xref: /plan9/sys/src/cmd/ip/imap4d/msg.c (revision ff8c3af2f44d95267f67219afa20ba82ff6cf7e4)
1 #include <u.h>
2 #include <libc.h>
3 #include <bio.h>
4 #include <libsec.h>
5 #include <auth.h>
6 #include <fcall.h>
7 #include "imap4d.h"
8 
9 static void	body64(int in, int out);
10 static void	bodystrip(int in, int out);
11 static void	cleanupHeader(Header *h);
12 static char	*domBang(char *s);
13 static void	freeMAddr(MAddr *a);
14 static void	freeMimeHdr(MimeHdr *mh);
15 static char	*headAddrSpec(char *e, char *w);
16 static MAddr	*headAddresses(void);
17 static MAddr	*headAddress(void);
18 static char	*headAtom(char *disallowed);
19 static int	headChar(int eat);
20 static char	*headDomain(char *e);
21 static MAddr	*headMAddr(MAddr *old);
22 static char	*headPhrase(char *e, char *w);
23 static char	*headQuoted(int start, int stop);
24 static char	*headSkipWhite(int);
25 static void	headSkip(void);
26 static char	*headSubDomain(void);
27 static char	*headText(void);
28 static void	headToEnd(void);
29 static char	*headWord(void);
30 static void	mimeDescription(Header *h);
31 static void	mimeDisposition(Header *h);
32 static void	mimeEncoding(Header *h);
33 static void	mimeId(Header *h);
34 static void	mimeLanguage(Header *h);
35 static void	mimeMd5(Header *h);
36 static MimeHdr	*mimeParams(void);
37 static void	mimeType(Header *h);
38 static MimeHdr	*mkMimeHdr(char *s, char *t, MimeHdr *next);
39 static void	msgAddDate(Msg *m);
40 static void	msgAddHead(Msg *m, char *head, char *body);
41 static int	msgBodySize(Msg *m);
42 static int	msgHeader(Msg *m, Header *h, char *file);
43 static long	msgReadFile(Msg *m, char *file, char **ss);
44 static int	msgUnix(Msg *m, int top);
45 static void	stripQuotes(char *q);
46 static MAddr	*unixFrom(char *s);
47 
48 
49 static char bogusBody[] =
50 	"This message contains null characters, so it cannot be displayed correctly.\r\n"
51 	"Most likely you were sent a bogus message or a binary file.\r\n"
52 	"\r\n"
53 	"Each of the following attachments has a different version of the message.\r\n"
54 	"The first is inlined with all non-printable characters stripped.\r\n"
55 	"The second contains the message as it was stored in your mailbox.\r\n"
56 	"The third has the initial header stripped.\r\n";
57 
58 static char bogusMimeText[] =
59 	"Content-Disposition: inline\r\n"
60 	"Content-Type: text/plain; charset=\"US-ASCII\"\r\n"
61 	"Content-Transfer-Encoding: 7bit\r\n";
62 
63 static char bogusMimeBinary[] =
64 	"Content-Disposition: attachment\r\n"
65 	"Content-Type: application/octet-stream\r\n"
66 	"Content-Transfer-Encoding: base64\r\n";
67 
68 /*
69  * stop list for header fields
70  */
71 static char	*headFieldStop = ":";
72 static char	*mimeTokenStop = "()<>@,;:\\\"/[]?=";
73 static char	*headAtomStop = "()<>@,;:\\\".[]";
74 static uchar	*headStr;
75 static uchar	*lastWhite;
76 
77 long
78 selectFields(char *dst, long n, char *hdr, SList *fields, int matches)
79 {
80 	SList *f;
81 	uchar *start;
82 	char *s;
83 	long m, nf;
84 
85 	headStr = (uchar*)hdr;
86 	m = 0;
87 	for(;;){
88 		start = headStr;
89 		s = headAtom(headFieldStop);
90 		if(s == nil)
91 			break;
92 		headSkip();
93 		for(f = fields; f != nil; f = f->next){
94 			if(cistrcmp(s, f->s) == !matches){
95 				nf = headStr - start;
96 				if(m + nf > n)
97 					return 0;
98 				memmove(&dst[m], start, nf);
99 				m += nf;
100 			}
101 		}
102 		free(s);
103 	}
104 	if(m + 3 > n)
105 		return 0;
106 	dst[m++] = '\r';
107 	dst[m++] = '\n';
108 	dst[m] = '\0';
109 	return m;
110 }
111 
112 void
113 freeMsg(Msg *m)
114 {
115 	Msg *k, *last;
116 
117 	free(m->iBuf);
118 	freeMAddr(m->to);
119 	if(m->replyTo != m->from)
120 		freeMAddr(m->replyTo);
121 	if(m->sender != m->from)
122 		freeMAddr(m->sender);
123 	if(m->from != m->unixFrom)
124 		freeMAddr(m->from);
125 	freeMAddr(m->unixFrom);
126 	freeMAddr(m->cc);
127 	freeMAddr(m->bcc);
128 	free(m->unixDate);
129 	cleanupHeader(&m->head);
130 	cleanupHeader(&m->mime);
131 	for(k = m->kids; k != nil; ){
132 		last = k;
133 		k = k->next;
134 		freeMsg(last);
135 	}
136 	free(m);
137 }
138 
139 ulong
140 msgSize(Msg *m)
141 {
142 	return m->head.size + m->size;
143 }
144 
145 int
146 infoIsNil(char *s)
147 {
148 	return s == nil || s[0] == '\0';
149 }
150 
151 char*
152 maddrStr(MAddr *a)
153 {
154 	char *host, *addr;
155 	int n;
156 
157 	host = a->host;
158 	if(host == nil)
159 		host = "";
160 	n = strlen(a->box) + strlen(host) + 2;
161 	if(a->personal != nil)
162 		n += strlen(a->personal) + 3;
163 	addr = emalloc(n);
164 	if(a->personal != nil)
165 		snprint(addr, n, "%s <%s@%s>", a->personal, a->box, host);
166 	else
167 		snprint(addr, n, "%s@%s", a->box, host);
168 	return addr;
169 }
170 
171 /*
172  * return actual name of f in m's fs directory
173  * this is special cased when opening m/rawbody, m/mimeheader, or m/rawheader,
174  * if the message was corrupted.  in that case,
175  * a temporary file is made to hold the base64 encoding of m/raw.
