ref: 518fd3ec8350a010e5ed6490e1106c66af8f4d02
dir: /sys/src/cmd/ip/pppoe.c/
/*
* User-level PPP over Ethernet (PPPoE) client.
* See RFC 2516
*/
#include <u.h>
#include <libc.h>
#include <ip.h>
void dumppkt(uchar*);
uchar *findtag(uchar*, int, int*, int);
void hexdump(uchar*, int);
int malformed(uchar*, int, int);
int pppoe(char*);
void execppp(int);
int alarmed;
int debug;
int sessid;
char *keyspec;
int primary;
char *pppnetmtpt;
char *acname;
char *pppname = "/bin/ip/ppp";
char *srvname = "";
char *wantac;
uchar *cookie;
int cookielen;
uchar etherdst[6];
int mtu = 1492;
void
usage(void)
{
fprint(2, "usage: pppoe [-Pd] [-A acname] [-S srvname] [-k keyspec] [-m mtu] [-x pppnet] [ether0]\n");
exits("usage");
}
int
catchalarm(void *a, char *msg)
{
USED(a);
if(strstr(msg, "alarm")){
alarmed = 1;
return 1;
}
if(debug)
fprint(2, "note rcved: %s\n", msg);
return 0;
}
void
main(int argc, char **argv)
{
int fd;
char *dev;
ARGBEGIN{
case 'A':
wantac = EARGF(usage());
break;
case 'P':
primary = 1;
break;
case 'S':
srvname = EARGF(usage());
break;
case 'd':
debug++;
break;
case 'm':
mtu = atoi(EARGF(usage()));
break;
case 'k':
keyspec = EARGF(usage());
break;
case 'x':
pppnetmtpt = EARGF(usage());
break;
default:
usage();
}ARGEND
switch(argc){
default:
usage();
case 0:
dev = "ether0";
break;
case 1:
dev = argv[0];
break;
}
fmtinstall('E', eipfmt);
atnotify(catchalarm, 1);
fd = pppoe(dev);
execppp(fd);
}
typedef struct Etherhdr Etherhdr;
struct Etherhdr {
uchar dst[6];
uchar src[6];
uchar type[2];
};
enum {
EtherHdrSz = 6+6+2,
EtherMintu = 60,
EtherPppoeDiscovery = 0x8863,
EtherPppoeSession = 0x8864,
};
uchar etherbcast[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
int
etherhdr(uchar *pkt, uchar *dst, int type)
{
Etherhdr *eh;
eh = (Etherhdr*)pkt;
memmove(eh->dst, dst, sizeof(eh->dst));
hnputs(eh->type, type);
return EtherHdrSz;
}
typedef struct Pppoehdr Pppoehdr;
struct Pppoehdr {
uchar verstype;
uchar code;
uchar sessid[2];
uchar length[2]; /* of payload */
};
enum {
PppoeHdrSz = 1+1+2+2,
Hdr = EtherHdrSz+PppoeHdrSz,
};
enum {
VersType = 0x11,
/* Discovery codes */
CodeDiscInit = 0x09, /* discovery init */
CodeDiscOffer = 0x07, /* discovery offer */
CodeDiscReq = 0x19, /* discovery request */
CodeDiscSess = 0x65, /* session confirmation */
/* Session codes */
CodeSession = 0x00,
};
int
pppoehdr(uchar *pkt, int code, int sessid)
{
Pppoehdr *ph;
ph = (Pppoehdr*)pkt;
ph->verstype = VersType;
ph->code = code;
hnputs(ph->sessid, sessid);
return PppoeHdrSz;
}
typedef struct Taghdr Taghdr;
struct Taghdr {
uchar type[2];
uchar length[2]; /* of value */
};
enum {
TagEnd = 0x0000, /* end of tag list */
TagSrvName = 0x0101, /* service name */
TagAcName = 0x0102, /* access concentrator name */
TagHostUniq = 0x0103, /* nonce */
TagAcCookie = 0x0104, /* a.c. cookie */
TagVendSpec = 0x0105, /* vendor specific */
TagRelaySessId = 0x0110, /* relay session id */
TagSrvNameErr = 0x0201, /* service name error (ascii) */
TagAcSysErr = 0x0202, /* a.c. system error */
};
int
tag(uchar *pkt, int type, void *value, int nvalue)
{
Taghdr *h;
h = (Taghdr*)pkt;
hnputs(h->type, type);
hnputs(h->length, nvalue);
memmove(pkt+4, value, nvalue);
return 4+nvalue;
}
/* PPPoE Active Discovery Initiation */
int
padi(uchar *pkt)
{
int sz, tagoff;
