From: Walter Alejandro Iglesias <wai@roquesor.com>
Subject: mail(1) add any header from command line (diff adapted from Debian)
To: tech@openbsd.org
Date: Thu, 29 Aug 2024 16:39:36 +0200

In another thread I mentioned that debian bsd-mailx package is a patched
version of OpenBSD mail(1) and that a useful feature present in that
version is the option to add any header from the command line (option
'-a' in this case).  The diff below is an adaptation I made from this:

  https://github.com/deepin-community/bsd-mailx/blob/master/debian/patches/04-Add-custom-header.patch

Where I:

  - Corrected a function declaration

  - Changed use strcpy() and strcat() for strndup() and strlcat().

  - Added checks in puthead() to avoid duplicated headers.

  - Modified man page entry.

After applying this patch you can:

  $ mail -a "Header: string" -a "AnotherHeader: string" ...

I'm not truly convinced of how reliable could be adding this.  I'd like
the experts opinion.  And if there could be any security implications.


Index: def.h
===================================================================
RCS file: /cvs/src/usr.bin/mail/def.h,v
diff -u -p -r1.17 def.h
--- def.h	28 Jan 2022 06:18:41 -0000	1.17
+++ def.h	29 Aug 2024 14:15:07 -0000
@@ -173,6 +173,7 @@ struct header {
 	struct name *h_to;		/* Dynamic "To:" string */
 	char *h_from;			/* User-specified "From:" string */
 	char *h_subject;		/* Subject string */
+	char *h_header;			/* Additional header string */
 	struct name *h_cc;		/* Carbon copies string */
 	struct name *h_bcc;		/* Blind carbon copies */
 	struct name *h_smopts;		/* Sendmail options */
Index: extern.h
===================================================================
RCS file: /cvs/src/usr.bin/mail/extern.h,v
diff -u -p -r1.30 extern.h
--- extern.h	21 May 2024 05:00:48 -0000	1.30
+++ extern.h	29 Aug 2024 14:15:07 -0000
@@ -162,7 +162,7 @@ void	 load(char *);
 struct var *
 	 lookup(char *);
 int	 mail(struct name *, struct name *, struct name *, struct name *,
-	       char *, char *);
+	       char *, char *, char *);
 void	 mail1(struct header *, int);
 void	 makemessage(FILE *, int);
 void	 mark(int);
Index: mail.1
===================================================================
RCS file: /cvs/src/usr.bin/mail/mail.1,v
diff -u -p -r1.83 mail.1
--- mail.1	31 Mar 2022 17:27:25 -0000	1.83
+++ mail.1	29 Aug 2024 14:15:07 -0000
@@ -63,6 +63,12 @@ with lines replaced by messages.
 .Pp
 The options are as follows:
 .Bl -tag -width Ds
+.It Fl a
+Specify additional header fields on the command line such as "X-Loop:
+foo@bar" etc.
+You have to use quotes if the string contains spaces.
+This argument may be specified more than once, the headers will then
+be concatenated.
 .It Fl b Ar list
 Send blind carbon copies to
 .Ar list .
@@ -1254,7 +1260,7 @@ and are not supported by this implementa
 .Nm mailx .
 .Pp
 The flags
-.Op Fl bcdEIrv
+.Op Fl abcdEIrv
 are extensions to the specification.
 .Sh HISTORY
 A
Index: main.c
===================================================================
RCS file: /cvs/src/usr.bin/mail/main.c,v
diff -u -p -r1.35 main.c
--- main.c	26 Jan 2021 18:21:47 -0000	1.35
+++ main.c	29 Aug 2024 14:15:07 -0000
@@ -103,6 +103,8 @@ main(int argc, char **argv)
 	struct name *to, *cc, *bcc, *smopts;
 	char *fromaddr;
 	char *subject;
+	char *header = NULL;
+	size_t hlen = 0;
 	char *ef;
 	char nosrc = 0;
 	char *rc;
@@ -136,7 +138,7 @@ main(int argc, char **argv)
 	smopts = NULL;
 	fromaddr = NULL;
 	subject = NULL;
-	while ((i = getopt(argc, argv, "EINb:c:dfinr:s:u:v")) != -1) {
+	while ((i = getopt(argc, argv, "EINa:b:c:dfeinr:s:u:v")) != -1) {
 		switch (i) {
 		case 'u':
 			/*
@@ -171,6 +173,32 @@ main(int argc, char **argv)
 			 */
 			subject = optarg;
 			break;
+
+		case 'a':
+			/*
+			 * Give additional header fields for sending from
+			 * non terminal
+			 */
+			if (header == NULL) {
+				header = strndup(optarg, strlen(optarg) + 1);
+				if (header == NULL)
+					err(1, NULL);
+                        } else {
+				header = realloc(header, strlen(optarg) +
+				    strlen(header) + 2);
+				if (header == NULL)
+					err(1, NULL);
+				hlen = strlcat(header, "\n",
+				    strlen(header) + 2);
+				if (hlen >= strlen(header) + 2)
+					errx(1, "main: header too long");
+				hlen = strlcat(header, optarg,
+				    strlen(optarg) + strlen(header) + 1);
+				if (hlen >= strlen(optarg) +
+				    strlen(header) + 1)
+					errx(1, "main: header too long");
+			}
+			break;
 		case 'f':
 			/*
 			 * User is specifying file to "edit" with Mail,
@@ -216,6 +244,7 @@ main(int argc, char **argv)
 			 */
 			bcc = cat(bcc, nalloc(optarg, GBCC));
 			break;
+		case 'e':
 		case 'E':
 			/*
 			 * Don't send messages with an empty body.
@@ -269,7 +298,7 @@ main(int argc, char **argv)
 		rc = "~/.mailrc";
 	load(expand(rc));
 	if (!rcvmode) {
-		mail(to, cc, bcc, smopts, fromaddr, subject);
+		mail(to, cc, bcc, smopts, fromaddr, subject, header);
 		/*
 		 * why wait?
 		 */
Index: send.c
===================================================================
RCS file: /cvs/src/usr.bin/mail/send.c,v
diff -u -p -r1.26 send.c
--- send.c	8 Mar 2023 04:43:11 -0000	1.26
+++ send.c	29 Aug 2024 14:15:07 -0000
@@ -279,13 +279,14 @@ statusput(struct message *mp, FILE *obuf
  */
 int
 mail(struct name *to, struct name *cc, struct name *bcc, struct name *smopts,
-     char *fromaddr, char *subject)
+     char *fromaddr, char *subject, char *header)
 {
 	struct header head;
 
