Qmsg, 0, c);
c->wq = qbypass(grekick, c);
}
static int
grestate(Conv *c, char *state, int n)
{
GREconv *grec;
char *ep, *p;
grec = c->ptcl;
p = state;
ep = p + n;
p = seprint(p, ep, "%s%s%s%shoa %V north %V south %V seq %ulx "
"pending %uld %uld buffered dl %uld %uld ul %uld %uld ulkey %.8ulx\n",
c->inuse? "Open ": "Closed ",
grec->raw? "raw ": "",
grec->dlsusp? "DL suspended ": "",
grec->ulsusp? "UL suspended ": "",
grec->hoa, grec->north, grec->south, grec->seq,
grec->dlpending.consumed, grec->dlpending.produced,
grec->dlbuffered.consumed, grec->dlbuffered.produced,
grec->ulbuffered.consumed, grec->ulbuffered.produced,
grec->ulkey);
return p - state;
}
static char*
greannounce(Conv*, char**, int)
{
return "gre does not support announce";
}
static void
greclose(Conv *c)
{
GREconv *grec;
Block *bp;
grec = c->ptcl;
/* Make sure we don't forward any more packets */
memset(grec->hoa, 0, sizeof grec->hoa);
memset(grec->north, 0, sizeof grec->north);
memset(grec->south, 0, sizeof grec->south);
qlock(&grec->lock);
while((bp = getring(&grec->dlpending)) != nil)
freeb(bp);
while((bp = getring(&grec->dlbuffered)) != nil)
freeb(bp);
while((bp = getring(&grec->ulbuffered)) != nil)
freeb(bp);
grec->dlpending.produced = grec->dlpending.consumed = 0;
grec->dlbuffered.produced = grec->dlbuffered.consumed = 0;
grec->ulbuffered.produced = grec->ulbuffered.consumed = 0;
qunlock(&grec->lock);
grec->raw = 0;
grec->seq = 0;
grec->dlsusp = grec->ulsusp = 1;
qhangup(c->rq, sessend);
qhangup(c->wq, sessend);
qhangup(c->eq, sessend);
ipmove(c->laddr, IPnoaddr);
ipmove(c->raddr, IPnoaddr);
c->lport = c->rport = 0;
}
static void
grekick(void *x, Block *bp)
{
Conv *c;
GREconv *grec;
GREhdr *gre;
uchar laddr[IPaddrlen], raddr[IPaddrlen];
if(bp == nil)
return;
c = x;
grec = c->ptcl;
/* Make space to fit ip header (gre header already there) */
bp = padblock(bp, GRE_IPONLY);
/* make sure the message has a GRE header */
bp = pullupblock(bp, GRE_IPONLY+GRE_IPPLUSGRE);
if(bp == nil)
return;
gre = (GREhdr *)bp->rp;
gre->vihl = IP_VER4;
if(grec->raw == 0){
v4tov6(raddr, gre->dst);
if(ipcmp(raddr, v4prefix) == 0)
memmove(gre->dst, c->raddr + IPv4off, IPv4addrlen);
v4tov6(laddr, gre->src);
if(ipcmp(laddr, v4prefix) == 0){
if(ipcmp(c->laddr, IPnoaddr) == 0)
/* pick interface closest to dest */
findlocalip(c->p->f, c->laddr, raddr);
memmove(gre->src, c->laddr + IPv4off, sizeof gre->src);
}
hnputs(gre->eproto, c->rport);
}
gre->proto = IP_GREPROTO;
gre->frag[0] = gre->frag[1] = 0;
grepdout++;
grebdout += BLEN(bp);
ipoput4(c->p->f, bp, 0, c->ttl, c->tos, nil);
}
static void
gredownlink(Conv *c, Block *bp)
{
Metablock *m;
GREconv *grec;
GREhdr *gre;
int hdrlen, suspended, extra;
ushort flags;
ulong seq;
gre = (GREhdr *)bp->rp;
if(gre->ttl == 1){
freeb(bp);
return;
}
/*
* We've received a packet with a GRE header and we need to
* re-adjust the packet header to strip all unwanted parts
* but leave room for only a sequence number.
*/
grec = c->ptcl;
flags = nhgets(gre->flags);
hdrlen = 0;
if(flags & GRE_cksum)
hdrlen += 2;
if(flags & GRE_routing){
print("%V routing info present. Discarding packet", gre->src);
freeb(bp);
return;
}
if(flags & (GRE_cksum|GRE_routing))
hdrlen += 2; /* Offset field */
if(flags & GRE_key)
hdrlen += 4;
if(flags & GRE_seq)
hdrlen += 4;
/*
* The outgoing packet only has the sequence number set. Make room
* for the sequence number.
