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- /*
- * 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");
- 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));
- }
- }
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