uchar *length;
sz = 0;
sz += etherhdr(pkt+sz, etherbcast, EtherPppoeDiscovery);
sz += pppoehdr(pkt+sz, CodeDiscInit, 0x0000);
length = pkt+sz-2;
tagoff = sz;
sz += tag(pkt+sz, TagSrvName, srvname, strlen(srvname));
hnputs(length, sz-tagoff);
return sz;
}
/* PPPoE Active Discovery Request */
int
padr(uchar *pkt)
{
int sz, tagoff;
uchar *length;
sz = 0;
sz += etherhdr(pkt+sz, etherdst, EtherPppoeDiscovery);
sz += pppoehdr(pkt+sz, CodeDiscReq, 0x0000);
length = pkt+sz-2;
tagoff = sz;
sz += tag(pkt+sz, TagSrvName, srvname, strlen(srvname));
sz += tag(pkt+sz, TagAcName, acname, strlen(acname));
if(cookie)
sz += tag(pkt+sz, TagAcCookie, cookie, cookielen);
hnputs(length, sz-tagoff);
return sz;
}
void
ewrite(int fd, void *buf, int nbuf)
{
char e[ERRMAX], path[64];
if(write(fd, buf, nbuf) != nbuf){
rerrstr(e, sizeof e);
strcpy(path, "unknown");
fd2path(fd, path, sizeof path);
sysfatal("write %d to %s: %s", nbuf, path, e);
}
}
void*
emalloc(long n)
{
void *v;
v = malloc(n);
if(v == nil)
sysfatal("out of memory");
return v;
}
int
aread(int timeout, int fd, void *buf, int nbuf)
{
int n;
alarmed = 0;
alarm(timeout);
n = read(fd, buf, nbuf);
alarm(0);
if(alarmed)
return -1;
if(n < 0)
sysfatal("read: %r");
if(n == 0)
sysfatal("short read");
return n;
}
int
pktread(int timeout, int fd, void *buf, int nbuf, int (*want)(uchar*))
{
int n, t2;
n = -1;
for(t2=timeout; t2<16000; t2*=2){
while((n = aread(t2, fd, buf, nbuf)) > 0){
if(malformed(buf, n, EtherPppoeDiscovery)){
if(debug)
fprint(2, "dropping pkt: %r\n");
continue;
}
if(debug)
dumppkt(buf);
if(!want(buf)){
if(debug)
fprint(2, "dropping unwanted pkt: %r\n");
continue;
}
break;
}
if(n > 0)
break;
}
return n;
}
int
bad(char *reason)
{
werrstr(reason);
return 0;
}
void*
copy(uchar *s, int len)
{
uchar *v;
v = emalloc(len+1);
memmove(v, s, len);
v[len] = '\0';
return v;
}
void
clearstate(void)
{
sessid = -1;
free(acname);
acname = nil;
free(cookie);
cookie = nil;
}
int
wantoffer(uchar *pkt)
{
int i, len;
uchar *s;
Etherhdr *eh;
Pppoehdr *ph;
eh = (Etherhdr*)pkt;
ph = (Pppoehdr*)(pkt+EtherHdrSz);
if(ph->code != CodeDiscOffer)
return bad("not an offer");
if(nhgets(ph->sessid) != 0x0000)
return bad("bad session id");
for(i=0;; i++){
if((s = findtag(pkt, TagSrvName, &len, i)) == nil)
return bad("no matching service name");
if(len == strlen(srvname) && memcmp(s, srvname, len) == 0)
break;
}
if((s = findtag(pkt, TagAcName, &len, 0)) == nil)
return bad("no ac name");
acname = copy(s, len);
if(wantac && strcmp(acname, wantac) != 0){
free(acname);
return bad("wrong ac name");
}
if(s = findtag(pkt, TagAcCookie, &len, 0)){
cookie = copy(s, len);
cookielen = len;
}
memmove(etherdst, eh->src, sizeof etherdst);
return 1;
}
int
wantsession(uchar *pkt)
{
int len;
uchar *s;
Pppoehdr *ph;
ph = (Pppoehdr*)(pkt+EtherHdrSz);
if(ph->code != CodeDiscSess)
return bad("not a session confirmation");
if(nhgets(ph->sessid) == 0x0000)
return bad("bad session id");
if(findtag(pkt, TagSrvName, &len, 0) == nil)
return bad("no service name");
if(findtag(pkt, TagSrvNameErr, &len, 0))
return bad("service name error");
if(findtag(pkt, TagAcSysErr, &len, 0))
return bad("ac system error");
/*
* rsc said: ``if there is no -S option given, the current code
* waits for an offer with service name == "".