*/
if(hdrlen != sizeof(ulong)){
extra = hdrlen - sizeof(ulong);
if(extra < 0 && bp->rp - bp->base < -extra){
print("gredownlink: cannot add sequence number\n");
freeb(bp);
return;
}
memmove(bp->rp + extra, bp->rp, sizeof(GREhdr));
bp->rp += extra;
assert(BLEN(bp) >= sizeof(GREhdr) + sizeof(ulong));
gre = (GREhdr *)bp->rp;
}
seq = grec->seq++;
hnputs(gre->flags, GRE_seq);
hnputl(bp->rp + sizeof(GREhdr), seq);
/*
* Keep rp and seq at the base. ipoput4 consumes rp for
* refragmentation.
*/
assert(bp->rp - bp->base >= sizeof(Metablock));
m = (Metablock *)bp->base;
m->rp = bp->rp;
m->seq = seq;
/*
* Here we make a decision what we're doing with the packet. We're
* doing this w/o holding a lock which means that later on in the
* process we may discover we've done the wrong thing. I don't want
* to call ipoput with the lock held.
*/
restart:
suspended = grec->dlsusp;
if(suspended){
if(!canqlock(&grec->lock)){
/*
* just give up. too bad, we lose a packet. this
* is just too hard and my brain already hurts.
*/
freeb(bp);
return;
}
if(!grec->dlsusp){
/*
* suspend race. We though we were suspended, but
* we really weren't.
*/
qunlock(&grec->lock);
goto restart;
}
/* Undo the incorrect ref count addition */
addring(&grec->dlbuffered, bp);
qunlock(&grec->lock);
return;
}
/*
* When we get here, we're not suspended. Proceed to send the
* packet.
*/
memmove(gre->src, grec->coa, sizeof gre->dst);
memmove(gre->dst, grec->south, sizeof gre->dst);
ipoput4(c->p->f, copyblock(bp, BLEN(bp)), nil, gre->ttl - 1, gre->tos, nil);
grepdout++;
grebdout += BLEN(bp);
/*
* Now make sure we didn't do the wrong thing.
*/
if(!canqlock(&grec->lock)){
freeb(bp); /* The packet just goes away */
return;
}
/* We did the right thing */
addring(&grec->dlpending, bp);
qunlock(&grec->lock);
}
static void
greuplink(Conv *c, Block *bp)
{
GREconv *grec;
GREhdr *gre;
ushort flags;
gre = (GREhdr *)bp->rp;
if(gre->ttl == 1)
return;
grec = c->ptcl;
memmove(gre->src, grec->coa, sizeof gre->src);
memmove(gre->dst, grec->north, sizeof gre->dst);
/*
* Add a key, if needed.
*/
if(grec->ulkey){
flags = nhgets(gre->flags);
if(flags & (GRE_cksum|GRE_routing)){
print("%V routing info present. Discarding packet\n",
gre->src);
freeb(bp);
return;
}
if((flags & GRE_key) == 0){
/* Make room for the key */
if(bp->rp - bp->base < sizeof(ulong)){
print("%V can't add key\n", gre->src);
freeb(bp);
return;
}
bp->rp -= 4;
memmove(bp->rp, bp->rp + 4, sizeof(GREhdr));
gre = (GREhdr *)bp->rp;
hnputs(gre->flags, flags | GRE_key);
}
/* Add the key */
hnputl(bp->rp + sizeof(GREhdr), grec->ulkey);
}
if(!canqlock(&grec->lock)){
freeb(bp);
return;
}
if(grec->ulsusp)
addring(&grec->ulbuffered, bp);
else{
ipoput4(c->p->f, bp, nil, gre->ttl - 1, gre->tos, nil);
grepuout++;
grebuout += BLEN(bp);
}
qunlock(&grec->lock);
}
static void
greiput(Proto *proto, Ipifc *, Block *bp)
{
int len, hdrlen;
ushort eproto, flags;
uchar raddr[IPaddrlen];
Conv *c, **p;
GREconv *grec;
GREhdr *gre;
GREpriv *gpriv;
Ip4hdr *ip;
/*
* We don't want to deal with block lists. Ever. The problem is
* that when the block is forwarded, devether.c puts the block into
* a queue that also uses ->next. Just do not use ->next here!