176  */
177 int
178 msgFile(Msg *m, char *f)
179 {
180 	Msg *parent, *p;
181 	Dir d;
182 	Tm tm;
183 	char buf[64], nbuf[2];
184 	uchar dbuf[64];
185 	int i, n, fd, fd1, fd2;
186 
187 	if(!m->bogus
188 	|| strcmp(f, "") != 0 && strcmp(f, "rawbody") != 0
189 	&& strcmp(f, "rawheader") != 0 && strcmp(f, "mimeheader") != 0
190 	&& strcmp(f, "info") != 0 && strcmp(f, "unixheader") != 0){
191 		if(strlen(f) > MsgNameLen)
192 			bye("internal error: msgFile name too long");
193 		strcpy(m->efs, f);
194 		return cdOpen(m->fsDir, m->fs, OREAD);
195 	}
196 
197 	/*
198 	 * walk up the stupid runt message parts for non-multipart messages
199 	 */
200 	parent = m->parent;
201 	if(parent != nil && parent->parent != nil){
202 		m = parent;
203 		parent = m->parent;
204 	}
205 	p = m;
206 	if(parent != nil)
207 		p = parent;
208 
209 	if(strcmp(f, "info") == 0 || strcmp(f, "unixheader") == 0){
210 		strcpy(p->efs, f);
211 		return cdOpen(p->fsDir, p->fs, OREAD);
212 	}
213 
214 	fd = imapTmp();
215 	if(fd < 0)
216 		return -1;
217 
218 	/*
219 	 * craft the message parts for bogus messages
220 	 */
221 	if(strcmp(f, "") == 0){
222 		/*
223 		 * make a fake directory for each kid
224 		 * all we care about is the name
225 		 */
226 		if(parent == nil){
227 			nulldir(&d);
228 			d.mode = DMDIR|0600;
229 			d.qid.type = QTDIR;
230 			d.name = nbuf;
231 			nbuf[1] = '\0';
232 			for(i = '1'; i <= '4'; i++){
233 				nbuf[0] = i;
234 				n = convD2M(&d, dbuf, sizeof(dbuf));
235 				if(n <= BIT16SZ)
236 					fprint(2, "bad convD2M %d\n", n);
237 				write(fd, dbuf, n);
238 			}
239 		}
240 	}else if(strcmp(f, "mimeheader") == 0){
241 		if(parent != nil){
242 			switch(m->id){
243 			case 1:
244 			case 2:
245 				fprint(fd, "%s", bogusMimeText);
246 				break;
247 			case 3:
248 			case 4:
249 				fprint(fd, "%s", bogusMimeBinary);
250 				break;
251 			}
252 		}
253 	}else if(strcmp(f, "rawheader") == 0){
254 		if(parent == nil){
255 			date2tm(&tm, m->unixDate);
256 			rfc822date(buf, sizeof(buf), &tm);
257 			fprint(fd,
258 				"Date: %s\r\n"
259 				"From: imap4 daemon <%s@%s>\r\n"
260 				"To: <%s@%s>\r\n"
261 				"Subject: This message was illegal or corrupted\r\n"
262 				"MIME-Version: 1.0\r\n"
263 				"Content-Type: multipart/mixed;\r\n\tboundary=\"upas-%s\"\r\n",
264 					buf, username, site, username, site, m->info[IDigest]);
265 		}
266 	}else if(strcmp(f, "rawbody") == 0){
267 		fd1 = msgFile(p, "raw");
268 		strcpy(p->efs, "rawbody");
269 		fd2 = cdOpen(p->fsDir, p->fs, OREAD);
270 		if(fd1 < 0 || fd2 < 0){
271 			close(fd);
272 			close(fd1);
273 			close(fd2);
274 			return -1;
275 		}
276 		if(parent == nil){
277 			fprint(fd,
278 				"This is a multi-part message in MIME format.\r\n"
279 				"--upas-%s\r\n"
280 				"%s"
281 				"\r\n"
282 				"%s"
283 				"\r\n",
284 					m->info[IDigest], bogusMimeText, bogusBody);
285 
286 			fprint(fd,
287 				"--upas-%s\r\n"
288 				"%s"
289 				"\r\n",
290 					m->info[IDigest], bogusMimeText);
291 			bodystrip(fd1, fd);
292 
293 			fprint(fd,
294 				"--upas-%s\r\n"
295 				"%s"
296 				"\r\n",
297 					m->info[IDigest], bogusMimeBinary);
298 			seek(fd1, 0, 0);
299 			body64(fd1, fd);
300 
301 			fprint(fd,
302 				"--upas-%s\r\n"
303 				"%s"
304 				"\r\n",
305 					m->info[IDigest], bogusMimeBinary);
306 			body64(fd2, fd);
307 
308 			fprint(fd, "--upas-%s--\r\n", m->info[IDigest]);
309 		}else{
310 			switch(m->id){
311 			case 1:
312 				fprint(fd, "%s", bogusBody);
313 				break;
314 			case 2:
315 				bodystrip(fd1, fd);
316 				break;
317 			case 3:
318 				body64(fd1, fd);
319 				break;
320 			case 4:
321 				body64(fd2, fd);
322 				break;
323 			}
324 		}
325 		close(fd1);
326 		close(fd2);
327 	}
328 	seek(fd, 0, 0);
329 	return fd;
330 }
331 
332 int
333 msgIsMulti(Header *h)
334 {
335 	return h->type != nil && cistrcmp("multipart", h->type->s) == 0;
336 }
337 
338 int
339 msgIsRfc822(Header *h)
340 {
341 	return h->type != nil && cistrcmp("message", h->type->s) == 0 && cistrcmp("rfc822", h->type->t) == 0;
342 }
343 
344 /*
345  * check if a message has been deleted by someone else
346  */
347 void
348 msgDead(Msg *m)
349 {
350 	if(m->expunged)
351 		return;
352 	*m->efs = '\0';
353 	if(!cdExists(m->fsDir, m->fs))
354 		m->expunged = 1;
355 }
356 
357 /*
358  * make sure the message has valid associated info
359  * used for ISubject, IDigest, IInReplyTo, IMessageId.
