PATCH: diablo style hashfeeds
"Miquel van Smoorenburg"
list-inn-workers at news.cistron.nl
Mon Mar 24 00:18:34 UTC 2008
In article <D837E9C8EA3F4A50BB80C3F1B49ED58D at Iulius>,
Julien ÉLIE <julien at trigofacile.com> wrote:
>Hi Miquel,
>
>It should be:
>
> md5_update(&context, (unsigned char *)MessageID, strlen(MessageID));
[..]
>I would put the quickhash calculation in the condition
>(hf->type == HASHFEED_QH) because it is otherwise always computed.
[..]
>Hmm... Something is then missing in the documentation:
[..]
> return "incorrect hash values for Q";
[..]
>+ 'Q', '^@?\d(-\d)?/\d(:\d)?$',
[..]
Thanks for all the suggestions. A revised version is attached. I
took your suggestion to change the offset separation character
from ':' to '_'. In fact I had already changed it to ';' in my
development version - but forgot to update the patch. I like ';'
more, but in case INN ever moves to bind-like syntax for config
files the ';' might not be a good choise.
diff -ruN t/inn-2.4.3/doc/pod/newsfeeds.pod inn-2.4.3/doc/pod/newsfeeds.pod
--- t/inn-2.4.3/doc/pod/newsfeeds.pod 2006-03-20 05:14:57.000000000 +0100
+++ inn-2.4.3/doc/pod/newsfeeds.pod 2008-03-24 01:06:28.000000000 +0100
@@ -382,6 +382,43 @@
new process will run with. This flag can be used to raise the priority to
normal if you're using the I<nicekids> parameter in F<inn.conf>.
+=item B<Q> I<hashfeed>
+
+The hashfeed match expression for this site. It must be in the form
+C<value/mod> or C<start-end/mod>. The message-id of the article is
+hashed using MD5, which results in a 128 bit hash. The lowest 32 bits
+(by default) are then taken as the C<hashfeed value>. If the hashfeed
+value modulus C<mod> plus one equals C<number> or is between C<start>
+and C<end>, the article will be fed to the site.
+
+Example:
+
+ Q1/2 Feeds about 50% of all articles to this site
+ Q2/2 Feeds the other 50% of all articles
+
+ Q1-3/10 Feeds about 30% of all articles
+ Q4-5/10 Feeds about 20% of all articles
+ Q6-10/10 Feeds about 50% of all articles
+
+If this flag is specified multiple times the contents will be
+logically ORed together (just one match needed).
+
+You can use an extended syntax of the form C<start-end/mod_offset>.
+As MD5 generates a 128-bit return value, it is possible to specify
+from which byte-offset the 32-bit integer used by hashfeed starts.
+The default for C<offset> is C<_0> and thirteen overlapping values
+from C<_0> to C<_12> can be used. Only four totally independent
+values exist: C<_0>, C<_4>, C<_8> and C<_12>.
+
+Therefore, it allows to a generate a second level of deterministic
+distribution. Indeed, if a news server is fed C<Q1/2>, it can go on
+splitting thanks to C<Q1-3/9_4> for instance.
+
+The algorithm is compatible with the one used by Diablo 5.1 and up.
+If you want to use the hashing method Diablo used before 5.1,
+put an '@' sign just after the 'Q' (for example: Q at 1/2). Note that
+offsets can't be used with the older hashing method.
+
=item B<S> I<size>
If the amount of data queued for the site gets to be larger than I<size>
diff -ruN t/inn-2.4.3/innd/art.c inn-2.4.3/innd/art.c
--- t/inn-2.4.3/innd/art.c 2006-03-20 05:14:57.000000000 +0100
+++ inn-2.4.3/innd/art.c 2008-03-24 00:54:08.000000000 +0100
@@ -9,6 +9,7 @@
#include "inn/innconf.h"
#include "inn/wire.h"
+#include "inn/md5.h"
#include "innd.h"
#include "ov.h"
#include "storage.h"
@@ -1553,6 +1562,88 @@
}
/*
+** Even though we have already calculated the message-id MD5sum,
+** we have to do it again since unfortunately HashMessageID()
+** lowercases the message-id first.
