File atftp-0.7-ack_heuristic.patch of Package atftp
Index: tftpd_file.c
===================================================================
--- tftpd_file.c.orig
+++ tftpd_file.c
@@ -406,7 +406,6 @@ int tftpd_send_file(struct thread_data *
int timeout_state = state;
int result;
long block_number = 0;
- long last_requested_block = -1;
long last_block = -1;
int data_size;
struct sockaddr_storage *sa = &data->client_info->client;
@@ -434,6 +433,11 @@ int tftpd_send_file(struct thread_data *
long prev_file_pos = 0;
int temp = 0;
+ long prev_sent_block = -1;
+ int prev_sent_count = 0;
+ int prev_ack_count = 0;
+ int curr_sent_count = 0;
+
/* look for mode option */
if (strcasecmp(data->tftp_options[OPT_MODE].value, "netascii") == 0)
{
@@ -819,8 +823,8 @@ int tftpd_send_file(struct thread_data *
&client_info->client));
sa = &client_info->client;
- /* rewind the last_requested_block counter */
- last_requested_block = -1;
+ /* rewind the prev_sent_block counter */
+ prev_sent_block = -1;
state = S_SEND_OACK;
break;
@@ -895,6 +899,7 @@ int tftpd_send_file(struct thread_data *
"source port mismatch, check bypassed");
}
}
+
/* The ACK is from the current client */
number_of_timeout = 0;
if (multicast)
@@ -908,24 +913,82 @@ int tftpd_send_file(struct thread_data *
logger(LOG_DEBUG, "received ACK <block: %ld>",
block_number);
- /* if turned on, check whether the block request isn't already fulfilled */
- if (tftpd_prevent_sas) {
- /* multicast, block numbers could contain gaps */
- if (multicast) {
- if (last_requested_block >= block_number) {
+ /* Now check the ACK number and possibly ignore the request */
+
+ /* multicast, block numbers could contain gaps */
+ if (multicast) {
+ /* if turned on, check whether the block request isn't already fulfilled */
+ if (tftpd_prevent_sas) {
+ if (prev_sent_block >= block_number) {
if (data->trace)
- logger(LOG_DEBUG, "received duplicated ACK <block: %d >= %d>", last_requested_block, block_number);
+ logger(LOG_DEBUG, "received duplicated ACK <block: %d >= %d>", prev_sent_block, block_number);
break;
} else
- last_requested_block = block_number;
- /* unicast, blocks should be requested one after another */
- } else {
- if (last_requested_block + 1 != block_number && last_requested_block != -1) {
+ prev_sent_block = block_number;
+ }
+ /* don't prevent thes SAS */
+ /* use a heuristic suggested by Vladimir Nadvornik */
+ else {
+ /* here comes the ACK again */
+ if (prev_sent_block == block_number) {
+ /* drop if number of ACKs == times of previous block sending */
+ if (++prev_ack_count == prev_sent_count) {
+ logger(LOG_DEBUG, "ACK count (%d) == previous block transmission count -> dropping ACK", prev_ack_count);
+ break;
+ }
+ /* else resend the block */
+ logger(LOG_DEBUG, "resending block %d", block_number + 1);
+ }
+ /* received ACK to sent block -> move on to next block */
+ else if (prev_sent_block < block_number) {
+ prev_sent_block = block_number;
+ prev_sent_count = curr_sent_count;
+ curr_sent_count = 0;
+ prev_ack_count = 1;
+ }
+ /* block with low number -> ignore it completely */
+ else {
+ logger(LOG_DEBUG, "ignoring ACK %d", block_number);
+ break;
+ }
+ }
+ /* unicast, blocks should be requested one after another */
+ } else {
+ /* if turned on, check whether the block request isn't already fulfilled */
+ if (tftpd_prevent_sas) {
+ if (prev_sent_block + 1 != block_number) {
+ logger(LOG_WARNING, "timeout: retrying...");
if (data->trace)
- logger(LOG_DEBUG, "received out of order ACK <block: %d != %d>", last_requested_block + 1, block_number);
+ logger(LOG_DEBUG, "received out of order ACK <block: %d != %d>", prev_sent_block + 1, block_number);
break;
- } else
- last_requested_block = block_number;
+ } else {
+ prev_sent_block = block_number;
+ }
+ /* don't prevent thes SAS */
+ /* use a heuristic suggested by Vladimir Nadvornik */
+ } else {
+ /* here comes the ACK again */
+ if (prev_sent_block == block_number) {
+ /* drop if number of ACKs == times of previous block sending */
+ if (++prev_ack_count == prev_sent_count) {
+ logger(LOG_DEBUG, "ACK count (%d) == previous block transmission count -> dropping ACK", prev_ack_count);
+ break;
+ }
+ /* else resend the block */
+ logger(LOG_DEBUG, "resending block %d", block_number + 1);
+ }
+ /* received ACK to sent block -> move on to next block */
+ else if (prev_sent_block < block_number) {
+ prev_sent_block = block_number;
+ prev_sent_count = curr_sent_count;
+ curr_sent_count = 0;
+ prev_ack_count = 1;
+ }
+ /* nor previous nor current block number -> ignore it completely */
+ else {
+ logger(LOG_DEBUG, "ignoring ACK %d", block_number);
+ break;
+ }
}
}
@@ -934,6 +997,8 @@ int tftpd_send_file(struct thread_data *
state = S_END;
break;
}
+
+ curr_sent_count++;
state = S_SEND_DATA;
break;
case GET_ERROR:
@@ -1028,7 +1093,7 @@ int tftpd_send_file(struct thread_data *
state = S_SEND_OACK;
fseek(fp, 0, SEEK_SET);
/* reset the last block received counter */
- last_requested_block = -1;
+ prev_sent_block = -1;
}
else
{
