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Fixes to newer tftp code in libstand:

Browse Source 
(1) Coding style changes.
 (2) If the server does not acknowledge any blocksize option,
     revert to the default blocksize of 512 bytes.
 (3) Send ACK if the first packet happens to be the last packet.
 (4) Do not accept blocksize greater than what was requested.
 (5) Drop any unwanted OACK received if a tftp transfer is already
     in progress.
 (6) Terminate incomplete transfers with a special no-error ERROR packet.
     Otherwise we rely on the tftp server to time out, which it does
     eventually, after re-sending the last packet several times and spamming
     the system log about it every time.  This idea is borrowed from the
     PXE client, which does exactly that.

Submitted by:  Alexander Kabaev <kan@FreeBSD.org>
Reviewed and Tested by: Santhanakrishnan Balraj <sbalraj at juniper dot net>
This commit is contained in:
Craig Rodrigues 2011-06-24 03:50:54 +00:00
parent 14de21443e
commit 23a5bce73f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=223488
1 changed files with 132 additions and 51 deletions
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183
lib/libstand/tftp.c
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@ -64,13 +64,13 @@ struct tftp_handle;
static int tftp_open(const char *path, struct open_file *f);
static int tftp_close(struct open_file *f);
static void tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len);
static int tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len);
static int tftp_read(struct open_file *f, void *buf, size_t size, size_t *resid);
static int tftp_write(struct open_file *f, void *buf, size_t size, size_t *resid);
static off_t tftp_seek(struct open_file *f, off_t offset, int where);
static int tftp_set_blksize(struct tftp_handle *h, const char *str);
static int tftp_stat(struct open_file *f, struct stat *sb);
static ssize_t sendrecv_tftp(struct tftp_handle *h,
static ssize_t sendrecv_tftp(struct tftp_handle *h,
ssize_t (*sproc)(struct iodesc *, void *, size_t),
void *sbuf, size_t ssize,
ssize_t (*rproc)(struct tftp_handle *h, void *, ssize_t, time_t, unsigned short *),
@ -93,7 +93,7 @@ static int tftpport = 2000;
static int is_open = 0;
/*
* The legacy TFTP_BLKSIZE value was 512.
* The legacy TFTP_BLKSIZE value was SEGSIZE(512).
* TFTP_REQUESTED_BLKSIZE of 1428 is (Ethernet MTU, less the TFTP, UDP and
* IP header lengths).
*/
@ -102,7 +102,7 @@ static int is_open = 0;
/*
* Choose a blksize big enough so we can test with Ethernet
* Jumbo frames in the future.
*/
*/
#define TFTP_MAX_BLKSIZE 9008
struct tftp_handle {
@ -113,7 +113,7 @@ struct tftp_handle {
int off;
char *path; /* saved for re-requests */
unsigned int tftp_blksize;
unsigned long tftp_tsize;
unsigned long tftp_tsize;
struct {
u_char header[HEADER_SIZE];
struct tftphdr t;
@ -121,7 +121,8 @@ struct tftp_handle {
} __packed __aligned(4) lastdata;
};
static const int tftperrors[8] = {
#define TFTP_MAX_ERRCODE EOPTNEG
static const int tftperrors[TFTP_MAX_ERRCODE + 1] = {
0, /* ??? */
ENOENT,
EPERM,
@ -129,10 +130,57 @@ static const int tftperrors[8] = {
EINVAL, /* ??? */
EINVAL, /* ??? */
EEXIST,
EINVAL /* ??? */
EINVAL, /* ??? */
EINVAL, /* Option negotiation failed. */
};
static ssize_t
static int tftp_getnextblock(struct tftp_handle *h);
/* send error message back. */
static void
tftp_senderr(struct tftp_handle *h, u_short errcode, const char *msg)
{
struct {
u_char header[HEADER_SIZE];
struct tftphdr t;
u_char space[63]; /* +1 from t */
} __packed __aligned(4) wbuf;
char *wtail;
int len;
len = strlen(msg);
if (len > sizeof(wbuf.space))
len = sizeof(wbuf.space);
wbuf.t.th_opcode = htons((u_short) ERROR);
wbuf.t.th_code = htons(errcode);
wtail = wbuf.t.th_msg;
bcopy(msg, wtail, len);
wtail[len] = '\0';
wtail += len + 1;
sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
}
static void
tftp_sendack(struct tftp_handle *h)
{
struct {
u_char header[HEADER_SIZE];
struct tftphdr t;
} __packed __aligned(4) wbuf;
char *wtail;
wbuf.t.th_opcode = htons((u_short) ACK);
wtail = (char *) &wbuf.t.th_block;
wbuf.t.th_block = htons((u_short) h->currblock);
