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- /*
- * tftpd - tftp service, see /lib/rfc/rfc783 (now rfc1350 + 234[789])
- */
- #include <u.h>
- #include <libc.h>
- #include <auth.h>
- #include <bio.h>
- #include <ip.h>
- #include <ndb.h>
- enum
- {
- Maxpath= 128,
- Maxerr= 256,
- Debug= 0,
- Opsize= sizeof(short),
- Blksize= sizeof(short),
- Hdrsize= Opsize + Blksize,
- Ackerr= -1,
- Ackok= 0,
- Ackrexmit= 1,
- /* op codes */
- Tftp_READ = 1,
- Tftp_WRITE = 2,
- Tftp_DATA = 3,
- Tftp_ACK = 4,
- Tftp_ERROR = 5,
- Tftp_OACK = 6, /* option acknowledge */
- Errnotdef = 0, /* see textual error instead */
- Errnotfound = 1,
- Errnoaccess = 2,
- Errdiskfull = 3,
- Errbadop = 4,
- Errbadtid = 5,
- Errexists = 6,
- Errnouser = 7,
- Errbadopt = 8, /* really bad option value */
- Defsegsize = 512,
- Maxsegsize = 65464, /* from rfc2348 */
- /*
- * bandt (viaduct) tunnels use smaller mtu than ether's
- * (1400 bytes for tcp mss of 1300 bytes).
- */
- Bandtmtu = 1400,
- /*
- * maximum size of block's data content, excludes hdrs,
- * notably IP/UDP and TFTP, using worst-case (IPv6) sizes.
- */
- Bandtblksz = Bandtmtu - 40 - 8,
- Bcavium = 1432, /* cavium's u-boot demands this size */
- };
- typedef struct Opt Opt;
- struct Opt {
- char *name;
- int *valp; /* set to client's value if within bounds */
- int min;
- int max;
- };
- int dbg;
- int restricted;
- int pid;
- /* options */
- int blksize = Defsegsize; /* excluding 4-byte header */
- int timeout = 5; /* seconds */
- int tsize;
- static Opt option[] = {
- "timeout", &timeout, 1, 255,
- /* see "hack" below */
- "blksize", &blksize, 8, Maxsegsize,
- "tsize", &tsize, 0, ~0UL >> 1,
- };
- void sendfile(int, char*, char*, int);
- void recvfile(int, char*, char*);
- void nak(int, int, char*);
- void ack(int, ushort);
- void clrcon(void);
- void setuser(void);
- char* sunkernel(char*);
- void remoteaddr(char*, char*, int);
- void doserve(int);
- char bigbuf[32768];
- char raddr[64];
- char *dir = "/lib/tftpd";
- char *dirsl;
- int dirsllen;
- char flog[] = "ipboot";
- char net[Maxpath];
- static char *opnames[] = {
- [Tftp_READ] "read",
- [Tftp_WRITE] "write",
- [Tftp_DATA] "data",
- [Tftp_ACK] "ack",
- [Tftp_ERROR] "error",
- [Tftp_OACK] "oack",
- };
- void
- usage(void)
- {
- fprint(2, "usage: %s [-dr] [-h homedir] [-s svc] [-x netmtpt]\n",
- argv0);
- exits("usage");
- }
- void
- main(int argc, char **argv)
- {
- char buf[64];
- char adir[64], ldir[64];
- int cfd, lcfd, dfd;
- char *svc = "69";
- setnetmtpt(net, sizeof net, nil);
- ARGBEGIN{
- case 'd':
- dbg++;
- break;
- case 'h':
- dir = EARGF(usage());
- break;
- case 'r':
- restricted = 1;
- break;
- case 's':
- svc = EARGF(usage());
- break;
- case 'x':
- setnetmtpt(net, sizeof net, EARGF(usage()));
- break;
- default:
- usage();
- }ARGEND
- snprint(buf, sizeof buf, "%s/", dir);
- dirsl = strdup(buf);
- dirsllen = strlen(dirsl);
- fmtinstall('E', eipfmt);
- fmtinstall('I', eipfmt);
- /*
- * setuser calls newns, and typical /lib/namespace files contain
- * "cd /usr/$user", so call setuser before chdir.