* that's silly. it should take the first one it gets.''
*/
if(srvname[0] != '\0') {
if((s = findtag(pkt, TagSrvName, &len, 0)) == nil)
return bad("no matching service name");
if(len != strlen(srvname) || memcmp(s, srvname, len) != 0)
return bad("no matching service name");
}
sessid = nhgets(ph->sessid);
return 1;
}
int
pppoe(char *ether)
{
char buf[64];
uchar pkt[1520];
int dfd, p[2], n, sfd, sz, timeout;
Pppoehdr *ph;
ph = (Pppoehdr*)(pkt+EtherHdrSz);
snprint(buf, sizeof buf, "%s!%d", ether, EtherPppoeDiscovery);
if((dfd = dial(buf, nil, nil, nil)) < 0)
sysfatal("dial %s: %r", buf);
snprint(buf, sizeof buf, "%s!%d", ether, EtherPppoeSession);
if((sfd = dial(buf, nil, nil, nil)) < 0)
sysfatal("dial %s: %r", buf);
for(timeout=250; timeout<16000; timeout*=2){
clearstate();
memset(pkt, 0, sizeof pkt);
sz = padi(pkt);
if(debug)
dumppkt(pkt);
if(sz < EtherMintu)
sz = EtherMintu;
ewrite(dfd, pkt, sz);
if(pktread(timeout, dfd, pkt, sizeof pkt, wantoffer) < 0)
continue;
memset(pkt, 0, sizeof pkt);
sz = padr(pkt);
if(debug)
dumppkt(pkt);
if(sz < EtherMintu)
sz = EtherMintu;
ewrite(dfd, pkt, sz);
if(pktread(timeout, dfd, pkt, sizeof pkt, wantsession) < 0)
continue;
break;
}
if(sessid < 0)
sysfatal("could not establish session");
rfork(RFNOTEG);
if(pipe(p) < 0)
sysfatal("pipe: %r");
switch(fork()){
case -1:
sysfatal("fork: %r");
default:
break;
case 0:
close(p[1]);
while((n = read(p[0], pkt+Hdr, sizeof pkt-Hdr)) > 0){
etherhdr(pkt, etherdst, EtherPppoeSession);
pppoehdr(pkt+EtherHdrSz, 0x00, sessid);
hnputs(pkt+Hdr-2, n);
sz = Hdr+n;
if(debug > 1){
dumppkt(pkt);
hexdump(pkt, sz);
}
if(sz < EtherMintu)
sz = EtherMintu;
if(write(sfd, pkt, sz) < 0){
if(debug)
fprint(2, "write to ether failed: %r");
_exits(nil);
}
}
_exits(nil);
}
switch(fork()){
case -1:
sysfatal("fork: %r");
default:
break;
case 0:
close(p[1]);
while((n = read(sfd, pkt, sizeof pkt)) > 0){
if(malformed(pkt, n, EtherPppoeSession)
|| ph->code != 0x00 || nhgets(ph->sessid) != sessid){
if(debug)
fprint(2, "malformed session pkt: %r\n");
if(debug)
dumppkt(pkt);
continue;
}
if(write(p[0], pkt+Hdr, nhgets(ph->length)) < 0){
if(debug)
fprint(2, "write to ppp failed: %r\n");
_exits(nil);
}
}
_exits(nil);
}
close(p[0]);
return p[1];
}
void
execppp(int fd)
{
char *argv[16];
int argc;
char smtu[10];
argc = 0;
argv[argc++] = pppname;
snprint(smtu, sizeof(smtu), "-m%d", mtu);
argv[argc++] = smtu;
argv[argc++] = "-F";
if(debug)
argv[argc++] = "-d";
if(primary)
argv[argc++] = "-P";
if(pppnetmtpt){
argv[argc++] = "-x";
argv[argc++] = pppnetmtpt;
}
if(keyspec){
argv[argc++] = "-k";
argv[argc++] = keyspec;
}
argv[argc] = nil;
dup(fd, 0);
dup(fd, 1);
exec(pppname, argv);
sysfatal("exec: %r");
}
uchar*
