Lua function may disable REC file storage

closes #27

README.md

@@ -239,7 +239,7 @@ Unless already provided by the package you installed, we recommend you create a
 
 The _recorder_ has, like _ocat_, a daunting number of options, most of which you will not require. Running either utility with the `-h` or `--help` switch will summarize their meanings. You can, for example launch with a specific storage directory, disable the HTTP server, change its port, etc.
 
-If you require authentication or TLS to connect to your MQTT broker, pay attention to the `$OTR_` environment variables listed in the help. 
+If you require authentication or TLS to connect to your MQTT broker, pay attention to the `$OTR_` environment variables listed in the help.
 
 Launch the recorder:
 
@@ -249,7 +249,7 @@ $ ./ot-recorder 'owntracks/#'
 
 Publish a location from your OwnTracks app and you should see the _recorder_ receive that on the console. If you haven't disabled Geo-lookups, you'll also see the address from which the publish originated.
 
-The location message received by the _recorder_ will be written to storage. 
+The location message received by the _recorder_ will be written to storage.
 
 ### Launching `ot-recorder` for _Hosted mode_
 
@@ -321,7 +321,7 @@ We recommend you keep reverse-geo lookups enabled, this data (country code `cc`,
 
 ## Monitoring
 
-In order to monitor the _recorder_, whenever an MQTT message is received, a `monitor` file located relative to STORAGEDEFAULT is maintained. It contains a single line of text: the epoch timestamp and the last received topic separated from each other by a space. 
+In order to monitor the _recorder_, whenever an MQTT message is received, a `monitor` file located relative to STORAGEDEFAULT is maintained. It contains a single line of text: the epoch timestamp and the last received topic separated from each other by a space.
 
 ```
 1439738692 owntracks/jjolie/ipad
@@ -500,6 +500,13 @@ written by OwnTracks Recorder version 0.3.0
 It is 14:10:01 in the year 2015 owntracks/jane/phone lat=48.858339 Avenue Anatole France, 75007 Paris, France
 ```
 
+### `putrec`
+
+An optional function you provide is called `putrec(u, d, s)`. If it exists,
+it is called with the current user in `u`, the device in `d` and the payload
+(which is possibly not JSON) in the string `s`. If your function returns a
+non-zero value, the _recorder_ will *not* write the REC file for this publish.
+
 ### Hooklets
 
 After running `otr_hook()`, the _recorder_ attempts to invoke a Lua function for each of the elements in the extended JSON. If, say, your Lua script contains a function called `hooklet_lat`, it will be invoked every time a `lat` is received as part of the JSON payload. Similarly with `hooklet_addr`, `hooklet_cc`, `hooklet_tst`, etc. These _hooklets_ are invoked with the same parameters as `otr_hook()`.

hooks.c

@@ -185,6 +185,40 @@ static void hooks_hooklet(struct udata *ud, char *topic, JsonNode *fullo)
 	}
 }
 
+/*
+ * Invoked from putrec() in storage. If the Lua putrec function is available
+ * and it returns non-zero, do not putrec.
+ */
+
+int hooks_norec(struct udata *ud, char *user, char *device, char *payload)
+{
+	struct luadata *ld = ud->luadata;
+	int rc;
+
+	if (ld == NULL)
+		return (0);
+
+	lua_settop(ld->L, 0);
+	lua_getglobal(ld->L, "putrec");
+	if (lua_type(ld->L, -1) != LUA_TFUNCTION) {
+		return (0);
+	}
+
+	lua_pushstring(ld->L, user);
+	lua_pushstring(ld->L, device);
+	lua_pushstring(ld->L, payload);
+
+	/* Invoke `hook' function in Lua with our args */
+	if (lua_pcall(ld->L, 3, 1, 0)) {
+		olog(LOG_ERR, "Failed to run putrec in Lua: %s", lua_tostring(ld->L, -1));
+		exit(1);
+	}
+
+	rc = (int)lua_tonumber(ld->L, -1);
+	printf("C: hooks_norec returns %d\n", rc);
+	return (rc);
+}
+
 void hooks_hook(struct udata *ud, char *topic, JsonNode *fullo)
 {
 	do_hook("otr_hook", ud, topic, fullo);