- */
- setuser();
- if(chdir(dir) < 0)
- sysfatal("can't get to directory %s: %r", dir);
- if(!dbg)
- switch(rfork(RFNOTEG|RFPROC|RFFDG)) {
- case -1:
- sysfatal("fork: %r");
- case 0:
- break;
- default:
- exits(0);
- }
- snprint(buf, sizeof buf, "%s/udp!*!%s", net, svc);
- cfd = announce(buf, adir);
- if (cfd < 0)
- sysfatal("announcing on %s: %r", buf);
- syslog(dbg, flog, "tftpd started on %s dir %s", buf, adir);
- // setuser();
- for(;;) {
- lcfd = listen(adir, ldir);
- if(lcfd < 0)
- sysfatal("listening on %s: %r", adir);
- switch(fork()) {
- case -1:
- sysfatal("fork: %r");
- case 0:
- dfd = accept(lcfd, ldir);
- if(dfd < 0)
- exits(0);
- remoteaddr(ldir, raddr, sizeof(raddr));
- pid = getpid();
- syslog(0, flog, "tftp %d connection from %s dir %s",
- pid, raddr, ldir);
- doserve(dfd);
- exits("done");
- break;
- default:
- close(lcfd);
- continue;
- }
- }
- }
- static Opt *
- handleopt(int fd, char *name, char *val)
- {
- int n;
- Opt *op;
- for (op = option; op < option + nelem(option); op++)
- if(cistrcmp(name, op->name) == 0) {
- n = strtol(val, nil, 10);
- if (n < op->min || n > op->max) {
- nak(fd, Errbadopt, "option value out of range");
- syslog(dbg, flog, "tftp bad option value from "
- "client: %s %s", name, val);
- sysfatal("bad option value from client: %s %s",
- name, val);
- }
- *op->valp = n;
- /* incoming 0 for tsize is uninteresting */
- if(cistrcmp("tsize", op->name) != 0)
- syslog(dbg, flog, "tftpd %d setting %s to client's %d",
- pid, name, n);
- return op;
- }
- return nil;
- }
- static vlong
- filesize(char *file)
- {
- vlong size;
- Dir *dp;
- dp = dirstat(file);
- if (dp == nil)
- return -1;
- size = dp->length;
- free(dp);
- return size;
- }
- /* copy word into bp iff it fits before ep, returns bytes to advance bp. */
- static int
- emits(char *word, char *bp, char *ep)
- {
- int len;
- len = strlen(word) + 1;
- if (bp + len >= ep)
- return -1;
- strcpy(bp, word);
- return len;
- }
- /* format number into bp iff it fits before ep. */
- static int
- emitn(vlong n, char *bp, char *ep)
- {
- char numb[32];
- snprint(numb, sizeof numb, "%lld", n);
- return emits(numb, bp, ep);
- }
- /*
- * send an OACK packet to respond to options. bail early with -1 on error.
- * p is the packet containing the options.
- *
- * hack: bandt (viaducts) uses smaller mtu than ether's
- * (1400 bytes for tcp mss of 1300 bytes),
- * so offer at most bandt's mtu minus headers,
- * to avoid failure of pxe booting via viaduct.
- * there's an exception for the cavium's u-boot.
