95 lines
4.0 KiB
Diff
95 lines
4.0 KiB
Diff
atftp exhibits the well known "Sorcerer's Apprentice Syndrome"(SAS) problem.
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According to RFC 1350, the fix to SAS is quite simple: further copies of the
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acknowledgment for a particular data block would be ignored.
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Patch originally from OpenSUSE:
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https://build.opensuse.org/package/view_file?file=atftp-0.7-sorcerers_apprentice.patch&package=atftp.539&project=openSUSE%3A12.1%3AUpdate&rev=84569792975e00573d7df597d2a6e895
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Upstream-Status: Pending
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Signed-off-by: Roy.Li <rongqing.li@windriver.com>
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Index: atftp-0.7/tftp_file.c
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===================================================================
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--- atftp-0.7.orig/tftp_file.c 2011-11-22 15:12:53.792744083 +0100
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+++ atftp-0.7/tftp_file.c 2011-11-22 15:13:51.706421893 +0100
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@@ -605,6 +605,7 @@
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int timeout_state = state; /* what state should we go on when timeout */
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int result;
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long block_number = 0;
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+ long last_requested_block = -1;
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long last_block = -1;
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int data_size; /* size of data received */
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int sockfd = data->sockfd; /* just to simplify calls */
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@@ -765,6 +766,17 @@
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connected = 1;
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}
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block_number = ntohs(tftphdr->th_block);
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+
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+ if (last_requested_block >= block_number)
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+ {
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+ if (data->trace)
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+ fprintf(stderr, "received duplicated ACK <block: %ld >= %ld>\n",
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+ last_requested_block, block_number);
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+ break;
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+ }
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+ else
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+ last_requested_block = block_number;
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+
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if (data->trace)
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fprintf(stderr, "received ACK <block: %ld>\n",
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block_number);
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Index: atftp-0.7/tftpd_file.c
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===================================================================
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--- atftp-0.7.orig/tftpd_file.c 2011-11-22 15:12:53.793744112 +0100
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+++ atftp-0.7/tftpd_file.c 2011-11-22 15:15:04.617534260 +0100
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@@ -403,6 +403,7 @@
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int timeout_state = state;
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int result;
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long block_number = 0;
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+ long last_requested_block = -1;
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long last_block = -1;
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int block_loops = 0;
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int data_size;
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@@ -859,6 +860,32 @@
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{
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logger(LOG_DEBUG, "received ACK <block: %d>", block_number);
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}
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+
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+ /* check whether the block request isn't already fulfilled */
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+
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+ /* multicast, block numbers could contain gaps */
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+ if (multicast) {
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+ if (last_requested_block >= block_number)
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+ {
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+ if (data->trace)
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+ logger(LOG_DEBUG, "received duplicated ACK <block: %d >= %d>", last_requested_block, block_number);
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+ break;
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+ }
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+ else
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+ last_requested_block = block_number;
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+ /* unicast, blocks should be requested one after another */
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+ } else {
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+ if (last_requested_block + 1 != block_number && last_requested_block != -1)
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+ {
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+ if (data->trace)
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+ logger(LOG_DEBUG, "received out of order ACK <block: %d != %d>", last_requested_block + 1, block_number);
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+ break;
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+ }
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+ else
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+ last_requested_block = block_number;
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+ }
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+
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+
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if (ntohs(tftphdr->th_block) == 65535)
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{
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block_loops++;
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@@ -958,6 +985,8 @@
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/* nedd to send an oack to that client */
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state = S_SEND_OACK;
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fseek(fp, 0, SEEK_SET);
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+ /* reset the last block received counter */
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+ last_requested_block = -1;
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}
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else
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{
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