From f25ebe658f178d7d32fd837e40669c4b6a613ea8 Mon Sep 17 00:00:00 2001
From: Eneas U de Queiroz <cotequeiroz@gmail.com>
Date: Thu, 5 Aug 2021 10:55:51 -0300
Subject: [PATCH] Verify compatibility before parsing config message

This adds a verion field to the ubus configuration message, to avoid
acting upon a message from an incompatible version of dawn.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
---
 src/include/datastorage.h | 5 +++++
 src/utils/msghandler.c    | 9 +++++++++
 src/utils/ubus.c          | 1 +
 3 files changed, 15 insertions(+)

diff --git a/src/include/datastorage.h b/src/include/datastorage.h
index 2553359..96f073c 100644
--- a/src/include/datastorage.h
+++ b/src/include/datastorage.h
@@ -52,6 +52,11 @@ void mac_array_delete(struct mac_entry_s* entry);
 // ---------------- Global variables ----------------
 /*** Metrics and configuration data ***/
 
+// TODO: Define a proper version string
+#ifndef DAWN_CONFIG_VERSION
+#define DAWN_CONFIG_VERSION "1"
+#endif
+
 // ---------------- Structs ----------------
 struct probe_metric_s {
     int ap_weight; // TODO: Never evaluated?
diff --git a/src/utils/msghandler.c b/src/utils/msghandler.c
index e27230b..c033ab7 100644
--- a/src/utils/msghandler.c
+++ b/src/utils/msghandler.c
@@ -553,6 +553,7 @@ int parse_to_clients(struct blob_attr* msg, int do_kick, uint32_t id) {
 }
 
 enum {
+    UCI_CONFIG_VERSION,
     UCI_TABLE_METRIC,
     UCI_TABLE_TIMES,
     __UCI_TABLE_MAX
@@ -605,6 +606,7 @@ enum {
 };
 
 static const struct blobmsg_policy uci_table_policy[__UCI_TABLE_MAX] = {
+        [UCI_CONFIG_VERSION ] = {.name = "version", .type = BLOBMSG_TYPE_STRING},
         [UCI_TABLE_METRIC] = {.name = "metric", .type = BLOBMSG_TYPE_TABLE},
         [UCI_TABLE_TIMES] = {.name = "times", .type = BLOBMSG_TYPE_TABLE}
 };
@@ -658,6 +660,13 @@ static int handle_uci_config(struct blob_attr* msg) {
     struct blob_attr* tb[__UCI_TABLE_MAX];
     blobmsg_parse(uci_table_policy, __UCI_TABLE_MAX, tb, blob_data(msg), blob_len(msg));
 
+    const char *version_string = blobmsg_get_string(tb[UCI_CONFIG_VERSION]);
+    if (version_string == NULL || strcmp(version_string, DAWN_CONFIG_VERSION)) {
+        fprintf(stderr, "Ignoring network config message with incompatible version string '%s'.\n",
+                version_string ? : "");
+        return -1;
+    }
+
     struct blob_attr* tb_metric[__UCI_METIC_MAX];
     blobmsg_parse(uci_metric_policy, __UCI_METIC_MAX, tb_metric, blobmsg_data(tb[UCI_TABLE_METRIC]), blobmsg_len(tb[UCI_TABLE_METRIC]));
 
diff --git a/src/utils/ubus.c b/src/utils/ubus.c
index 6af745d..eccae24 100644
--- a/src/utils/ubus.c
+++ b/src/utils/ubus.c
@@ -1366,6 +1366,7 @@ int uci_send_via_network()
     void *metric, *times;
 
     blob_buf_init(&b, 0);
+    blobmsg_add_string(&b, "version", DAWN_CONFIG_VERSION);
     metric = blobmsg_open_table(&b, "metric");
     blobmsg_add_u32(&b, "ht_support", dawn_metric.ht_support);
     blobmsg_add_u32(&b, "vht_support", dawn_metric.vht_support);