- */
- static int
- options(int fd, char *buf, int bufsz, char *file, ushort oper, char *p, int dlen)
- {
- int nmlen, vallen, olen, nopts;
- vlong size;
- char *val, *bp, *ep;
- Opt *op;
- buf[0] = 0;
- buf[1] = Tftp_OACK;
- bp = buf + Opsize;
- ep = buf + bufsz;
- nopts = 0;
- for (; dlen > 0 && *p != '\0'; p = val + vallen, bp += olen) {
- nmlen = strlen(p) + 1; /* include NUL */
- if (nmlen > dlen)
- break;
- dlen -= nmlen;
- val = p + nmlen;
- if (dlen <= 0 || *val == '\0')
- break;
- vallen = strlen(val) + 1;
- if (vallen > dlen)
- break;
- dlen -= vallen;
- nopts++;
- olen = 0;
- op = handleopt(fd, p, val);
- if (op == nil)
- continue;
- /* append OACK response to buf */
- nmlen = emits(p, bp, ep); /* option name */
- if (nmlen < 0)
- return -1;
- bp += nmlen;
- if (oper == Tftp_READ && cistrcmp(p, "tsize") == 0) {
- size = filesize(file);
- if (size == -1) {
- nak(fd, Errnotfound, "no such file");
- syslog(dbg, flog, "tftpd tsize for "
- "non-existent file %s", file);
- // *op->valp = 0;
- // olen = emits("0", bp, ep);
- return -1;
- }
- *op->valp = size;
- olen = emitn(size, bp, ep);
- syslog(dbg, flog, "tftpd %d %s tsize is %,lld",
- pid, file, size);
- } else if (oper == Tftp_READ && cistrcmp(p, "blksize") == 0 &&
- blksize > Bandtblksz && blksize != Bcavium) {
- *op->valp = blksize = Bandtblksz;
- olen = emitn(blksize, bp, ep);
- syslog(dbg, flog, "tftpd %d overriding blksize to %d",
- pid, blksize);
- } else
- olen = emits(val, bp, ep); /* use requested value */
- }
- if (nopts == 0)
- return 0; /* no options actually seen */
- if (write(fd, buf, bp - buf) < bp - buf) {
- syslog(dbg, flog, "tftpd network write error on oack to %s: %r",
- raddr);
- sysfatal("tftpd: network write error: %r");
- }
- if(Debug)
- syslog(dbg, flog, "tftpd oack: options to %s", raddr);
- return nopts;
- }
- static void
- optlog(char *bytes, char *p, int dlen)
- {
- char *bp;
- bp = bytes;
- sprint(bp, "tftpd %d option bytes: ", dlen);
- bp += strlen(bp);
- for (; dlen > 0; dlen--, p++)
- *bp++ = *p? *p: ' ';
- *bp = '\0';
- syslog(dbg, flog, "%s", bytes);
- }
- /*
- * replace one occurrence of %[ICE] with ip, cfgpxe name, or ether mac, resp.
- * we can't easily use $ because u-boot has stranger quoting rules than sh.
- */
- char *
- mapname(char *file)
- {
- int nf;
- char *p, *newnm, *cur, *arpf, *ln, *remip, *bang;
- char *fields[4];
- Biobuf *arp;
- p = strchr(file, '%');
- if (p == nil || p[1] == '\0')
- return strdup(file);
- remip = strdup(raddr);
- newnm = mallocz(strlen(file) + Maxpath, 1);
- if (remip == nil || newnm == nil)
- sysfatal("out of memory");
- bang = strchr(remip, '!');
- if (bang)
- *bang = '\0'; /* remove !port */
- memmove(newnm, file, p - file); /* copy up to % */
- cur = newnm + strlen(newnm);
- switch(p[1]) {
- case 'I':
- strcpy(cur, remip); /* remote's IP */
- break;
- case 'C':
- strcpy(cur, "/cfg/pxe/");
- cur += strlen(cur);
- /* fall through */
- case 'E':
- /* look up remote's IP in /net/arp to get mac. */
- arpf = smprint("%s/arp", net);