360  */
361 int
362 msgInfo(Msg *m)
363 {
364 	char *s;
365 	int i;
366 
367 	if(m->info[0] != nil)
368 		return 1;
369 
370 	i = msgReadFile(m, "info", &m->iBuf);
371 	if(i < 0)
372 		return 0;
373 
374 	s = m->iBuf;
375 	for(i = 0; i < IMax; i++){
376 		m->info[i] = s;
377 		s = strchr(s, '\n');
378 		if(s == nil)
379 			break;
380 		*s++ = '\0';
381 	}
382 	for(; i < IMax; i++)
383 		m->info[i] = nil;
384 
385 	for(i = 0; i < IMax; i++)
386 		if(infoIsNil(m->info[i]))
387 			m->info[i] = nil;
388 
389 	return 1;
390 }
391 
392 /*
393  * make sure the message has valid mime structure
394  * and sub-messages
395  */
396 int
397 msgStruct(Msg *m, int top)
398 {
399 	Msg *k, head, *last;
400 	Dir *d;
401 	char *s;
402 	ulong max, id;
403 	int i, nd, fd, ns;
404 
405 	if(m->kids != nil)
406 		return 1;
407 
408 	if(m->expunged
409 	|| !msgInfo(m)
410 	|| !msgUnix(m, top)
411 	|| !msgBodySize(m)
412 	|| !msgHeader(m, &m->mime, "mimeheader")
413 	|| (top || msgIsRfc822(&m->mime) || msgIsMulti(&m->mime)) && !msgHeader(m, &m->head, "rawheader")){
414 		if(top && m->bogus && !(m->bogus & BogusTried)){
415 			m->bogus |= BogusTried;
416 			return msgStruct(m, top);
417 		}
418 		msgDead(m);
419 		return 0;
420 	}
421 
422 	/*
423 	 * if a message has no kids, it has a kid which is just the body of the real message
424 	 */
425 	if(!msgIsMulti(&m->head) && !msgIsMulti(&m->mime) && !msgIsRfc822(&m->head) && !msgIsRfc822(&m->mime)){
426 		k = MKZ(Msg);
427 		k->id = 1;
428 		k->fsDir = m->fsDir;
429 		k->bogus = m->bogus;
430 		k->parent = m->parent;
431 		ns = m->efs - m->fs;
432 		k->fs = emalloc(ns + (MsgNameLen + 1));
433 		memmove(k->fs, m->fs, ns);
434 		k->efs = k->fs + ns;
435 		*k->efs = '\0';
436 		k->size = m->size;
437 		m->kids = k;
438 		return 1;
439 	}
440 
441 	/*
442 	 * read in all child messages messages
443 	 */
444 	fd = msgFile(m, "");
445 	if(fd < 0){
446 		msgDead(m);
447 		return 0;
448 	}
449 
450 	max = 0;
451 	head.next = nil;
452 	last = &head;
453 	while((nd = dirread(fd, &d)) > 0){
454 		for(i = 0; i < nd; i++){
455 			s = d[i].name;
456 			id = strtol(s, &s, 10);
457 			if(id <= max || *s != '\0'
458 			|| (d[i].mode & DMDIR) != DMDIR)
459 				continue;
460 
461 			max = id;
462 
463 			k = MKZ(Msg);
464 			k->id = id;
465 			k->fsDir = m->fsDir;
466 			k->bogus = m->bogus;
467 			k->parent = m;
468 			ns = strlen(m->fs);
469 			k->fs = emalloc(ns + 2 * (MsgNameLen + 1));
470 			k->efs = seprint(k->fs, k->fs + ns + (MsgNameLen + 1), "%s%lud/", m->fs, id);
471 			k->prev = last;
472 			k->size = ~0UL;
473 			k->lines = ~0UL;
474 			last->next = k;
475 			last = k;
476 		}
477 	}
478 	close(fd);
479 	m->kids = head.next;
480 
481 	/*
482 	 * if kids fail, just whack them
483 	 */
484 	top = top && (msgIsRfc822(&m->head) || msgIsMulti(&m->head));
485 	for(k = m->kids; k != nil; k = k->next){
486 		if(!msgStruct(k, top)){
487 			for(k = m->kids; k != nil; ){
488 				last = k;
489 				k = k->next;
490 				freeMsg(last);
491 			}
492 			m->kids = nil;
493 			break;
494 		}
495 	}
496 	return 1;
497 }
498 
499 static long
500 msgReadFile(Msg *m, char *file, char **ss)
501 {
502 	Dir *d;
503 	char *s, buf[BufSize];
504 	vlong length;
505 	long n, nn;
506 	int fd;
507 
508 	fd = msgFile(m, file);
509 	if(fd < 0){
510 		msgDead(m);
511 		return -1;
512 	}
513 
514 	n = read(fd, buf, BufSize);
515 	if(n < BufSize){
516 		close(fd);
517 		if(n < 0){
518 			*ss = nil;
519 			return -1;
520 		}
521 		s = emalloc(n + 1);
522 		memmove(s, buf, n);
523 		s[n] = '\0';
524 		*ss = s;
525 		return n;
526 	}
527 
528 	d = dirfstat(fd);
529 	if(d == nil){
530 		close(fd);
531 		return -1;
532 	}
533 	length = d->length;
534 	free(d);
535 	nn = length;
536 	s = emalloc(nn + 1);
537 	memmove(s, buf, n);
538 	if(nn > n)
539 		nn = readn(fd, s+n, nn-n) + n;
540 	close(fd);
541 	if(nn != length){
542 		free(s);
543 		return -1;
544 	}
545 	s[nn] = '\0';
546 	*ss = s;
547 	return nn;
548 }
549 
550 static void
551 freeMAddr(MAddr *a)
552 {
553 	MAddr *p;
554 
555 	while(a != nil){
556 		p = a;
557 		a = a->next;
558 		free(p->personal);
559 		free(p->box);
560 		free(p->host);
561 		free(p);
562 	}
563 }
564 
565 /*
566  * the message is corrupted or illegal.
567  * reset message fields.  msgStruct will reparse the message,
568  * relying on msgFile to make up corrected body parts.
569  */
570 static int
571 msgBogus(Msg *m, int flags)
572 {
573 	if(!(m->bogus & flags))
574 		m->bogus |= flags;
575 	m->lines = ~0;
576 	free(m->head.buf);
577 	free(m->mime.buf);
578 	memset(&m->head, 0, sizeof(Header));
579 	memset(&m->mime, 0, sizeof(Header));
580 	return 0;
581 }
582 
583 /*
584  *  stolen from upas/marshal; base64 encodes from one fd to another.
585  *
586  *  the size of buf is very important to enc64.  Anything other than
587  *  a multiple of 3 will cause enc64 to output a termination sequence.
588  *  To ensure that a full buf corresponds to a multiple of complete lines,
589  *  we make buf a multiple of 3*18 since that's how many enc64 sticks on
590  *  a single line.  This avoids short lines in the output which is pleasing
591  *  but not necessary.
