Add basic config file parsing

Rather than requiring all the parameters on the command line read a
config file. The command line can still override all options.

diff --git a/mqtt-arp.c b/mqtt-arp.c
index de0fcccea27cce24f0f2b4ffb3aeb6fcda8cc2b0..2836366b40391dfa6d9373e8fb9e316268f91d28 100644 (file)
--- a/mqtt-arp.c
+++ b/mqtt-arp.c
@@ -16,6 +16,8 @@
  * You should have received a copy of the GNU General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
+#include <ctype.h>
+#include <errno.h>
 #include <getopt.h>
 #include <signal.h>
 #include <stdbool.h>
@@ -38,6 +40,7 @@
 #define MQTT_PORT      8883
 #define MQTT_TOPIC     "location/by-mac"
 #define LOCATION       "home"
+#define CONFIG_FILE    "/etc/mqtt-arp.conf"
 
 /* How often (in seconds) to report that we see a device */
 #define REPORT_INTERVAL        (2 * 60)
@@ -283,6 +286,61 @@ int netlink_init(void)
        return sock;
 }
 
+int read_config(char *file, struct ma_config *config, int *macs)
+{
+       FILE *f;
+       char line[256];
+       int i;
+
+       f = fopen(file, "r");
+       if (f == NULL)
+               return errno;
+
+#define INT_OPTION(opt, var) \
+       if (strncmp(line, opt " ", sizeof(opt)) == 0) { \
+               var = atoi(&line[sizeof(opt)]);          \
+       }
+#define STRING_OPTION(opt, var) \
+       if (strncmp(line, opt " ", sizeof(opt)) == 0) { \
+               var = strdup(&line[sizeof(opt)]);       \
+       }
+
+       while (fgets(line, sizeof(line), f) != NULL) {
+               for (i = strlen(line) - 1; i >= 0 && isspace(line[i]); i--)
+                       line[i] = '\0';
+               if (line[0] == '\0' || line[0] == '#')
+                       continue;
+
+               if (strncmp(line, "mac ", 4) == 0) {
+                       if (*macs >= MAX_MACS) {
+                               printf("Can only accept %d MAC addresses to"
+                                       " watch for.\n", MAX_MACS);
+                               exit(EXIT_FAILURE);
+                       }
+                       sscanf(&line[4],
+                               "%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;
+                       (*macs)++;
+               } else
+               STRING_OPTION("mqtt_host", config->mqtt_host) else
+               INT_OPTION("mqtt_port", config->mqtt_port) else
+               STRING_OPTION("mqtt_user", config->mqtt_username) else
+               STRING_OPTION("mqtt_pass", config->mqtt_password) else
+               STRING_OPTION("mqtt_topic", config->mqtt_topic) else
+               STRING_OPTION("location", config->location) else
+               STRING_OPTION("capath", config->capath)
+       }
+       fclose(f);
+
+       return 0;
+}
+
 struct option long_options[] = {
        { "capath", required_argument, 0, 'c' },
        { "host", required_argument, 0, 'h' },
@@ -308,6 +366,9 @@ int main(int argc, char *argv[])
        bzero(&config, sizeof(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",
                                long_options, &option_index);

diff --git a/mqtt-arp.conf b/mqtt-arp.conf
new file mode 100644 (file)
index 0000000..7c80617
--- /dev/null
+++ b/mqtt-arp.conf
@@ -0,0 +1,15 @@
+# Example config file for mqtt-arp
+# Commented out entries are the defaults
+#mqtt_host mqtt-host
+#mqtt_port 8883
+mqtt_user mqtt-arp
+mqtt_pass mypassword
+#mqtt_topic location/by-mac
+
+#location home
+capath /etc/ssl/certs/ca-certificates.crt
+
+# Up to MAX_MACS (8 by default) addresses supported
+mac 00:11:22:33:44:55
+mac 00:66:77:88:99:aa
+mac 00:bb:cc:dd:ee:ff