- arp = Bopen(arpf, OREAD);
- free(arpf);
- if (arp == nil)
- break;
- /* read lines looking for remip in 3rd field of 4 */
- while ((ln = Brdline(arp, '\n')) != nil) {
- ln[Blinelen(arp)-1] = 0;
- nf = tokenize(ln, fields, nelem(fields));
- if (nf >= 4 && strcmp(fields[2], remip) == 0) {
- strcpy(cur, fields[3]);
- break;
- }
- }
- Bterm(arp);
- break;
- }
- strcat(newnm, p + 2); /* tail following %x */
- free(remip);
- return newnm;
- }
- void
- doserve(int fd)
- {
- int dlen, opts;
- char *mode, *p, *file;
- short op;
- dlen = read(fd, bigbuf, sizeof(bigbuf)-1);
- if(dlen < 0)
- sysfatal("listen read: %r");
- bigbuf[dlen] = '\0';
- op = (bigbuf[0]<<8) | bigbuf[1];
- dlen -= Opsize;
- mode = file = bigbuf + Opsize;
- while(*mode != '\0' && dlen--)
- mode++;
- mode++;
- p = mode;
- while(*p && dlen--)
- p++;
- file = mapname(file); /* we don't free the result; minor leak */
- if(dlen == 0) {
- nak(fd, 0, "bad tftpmode");
- close(fd);
- syslog(dbg, flog, "tftpd %d bad mode %s for file %s from %s",
- pid, mode, file, raddr);
- return;
- }
- if(op != Tftp_READ && op != Tftp_WRITE) {
- nak(fd, Errbadop, "Illegal TFTP operation");
- close(fd);
- syslog(dbg, flog, "tftpd %d bad request %d (%s) %s", pid, op,
- (op < nelem(opnames)? opnames[op]: "gok"), raddr);
- return;
- }
- if(restricted){
- if(file[0] == '#' || strncmp(file, "../", 3) == 0 ||
- strstr(file, "/../") != nil ||
- (file[0] == '/' && strncmp(file, dirsl, dirsllen) != 0)){
- nak(fd, Errnoaccess, "Permission denied");
- close(fd);
- syslog(dbg, flog, "tftpd %d bad request %d from %s file %s",
- pid, op, raddr, file);
- return;
- }
- }
- /*
- * options are supposed to be negotiated, but the cavium board's
- * u-boot really wants us to use a block size of 1432 bytes and won't
- * take `no' for an answer.
- */
- p++; /* skip NUL after mode */
- dlen--;
- opts = 0;
- if(dlen > 0) { /* might have options */
- char bytes[32*1024];
- if(Debug)
- optlog(bytes, p, dlen);
- opts = options(fd, bytes, sizeof bytes, file, op, p, dlen);
- if (opts < 0)
- return;
- }
- if(op == Tftp_READ)
- sendfile(fd, file, mode, opts);
- else
- recvfile(fd, file, mode);
- }
- void
- catcher(void *junk, char *msg)
- {
- USED(junk);
- if(strncmp(msg, "exit", 4) == 0)
- noted(NDFLT);
- noted(NCONT);
- }
- static int
- awaitack(int fd, int block)
- {
- int ackblock, al, rxl;
- ushort op;
- uchar ack[1024];
- for(rxl = 0; rxl < 10; rxl++) {
- memset(ack, 0, Hdrsize);
- alarm(1000);
- al = read(fd, ack, sizeof(ack));
- alarm(0);
- if(al < 0) {
- if (Debug)
- syslog(dbg, flog, "tftpd %d timed out "
- "waiting for ack from %s", pid, raddr);
- return Ackrexmit;
- }
- op = ack[0]<<8|ack[1];
- if(op == Tftp_ERROR) {
- if (Debug)
- syslog(dbg, flog, "tftpd %d got error "
- "waiting for ack from %s", pid, raddr);
- return Ackerr;
- } else if(op != Tftp_ACK) {
- syslog(dbg, flog, "tftpd %d rcvd %s op from %s", pid,
- (op < nelem(opnames)? opnames[op]: "gok"),
- raddr);
- return Ackerr;
- }
- ackblock = ack[2]<<8|ack[3];
- if (Debug)
- syslog(dbg, flog, "tftpd %d read ack of %d bytes "