592  */
593 static int
594 enc64x18(char *out, int lim, uchar *in, int n)
595 {
596 	int m, mm, nn;
597 
598 	nn = 0;
599 	for(; n > 0; n -= m){
600 		m = 18 * 3;
601 		if(m > n)
602 			m = n;
603 		mm = enc64(out, lim - nn, in, m);
604 		in += m;
605 		out += mm;
606 		*out++ = '\r';
607 		*out++ = '\n';
608 		nn += mm + 2;
609 	}
610 	return nn;
611 }
612 
613 static void
614 body64(int in, int out)
615 {
616 	uchar buf[3*18*54];
617 	char obuf[3*18*54*2];
618 	int m, n;
619 
620 	for(;;){
621 		n = read(in, buf, sizeof(buf));
622 		if(n < 0)
623 			return;
624 		if(n == 0)
625 			break;
626 		m = enc64x18(obuf, sizeof(obuf), buf, n);
627 		if(write(out, obuf, m) < 0)
628 			return;
629 	}
630 }
631 
632 /*
633  * strip all non-printable characters from a file
634  */
635 static void
636 bodystrip(int in, int out)
637 {
638 	uchar buf[3*18*54];
639 	int m, n, i, c;
640 
641 	for(;;){
642 		n = read(in, buf, sizeof(buf));
643 		if(n < 0)
644 			return;
645 		if(n == 0)
646 			break;
647 		m = 0;
648 		for(i = 0; i < n; i++){
649 			c = buf[i];
650 			if(c > 0x1f && c < 0x7f		/* normal characters */
651 			|| c >= 0x9 && c <= 0xd)	/* \t, \n, vertical tab, form feed, \r */
652 				buf[m++] = c;
653 		}
654 
655 		if(m && write(out, buf, m) < 0)
656 			return;
657 	}
658 }
659 
660 /*
661  * read in the message body to count \n without a preceding \r
662  */
663 static int
664 msgBodySize(Msg *m)
665 {
666 	Dir *d;
667 	char buf[BufSize + 2], *s, *se;
668 	vlong length;
669 	ulong size, lines, bad;
670 	int n, fd, c;
671 
672 	if(m->lines != ~0UL)
673 		return 1;
674 	fd = msgFile(m, "rawbody");
675 	if(fd < 0)
676 		return 0;
677 	d = dirfstat(fd);
678 	if(d == nil){
679 		close(fd);
680 		return 0;
681 	}
682 	length = d->length;
683 	free(d);
684 
685 	size = 0;
686 	lines = 0;
687 	bad = 0;
688 	buf[0] = ' ';
689 	for(;;){
690 		n = read(fd, &buf[1], BufSize);
691 		if(n <= 0)
692 			break;
693 		size += n;
694 		se = &buf[n + 1];
695 		for(s = &buf[1]; s < se; s++){
696 			c = *s;
697 			if(c == '\0'){
698 				close(fd);
699 				return msgBogus(m, BogusBody);
700 			}
701 			if(c != '\n')
702 				continue;
703 			if(s[-1] != '\r')
704 				bad++;
705 			lines++;
706 		}
707 		buf[0] = buf[n];
708 	}
709 	if(size != length)
710 		bye("bad length reading rawbody");
711 	size += bad;
712 	m->size = size;
713 	m->lines = lines;
714 	close(fd);
715 	return 1;
716 }
717 
718 /*
719  * retrieve information from the unixheader file
720  */
721 static int
722 msgUnix(Msg *m, int top)
723 {
724 	Tm tm;
725 	char *s, *ss;
726 
727 	if(m->unixDate != nil)
728 		return 1;
729 
730 	if(!top){
731 bogus:
732 		m->unixDate = estrdup("");
733 		m->unixFrom = unixFrom(nil);
734 		return 1;
735 	}
736 
737 	if(msgReadFile(m, "unixheader", &ss) < 0)
738 		return 0;
739 	s = ss;
740 	s = strchr(s, ' ');
741 	if(s == nil){
742 		free(ss);
743 		goto bogus;
744 	}
745 	s++;
746 	m->unixFrom = unixFrom(s);
747 	s = (char*)headStr;
748 	if(date2tm(&tm, s) == nil)
749 		s = m->info[IUnixDate];
750 	m->unixDate = estrdup(s);
751 	free(ss);
752 	return 1;
753 }
754 
755 /*
756  * parse the address in the unix header
757  * last line of defence, so must return something
758  */
759 static MAddr *
760 unixFrom(char *s)
761 {
762 	MAddr *a;
763 	char *e, *t;
764 
765 	if(s == nil)
766 		return nil;
767 	headStr = (uchar*)s;
768 	t = emalloc(strlen(s) + 2);
769 	e = headAddrSpec(t, nil);
770 	if(e == nil)
771 		a = nil;
772 	else{
773 		if(*e != '\0')
774 			*e++ = '\0';
775 		else
776 			e = site;
777 		a = MKZ(MAddr);
778 
779 		a->box = estrdup(t);
780 		a->host = estrdup(e);
781 	}
782 	free(t);
783 	return a;
784 }
785 
786 /*
787  * read in the entire header,
788  * and parse out any existing mime headers
789  */
790 static int
791 msgHeader(Msg *m, Header *h, char *file)
792 {
793 	char *s, *ss, *t, *te;
794 	ulong lines, n, nn;
795 	long ns;
796 	int dated, c;
797 
798 	if(h->buf != nil)
799 		return 1;
800 
801 	ns = msgReadFile(m, file, &ss);
802 	if(ns < 0)
803 		return 0;
804 	s = ss;
805 	n = ns;
806 
807 	/*
808 	 * count lines ending with \n and \r\n
809 	 * add an extra line at the end, since upas/fs headers
810 	 * don't have a terminating \r\n
811 	 */
812 	lines = 1;
813 	te = s + ns;
814 	for(t = s; t < te; t++){
815 		c = *t;
816 		if(c == '\0')
817 			return msgBogus(m, BogusHeader);
818 		if(c != '\n')
819 			continue;
820 		if(t == s || t[-1] != '\r')
821 			n++;
822 		lines++;
823 	}
824 	if(t > s && t[-1] != '\n'){
825 		if(t[-1] != '\r')
826 			n++;
827 		n++;
828 	}
829 	n += 2;
830 	h->buf = emalloc(n + 1);
831 	h->size = n;
832 	h->lines = lines;
833 
834 	/*
835 	 * make sure all headers end in \r\n
836 	 */
837 	nn = 0;
838 	for(t = s; t < te; t++){
839 		c = *t;
840 		if(c == '\n'){
841 			if(!nn || h->buf[nn - 1] != '\r')
842 				h->buf[nn++] = '\r';
843 			lines++;
844 		}
845 		h->buf[nn++] = c;
846 	}
847 	if(nn && h->buf[nn-1] != '\n'){
848 		if(h->buf[nn-1] != '\r')
849 			h->buf[nn++] = '\r';
850 		h->buf[nn++] = '\n';
851 	}
852 	h->buf[nn++] = '\r';