+*/
+
+static unsigned int
+HashFeedMD5(char *MessageID, unsigned int offset)
+{
+ static char LastMessageID[128];
+ static char *LastMessageIDPtr;
+ static struct md5_context context;
+ unsigned int ret;
+
+ if (offset > 12)
+ return 0;
+
+ /* Some light caching */
+ if (MessageID != LastMessageIDPtr ||
+ strcmp(MessageID, LastMessageID) != 0) {
+ md5_init(&context);
+ md5_update(&context, (unsigned char *)MessageID, strlen(MessageID));
+ md5_final(&context);
+ LastMessageIDPtr = MessageID;
+ strncpy(LastMessageID, MessageID, sizeof(LastMessageID) - 1);
+ LastMessageID[sizeof(LastMessageID) - 1] = 0;
+ }
+
+ memcpy(&ret, &context.digest[12 - offset], 4);
+
+ return ntohl(ret);
+}
+
+/*
+** Old-style diablo quickhash
+**
+*/
+static unsigned int
+HashFeedQH(char *MessageID, unsigned int *tmp)
+{
+ unsigned char *p;
+ unsigned int h;
+ int n;
+
+ if (*tmp != (unsigned int)-1)
+ return *tmp;
+
+ p = (unsigned char *)MessageID;
+ n = 0;
+ while (*p)
+ n += *p++;
+ *tmp = (unsigned int)n;
+
+ return *tmp;
+}
+
+/*
+** Return true if an element of the HASHFEEDLIST matches
+** the hash of the message-id.
+*/
+static bool
+HashFeedMatch(HASHFEEDLIST *hf, char *MessageID)
+{
+ unsigned int qh = (unsigned int)-1;
+ unsigned int h;
+
+ while (hf) {
+ if (hf->type == HASHFEED_MD5)
+ h = HashFeedMD5(MessageID, hf->offset);
+ else if (hf->type == HASHFEED_QH)
+ h = HashFeedQH(MessageID, &qh);
+ else
+ continue;
+ if ((h % hf->mod + 1) >= hf->begin &&
+ (h % hf->mod + 1) <= hf->end)
+ return true;
+ hf = hf->next;
+ }
+
+ return false;
+}
+
+/*
** Propagate an article to the sites have "expressed an interest."
*/
static void
@@ -1625,6 +1716,11 @@
* cross-posting. */
continue;
+ if (sp->HashFeedList &&
+ !HashFeedMatch(sp->HashFeedList, HDR(HDR__MESSAGE_ID)))
+ /* hashfeed doesn't match */
+ continue;
+
if (list && *list != NULL && sp->Distributions &&
!DISTwantany(sp->Distributions, list))
/* Not in the site's desired list of distributions. */
diff -ruN t/inn-2.4.3/innd/innd.h inn-2.4.3/innd/innd.h
--- t/inn-2.4.3/innd/innd.h 2006-03-20 05:14:57.000000000 +0100
+++ inn-2.4.3/innd/innd.h 2008-03-24 00:52:29.000000000 +0100
@@ -407,6 +409,22 @@
/*
+** Diablo-style hashed feeds or hashfeeds.
