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