- "for block %d", pid, al, ackblock);
- if(ackblock == block)
- return Ackok; /* for block just sent */
- else if(ackblock == block + 1) /* intel pxe eof bug */
- return Ackok;
- else if(ackblock == 0xffff)
- return Ackrexmit;
- else
- /* ack is for some other block; ignore it, try again */
- syslog(dbg, flog, "tftpd %d expected ack for block %d, "
- "got %d", pid, block, ackblock);
- }
- return Ackrexmit;
- }
- void
- sendfile(int fd, char *name, char *mode, int opts)
- {
- int file, block, ret, rexmit, n, txtry;
- uchar buf[Maxsegsize+Hdrsize];
- char errbuf[Maxerr];
- file = -1;
- syslog(dbg, flog, "tftpd %d send file '%s' %s to %s",
- pid, name, mode, raddr);
- name = sunkernel(name);
- if(name == 0){
- nak(fd, 0, "not in our database");
- goto error;
- }
- notify(catcher);
- file = open(name, OREAD);
- if(file < 0) {
- errstr(errbuf, sizeof errbuf);
- nak(fd, 0, errbuf);
- goto error;
- }
- block = 0;
- rexmit = Ackok;
- n = 0;
- /*
- * if we sent an oack previously, wait for the client's ack or error.
- * if we get no ack for our oack, it could be that we returned
- * a tsize that the client can't handle, or it could be intel
- * pxe just read-with-tsize to get size, couldn't be bothered to
- * ack our oack and has just gone ahead and issued another read.
- */
- if(opts && awaitack(fd, 0) != Ackok)
- goto error;
- for(txtry = 0; txtry < timeout;) {
- if(rexmit == Ackok) {
- block++;
- buf[0] = 0;
- buf[1] = Tftp_DATA;
- buf[2] = block>>8;
- buf[3] = block;
- n = read(file, buf+Hdrsize, blksize);
- if(n < 0) {
- errstr(errbuf, sizeof errbuf);
- nak(fd, 0, errbuf);
- goto error;
- }
- txtry = 0;
- }
- else {
- syslog(dbg, flog, "tftpd %d rexmit %d %s:%d to %s",
- pid, Hdrsize+n, name, block, raddr);
- txtry++;
- }
- ret = write(fd, buf, Hdrsize+n);
- if(ret < Hdrsize+n) {
- syslog(dbg, flog,
- "tftpd network write error on %s to %s: %r",
- name, raddr);
- sysfatal("tftpd: network write error: %r");
- }
- if (Debug)
- syslog(dbg, flog, "tftpd %d sent block %d", pid, block);
- rexmit = awaitack(fd, block);
- if (rexmit == Ackerr)
- break;
- if(ret != blksize+Hdrsize && rexmit == Ackok)
- break;
- }
- syslog(dbg, flog, "tftpd %d done sending file '%s' %s to %s",
- pid, name, mode, raddr);
- error:
- close(fd);
- close(file);
- }
- void
- recvfile(int fd, char *name, char *mode)
- {
- ushort op, block, inblock;
- uchar buf[Maxsegsize+8];
- char errbuf[Maxerr];
- int n, ret, file;
- syslog(dbg, flog, "receive file '%s' %s from %s", name, mode, raddr);
- file = create(name, OWRITE, 0666);
- if(file < 0) {
- errstr(errbuf, sizeof errbuf);
- nak(fd, 0, errbuf);
- syslog(dbg, flog, "can't create %s: %r", name);
- return;
- }
- block = 0;
- ack(fd, block);
- block++;
- for (;;) {
- alarm(15000);
- n = read(fd, buf, blksize+8);
- alarm(0);
- if(n < 0) {
- syslog(dbg, flog, "tftpd: network error reading %s: %r",
- name);
- goto error;
- }
- /*
- * NB: not `<='; just a header is legal and happens when
- * file being read is a multiple of segment-size bytes long.
