RE: [dspam-users] Example.c File

The fact that it worked before (with a different version of dspam) might
have been a fluke. I've had many cases of pointer problems being masked for
months if not years, and then a change to the "shape" of the memory has
caused the problems to appear.

By memory shape, I mean layout of structures in memory, alignment on or
around memory page boundaries, size of call stacks which can be changed by
use of new structures, changing definitions of existing structures, adding
or subtracting variables, even adding or subtracting significant amounts of
code.

I suspect the simple act of upgrading the dspam api might have caused your
memory shape to have changed, exposing an existing problem.

You may want to run valgrind (free memory debugger for Linux) on your
system, and watch particularly for uninitialized memory usage and misaligned
memory access. Be sure to exercise as many paths of your code as possible.
I have a theory that memory errors are most often accompanied by logic
errors in nearby locations, such that running a memory debugger often leads
to other problems being detected and fixed.

>From: ". kibble ." <jelly_bean_junky@hotmail.com>
>
>Got it working, however not in a way that I totally think is right... I've
>classified the message to generate the signature [&SIG] and then set it as
>you pointed out was wrong in the last email.
>
>However I'm not entirely sure why it worked before and not now... Was there
>some piece of code which worked out that CTX->signature was NULL and then
>reclassified the message anyways?? If this has changed, I'm curious to know
>why exactly, redundant code perhaps... Only the developers will know. [Care
>to shed any light in this area]
>
>Anyway's, here what I did for future use and thank you for the help:
>/** some function or another... */
> int sflag = 0;
> char * message = malloc(1);
> DSPAM_CTX * CTX = NULL; /** DSPAM Context */
> struct _ds_spam_signature SIG; /** Example signature */
>
> message = read_emailmem(message);
>
> switch (spamflag) {
> case SPAMREPT: /** set up the context for error correction as spam */
> /** log_write(0, LOG_MAIN, "LOG: SPAMREPT function reached"); */
> CTX = dspam_create((char *)sender_address, NULL, NULL, DSM_PROCESS,
>DSF_CHAINED);
> CTX = attach_ctx_dbaccess(CTX);
> if (CTX == NULL) {
> log_write(0, LOG_MAIN, "ERROR: dspam_create failed!\n");
> sflag = 1;
> }
> CTX->classification = DSR_ISSPAM;
> CTX->source = DSS_ERROR;
> CTX->algorithms = DSA_GRAHAM | DSA_BURTON | DSP_GRAHAM;
> break;
> case FALSEPOS: /** set up the context for error correction as innocent */
> /** log_write(0, LOG_MAIN, "LOG: FALSEPOS function reached"); */
> CTX = dspam_create((char *)sender_address, NULL, NULL, DSM_PROCESS,
>DSF_SBPH | DSF_SIGNATURE | DSF_NOISE);
> CTX = attach_ctx_dbaccess(CTX);
> if (CTX == NULL) {
> log_write(0, LOG_MAIN, "dspam_create failed!");
> break;
> }
> CTX->algorithms = DSA_GRAHAM | DSA_BURTON | DSP_GRAHAM;
> if (dspam_process(CTX, message) != 0) { /** Call DSPAM's processor with
>the message text */
> log_write(0, LOG_MAIN, "dspam_process failed!");
> dspam_destroy(CTX);
> break;
> }
> if (CTX->signature != NULL) {
> SIG.data = malloc(CTX->signature->length);
> if (SIG.data != NULL) {
> memcpy(SIG.data, CTX->signature->data, CTX->signature->length);
> }
> }
> SIG.length = CTX->signature->length;
>
> dspam_destroy(CTX); /** Destroy the context */
> memset(&CTX, 0x0, sizeof(CTX));
> free(CTX);
>
> CTX = dspam_create((char *)sender_address, NULL, NULL, DSM_PROCESS,
>DSF_CHAINED | DSF_SIGNATURE);
> CTX = attach_ctx_dbaccess(CTX);
> if (CTX == NULL) {
> log_write(0, LOG_MAIN, "ERROR: dspam_create failed!\n");
> sflag = 1;
> }
> CTX->classification = DSR_ISINNOCENT;
> CTX->source = DSS_ERROR;
> CTX->algorithms = DSA_GRAHAM | DSA_BURTON | DSP_GRAHAM;
> CTX->signature = &SIG; /** Attach the signature to the context */
> break;
> default: /** no reporting required, scan for spam perhaps ? */
> log_write(0, LOG_MAIN, "report_spam -> no reporting required");
> break;
> }
>
> /** log_write(0, LOG_MAIN, "LOG: Processing spam..."); */
> if (dspam_process(CTX, message) != 0) { /** Call DSPAM */
> log_write(0, LOG_MAIN, "ERROR: dspam_process failed!");
> sflag = 1;
> }
>
>/** end of snippit */
>
>>From: ". kibble ." <jelly_bean_junky@hotmail.com>
>>To: dspam-users@lists.nuclearelephant.com
>>Subject: RE: [dspam-users] Example.c File
>>Date: Wed, 07 Sep 2005 22:11:47 +0100
>>
>>
