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TFTP: block id wrap bug fix

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In a normal expression, doing [unsigned short] + 1 will not wrap
at 16 bits so the comparisons and outputs were done wrong. I
added a macro do make sure it gets done right.

Douglas Kilpatrick filed bug report #3004787 about it:
http://curl.haxx.se/bug/view.cgi?id=3004787
This commit is contained in:
Daniel Stenberg 2010-05-21 23:04:15 +02:00
parent 700335103e
commit 0a29e2445c
3 changed files with 19 additions and 8 deletions
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6
CHANGES
View File

@ -6,6 +6,12 @@
Changelog
Daniel Stenberg (21 May 2010)
- Douglas Kilpatrick filed bug report #3004787 and pointed out that the TFTP
code didn't handle block id wraps correctly. His suggested fix inspired the
fix I committed.
(http://curl.haxx.se/bug/view.cgi?id=3004787)
Daniel Stenberg (20 May 2010)
- Tanguy Fautre brought a fix to allow curl to build with Microsoft VC10.

3
RELEASE-NOTES
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@ -31,6 +31,7 @@ This release includes the following bugfixes:
o ignore response-body on redirect even if compressed
o OpenSSL handshake state-machine for multi interface
o TFTP timeout option sent correctly
o TFTP block id wrap
This release includes the following known bugs:
@ -41,6 +42,6 @@ advice from friends like these:
Rainer Canavan, Paul Howarth, Jerome Vouillon, Ruslan Gazizov, Yang Tse,
Kamil Dudka, Alex Bligh, Ben Greear, Hoi-Ho Chan, Howard Chu, Dirk Manske,
Pavel Raiskup, John-Mark Bell, Eric Mertens, Tor Arntsen
Pavel Raiskup, John-Mark Bell, Eric Mertens, Tor Arntsen, Douglas Kilpatrick
Thanks! (and sorry if I forgot to mention someone)

18
lib/tftp.c
View File

@ -572,6 +572,10 @@ static CURLcode tftp_send_first(tftp_state_data_t *state, tftp_event_t event)
return res;
}
/* the next blocknum is x + 1 but it needs to wrap at an unsigned 16bit
boundary */
#define NEXT_BLOCKNUM(x) (((x)+1)&0xffff)
/**********************************************************
*
* tftp_rx
@ -590,14 +594,14 @@ static CURLcode tftp_rx(tftp_state_data_t *state, tftp_event_t event)
case TFTP_EVENT_DATA:
/* Is this the block we expect? */
rblock = getrpacketblock(&state->rpacket);
if((state->block+1) != rblock) {
if(NEXT_BLOCKNUM(state->block) != rblock) {
/* No, log it, up the retry count and fail if over the limit */
infof(data,
"Received unexpected DATA packet block %d\n", rblock);
state->retries++;
if(state->retries>state->retry_max) {
failf(data, "tftp_rx: giving up waiting for block %d",
state->block+1);
NEXT_BLOCKNUM(state->block));
return CURLE_TFTP_ILLEGAL;
}
}
@ -650,7 +654,7 @@ static CURLcode tftp_rx(tftp_state_data_t *state, tftp_event_t event)
state->retries++;
infof(data,
"Timeout waiting for block %d ACK. Retries = %d\n",
state->block+1, state->retries);
NEXT_BLOCKNUM(state->block), state->retries);
if(state->retries > state->retry_max) {
state->error = TFTP_ERR_TIMEOUT;
state->state = TFTP_STATE_FIN;
@ -773,7 +777,7 @@ static CURLcode tftp_tx(tftp_state_data_t *state, tftp_event_t event)
/* Increment the retry counter and log the timeout */
state->retries++;
infof(data, "Timeout waiting for block %d ACK. "
" Retries = %d\n", state->block+1, state->retries);
" Retries = %d\n", NEXT_BLOCKNUM(state->block), state->retries);
/* Decide if we've had enough */
if(state->retries > state->retry_max) {
state->error = TFTP_ERR_TIMEOUT;
@ -1102,10 +1106,10 @@ static CURLcode tftp_receive_packet(struct connectdata *conn)
case TFTP_EVENT_DATA:
/* Don't pass to the client empty or retransmitted packets */
if(state->rbytes > 4 &&
((state->block+1) == getrpacketblock(&state->rpacket))) {
(NEXT_BLOCKNUM(state->block) == getrpacketblock(&state->rpacket))) {
result = Curl_client_write(conn, CLIENTWRITE_BODY,
(char *)state->rpacket.data+4,
state->rbytes-4);
(char *)state->rpacket.data+4,
state->rbytes-4);
if(result) {
tftp_state_machine(state, TFTP_EVENT_ERROR);
return result;