From b6c4055a868345ca1cb76e737b5b0494fab8989c Mon Sep 17 00:00:00 2001
From: claes <claes@holmerson.net>
Date: Sat, 10 Jun 2023 22:01:43 +0200
Subject: [PATCH] Make the config file overridable

---
 mqtt-arp.c | 113 +++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 93 insertions(+), 20 deletions(-)

diff --git a/mqtt-arp.c b/mqtt-arp.c
index bc65fbb..024f44c 100644
--- a/mqtt-arp.c
+++ b/mqtt-arp.c
@@ -293,8 +293,10 @@ int read_config(char *file, struct ma_config *config, int *macs)
 	int i;
 
 	f = fopen(file, "r");
-	if (f == NULL)
+	if (f == NULL) {
+		fprintf(stderr, "Could not read config file %s\n", file);
 		return errno;
+	}
 
 #define INT_OPTION(opt, var) \
 	if (strncmp(line, opt " ", sizeof(opt)) == 0) { \
@@ -341,6 +343,67 @@ int read_config(char *file, struct ma_config *config, int *macs)
 	return 0;
 }
 
+void override_config(const struct ma_config *source, struct ma_config *target)
+{
+	int i;
+
+	if (source->mqtt_host != NULL) {
+		target->mqtt_host = source->mqtt_host;
+	}
+	if (source->mqtt_port != 0) {
+		target->mqtt_port = source->mqtt_port;
+	}
+	if (source->mqtt_username != NULL) {
+		target->mqtt_username = source->mqtt_username;
+	}
+	if (source->mqtt_password != NULL) {
+		target->mqtt_password = source->mqtt_password;
+	}
+	if (source->mqtt_topic != NULL) {
+		target->mqtt_topic = source->mqtt_topic;
+	}
+	if (source->location != NULL) {
+		target->location = source->location;
+	}
+	if (source->capath != NULL) {
+		target->capath = source->capath;
+	}
+	for (i = 0; i < MAX_MACS; ++i) {
+		if (source->macs[i].valid) {
+			memcpy(&target->macs[i], &source->macs[i], sizeof(struct mac_entry));
+		}
+	}
+}
+
+void print_config(const struct ma_config *config)
+{
+	int i, j;
+
+	printf("Config:\n");
+	printf("mqtt_host: %s\n", config->mqtt_host ? config->mqtt_host : "NULL");
+	printf("mqtt_port: %d\n", config->mqtt_port);
+	printf("mqtt_username: %s\n", config->mqtt_username ? config->mqtt_username : "NULL");
+	printf("mqtt_password: %s\n", config->mqtt_password ? config->mqtt_password : "NULL");
+	printf("mqtt_topic: %s\n", config->mqtt_topic ? config->mqtt_topic : "NULL");
+	printf("location: %s\n", config->location ? config->location : "NULL");
+	printf("capath: %s\n", config->capath ? config->capath : "NULL");
+
+	for (i = 0; i < MAX_MACS; ++i) {
+		if (config->macs[i].valid) {
+			printf("macs[%d]: { valid: true, mac: ", i);
+			for (j = 0; j < 6; ++j) {
+				printf("%02x", config->macs[i].mac[j]);
+				if (j < 5) {
+					printf(":");
+				}
+			}
+			printf("\n");
+		} else {
+			printf("macs[%d]: { valid: false }\n", i);
+		}
+	}
+}
+
 struct option long_options[] = {
 	{ "capath", required_argument, 0, 'c' },
 	{ "host", required_argument, 0, 'h' },
@@ -351,6 +414,7 @@ struct option long_options[] = {
 	{ "topic", required_argument, 0, 't' },
 	{ "username", required_argument, 0, 'u' },
 	{ "verbose", no_argument, 0, 'v' },
+	{ "configfile", required_argument, 0, 'f' },
 	{ 0, 0, 0, 0 }
 };
 
@@ -359,32 +423,34 @@ int main(int argc, char *argv[])
 	int sock;
 	struct mosquitto *mosq;
 	struct ma_config config;
+	struct ma_config cmdline_config;
 	int option_index = 0;
 	int macs = 0;
 	int c;
+	char *config_file = CONFIG_FILE;
 
 	bzero(&config, sizeof(config));
+	bzero(&cmdline_config, sizeof(cmdline_config));
 	config.mqtt_port = MQTT_PORT;
 
-	/* Read config before parsing command line */
-	read_config(CONFIG_FILE, &config, &macs);
-
 	while (1) {
-		c = getopt_long(argc, argv, "c:h:l:m:p:P:t:u:v",
+		c = getopt_long(argc, argv, "c:h:l:m:p:P:t:u:f:v",
 				long_options, &option_index);
 
 		if (c == -1)
 			break;
-
 		switch (c) {
+		case 'f':
+			config_file = optarg;
+			break;
 		case 'c':
-			config.capath = optarg;
+			cmdline_config.capath = optarg;
 			break;
 		case 'h':
-			config.mqtt_host = optarg;
+			cmdline_config.mqtt_host = optarg;
 			break;
 		case 'l':
-			config.location = optarg;
+			cmdline_config.location = optarg;
 			break;
 		case 'm':
 			if (macs >= MAX_MACS) {
@@ -394,26 +460,26 @@ int main(int argc, char *argv[])
 			}
 			sscanf(optarg,
 				"%02hhx:%02hhx:%02hhx:%02hhx:%02hhx:%02hhx",
-				&config.macs[macs].mac[0],
-				&config.macs[macs].mac[1],
-				&config.macs[macs].mac[2],
-				&config.macs[macs].mac[3],
-				&config.macs[macs].mac[4],
-				&config.macs[macs].mac[5]);
-			config.macs[macs].valid = true;
+				&cmdline_config.macs[macs].mac[0],
+				&cmdline_config.macs[macs].mac[1],
+				&cmdline_config.macs[macs].mac[2],
+				&cmdline_config.macs[macs].mac[3],
+				&cmdline_config.macs[macs].mac[4],
+				&cmdline_config.macs[macs].mac[5]);
+			cmdline_config.macs[macs].valid = true;
 			macs++;
 			break;
 		case 'p':
-			config.mqtt_port = atoi(optarg);
+			cmdline_config.mqtt_port = atoi(optarg);
 			break;
 		case 'P':
-			config.mqtt_password = optarg;
+			cmdline_config.mqtt_password = optarg;
 			break;
 		case 't':
-			config.mqtt_topic = optarg;
+			cmdline_config.mqtt_topic = optarg;
 			break;
 		case 'u':
-			config.mqtt_username = optarg;
+			cmdline_config.mqtt_username = optarg;
 			break;
 		case 'v':
 			debug = true;
@@ -424,6 +490,10 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	read_config(config_file, &config, &macs);
+
+	override_config(&cmdline_config, &config);
+
 	if (!config.mqtt_host)
 		config.mqtt_host = MQTT_HOST;
 	if (!config.mqtt_topic)
@@ -431,6 +501,9 @@ int main(int argc, char *argv[])
 	if (!config.location)
 		config.location = LOCATION;
 
+	if (debug)
+		print_config(&config);
+
 	signal(SIGTERM, shutdown_request);
 
 	sock = netlink_init();
-- 
2.39.2