findtag(uchar *pkt, int tagtype, int *plen, int skip)
{
int len, sz, totlen;
uchar *tagdat, *v;
Etherhdr *eh;
Pppoehdr *ph;
Taghdr *t;
eh = (Etherhdr*)pkt;
ph = (Pppoehdr*)(pkt+EtherHdrSz);
tagdat = pkt+Hdr;
if(nhgets(eh->type) != EtherPppoeDiscovery)
return nil;
totlen = nhgets(ph->length);
sz = 0;
while(sz+4 <= totlen){
t = (Taghdr*)(tagdat+sz);
v = tagdat+sz+4;
len = nhgets(t->length);
if(sz+4+len > totlen)
break;
if(nhgets(t->type) == tagtype && skip-- == 0){
*plen = len;
return v;
}
sz += 2+2+len;
}
return nil;
}
void
dumptags(uchar *tagdat, int ntagdat)
{
int i,len, sz;
uchar *v;
Taghdr *t;
sz = 0;
while(sz+4 <= ntagdat){
t = (Taghdr*)(tagdat+sz);
v = tagdat+sz+2+2;
len = nhgets(t->length);
if(sz+4+len > ntagdat)
break;
fprint(2, "\t0x%x %d: ", nhgets(t->type), len);
switch(nhgets(t->type)){
case TagEnd:
fprint(2, "end of tag list\n");
break;
case TagSrvName:
fprint(2, "service '%.*s'\n", len, (char*)v);
break;
case TagAcName:
fprint(2, "ac '%.*s'\n", len, (char*)v);
break;
case TagHostUniq:
fprint(2, "nonce ");
Hex:
for(i=0; i<len; i++)
fprint(2, "%.2ux", v[i]);
fprint(2, "\n");
break;
case TagAcCookie:
fprint(2, "ac cookie ");
goto Hex;
case TagVendSpec:
fprint(2, "vend spec ");
goto Hex;
case TagRelaySessId:
fprint(2, "relay ");
goto Hex;
case TagSrvNameErr:
fprint(2, "srverr '%.*s'\n", len, (char*)v);
break;
case TagAcSysErr:
fprint(2, "syserr '%.*s'\n", len, (char*)v);
break;
}
sz += 2+2+len;
}
if(sz != ntagdat)
fprint(2, "warning: only dumped %d of %d bytes\n", sz, ntagdat);
}
void
dumppkt(uchar *pkt)
{
int et;
Etherhdr *eh;
Pppoehdr *ph;
eh = (Etherhdr*)pkt;
ph = (Pppoehdr*)(pkt+EtherHdrSz);
et = nhgets(eh->type);
fprint(2, "%E -> %E type 0x%x\n",
eh->src, eh->dst, et);
switch(et){
case EtherPppoeDiscovery:
case EtherPppoeSession:
fprint(2, "\tvers %d type %d code 0x%x sessid 0x%x length %d\n",
ph->verstype>>4, ph->verstype&15,
ph->code, nhgets(ph->sessid), nhgets(ph->length));
if(et == EtherPppoeDiscovery)
dumptags(pkt+Hdr, nhgets(ph->length));
}
}
int
malformed(uchar *pkt, int n, int wantet)
{
int et;
Etherhdr *eh;
Pppoehdr *ph;
eh = (Etherhdr*)pkt;
ph = (Pppoehdr*)(pkt+EtherHdrSz);
if(n < Hdr || n < Hdr+nhgets(ph->length)){
werrstr("packet too short %d != %d", n, Hdr+nhgets(ph->length));
return 1;
}
et = nhgets(eh->type);
if(et != wantet){
werrstr("wrong ethernet packet type 0x%x != 0x%x", et, wantet);
return 1;
}
return 0;
}
void
hexdump(uchar *a, int na)
{
int i;
char buf[80];
buf[0] = '\0';
for(i=0; i<na; i++){
sprint(buf+strlen(buf), " %.2ux", a[i]);
if(i%16 == 7)
sprint(buf+strlen(buf), " --");
if(i%16==15){
sprint(buf+strlen(buf), "\n");
write(2, buf, strlen(buf));
buf[0] = 0;
}
}
if(i%16){
sprint(buf+strlen(buf), "\n");
write(2, buf, strlen(buf));
}
}