853 	h->buf[nn++] = '\n';
854 	h->buf[nn] = '\0';
855 	if(nn != n)
856 		bye("misconverted header %d %d", nn, n);
857 	free(s);
858 
859 	/*
860 	 * and parse some mime headers
861 	 */
862 	headStr = (uchar*)h->buf;
863 	dated = 0;
864 	while(s = headAtom(headFieldStop)){
865 		if(cistrcmp(s, "content-type") == 0)
866 			mimeType(h);
867 		else if(cistrcmp(s, "content-transfer-encoding") == 0)
868 			mimeEncoding(h);
869 		else if(cistrcmp(s, "content-id") == 0)
870 			mimeId(h);
871 		else if(cistrcmp(s, "content-description") == 0)
872 			mimeDescription(h);
873 		else if(cistrcmp(s, "content-disposition") == 0)
874 			mimeDisposition(h);
875 		else if(cistrcmp(s, "content-md5") == 0)
876 			mimeMd5(h);
877 		else if(cistrcmp(s, "content-language") == 0)
878 			mimeLanguage(h);
879 		else if(h == &m->head && cistrcmp(s, "from") == 0)
880 			m->from = headMAddr(m->from);
881 		else if(h == &m->head && cistrcmp(s, "to") == 0)
882 			m->to = headMAddr(m->to);
883 		else if(h == &m->head && cistrcmp(s, "reply-to") == 0)
884 			m->replyTo = headMAddr(m->replyTo);
885 		else if(h == &m->head && cistrcmp(s, "sender") == 0)
886 			m->sender = headMAddr(m->sender);
887 		else if(h == &m->head && cistrcmp(s, "cc") == 0)
888 			m->cc = headMAddr(m->cc);
889 		else if(h == &m->head && cistrcmp(s, "bcc") == 0)
890 			m->bcc = headMAddr(m->bcc);
891 		else if(h == &m->head && cistrcmp(s, "date") == 0)
892 			dated = 1;
893 		headSkip();
894 		free(s);
895 	}
896 
897 	if(h == &m->head){
898 		if(m->from == nil){
899 			m->from = m->unixFrom;
900 			if(m->from != nil){
901 				s = maddrStr(m->from);
902 				msgAddHead(m, "From", s);
903 				free(s);
904 			}
905 		}
906 		if(m->sender == nil)
907 			m->sender = m->from;
908 		if(m->replyTo == nil)
909 			m->replyTo = m->from;
910 
911 		if(infoIsNil(m->info[IDate]))
912 			m->info[IDate] = m->unixDate;
913 		if(!dated && m->from != nil)
914 			msgAddDate(m);
915 	}
916 	return 1;
917 }
918 
919 /*
920  * prepend head: body to the cached header
921  */
922 static void
923 msgAddHead(Msg *m, char *head, char *body)
924 {
925 	char *s;
926 	long size, n;
927 
928 	n = strlen(head) + strlen(body) + 4;
929 	size = m->head.size + n;
930 	s = emalloc(size + 1);
931 	snprint(s, size + 1, "%s: %s\r\n%s", head, body, m->head.buf);
932 	free(m->head.buf);
933 	m->head.buf = s;
934 	m->head.size = size;
935 	m->head.lines++;
936 }
937 
938 static void
939 msgAddDate(Msg *m)
940 {
941 	Tm tm;
942 	char buf[64];
943 
944 	/* don't bother if we don't have a date */
945 	if(infoIsNil(m->info[IDate]))
946 		return;
947 
948 	date2tm(&tm, m->info[IDate]);
949 	rfc822date(buf, sizeof(buf), &tm);
950 	msgAddHead(m, "Date", buf);
951 }
952 
953 static MimeHdr*
954 mkMimeHdr(char *s, char *t, MimeHdr *next)
955 {
956 	MimeHdr *mh;
957 
958 	mh = MK(MimeHdr);
959 	mh->s = s;
960 	mh->t = t;
961 	mh->next = next;
962 	return mh;
963 }
964 
965 static void
966 freeMimeHdr(MimeHdr *mh)
967 {
968 	MimeHdr *last;
969 
970 	while(mh != nil){
971 		last = mh;
972 		mh = mh->next;
973 		free(last->s);
974 		free(last->t);
975 		free(last);
976 	}
977 }
978 
979 static void
980 cleanupHeader(Header *h)
981 {
982 	freeMimeHdr(h->type);
983 	freeMimeHdr(h->id);
984 	freeMimeHdr(h->description);
985 	freeMimeHdr(h->encoding);
986 	freeMimeHdr(h->md5);
987 	freeMimeHdr(h->disposition);
988 	freeMimeHdr(h->language);
989 }
990 
991 /*
992  * parser for rfc822 & mime header fields
993  */
994 
995 /*
996  * type		: 'content-type' ':' token '/' token params
997  */
998 static void
999 mimeType(Header *h)
1000 {
1001 	char *s, *t;
1002 
1003 	if(headChar(1) != ':')
1004 		return;
1005 	s = headAtom(mimeTokenStop);
1006 	if(s == nil || headChar(1) != '/'){
1007 		free(s);
1008 		return;
1009 	}
1010 	t = headAtom(mimeTokenStop);
1011 	if(t == nil){
1012 		free(s);
1013 		return;
1014 	}
1015 	h->type = mkMimeHdr(s, t, mimeParams());
1016 }
1017 
1018 /*
1019  * params	:
1020  *		| params ';' token '=' token
1021  * 		| params ';' token '=' quoted-str
1022  */
1023 static MimeHdr*
1024 mimeParams(void)
1025 {
1026 	MimeHdr head, *last;
1027 	char *s, *t;
1028 
1029 	head.next = nil;
1030 	last = &head;
1031 	for(;;){
1032 		if(headChar(1) != ';')
1033 			break;
1034 		s = headAtom(mimeTokenStop);
1035 		if(s == nil || headChar(1) != '='){
1036 			free(s);
1037 			break;
1038 		}
1039 		if(headChar(0) == '"'){
1040 			t = headQuoted('"', '"');
1041 			stripQuotes(t);
1042 		}else
1043 			t = headAtom(mimeTokenStop);
1044 		if(t == nil){
1045 			free(s);
1046 			break;
1047 		}
1048 		last->next = mkMimeHdr(s, t, nil);
1049 		last = last->next;
1050 	}
1051 	return head.next;
1052 }
1053 
1054 /*
1055  * encoding	: 'content-transfer-encoding' ':' token
1056  */
1057 static void
1058 mimeEncoding(Header *h)
1059 {
1060 	char *s;
1061 
1062 	if(headChar(1) != ':')
1063 		return;
1064 	s = headAtom(mimeTokenStop);
1065 	if(s == nil)
1066 		return;
1067 	h->encoding = mkMimeHdr(s, nil, nil);
1068 }
1069 
1070 /*
1071  * mailaddr	: ':' addresses
1072  */