*/
if(bp->next != nil)
bp = pullupblock(bp, blocklen(bp));
gre = (GREhdr *)bp->rp;
if(BLEN(bp) < sizeof(GREhdr) || gre->proto != IP_GREPROTO){
freeb(bp);
return;
}
v4tov6(raddr, gre->src);
eproto = nhgets(gre->eproto);
flags = nhgets(gre->flags);
hdrlen = sizeof(GREhdr);
if(flags & GRE_cksum)
hdrlen += 2;
if(flags & GRE_routing){
print("%I routing info present. Discarding packet\n", raddr);
freeb(bp);
return;
}
if(flags & (GRE_cksum|GRE_routing))
hdrlen += 2; /* Offset field */
if(flags & GRE_key)
hdrlen += 4;
if(flags & GRE_seq)
hdrlen += 4;
qlock(proto);
if(eproto == 0x0800 && BLEN(bp) - hdrlen >= sizeof(Ip4hdr)){
ip = (Ip4hdr *)(bp->rp + hdrlen);
/*
* Look for a conversation structure for this port and address, or
* match the retunnel part, or match on the raw flag.
*/
for(p = proto->conv; *p; p++) {
c = *p;
if(c->inuse == 0)
continue;
/*
* Do not stop this session - blocking here
* implies that etherread is blocked.
*/
grec = c->ptcl;
if(memcmp(ip->dst, grec->hoa, sizeof ip->dst) == 0){
grepdin++;
grebdin += BLEN(bp);
gredownlink(c, bp);
qunlock(proto);
return;
}
if(memcmp(ip->src, grec->hoa, sizeof ip->src) == 0){
grepuin++;
grebuin += BLEN(bp);
greuplink(c, bp);
qunlock(proto);
return;
}
}
}
/*
* when we get here, none of the forwarding tunnels matched. now
* try to match on raw and conversational sessions.
*/
for(c = nil, p = proto->conv; *p; p++) {
c = *p;
if(c->inuse == 0)
continue;
/*
* Do not stop this session - blocking here
* implies that etherread is blocked.
*/
grec = c->ptcl;
if(c->rport == eproto &&
(grec->raw || ipcmp(c->raddr, raddr) == 0))
break;
}
qunlock(proto);
if(*p == nil){
freeb(bp);
return;
}
/*
* Trim the packet down to data size
*/
len = nhgets(gre->len) - GRE_IPONLY;
if(len < GRE_IPPLUSGRE){
freeb(bp);
return;
}
bp = trimblock(bp, GRE_IPONLY, len);
if(bp == nil){
gpriv = proto->priv;
gpriv->lenerr++;
return;
}
qpass(c->rq, bp);
}
int
grestats(Proto *gre, char *buf, int len)
{
GREpriv *gpriv;
gpriv = gre->priv;
return snprint(buf, len,
"gre: %llud %llud %llud %llud %llud %llud %llud %llud, lenerrs %llud\n",
grepdin, grepdout, grepuin, grepuout,
grebdin, grebdout, grebuin, grebuout, gpriv->lenerr);
}
static char *
grectlraw(Conv *c, int, char **)
{
GREconv *grec;
grec = c->ptcl;
grec->raw = 1;
return nil;
}
static char *
grectlcooked(Conv *c, int, char **)
{
GREconv *grec;
grec = c->ptcl;
grec->raw = 0;
return nil;
}
static char *
grectlretunnel(Conv *c, int, char **argv)
{
GREconv *grec;
uchar ipaddr[4];
grec = c->ptcl;
if(memcmp(grec->hoa, nulladdr, sizeof grec->hoa))
return "tunnel already set up";
v4parseip(ipaddr, argv[1]);
if(memcmp(ipaddr, nulladdr, sizeof ipaddr) == 0)
return "bad hoa";
memmove(grec->hoa, ipaddr, sizeof grec->hoa);
v4parseip(ipaddr, argv[2]);
memmove(grec->north, ipaddr, sizeof grec->north);
v4parseip(ipaddr, argv[3]);
memmove(grec->south, ipaddr, sizeof grec->south);
v4parseip(ipaddr, argv[4]);
memmove(grec->coa, ipaddr, sizeof grec->coa);
grec->ulsusp = 1;
grec->dlsusp = 0;
return nil;
}
static char *
grectlreport(Conv *c, int, char **argv)
{
ulong seq;
Block *bp;
Bring *r;
GREconv *grec;
Metablock *m;
grec = c->ptcl;
seq = strtoul(argv[1], nil, 0);
qlock(&grec->lock);
r = &grec->dlpending;
while(r->produced - r->consumed > 0){
bp = r->ring[r->consumed & Ringmask];
assert(bp && bp->rp - bp->base >= sizeof(Metablock));
m = (Metablock *)bp->base;
if((long)(seq - m->seq) <= 0)
break;
r->ring[r->consumed & Ringmask] = nil;