- */
- if(n < Hdrsize) {
- syslog(dbg, flog,
- "tftpd: short read from network, reading %s",
- name);
- goto error;
- }
- op = buf[0]<<8|buf[1];
- if(op == Tftp_ERROR) {
- syslog(dbg, flog, "tftpd: tftp error reading %s", name);
- goto error;
- }
- n -= Hdrsize;
- inblock = buf[2]<<8|buf[3];
- if(op == Tftp_DATA) {
- if(inblock == block) {
- ret = write(file, buf+Hdrsize, n);
- if(ret != n) {
- errstr(errbuf, sizeof errbuf);
- nak(fd, 0, errbuf);
- syslog(dbg, flog,
- "tftpd: error writing %s: %s",
- name, errbuf);
- goto error;
- }
- ack(fd, block);
- block++;
- } else
- ack(fd, 0xffff); /* tell him to resend */
- }
- }
- error:
- close(file);
- }
- void
- ack(int fd, ushort block)
- {
- uchar ack[4];
- int n;
- ack[0] = 0;
- ack[1] = Tftp_ACK;
- ack[2] = block>>8;
- ack[3] = block;
- n = write(fd, ack, 4);
- if(n < 4)
- sysfatal("network write: %r");
- }
- void
- nak(int fd, int code, char *msg)
- {
- char buf[128];
- int n;
- buf[0] = 0;
- buf[1] = Tftp_ERROR;
- buf[2] = 0;
- buf[3] = code;
- strcpy(buf+4, msg);
- n = strlen(msg) + 4 + 1;
- if(write(fd, buf, n) < n)
- sysfatal("write nak: %r");
- }
- void
- setuser(void)
- {
- int fd;
- fd = open("#c/user", OWRITE);
- if(fd < 0 || write(fd, "none", strlen("none")) < 0)
- sysfatal("can't become none: %r");
- close(fd);
- if(newns("none", nil) < 0)
- sysfatal("can't build namespace: %r");
- }
- char*
- lookup(char *sattr, char *sval, char *tattr, char *tval, int len)
- {
- static Ndb *db;
- char *attrs[1];
- Ndbtuple *t;
- if(db == nil)
- db = ndbopen(0);
- if(db == nil)
- return nil;
- if(sattr == nil)
- sattr = ipattr(sval);
- attrs[0] = tattr;
- t = ndbipinfo(db, sattr, sval, attrs, 1);
- if(t == nil)
- return nil;
- strncpy(tval, t->val, len);
- tval[len-1] = 0;
- ndbfree(t);
- return tval;
- }
- /*
- * for sun kernel boots, replace the requested file name with
- * a one from our database. If the database doesn't specify a file,
- * don't answer.
- */
- char*
- sunkernel(char *name)
- {
- ulong addr;
- uchar v4[IPv4addrlen];
- uchar v6[IPaddrlen];
- char buf[256];
- char ipbuf[128];
- char *suffix;
- addr = strtoul(name, &suffix, 16);
- if(suffix-name != 8 || (strcmp(suffix, "") != 0 && strcmp(suffix, ".SUN") != 0))
- return name;
- v4[0] = addr>>24;
- v4[1] = addr>>16;
- v4[2] = addr>>8;
- v4[3] = addr;
- v4tov6(v6, v4);
- sprint(ipbuf, "%I", v6);
- return lookup("ip", ipbuf, "bootf", buf, sizeof buf);
- }
- void
- remoteaddr(char *dir, char *raddr, int len)
- {
- char buf[64];
- int fd, n;
- snprint(buf, sizeof(buf), "%s/remote", dir);
- fd = open(buf, OREAD);
- if(fd < 0){
- snprint(raddr, sizeof(raddr), "unknown");
- return;
- }
- n = read(fd, raddr, len-1);
- close(fd);
- if(n <= 0){
- snprint(raddr, sizeof(raddr), "unknown");
- return;
- }
- if(n > 0)
- n--;
- raddr[n] = 0;
- }
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