1073 static MAddr*
1074 headMAddr(MAddr *old)
1075 {
1076 	MAddr *a;
1077 
1078 	if(headChar(1) != ':')
1079 		return old;
1080 
1081 	if(headChar(0) == '\n')
1082 		return old;
1083 
1084 	a = headAddresses();
1085 	if(a == nil)
1086 		return old;
1087 
1088 	freeMAddr(old);
1089 	return a;
1090 }
1091 
1092 /*
1093  * addresses	: address | addresses ',' address
1094  */
1095 static MAddr*
1096 headAddresses(void)
1097 {
1098 	MAddr *addr, *tail, *a;
1099 
1100 	addr = headAddress();
1101 	if(addr == nil)
1102 		return nil;
1103 	tail = addr;
1104 	while(headChar(0) == ','){
1105 		headChar(1);
1106 		a = headAddress();
1107 		if(a == nil){
1108 			freeMAddr(addr);
1109 			return nil;
1110 		}
1111 		tail->next = a;
1112 		tail = a;
1113 	}
1114 	return addr;
1115 }
1116 
1117 /*
1118  * address	: mailbox | group
1119  * group	: phrase ':' mboxes ';' | phrase ':' ';'
1120  * mailbox	: addr-spec
1121  *		| optphrase '<' addr-spec '>'
1122  *		| optphrase '<' route ':' addr-spec '>'
1123  * optphrase	: | phrase
1124  * route	: '@' domain
1125  *		| route ',' '@' domain
1126  * personal names are the phrase before '<',
1127  * or a comment before or after a simple addr-spec
1128  */
1129 static MAddr*
1130 headAddress(void)
1131 {
1132 	MAddr *addr;
1133 	uchar *hs;
1134 	char *s, *e, *w, *personal;
1135 	int c;
1136 
1137 	s = emalloc(strlen((char*)headStr) + 2);
1138 	e = s;
1139 	personal = headSkipWhite(1);
1140 	c = headChar(0);
1141 	if(c == '<')
1142 		w = nil;
1143 	else{
1144 		w = headWord();
1145 		c = headChar(0);
1146 	}
1147 	if(c == '.' || c == '@' || c == ',' || c == '\n' || c == '\0'){
1148 		lastWhite = headStr;
1149 		e = headAddrSpec(s, w);
1150 		if(personal == nil){
1151 			hs = headStr;
1152 			headStr = lastWhite;
1153 			personal = headSkipWhite(1);
1154 			headStr = hs;
1155 		}
1156 	}else{
1157 		if(c != '<' || w != nil){
1158 			free(personal);
1159 			if(!headPhrase(e, w)){
1160 				free(s);
1161 				return nil;
1162 			}
1163 
1164 			/*
1165 			 * ignore addresses with groups,
1166 			 * so the only thing left if <
1167 			 */
1168 			c = headChar(1);
1169 			if(c != '<'){
1170 				free(s);
1171 				return nil;
1172 			}
1173 			personal = estrdup(s);
1174 		}else
1175 			headChar(1);
1176 
1177 		/*
1178 		 * after this point, we need to free personal before returning.
1179 		 * set e to nil to everything afterwards fails.
1180 		 *
1181 		 * ignore routes, they are useless, and heavily discouraged in rfc1123.
1182 		 * imap4 reports them up to, but not including, the terminating :
1183 		 */
1184 		e = s;
1185 		c = headChar(0);
1186 		if(c == '@'){
1187 			for(;;){
1188 				c = headChar(1);
1189 				if(c != '@'){
1190 					e = nil;
1191 					break;
1192 				}
1193 				headDomain(e);
1194 				c = headChar(1);
1195 				if(c != ','){
1196 					e = s;
1197 					break;
1198 				}
1199 			}
1200 			if(c != ':')
1201 				e = nil;
1202 		}
1203 
1204 		if(e != nil)
1205 			e = headAddrSpec(s, nil);
1206 		if(headChar(1) != '>')
1207 			e = nil;
1208 	}
1209 
1210 	/*
1211 	 * e points to @host, or nil if an error occured
1212 	 */
1213 	if(e == nil){
1214 		free(personal);
1215 		addr = nil;
1216 	}else{
1217 		if(*e != '\0')
1218 			*e++ = '\0';
1219 		else
1220 			e = site;
1221 		addr = MKZ(MAddr);
1222 
1223 		addr->personal = personal;
1224 		addr->box = estrdup(s);
1225 		addr->host = estrdup(e);
1226 	}
1227 	free(s);
1228 	return addr;
1229 }
1230 
1231 /*
1232  * phrase	: word
1233  *		| phrase word
1234  * w is the optional initial word of the phrase
1235  * returns the end of the phrase, or nil if a failure occured
1236  */
1237 static char*
1238 headPhrase(char *e, char *w)
1239 {
1240 	int c;
1241 
1242 	for(;;){
1243 		if(w == nil){
1244 			w = headWord();
1245 			if(w == nil)
1246 				return nil;
1247 		}
1248 		if(w[0] == '"')
1249 			stripQuotes(w);
1250 		strcpy(e, w);
1251 		free(w);
1252 		w = nil;
1253 		e = strchr(e, '\0');
1254 		c = headChar(0);
1255 		if(c <= ' ' || strchr(headAtomStop, c) != nil && c != '"')
1256 			break;
1257 		*e++ = ' ';
1258 		*e = '\0';
1259 	}
1260 	return e;
1261 }
1262 
1263 /*
1264  * addr-spec	: local-part '@' domain
1265  *		| local-part			extension to allow ! and local names
1266  * local-part	: word
1267  *		| local-part '.' word
1268  *
1269  * if no '@' is present, rewrite d!e!f!u as @d,@e:u@f,
1270  * where d, e, f are valid domain components.
1271  * the @d,@e: is ignored, since routes are ignored.
1272  * perhaps they should be rewritten as e!f!u@d, but that is inconsistent with upas.
1273  *
1274  * returns a pointer to '@', the end if none, or nil if there was an error
1275  */
1276 static char*
1277 headAddrSpec(char *e, char *w)
1278 {
1279 	char *s, *at, *b, *bang, *dom;
1280 	int c;
1281 
1282 	s = e;
1283 	for(;;){
1284 		if(w == nil){
1285 			w = headWord();
1286 			if(w == nil)
1287 				return nil;
1288 		}
1289 		strcpy(e, w);
1290 		free(w);
1291 		w = nil;
1292 		e = strchr(e, '\0');
1293 		lastWhite = headStr;
1294 		c = headChar(0);
1295 		if(c != '.')
