From 0db83386f2effba1be59ed301d9b400b57207b0a Mon Sep 17 00:00:00 2001
From: Christian Hesse <mail@eworm.de>
Date: Tue, 15 Mar 2016 15:40:02 +0100
Subject: add built in config for fallback

---
 config.def.h | 14 ++++++++++++++
 dyndhcpd.c   | 39 +++++++++++++++++++--------------------
 2 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/config.def.h b/config.def.h
index 0195c03..43cddc3 100644
--- a/config.def.h
+++ b/config.def.h
@@ -22,6 +22,20 @@
 #define PIDFILE		"/run/dhcpd-%s.pid"
 #define LEASESFILE	"/var/lib/dhcp/dhcp-%s.leases"
 
+#define FALLBACKCONFIG \
+	"# fallback dhcpd.conf for interface __INTERFACE__\n" \
+	"# generated by dyndhcpd/__VERSION__\n" \
+	"\n" \
+	"authoritative;\n" \
+	"option domain-name \"__DOMAINNAME__\";\n" \
+	"\n" \
+	"subnet __NETADDRESS__ netmask __NETMASK__ {\n" \
+	"\toption broadcast-address __BROADCAST__;\n" \
+	"\toption routers __ADDRESS__;\n" \
+	"\toption domain-name-servers __ADDRESS__;\n" \
+	"\trange __MINDHCP__ __MAXDHCP__;\n" \
+	"}"
+
 #endif /* _CONFIG_H */
 
 // vim: set syntax=c:
diff --git a/dyndhcpd.c b/dyndhcpd.c
index 5cbfb79..134e845 100644
--- a/dyndhcpd.c
+++ b/dyndhcpd.c
@@ -47,7 +47,7 @@ int main(int argc, char ** argv) {
 
 	char * template = NULL;
 	FILE * templatefile;
-	const char * templatefilename = NULL;
+	const char * templatefilename = CONFIG_TEMPLATE;
 	char * config = NULL;
 	FILE * configfile;
 	char * configfilename = NULL;
@@ -209,26 +209,25 @@ int main(int argc, char ** argv) {
 			}
 
 			/* open the template for reading */
-			if (templatefilename == NULL)
-				templatefilename = CONFIG_TEMPLATE;
-			if ((templatefile = fopen(templatefilename, "r")) == NULL) {
-				fprintf(stderr, "Failed opening config template for reading.\n");
-				goto out;
-			}
-
-			/* seek to the and so we know the file size */
-			fseek(templatefile, 0, SEEK_END);
-			fsize = ftell(templatefile);
-			fseek(templatefile, 0, SEEK_SET);
-
-			/* allocate memory and read file */
-			template = malloc(fsize + 1);
-			if ((fread(template, fsize, 1, templatefile)) != 1) {
-				fprintf(stderr, "Failed reading config template.\n");
-				goto out;
+			if ((templatefile = fopen(templatefilename, "r")) != NULL) {
+				/* seek to the and so we know the file size */
+				fseek(templatefile, 0, SEEK_END);
+				fsize = ftell(templatefile);
+				fseek(templatefile, 0, SEEK_SET);
+
+				/* allocate memory and read file */
+				template = malloc(fsize + 1);
+				if ((fread(template, fsize, 1, templatefile)) != 1) {
+					fprintf(stderr, "Failed reading config template.\n");
+					goto out;
+				}
+				fclose(templatefile);
+				template[fsize] = 0;
+			} else {
+				fprintf(stderr, "Failed opening config template for reading.\n"
+						"Using fallback to built in defaults, functionality is limited.\n");
+				template = strdup(FALLBACKCONFIG);
 			}
-			fclose(templatefile);
-			template[fsize] = 0;
 
 			/* replace strings with real values */
 			for (tmp = template; *tmp;) {
-- 
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