mqtt test client

test/.gitignore

@@ -1,2 +1,4 @@
 airspeed
 heading
+mqtt
+mqtt.h

test/mqtt.c

@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <errno.h>
+#include <string.h>
+
+// https://mosquitto.org/api/files/mosquitto-h.html
+#include <mosquitto.h>
+
+#include "mqtt.h"
+
+int main(int argc, char *argv[]) {
+    int err;
+    struct mosquitto *mqtt;
+    
+    
+    
+    err = mosquitto_lib_init();
+    if (err) {
+        fprintf(stderr, "Error initalizing mosquitto lib (%d): %s\n", err, mosquitto_strerror(err));
+        exit(EXIT_FAILURE);
+    }
+
+    mqtt = mosquitto_new(MQTT_USER, true, NULL);
+    if (mqtt == NULL) {
+        fprintf(stderr, "Error creating mosquitto instance (%d): %s\n", errno, strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+
+    err = mosquitto_username_pw_set(mqtt, MQTT_USER, MQTT_PASS);
+    if (err) {
+        fprintf(stderr, "Error setting username & password (%d): %s\n", err, mosquitto_strerror(err));
+        exit(EXIT_FAILURE);
+    }
+    
+    err = mosquitto_connect(mqtt, "openhab.sugarland.lan", 1883, 10);
+    if (err) {
+        fprintf(stderr, "Error on connection of type ");
+        if (err == MOSQ_ERR_ERRNO) {
+            fprintf(stderr, "system (%d): %s\n", errno, strerror(errno));
+        } else {
+            fprintf(stderr, "mosquitto (%d): %s\n", err, mosquitto_strerror(err));
+        }
+        exit(EXIT_FAILURE);
+    }
+
+    char *foo = "blah";
+    err = mosquitto_publish(mqtt, NULL, "/xplane/foo", strlen(foo), foo, 0, false);
+    if (err) {
+        fprintf(stderr, "Error publishing message (%d): %s\n", err, mosquitto_strerror(err));
+        exit(EXIT_FAILURE);
+    }
+
+    err = mosquitto_disconnect(mqtt);
+    // ignore error
+
+    mosquitto_destroy(mqtt);
+}