1296 			break;
1297 		headChar(1);
1298 		*e++ = '.';
1299 		*e = '\0';
1300 	}
1301 
1302 	if(c != '@'){
1303 		/*
1304 		 * extenstion: allow name without domain
1305 		 * check for domain!xxx
1306 		 */
1307 		bang = domBang(s);
1308 		if(bang == nil)
1309 			return e;
1310 
1311 		/*
1312 		 * if dom1!dom2!xxx, ignore dom1!
1313 		 */
1314 		dom = s;
1315 		for(; b = domBang(bang + 1); bang = b)
1316 			dom = bang + 1;
1317 
1318 		/*
1319 		 * convert dom!mbox into mbox@dom
1320 		 */
1321 		*bang = '@';
1322 		strrev(dom, bang);
1323 		strrev(bang+1, e);
1324 		strrev(dom, e);
1325 		bang = &dom[e - bang - 1];
1326 		if(dom > s){
1327 			bang -= dom - s;
1328 			for(e = s; *e = *dom; e++)
1329 				dom++;
1330 		}
1331 
1332 		/*
1333 		 * eliminate a trailing '.'
1334 		 */
1335 		if(e[-1] == '.')
1336 			e[-1] = '\0';
1337 		return bang;
1338 	}
1339 	headChar(1);
1340 
1341 	at = e;
1342 	*e++ = '@';
1343 	*e = '\0';
1344 	if(!headDomain(e))
1345 		return nil;
1346 	return at;
1347 }
1348 
1349 /*
1350  * find the ! in domain!rest, where domain must have at least
1351  * one internal '.'
1352  */
1353 static char*
1354 domBang(char *s)
1355 {
1356 	int dot, c;
1357 
1358 	dot = 0;
1359 	for(; c = *s; s++){
1360 		if(c == '!'){
1361 			if(!dot || dot == 1 && s[-1] == '.' || s[1] == '\0')
1362 				return nil;
1363 			return s;
1364 		}
1365 		if(c == '"')
1366 			break;
1367 		if(c == '.')
1368 			dot++;
1369 	}
1370 	return nil;
1371 }
1372 
1373 /*
1374  * domain	: sub-domain
1375  *		| domain '.' sub-domain
1376  * returns the end of the domain, or nil if a failure occured
1377  */
1378 static char*
1379 headDomain(char *e)
1380 {
1381 	char *w;
1382 
1383 	for(;;){
1384 		w = headSubDomain();
1385 		if(w == nil)
1386 			return nil;
1387 		strcpy(e, w);
1388 		free(w);
1389 		e = strchr(e, '\0');
1390 		lastWhite = headStr;
1391 		if(headChar(0) != '.')
1392 			break;
1393 		headChar(1);
1394 		*e++ = '.';
1395 		*e = '\0';
1396 	}
1397 	return e;
1398 }
1399 
1400 /*
1401  * id		: 'content-id' ':' msg-id
1402  * msg-id	: '<' addr-spec '>'
1403  */
1404 static void
1405 mimeId(Header *h)
1406 {
1407 	char *s, *e, *w;
1408 
1409 	if(headChar(1) != ':')
1410 		return;
1411 	if(headChar(1) != '<')
1412 		return;
1413 
1414 	s = emalloc(strlen((char*)headStr) + 3);
1415 	e = s;
1416 	*e++ = '<';
1417 	e = headAddrSpec(e, nil);
1418 	if(e == nil || headChar(1) != '>'){
1419 		free(s);
1420 		return;
1421 	}
1422 	e = strchr(e, '\0');
1423 	*e++ = '>';
1424 	e[0] = '\0';
1425 	w = strdup(s);
1426 	free(s);
1427 	h->id = mkMimeHdr(w, nil, nil);
1428 }
1429 
1430 /*
1431  * description	: 'content-description' ':' *text
1432  */
1433 static void
1434 mimeDescription(Header *h)
1435 {
1436 	if(headChar(1) != ':')
1437 		return;
1438 	headSkipWhite(0);
1439 	h->description = mkMimeHdr(headText(), nil, nil);
1440 }
1441 
1442 /*
1443  * disposition	: 'content-disposition' ':' token params
1444  */
1445 static void
1446 mimeDisposition(Header *h)
1447 {
1448 	char *s;
1449 
1450 	if(headChar(1) != ':')
1451 		return;
1452 	s = headAtom(mimeTokenStop);
1453 	if(s == nil)
1454 		return;
1455 	h->disposition = mkMimeHdr(s, nil, mimeParams());
1456 }
1457 
1458 /*
1459  * md5		: 'content-md5' ':' token
1460  */
1461 static void
1462 mimeMd5(Header *h)
1463 {
1464 	char *s;
1465 
1466 	if(headChar(1) != ':')
1467 		return;
1468 	s = headAtom(mimeTokenStop);
1469 	if(s == nil)
1470 		return;
1471 	h->md5 = mkMimeHdr(s, nil, nil);
1472 }
1473 
1474 /*
1475  * language	: 'content-language' ':' langs
1476  * langs	: token
1477  *		| langs commas token
1478  * commas	: ','
1479  *		| commas ','
1480  */
1481 static void
1482 mimeLanguage(Header *h)
1483 {
1484 	MimeHdr head, *last;
1485 	char *s;
1486 
1487 	head.next = nil;
1488 	last = &head;
1489 	for(;;){
1490 		s = headAtom(mimeTokenStop);
1491 		if(s == nil)
1492 			break;
1493 		last->next = mkMimeHdr(s, nil, nil);
1494 		last = last->next;
1495 		while(headChar(0) != ',')
1496 			headChar(1);
1497 	}
1498 	h->language = head.next;
1499 }
1500 
1501 /*
1502  * token	: 1*<char 33-255, except "()<>@,;:\\\"/[]?=" aka mimeTokenStop>
1503  * atom		: 1*<chars 33-255, except "()<>@,;:\\\".[]" aka headAtomStop>
1504  * note this allows 8 bit characters, which occur in utf.
