sfeed_mbox: add option to print content

- Add SFEED_MBOX_CONTENT environment option. When set to "1" it outputs the
  content aswell.  This is disabled by default for security reasons, because many
  clients handle HTML in an insecure way.

- Print link and enclosure on one line and align them.

2 files changed, 85 insertions, 10 deletions

diff --git a/sfeed_mbox.1 b/sfeed_mbox.1
index 5182324..407f3c5 100644
--- a/sfeed_mbox.1
+++ b/sfeed_mbox.1
@@ -1,4 +1,4 @@
-.Dd March 15, 2020
+.Dd July 6, 2020
 .Dt SFEED_MBOX 1
 .Os
 .Sh NAME
@@ -28,12 +28,21 @@ The mbox data can be further processed by tools like
 or
 .Xr fdm 1
 for example.
-See the README file for some useful examples.
+See the README file for some examples.
 .Sh CUSTOM HEADERS
 To make further filtering simpler some custom headers are set:
 .Bl -tag -width Ds
 .It X-Feedname
-The feedname (as set in sfeedrc).
+The feedname, this is the basename of the
+.Ar file .
+.El
+.Sh ENVIRONMENT VARIABLES
+.Bl -tag -width Ds
+.It Ev SFEED_MBOX_CONTENT
+Include the content.
+This is very insecure for some of the mail clients that interpret HTML code in
+an unsafe way.
+By default this is set to "0".
 .El
 .Sh EXIT STATUS
 .Ex -std
diff --git a/sfeed_mbox.c b/sfeed_mbox.c
index a734504..5803cea 100644
--- a/sfeed_mbox.c
+++ b/sfeed_mbox.c
@@ -9,6 +9,7 @@
 static char *line;
 static size_t linesize;
 static char host[256], *user, dtimebuf[32], mtimebuf[32];
+static int usecontent = 0; /* env variable: $SFEED_MBOX_CONTENT */
 
 static unsigned long
 djb2(unsigned char *s, unsigned long hash)
@@ -20,6 +21,38 @@ djb2(unsigned char *s, unsigned long hash)
 	return hash;
 }
 
+/* Unescape / decode fields printed by string_print_encoded()
+ * "\\" to "\", "\t", to TAB, "\n" to newline. Unrecognised escape sequences
+ * are ignored: "\z" etc. Mangle "From " in mboxrd style (always prefix >). */
+static void
+printcontent(const char *s, FILE *fp)
+{
+escapefrom:
+	for (; *s == '>'; s++)
+		fputc('>', fp);
+	/* escape "From ", mboxrd-style. */
+	if (!strncmp(s, "From ", 5))
+		fputc('>', fp);
+
+	for (; *s; s++) {
+		switch (*s) {
+		case '\\':
+			s++;
+			switch (*s) {
+			case 'n':
+				fputc('\n', fp);
+				s++;
+				goto escapefrom;
+			case '\\': fputc('\\', fp); break;
+			case 't':  fputc('\t', fp); break;
+			}
+			break;
+		default:
+			fputc(*s, fp); break;
+		}
+	}
+}
+
 static void
 printfeed(FILE *fp, const char *feedname)
 {
@@ -28,6 +61,7 @@ printfeed(FILE *fp, const char *feedname)
 	time_t parsedtime;
 	unsigned long hash;
 	ssize_t linelen;
+	int ishtml;
 
 	while ((linelen = getline(&line, &linesize, fp)) > 0) {
 		if (line[linelen - 1] == '\n')
@@ -54,14 +88,44 @@ printfeed(FILE *fp, const char *feedname)
 		       fields[FieldUnixTimestamp],
 		       fields[FieldUnixTimestamp][0] ? "." : "",
 		       hash, feedname);
-		printf("Content-Type: text/plain; charset=\"utf-8\"\n");
-		printf("Content-Transfer-Encoding: binary\n");
-		printf("X-Feedname: %s\n\n", feedname);
 
-		printf("%s\n", fields[FieldLink]);
-		if (fields[FieldEnclosure][0])
-			printf("\nEnclosure:\n%s\n", fields[FieldEnclosure]);
+		ishtml = usecontent && !strcmp(fields[FieldContentType], "html");
+		if (ishtml)
+			fputs("Content-Type: text/html; charset=\"utf-8\"\n", stdout);
+		else
+			fputs("Content-Type: text/plain; charset=\"utf-8\"\n", stdout);
+		fputs("Content-Transfer-Encoding: binary\n", stdout);
+		printf("X-Feedname: %s\n", feedname);
 		fputs("\n", stdout);
+
+		if (ishtml) {
+			fputs("<p>\n", stdout);
+			if (fields[FieldLink][0]) {
+				fputs("Link: <a href=\"", stdout);
+				xmlencode(fields[FieldLink], stdout);
+				fputs("\">", stdout);
+				fputs(fields[FieldLink], stdout);
+				fputs("</a><br/>\n", stdout);
+			}
+			if (fields[FieldEnclosure][0]) {
+				fputs("Enclosure: <a href=\"", stdout);
+				xmlencode(fields[FieldEnclosure], stdout);
+				fputs("\">", stdout);
+				fputs(fields[FieldEnclosure], stdout);
+				fputs("</a><br/>\n", stdout);
+			}
+			fputs("</p>\n", stdout);
+		} else {
+			if (fields[FieldLink][0])
+				printf("Link:      %s\n", fields[FieldLink]);
+			if (fields[FieldEnclosure][0])
+				printf("Enclosure: %s\n", fields[FieldEnclosure]);
+		}
+		if (usecontent) {
+			fputs("\n", stdout);
+			printcontent(fields[FieldContent], stdout);
+		}
+		fputs("\n\n", stdout);
 	}
 }
 
@@ -71,12 +135,14 @@ main(int argc, char *argv[])
 	struct tm tmnow;
 	time_t now;
 	FILE *fp;
-	char *name;
+	char *name, *tmp;
 	int i;
 
 	if (pledge(argc == 1 ? "stdio" : "stdio rpath", NULL) == -1)
 		err(1, "pledge");
 
+	if ((tmp = getenv("SFEED_MBOX_CONTENT")))
+		usecontent = !strcmp(tmp, "1");
 	if (!(user = getenv("USER")))
 		user = "you";
 	if (gethostname(host, sizeof(host)) == -1)