wtail += 2;
sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
}
static ssize_t
recvtftp(struct tftp_handle *h, void *pkt, ssize_t len, time_t tleft,
unsigned short *rtype)
{
@ -170,7 +218,7 @@ recvtftp(struct tftp_handle *h, void *pkt, ssize_t len, time_t tleft,
return got;
}
case ERROR:
if ((unsigned) ntohs(t->th_code) >= 8) {
if ((unsigned) ntohs(t->th_code) > TFTP_MAX_ERRCODE) {
printf("illegal tftp error %d\n", ntohs(t->th_code));
errno = EIO;
} else {
@ -182,14 +230,30 @@ recvtftp(struct tftp_handle *h, void *pkt, ssize_t len, time_t tleft,
return (-1);
case OACK: {
struct udphdr *uh;
int tftp_oack_len = len - sizeof(t->th_opcode);
tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len);
int tftp_oack_len;
/*
* Unexpected OACK. TFTP transfer already in progress.
* Drop the pkt.
*/
if (d->xid != 1) {
return (-1);
}
/*
* Remember which port this OACK came from,
* because we need to send the ACK back to it.
* Remember which port this OACK came from, because we need
* to send the ACK or errors back to it.
*/
uh = (struct udphdr *) pkt - 1;
d->destport = uh->uh_sport;
/* Parse options ACK-ed by the server. */
tftp_oack_len = len - sizeof(t->th_opcode);
if (tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len) != 0) {
tftp_senderr(h, EOPTNEG, "Malformed OACK");
errno = EIO;
return (-1);
}
return (0);
}
default:
@ -201,7 +265,7 @@ recvtftp(struct tftp_handle *h, void *pkt, ssize_t len, time_t tleft,
}
/* send request, expect first block (or error) */
static int
static int
tftp_makereq(struct tftp_handle *h)
{
struct {
@ -250,26 +314,28 @@ tftp_makereq(struct tftp_handle *h)
h->iodesc->destport = htons(IPPORT_TFTP);
h->iodesc->xid = 1; /* expected block */
h->currblock = 0;
h->islastblock = 0;
h->validsize = 0;
res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
&recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);
if (rtype == OACK) {
wbuf.t.th_opcode = htons((u_short)ACK);
wtail = (char *) &wbuf.t.th_block;
wbuf.t.th_block = htons(0);
wtail += 2;
rtype = 0;
res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
&recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);
}
if (rtype == OACK)
return (tftp_getnextblock(h));
/* Server ignored our blksize request, revert to TFTP default. */
h->tftp_blksize = SEGSIZE;
switch (rtype) {
case DATA: {
h->currblock = 1;
h->validsize = res;
h->islastblock = 0;
if (res < h->tftp_blksize)
if (res < h->tftp_blksize) {
h->islastblock = 1; /* very short file */
tftp_sendack(h);
}
return (0);
}
case ERROR:
@ -320,7 +386,7 @@ tftp_getnextblock(struct tftp_handle *h)
return (0);
}
static int
static int
tftp_open(const char *path, struct open_file *f)
{
struct tftp_handle *tftpfile;
@ -365,7 +431,7 @@ tftp_open(const char *path, struct open_file *f)
return (0);
}
static int
static int
tftp_read(struct open_file *f, void *addr, size_t size,
size_t *resid /* out */)
{
@ -381,9 +447,11 @@ tftp_read(struct open_file *f, void *addr, size_t size,
needblock = tftpfile->off / tftpfile->tftp_blksize + 1;
if (tftpfile->currblock > needblock) /* seek backwards */
if (tftpfile->currblock > needblock) { /* seek backwards */
tftp_senderr(tftpfile, 0, "No error: read aborted");
tftp_makereq(tftpfile); /* no error check, it worked
* for open */
}
while (tftpfile->currblock < needblock) {
int res;
@ -452,7 +520,7 @@ tftp_close(struct open_file *f)
return (0);
}
static int
static int
tftp_write(struct open_file *f __unused, void *start __unused, size_t size __unused,
size_t *resid __unused /* out */)
{
@ -473,7 +541,7 @@ tftp_stat(struct open_file *f, struct stat *sb)
return (0);
}
static off_t
static off_t
tftp_seek(struct open_file *f, off_t offset, int where)
{
struct tftp_handle *tftpfile;
@ -494,7 +562,7 @@ tftp_seek(struct open_file *f, off_t offset, int where)
}
static ssize_t
sendrecv_tftp(struct tftp_handle *h,
sendrecv_tftp(struct tftp_handle *h,
ssize_t (*sproc)(struct iodesc *, void *, size_t),
void *sbuf, size_t ssize,
ssize_t (*rproc)(struct tftp_handle *, void *, ssize_t, time_t, unsigned short *),
@ -562,9 +630,9 @@ tftp_set_blksize(struct tftp_handle *h, const char *str)
/*
* Only accept blksize value if it is numeric.
