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Subject: Re: [9front] [Bug] [PATCH] Mail cannot cope with multi-line header fields
Date: Mon, 14 Sep 2020 23:49:01 +0200
From: theinicke@bss-wf.de
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X-Bullshit: information XML over YAML package reduce/map database framework 

> I think I like your idea of doing it in copy822. How's this?

This is fine except for the potential corner case of having CRLF inside a quoted string in one of the header fields treated by addr822.

That is in rfc2855 it says in section 3.2.5 "Since a quoted-string is allowed to contain FWS, folding is permitted.". If we want to follow this path of fixing it here, then I think we also would have to at least amend the condition in /sys/src/cmd/upas/fs/mbox.c:763 (776 after applying your patch).

--
Tobias Heinicke

diff -r 9f6e77258f69 sys/src/cmd/upas/fs/mbox.c
--- a/sys/src/cmd/upas/fs/mbox.c	Thu Sep 10 16:26:42 2020 -0700
+++ b/sys/src/cmd/upas/fs/mbox.c	Mon Sep 14 23:40:27 2020 +0200
@@ -733,6 +733,19 @@
 }
 
 static char*
+unfold(char *s)
+{
+	char *p, *q;
+
+	q = s;
+	for(p = q; *p != '\0'; p++)
+		if(*p != '\r' && *p != '\n')
+			*q++ = *p;
+	*q = '\0';
+	return s;
+}
+
+static char*
 addr822(char *p, char **ac)
 {
 	int n, c, space, incomment, addrdone, inanticomment, quoted;
@@ -760,7 +773,7 @@
 			for(p++; c = *p; p++){
 				if(ac && c == '"')
 					break;
-				if(!addrdone && !incomment)
+				if(!addrdone && !incomment && c != '\r' && c != '\n')
 					ps = sputc(ps, e, c);
 				if(!quoted && *p == '"')
 					break;
@@ -883,7 +896,7 @@
 static char*
 copy822(Message*, Header *h, char*, char *p)
 {
-	return rtrim(strdup(skipwhite(p + h->len)));
+	return rtrim(unfold(strdup(skipwhite(p + h->len))));
 }
 
 static char*