+*/
+#define HASHFEED_QH 1
+#define HASHFEED_MD5 2
+
+typedef struct _HASHFEEDLIST {
+ int type;
+ unsigned int begin;
+ unsigned int end;
+ unsigned int mod;
+ unsigned int offset;
+ struct _HASHFEEDLIST *next;
+} HASHFEEDLIST;
+
+
+/*
** A site may reject something in its subscription list if it has
** too many hops, or a bad distribution.
*/
@@ -458,6 +476,7 @@
struct buffer Buffer;
bool Buffered;
char ** Originator;
+ HASHFEEDLIST * HashFeedList;
int Next;
int Prev;
} SITE;
diff -ruN t/inn-2.4.3/innd/newsfeeds.c inn-2.4.3/innd/newsfeeds.c
--- t/inn-2.4.3/innd/newsfeeds.c 2006-03-20 05:14:57.000000000 +0100
+++ inn-2.4.3/innd/newsfeeds.c 2008-03-24 00:51:43.000000000 +0100
@@ -448,6 +448,7 @@
int isp;
SITE *nsp;
struct buffer b;
+ HASHFEEDLIST *hf;
b = sp->Buffer;
*sp = SITEnull;
@@ -467,6 +468,7 @@
sp->NeedOverviewCreation = false;
sp->FeedwithoutOriginator = false;
sp->DropFiltered = false;
+ sp->HashFeedList = NULL;
/* Nip off the first field, the site name. */
if ((f2 = strchr(Entry, NF_FIELD_SEP)) == NULL)
@@ -603,6 +605,36 @@
if (*++p && CTYPE(isdigit, *p))
sp->Nice = atoi(p);
break;
+ case 'Q':
+ hf = xmalloc(sizeof(HASHFEEDLIST));
+ p++;
+ if (*p == '@') {
+ p++;
+ hf->type = HASHFEED_QH;
+ } else
+ hf->type = HASHFEED_MD5;
+ if ((u = strchr(p, '_')) != NULL) {
+ if (sscanf(u + 1, "%u", &hf->offset) != 1 || hf->offset > 12) {
+ free(hf);
+ return "invalid hash offset for Q";
+ }
+ } else
+ hf->offset = 0;
+ if (sscanf(p, "%u-%u/%u", &hf->begin, &hf->end, &hf->mod) != 3) {
+ if (sscanf(p, "%u/%u", &hf->begin, &hf->mod) == 2) {
+ hf->end = hf->begin;
+ } else {
+ free(hf);
+ return "hash not in x/z or x-y/z format for Q";
+ }
+ if (hf->begin > hf->end || hf->end > hf->mod) {
+ free(hf);
+ return "incorrect hash values for Q";
+ }
+ }
+ hf->next = sp->HashFeedList;
+ sp->HashFeedList = hf;
+ break;
case 'S':
if (*++p && CTYPE(isdigit, *p))
sp->StartSpooling = atol(p);
diff -ruN t/inn-2.4.3/innd/site.c inn-2.4.3/innd/site.c
--- t/inn-2.4.3/innd/site.c 2006-03-20 05:14:57.000000000 +0100
+++ inn-2.4.3/innd/site.c 2008-03-15 14:52:31.000000000 +0100
@@ -997,6 +1004,7 @@
SITEfree(SITE *sp)
{
SITE *s;
+ HASHFEEDLIST *hf, *hn;
int new;
int i;
@@ -1051,6 +1059,13 @@
sp->FNLnames.data = NULL;
sp->FNLnames.size = 0;
}
+ if (sp->HashFeedList) {
+ for (hf = sp->HashFeedList; hf; hf = hn) {
+ hn = hf->next;
+ free(hf);
+ }
+ sp->HashFeedList = NULL;
+ }
/* If this site was a master, find a new one. */
if (sp->IsMaster) {
diff -ruN t/inn-2.4.3/scripts/inncheck.in inn-2.4.3/scripts/inncheck.in
--- t/inn-2.4.3/scripts/inncheck.in 2006-03-20 05:14:57.000000000 +0100
+++ inn-2.4.3/scripts/inncheck.in 2008-03-24 00:54:49.000000000 +0100
@@ -367,6 +367,7 @@
'N', '^[mu]$',
'O', '^\S+$',
'P', '^\d+$',
+ 'Q', '^@?\d(-\d)?/\d(:\d)?$',
'S', '^\d+$',
'T', '^[cflmpx]$',
'W', '^[befghmnpst*DGHNPOR]*$',
--
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