* RFC2348 specifies that acceptable valuesare 8-65464
* 8-65464 . Let's choose a limit less than MAXRSPACE
*/
* RFC2348 specifies that acceptable values are 8-65464.
* Let's choose a limit less than MAXRSPACE.
*/
if (*endptr == '\0' && new_blksize >= 8
&& new_blksize <= TFTP_MAX_BLKSIZE) {
h->tftp_blksize = new_blksize;
@ -597,13 +665,12 @@ tftp_set_blksize(struct tftp_handle *h, const char *str)
* optN, valueN
* The final option/value acknowledgment pair.
*/
static void
static int
tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
{
/*
* We parse the OACK strings into an array
* of name-value pairs.
*
*/
char *tftp_options[128] = { 0 };
char *val = buf;
@ -612,18 +679,22 @@ tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
int blksize_is_set = 0;
int tsize = 0;
while ( option_idx < 128 && i < len ) {
if (buf[i] == '\0') {
if (&buf[i] > val) {
tftp_options[option_idx] = val;
val = &buf[i] + 1;
++option_idx;
}
}
++i;
unsigned int orig_blksize;
while (option_idx < 128 && i < len) {
if (buf[i] == '\0') {
if (&buf[i] > val) {
tftp_options[option_idx] = val;
val = &buf[i] + 1;
++option_idx;
}
}
++i;
}
/* Save the block size we requested for sanity check later. */
orig_blksize = h->tftp_blksize;
/*
* Parse individual TFTP options.
* * "blksize" is specified in RFC2348.
@ -631,27 +702,37 @@ tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
*/
for (i = 0; i < option_idx; i += 2) {
if (strcasecmp(tftp_options[i], "blksize") == 0) {
if (i + 1 < option_idx) {
if (i + 1 < option_idx)
blksize_is_set =
tftp_set_blksize(h, tftp_options[i + 1]);
}
} else if (strcasecmp(tftp_options[i], "tsize") == 0) {
if (i + 1 < option_idx) {
if (i + 1 < option_idx)
tsize = strtol(tftp_options[i + 1], (char **)NULL, 10);
}
} else {
/* Do not allow any options we did not expect to be ACKed. */
printf("unexpected tftp option '%s'\n", tftp_options[i]);
return (-1);
}
}
if (!blksize_is_set) {
/*
* If TFTP blksize was not set, try defaulting
* to the legacy TFTP blksize of 512
* to the legacy TFTP blksize of SEGSIZE(512)
*/
h->tftp_blksize = 512;
h->tftp_blksize = SEGSIZE;
} else if (h->tftp_blksize > orig_blksize) {
/*
* Server should not be proposing block sizes that
* exceed what we said we can handle.
*/
printf("unexpected blksize %u\n", h->tftp_blksize);
return (-1);
}
#ifdef TFTP_DEBUG
printf("tftp_blksize: %u\n", h->tftp_blksize);
printf("tftp_tsize: %lu\n", h->tftp_tsize);
#endif
return 0;
}