[tin 1.7.x] filter.c/nntplib.c fix for broken OVER(view)

the following patch is against a crash seen on news.mozilla.org
(which is horrible broken (OVER response if different fom XOVER
response and dosen't follow draft-ietf-nntpext-base-27.txt) in
netscape.public.beta.feedback.help (which has a lot of "broken" overview
entries in the OVER case) with a filter entry based on message-id
(and other stuff which isn't relevant in this case)
asthe server responses to LIST EXTENSIONS and claims it knows OVER
tin uses OVER instead of XOVER...

| OVER 294-308
| 224 data follows
| Subject:From:Date:Bytes:Lines
| 294	4282 monografia monografias teses =?ISO-8859-1?Q?disserta=E7=F5es?=  trabalhos escolares 4282	"monografia " <[email protected]>	Wed, 20 Apr 2005 00:11:41-0300 824	14
[...]
| XOVER -
| 224 data follows
| 294	4282 monografia monografias teses =?ISO-8859-1?Q?disserta=E7=F5es?=  trabalhos escolares 4282	"mongrafia  " <[email protected]>	Wed, 20 Apr 2005 00:11:41-0300	<[email protected]>	824	14
[...]

here is what gdb said:
| #0  0x080592f9 in test_regex (string=0x14 <Address 0x14 out of bounds>, regex=Variable "regex" is not available.) at ./filter.c:211
| #1  0x0805c32b in filter_articles (group=0x8141a78) at ./filter.c:1960
| #2  0x0804f55d in index_group (group=0x8141a78) at ./art.c:478 
[...]
| (gdb) frame 1
| #1  0x0805c32b in filter_articles (group=0x8141a78) at ./filter.c:1960
| 1960                                                    x = test_regex(mymsgid, ptr[j].msgid, FALSE, &regex_cache_msgid[j]);
| (gdb) print *group
| $1 = {name = 0x81bbba8 "netscape.public.beta.feedback.help", aliasedto = 0x0, 
|  description = 0x81bd9c8 "?", spooldir = 0x8126000 "", moderated = 121 'y',
|  count = -1, xmax = 308, xmin = 188, type = 1, inrange = 0, 
|  read_during_session = 1, art_was_posted = 0, subscribed = 0, newgroup = 0,
|  bogus = 0, next = -1, newsrc = {present = 1, num_unread = 15, xmax = 308,
|    xmin = 188, xbitlen = 121, xbitmap = 0x81bf288 ""}, attribute = 0x8114040, glob_filter = 0x80fc340}
| (gdb) print *group->glob_filter
| $2 = {max = 36, num = 36, filter = 0x81bdca0}
| (gdb) print *group->glob_filter->filter
| $3 = {comment = 0x0, scope = 0x81bbce8 "*,!akk.*,!tin.*,!local.*,!control*",
|      subj = 0x81bbd98 "(?:^(?:(?:A[Ww]|REPOST|re)\\s?:|[^a-z\\d]+?$|[!?*]|[Rr]e:\\S)|[*$!?]{3,})(?# case sensitive!)",
|      from = 0x81bc2a0 "(?:\\s+[a-z]|(?:(?i)(?:^\\S+\\s*\\S+$|\\s\\s|\\bname\\b|root@|(?:aol|hotmail|bigfoot|yahoo|mailexcite|poboxes)\\.com|@(?:cww|bigfoot|germanynet|cityweb)\\.de|@(?:earthlink|usa)\\.net|^[^(]*(?<=\\.invalid)\\s?)))",
|      msgid = 0x81bbd78 "(?i)<(?:repost|\\S{40,}@)", lines_cmp = 2 '\002', 
|      lines_num = 4, gnksa_cmp = 0 '\0', gnksa_num = 0, score = -31,
|      xref = 0x81bc370 "(([^,]+,){30,}|(^|,)(junk|control)($|,)|(^|,)(alt\\.){6,})",
|      time = 0, next = 0x81bdcd8, inscope = 1, icase = 0, fullref = 6}
| (gdb) print i
| $6 = 0
| (gdb) print *&arts[0]
| $8 = {artnum = 294,  
|   subject = 0x81bed90 "4282 monografia monografias teses dissertações trabalhos escolares 4282", from = 0x81be700 "[email protected]",
|   name = 0x81b5760 "monografia ", gnksa_code = 0, date = 1113966701, 
|   xref = 0x0, msgid = 0x0, refs = 0x0, refptr = 0x0, line_count = -1,
                                         ^^^^^^^^^^^^^
|   archive = 0x0, tagged = 0, thread = -1, prev = -1, score = 0, status = 1,
|   killed = 0, zombie = 0, delete_it = 0, selected = 0, inrange = 0, matched = 0}
| (gdb) print *&arts[0]->refptr->txt
| Cannot access memory at address 0x14

there might be other locations in the code which need similar
protection

--- filter.c	2005-06-28 10:31:21.000000000 +0200
+++ filter.c	2005-07-06 02:56:24.967010142 +0200
@@ -77,8 +74,8 @@
  * Easier access to hashed msgids. Note that in REFS(), y must be free()d
  * msgid is mandatory in an article and cannot be NULL
  */
-#define MSGID(x)			(x->refptr->txt)
-#define REFS(x,y)			((y = get_references(x->refptr->parent)) ? y : "")
+#define MSGID(x)			(x->refptr ? x->refptr->txt : "")
+#define REFS(x,y)			((y = get_references(x->refptr ? x->refptr->parent : NULL)) ? y : "")
 
 /*
  * global filter array
@@ -1936,7 +1933,7 @@
 							break;
 
 						case FILTER_MSGID_LAST:
-							myrefs = (art->refptr->parent) ? art->refptr->parent->txt : "";
+							myrefs = art->refptr ? (art->refptr->parent ? art->refptr->parent->txt : "") : "";
 							mymsgid = MSGID(art);
 							break;
 
--- nntplib.c	2005-06-28 10:31:21.000000000 +0200
+++ nntplib.c	2005-07-06 03:45:14.777744512 +0200
@@ -1104,9 +1104,13 @@
 		buf[0] = '\0';
 		i = new_nntp_command("LIST EXTENSIONS", OK_EXTENSIONS, buf, sizeof(buf));
 		switch (i) {
+			case 215:	/* Netscape-Collabra/3.52 is badly broken; NetWare-News-Server/5.1 */
+				while ((ptr = tin_fgets(FAKE_NNTP_FP, FALSE)) != NULL)
+					;
+				break;
+			
 			case OK_EXTENSIONS:	/* as defined draft-ietf-nntpext-base-24.txt */
 			case 205:	/* M$ Exchange 5.5 */
-			case 215:	/* Netscape-Collabra/3.52 && NetWare-News-Server/5.1 */
 				nntp_caps.type = LIST_EXTENSIONS;
 				while ((ptr = tin_fgets(FAKE_NNTP_FP, FALSE)) != NULL) {
 					if (nntp_caps.type == LIST_EXTENSIONS) {