--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/f-demime/msgstate.c	Sat May 06 06:14:03 2023 +0000
@@ -0,0 +1,110 @@
+/*
+ * This module implements the message state machine, receiving input lines
+ * and message start/end markers from the input processing main loop.
+ */
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include "defs.h"
+
+enum msg_state msg_state;
+enum msg_hdr_state hdr_state;
+unsigned mp_nest_level;
+char mp_boundaries[MAX_MP_NESTING][MAX_MP_BOUNDARY+1];
+int mp_is_digest[MAX_MP_NESTING];
+char cont_type_buf[HDR_BUF_SIZE], cont_te_buf[HDR_BUF_SIZE];
+int got_cont_type, got_cont_te;
+
+void
+start_entity_hdr()
+{
+	msg_state = MSG_STATE_HEADER;
+	hdr_state = HDR_STATE_BEGIN;
+	got_cont_type = 0;
+	got_cont_te = 0;
+}
+
+void
+begin_new_message()
+{
+	mp_nest_level = 0;
+	start_entity_hdr();
+}
+
+static void
+emit_prefrom_warning()
+{
+	static int done;
+
+	if (done)
+		return;
+	fprintf(stderr,
+		"f-demime warning: data present before the first From\n");
+	done = 1;
+}
+
+static int
+check_mp_terminator(line)
+	char *line;
+{
+	unsigned lev, bndlen;
+	char *bnd, *cp;
+
+	if (line[0] != '-' || line[1] != '-')
+		return(0);
+	for (lev = 0; lev < mp_nest_level; lev++) {
+		bnd = mp_boundaries[lev];
+		bndlen = strlen(bnd);
+		if (strncmp(line+2, bnd, bndlen))
+			continue;
+		finish_msg_body();
+		puts(line);
+		cp = line + 2 + bndlen;
+		if (!*cp || isspace(*cp)) {
+			mp_nest_level = lev + 1;
+			start_entity_hdr();
+			return(1);
+		}
+		if (cp[0] != '-' || cp[1] != '-')
+			puts("X-Fdemime-Error: invalid delimiter line");
+		mp_nest_level = lev;
+		msg_state = MSG_STATE_BODY_PASS;
+		return(1);
+	}
+	return(0);
+}
+
+void
+message_input_line(line)
+	char *line;
+{
+	if (check_mp_terminator(line))
+		return;
+	switch (msg_state) {
+	case MSG_STATE_UNDEF:
+		emit_prefrom_warning();
+		puts(line);
+		return;
+	case MSG_STATE_HEADER:
+		header_input_line(line);
+		return;
+	case MSG_STATE_BODY_PASS:
+		puts(line);
+		return;
+	case MSG_STATE_PTEXT_B64:
+	case MSG_STATE_BLOB_B64:
+	case MSG_STATE_B64_TO_QP:
+		base64_input_line(line);
+		return;
+	case MSG_STATE_PTEXT_QP:
+		qpdec_input_line(line);
+		return;
+	default:
+		fprintf(stderr,
+		"f-demime internal error: bad state in message_input_line()\n");
+		abort();
+	}
+}