hooks.h

@@ -13,6 +13,7 @@ struct luadata {
 struct luadata *hooks_init(struct udata *ud, char *luascript);
 void hooks_exit(struct luadata *, char *reason);
 void hooks_hook(struct udata *ud, char *topic, JsonNode *obj);
+int hooks_norec(struct udata *ud, char *user, char *device, char *payload);
 
 #endif /* WITH_LUA */
 

ot-recorder.c

@@ -260,18 +260,25 @@ JsonNode *csv_to_json(char *payload)
 
 #define RECFORMAT "%s\t%-18s\t%s\n"
 
-static void putrec(time_t now, UT_string *reltopic, UT_string *username, UT_string *device, char *string)
+/*
+ * Store payload in REC file unless our Lua putrec() function says
+ * we shouldn't for this particular user/device combo.
+ */
+
+static void putrec(struct udata *ud, time_t now, UT_string *reltopic, UT_string *username, UT_string *device, char *string)
 {
 	FILE *fp;
 
-	if ((fp = pathn("a", "rec", username, device, "rec")) == NULL) {
-		olog(LOG_ERR, "Cannot write REC for %s/%s: %m",
-			UB(username), UB(device));
-	}
+	if (hooks_norec(ud, UB(username), UB(device), string) == 0) {
+		if ((fp = pathn("a", "rec", username, device, "rec")) == NULL) {
+			olog(LOG_ERR, "Cannot write REC for %s/%s: %m",
+				UB(username), UB(device));
+		}
 
-	fprintf(fp, RECFORMAT, isotime(now),
+		fprintf(fp, RECFORMAT, isotime(now),
 			UB(reltopic), string);
-	fclose(fp);
+		fclose(fp);
+	}
 }
 
 void on_message(struct mosquitto *mosq, void *userdata, const struct mosquitto_message *m)
@@ -379,7 +386,7 @@ void on_message(struct mosquitto *mosq, void *userdata, const struct mosquitto_m
 	if ((json = json_decode(m->payload)) == NULL) {
 		if ((json = csv_to_json(m->payload)) == NULL) {
 			/* It's not JSON or it's not a location CSV; store it */
-			putrec(now, reltopic, username, device, bindump(m->payload, m->payloadlen));
+			putrec(ud, now, reltopic, username, device, bindump(m->payload, m->payloadlen));
 			return;
 		}
 	}
@@ -420,14 +427,14 @@ void on_message(struct mosquitto *mosq, void *userdata, const struct mosquitto_m
 		case T_LWT:
 		case T_STEPS:
 		case T_WAYPOINTS:
-			putrec(now, reltopic, username, device, bindump(m->payload, m->payloadlen));
+			putrec(ud, now, reltopic, username, device, bindump(m->payload, m->payloadlen));
 			goto cleanup;
 		case T_WAYPOINT:
 		case T_TRANSITION:
 		case T_LOCATION:
 			break;
 		default:
-			putrec(now, reltopic, username, device, bindump(m->payload, m->payloadlen));
+			putrec(ud, now, reltopic, username, device, bindump(m->payload, m->payloadlen));
 			goto cleanup;
 	}
 
@@ -542,7 +549,7 @@ void on_message(struct mosquitto *mosq, void *userdata, const struct mosquitto_m
 
 	if (!pingping) {
 		if ((jsonstring = json_stringify(json, NULL)) != NULL) {
-			putrec(now, reltopic, username, device, jsonstring);
+			putrec(ud, now, reltopic, username, device, jsonstring);
 			free(jsonstring);
 		}
 	}