>>Excellent, thanks for the pointer, I will do this over the next few days
>>as I'm away but will take the laptop with me and a copy of dspam's source
>>code to review...
>>
>>>From: "Russ Fink" <russfink@hotmail.com>
>>>To: jelly_bean_junky@hotmail.com, dspam-users@lists.nuclearelephant.com
>>>Subject: RE: [dspam-users] Example.c File
>>>Date: Wed, 07 Sep 2005 11:21:22 -0400
>>>
>>>Sorry, I have been out for a few days.
>>>
>>>From your code snippet, I don't see where SIG is getting populated, just
>>>declared. The code sets CTX->signature to &SIG, but SIG has nothing in
>>>it - just an empty structure at this point. You need to populate it
>>>using the driver of MySQL.
>>>
>>>My advice, what I would have to do, is look at how dspam.c does it. Grep
>>>for "signature" and you should find the answer.
>>>
>>>In generic terms, the spam "signature" is really a unique identifier
>>>assigned by the back-end database implementation. In the case of
>>>sqlite3, it takes a hash of the system time and date and assigns that as
>>>the signature of the message. Of course, this assumes only one message
>>>is processed at a given time/date, and I believe this will be changed at
>>>some point in the future. The "CTX->signature" is a pointer to the
>>>signature structure, which is created from this hash by a call.
>>>
>>>If you're using pristine mode, no signature is needed, and no signature
>>>is generated.
>>>
>>>Spend some time with dspam.c and it should help. I think that's kinda
>>>what everyone else does that programs directly to the API.
>>>
>>>Russ
>>>
>>>>>>int report_spam(int spamflag) {
>>>>>>
>>>>>> int sflag = 0;
>>>>>> char * message = malloc(1);
>>>>>> DSPAM_CTX * CTX = NULL; /** DSPAM Context */
>>>>>> struct _ds_spam_signature SIG; /** Example signature */
>>>>>>
>>>>>> message = read_emailmem(message);
>>>>>>
>>>>>> switch (spamflag) {
>>>>>> case SPAMREPT: /** set up the context for error correction
>>>>>>as spam */
>>>>>> log_write(0, LOG_MAIN, "LOG: SPAMREPT function reached");
>>>>>> CTX = dspam_create((char *)sender_address, NULL, NULL,
>>>>>>DSM_PROCESS, DSF_CHAINED);
>>>>>> CTX = attach_ctx_dbaccess(CTX);
>>>>>> if (CTX == NULL) {
>>>>>> log_write(0, LOG_MAIN, "ERROR: dspam_create
>>>>>>failed!\n");
>>>>>> sflag = 1;
>>>>>> }
>>>>>> CTX->classification = DSR_ISSPAM;
>>>>>> CTX->source = DSS_ERROR;
>>>>>> CTX->algorithms = DSA_GRAHAM | DSA_BURTON |
>>>>>>DSP_GRAHAM;
>>>>>> break;
>>>>>> case FALSEPOS: /** set up the context for error correction
>>>>>>as innocent */
>>>>>> log_write(0, LOG_MAIN, "LOG: FALSEPOS function reached");
>>>>>> CTX = dspam_create((char *)sender_address, NULL, NULL,
>>>>>>DSM_PROCESS, DSF_CHAINED | DSF_SIGNATURE);
>>>>>> CTX = attach_ctx_dbaccess(CTX);
>>>>>> if (CTX == NULL) {
>>>>>> log_write(0, LOG_MAIN, "ERROR: dspam_create
>>>>>>failed!\n");
>>>>>> sflag = 1;
>>>>>> }
>>>>>> CTX->classification = DSR_ISINNOCENT;
>>>>>> CTX->source = DSS_ERROR;
>>>>>> CTX->algorithms = DSA_GRAHAM | DSA_BURTON |
>>>>>>DSP_GRAHAM;
>>>>>> CTX->signature = &SIG; /** Attach the signature to
>>>>>>the context */
>>>>>> break;
>>>>>> default: /** no reporting required, scan for spam perhaps ?
>>>>>>*/
>>>>>> log_write(0, LOG_MAIN, "report_spam -> no reporting
>>>>>>required");
>>>>>> break;
>>>>>> }
>>>>>>
>>>>>> log_write(0, LOG_MAIN, "LOG: Processing spam...");
>>>>>> if (dspam_process(CTX, message) != 0) { /** Call DSPAM */
>>>>>> log_write(0, LOG_MAIN, "ERROR: dspam_process failed!");
>>>>>> sflag = 1;
>>>>>> }
>>>>>>
>>>>>> log_write(0, LOG_MAIN, "ERROR: report_spam: dspam_destroy
>>>>>>beginning");
>>>>>> dspam_destroy(CTX); /** Destroy the context */
>>>>>>
>>>>>> memset(message, 0x0, sizeof(message));
>>>>>> free(message);
>>>>>> memset(&CTX, 0x0, sizeof(CTX));
>>>>>> free(CTX);
>>>>>>
>>>>>> if (sflag == 0) {
>>>>>> log_write(0, LOG_MAIN, "<= %s [%s] P=%s A=%s:%s",
>>>>>> (char *)sender_address, (char *)sender_host_address, (char
>>>>>>*)received_protocol,
>>>>>> (char *)sender_host_authenticated, (char
>>>>>>*)sender_address);
>>>>>> log_write(0, LOG_MAIN, "=> (null) <%s> R=system_localuser
>>>>>>T=local_delivery",
>>>>>> (char *)recipients_list[0].address);
>>>>>> }
>>>>>>
>>>>>> /** if we are reporting, which is pretty much so if you reach
>>>>>>here, we blackhole the email */
>>>>>> recipients_count = 0;
>>>>>>
>>>>>> return(sflag);
>>>>>>} /** report_spam */
>>>
>>>
>>
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Received on Sat Sep 10 10:52:14 2005