ref: 403fef45c1a65aa74c449764e2857597fc03290a
dir: /sys/src/cmd/ip/tftpd.c/
/*
* 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>
enum
{
Maxpath= 128,
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);
void remoteaddr(char*, char*, int);
void doserve(int);
char bigbuf[32768];
char raddr[64];
char *dirsl;
int dirsllen;
char *homedir = "/";
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':
homedir = 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
dirsllen = strlen(homedir);
while(dirsllen > 0 && homedir[dirsllen-1] == '/')
dirsllen--;
dirsl = smprint("%.*s/", utfnlen(homedir, dirsllen), homedir);
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(homedir) < 0)
sysfatal("can't get to directory %s: %r", homedir);
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;
olen = 0;
op = handleopt(fd, p, val);
if (op == nil)
continue;
nopts++;
/* 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 & 0xffff))
return Ackok; /* for block just sent */
else if(ackblock == (block + 1 & 0xffff)) /* 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[ERRMAX];
syslog(dbg, flog, "tftpd %d send file '%s' %s to %s",
pid, name, mode, raddr);
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[ERRMAX];
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: %s", name, errbuf);
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;
n = 5 + strlen(msg);
if(n > sizeof(buf))
n = sizeof(buf);
buf[0] = 0;
buf[1] = Tftp_ERROR;
buf[2] = 0;
buf[3] = code;
memmove(buf+4, msg, n - 5);
buf[n-1] = 0;
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");
}
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;
}