 	head.h_to = to;
 	head.h_from = fromaddr;
 	head.h_subject = subject;
+	head.h_header = header;
 	head.h_cc = cc;
 	head.h_bcc = bcc;
 	head.h_smopts = smopts;
@@ -306,6 +307,7 @@ sendmail(void *v)
 	head.h_to = extract(str, GTO);
 	head.h_from = NULL;
 	head.h_subject = NULL;
+	head.h_header = NULL;
 	head.h_cc = NULL;
 	head.h_bcc = NULL;
 	head.h_smopts = NULL;
@@ -519,16 +521,22 @@ puthead(struct header *hp, FILE *fo, int
 
 	gotcha = 0;
 	from = hp->h_from ? hp->h_from : value("from");
-	if (from != NULL)
+	if (from != NULL && strstr(hp->h_header, "From:") == NULL)
 		fprintf(fo, "From: %s\n", from), gotcha++;
-	if (hp->h_to != NULL && w & GTO)
+	if (hp->h_to != NULL && w & GTO && strstr(hp->h_header,
+	    "To:") == NULL)
 		fmt("To:", hp->h_to, fo, w&GCOMMA), gotcha++;
-	if (hp->h_subject != NULL && w & GSUBJECT)
+	if (hp->h_subject != NULL && w & GSUBJECT && strstr(hp->h_header,
+	    "Subject:") == NULL)
 		fprintf(fo, "Subject: %s\n", hp->h_subject), gotcha++;
-	if (hp->h_cc != NULL && w & GCC)
+	if (hp->h_cc != NULL && w & GCC && strstr(hp->h_header,
+	    "Cc:") == NULL)
 		fmt("Cc:", hp->h_cc, fo, w&GCOMMA), gotcha++;
-	if (hp->h_bcc != NULL && w & GBCC)
+	if (hp->h_bcc != NULL && w & GBCC && strstr(hp->h_header,
+	    "Bcc:") == NULL)
 		fmt("Bcc:", hp->h_bcc, fo, w&GCOMMA), gotcha++;
+	if (hp->h_header != NULL && w)
+		fprintf(fo, "%s\n", hp->h_header), gotcha++;
 	if (gotcha && w & GNL)
 		(void)putc('\n', fo);
 	return(0);


-- 
Walter