r->consumed++;
freeb(bp);
}
qunlock(&grec->lock);
return nil;
}
static char *
grectldlsuspend(Conv *c, int, char **)
{
GREconv *grec;
grec = c->ptcl;
if(grec->dlsusp)
return "already suspended";
grec->dlsusp = 1;
return nil;
}
static char *
grectlulsuspend(Conv *c, int, char **)
{
GREconv *grec;
grec = c->ptcl;
if(grec->ulsusp)
return "already suspended";
grec->ulsusp = 1;
return nil;
}
static char *
grectldlresume(Conv *c, int, char **)
{
GREconv *grec;
GREhdr *gre;
Block *bp;
grec = c->ptcl;
qlock(&grec->lock);
if(!grec->dlsusp){
qunlock(&grec->lock);
return "not suspended";
}
while((bp = getring(&grec->dlbuffered)) != nil){
gre = (GREhdr *)bp->rp;
qunlock(&grec->lock);
ipoput4(c->p->f, copyblock(bp, BLEN(bp)), nil, gre->ttl - 1, gre->tos, nil);
qlock(&grec->lock);
addring(&grec->dlpending, bp);
}
grec->dlsusp = 0;
qunlock(&grec->lock);
return nil;
}
static char *
grectlulresume(Conv *c, int, char **)
{
GREconv *grec;
GREhdr *gre;
Block *bp;
grec = c->ptcl;
qlock(&grec->lock);
while((bp = getring(&grec->ulbuffered)) != nil){
gre = (GREhdr *)bp->rp;
qunlock(&grec->lock);
ipoput4(c->p->f, bp, nil, gre->ttl - 1, gre->tos, nil);
qlock(&grec->lock);
}
grec->ulsusp = 0;
qunlock(&grec->lock);
return nil;
}
static char *
grectlforward(Conv *c, int, char **argv)
{
Block *bp;
GREconv *grec;
GREhdr *gre;
Metablock *m;
grec = c->ptcl;
v4parseip(grec->south, argv[1]);
memmove(grec->north, grec->south, sizeof grec->north);
qlock(&grec->lock);
if(!grec->dlsusp){
qunlock(&grec->lock);
return "not suspended";
}
grec->dlsusp = 0;
grec->ulsusp = 0;
while((bp = getring(&grec->dlpending)) != nil){
assert(bp->rp - bp->base >= sizeof(Metablock));
m = (Metablock *)bp->base;
assert(m->rp >= bp->base && m->rp < bp->lim);
bp->rp = m->rp;
gre = (GREhdr *)bp->rp;
memmove(gre->src, grec->coa, sizeof gre->dst);
memmove(gre->dst, grec->south, sizeof gre->dst);
qunlock(&grec->lock);
ipoput4(c->p->f, bp, nil, gre->ttl - 1, gre->tos, nil);
qlock(&grec->lock);
}
while((bp = getring(&grec->dlbuffered)) != nil){
gre = (GREhdr *)bp->rp;
memmove(gre->src, grec->coa, sizeof gre->dst);
memmove(gre->dst, grec->south, sizeof gre->dst);
qunlock(&grec->lock);
ipoput4(c->p->f, bp, nil, gre->ttl - 1, gre->tos, nil);
qlock(&grec->lock);
}
while((bp = getring(&grec->ulbuffered)) != nil){
gre = (GREhdr *)bp->rp;
memmove(gre->src, grec->coa, sizeof gre->dst);
memmove(gre->dst, grec->south, sizeof gre->dst);
qunlock(&grec->lock);
ipoput4(c->p->f, bp, nil, gre->ttl - 1, gre->tos, nil);
qlock(&grec->lock);
}
qunlock(&grec->lock);
return nil;
}
static char *
grectlulkey(Conv *c, int, char **argv)
{
GREconv *grec;
grec = c->ptcl;
grec->ulkey = strtoul(argv[1], nil, 0);
return nil;
}
char *
grectl(Conv *c, char **f, int n)
{
int i;
if(n < 1)
return "too few arguments";
for(i = 0; i < Ncmds; i++)
if(strcmp(f[0], grectls[i].cmd) == 0)
break;
if(i == Ncmds)
return "no such command";
if(grectls[i].argc != 0 && grectls[i].argc != n)
return "incorrect number of arguments";
return grectls[i].f(c, n, f);
}
void
greinit(Fs *fs)
{
Proto *gre;
gre = smalloc(sizeof(Proto));
gre->priv = smalloc(sizeof(GREpriv));
gre->name = "gre";
gre->connect = greconnect;
gre->announce = greannounce;
gre->state = grestate;
gre->create = grecreate;
gre->close = greclose;
gre->rcv = greiput;
gre->ctl = grectl;
gre->advise = nil;
gre->stats = grestats;
gre->ipproto = IP_GREPROTO;
gre->nc = 64;
gre->ptclsize = sizeof(GREconv);
Fsproto(fs, gre);
}