1505  */
1506 static char*
1507 headAtom(char *disallowed)
1508 {
1509 	char *s;
1510 	int c, ns, as;
1511 
1512 	headSkipWhite(0);
1513 
1514 	s = emalloc(StrAlloc);
1515 	as = StrAlloc;
1516 	ns = 0;
1517 	for(;;){
1518 		c = *headStr++;
1519 		if(c <= ' ' || strchr(disallowed, c) != nil){
1520 			headStr--;
1521 			break;
1522 		}
1523 		s[ns++] = c;
1524 		if(ns >= as){
1525 			as += StrAlloc;
1526 			s = erealloc(s, as);
1527 		}
1528 	}
1529 	if(ns == 0){
1530 		free(s);
1531 		return 0;
1532 	}
1533 	s[ns] = '\0';
1534 	return s;
1535 }
1536 
1537 /*
1538  * sub-domain	: atom | domain-lit
1539  */
1540 static char *
1541 headSubDomain(void)
1542 {
1543 	if(headChar(0) == '[')
1544 		return headQuoted('[', ']');
1545 	return headAtom(headAtomStop);
1546 }
1547 
1548 /*
1549  * word	: atom | quoted-str
1550  */
1551 static char *
1552 headWord(void)
1553 {
1554 	if(headChar(0) == '"')
1555 		return headQuoted('"', '"');
1556 	return headAtom(headAtomStop);
1557 }
1558 
1559 /*
1560  * q is a quoted string.  remove enclosing " and and \ escapes
1561  */
1562 static void
1563 stripQuotes(char *q)
1564 {
1565 	char *s;
1566 	int c;
1567 
1568 	if(q == nil)
1569 		return;
1570 	s = q++;
1571 	while(c = *q++){
1572 		if(c == '\\'){
1573 			c = *q++;
1574 			if(!c)
1575 				return;
1576 		}
1577 		*s++ = c;
1578 	}
1579 	s[-1] = '\0';
1580 }
1581 
1582 /*
1583  * quoted-str	: '"' *(any char but '"\\\r', or '\' any char, or linear-white-space) '"'
1584  * domain-lit	: '[' *(any char but '[]\\\r', or '\' any char, or linear-white-space) ']'
1585  */
1586 static char *
1587 headQuoted(int start, int stop)
1588 {
1589 	char *s;
1590 	int c, ns, as;
1591 
1592 	if(headChar(1) != start)
1593 		return nil;
1594 	s = emalloc(StrAlloc);
1595 	as = StrAlloc;
1596 	ns = 0;
1597 	s[ns++] = start;
1598 	for(;;){
1599 		c = *headStr;
1600 		if(c == stop){
1601 			headStr++;
1602 			break;
1603 		}
1604 		if(c == '\0'){
1605 			free(s);
1606 			return nil;
1607 		}
1608 		if(c == '\r'){
1609 			headStr++;
1610 			continue;
1611 		}
1612 		if(c == '\n'){
1613 			headStr++;
1614 			while(*headStr == ' ' || *headStr == '\t' || *headStr == '\r' || *headStr == '\n')
1615 				headStr++;
1616 			c = ' ';
1617 		}else if(c == '\\'){
1618 			headStr++;
1619 			s[ns++] = c;
1620 			c = *headStr;
1621 			if(c == '\0'){
1622 				free(s);
1623 				return nil;
1624 			}
1625 			headStr++;
1626 		}else
1627 			headStr++;
1628 		s[ns++] = c;
1629 		if(ns + 1 >= as){	/* leave room for \c or "0 */
1630 			as += StrAlloc;
1631 			s = erealloc(s, as);
1632 		}
1633 	}
1634 	s[ns++] = stop;
1635 	s[ns] = '\0';
1636 	return s;
1637 }
1638 
1639 /*
1640  * headText	: contents of rest of header line
1641  */
1642 static char *
1643 headText(void)
1644 {
1645 	uchar *v;
1646 	char *s;
1647 
1648 	v = headStr;
1649 	headToEnd();
1650 	s = emalloc(headStr - v + 1);
1651 	memmove(s, v, headStr - v);
1652 	s[headStr - v] = '\0';
1653 	return s;
1654 }
1655 
1656 /*
1657  * white space is ' ' '\t' or nested comments.
1658  * skip white space.
1659  * if com and a comment is seen,
1660  * return it's contents and stop processing white space.
1661  */
1662 static char*
1663 headSkipWhite(int com)
1664 {
1665 	char *s;
1666 	int c, incom, as, ns;
1667 
1668 	s = nil;
1669 	as = StrAlloc;
1670 	ns = 0;
1671 	if(com)
1672 		s = emalloc(StrAlloc);
1673 	incom = 0;
1674 	for(; c = *headStr; headStr++){
1675 		switch(c){
1676 		case ' ':
1677 		case '\t':
1678 		case '\r':
1679 			c = ' ';
1680 			break;
1681 		case '\n':
1682 			c = headStr[1];
1683 			if(c != ' ' && c != '\t')
1684 				goto breakout;
1685 			c = ' ';
1686 			break;
1687 		case '\\':
1688 			if(com && incom)
1689 				s[ns++] = c;
1690 			c = headStr[1];
1691 			if(c == '\0')
1692 				goto breakout;
1693 			headStr++;
1694 			break;
1695 		case '(':
1696 			incom++;
1697 			if(incom == 1)
1698 				continue;
1699 			break;
1700 		case ')':
1701 			incom--;
1702 			if(com && !incom){
1703 				s[ns] = '\0';
1704 				return s;
1705 			}
1706 			break;
1707 		default:
1708 			if(!incom)
1709 				goto breakout;
1710 			break;
1711 		}
1712 		if(com && incom && (c != ' ' || ns > 0 && s[ns-1] != ' ')){
1713 			s[ns++] = c;
1714 			if(ns + 1 >= as){	/* leave room for \c or 0 */
1715 				as += StrAlloc;
1716 				s = erealloc(s, as);
1717 			}
1718 		}
1719 	}
1720 breakout:;
1721 	free(s);
1722 	return nil;
1723 }
1724 
1725 /*
1726  * return the next non-white character
1727  */
1728 static int
1729 headChar(int eat)
1730 {
1731 	int c;
1732 
1733 	headSkipWhite(0);
1734 	c = *headStr;
1735 	if(eat && c != '\0' && c != '\n')
1736 		headStr++;
1737 	return c;
1738 }
1739 
1740 static void
1741 headToEnd(void)
1742 {
1743 	uchar *s;
1744 	int c;
1745 
1746 	for(;;){
1747 		s = headStr;
1748 		c = *s++;
1749 		while(c == '\r')
1750 			c = *s++;
1751 		if(c == '\n'){
1752 			c = *s++;
1753 			if(c != ' ' && c != '\t')
1754 				return;
1755 		}
1756 		if(c == '\0')
1757 			return;
1758 		headStr = s;
1759 	}
1760 }
1761 
1762 static void
1763 headSkip(void)
1764 {
1765 	int c;
1766 
1767 	while(c = *headStr){
1768 		headStr++;
1769 		if(c == '\n'){
1770 			c = *headStr;
1771 			if(c == ' ' || c == '\t')
1772 				continue;
1773 			return;
1774 		}
1775 	}
1776 }
1777