RSU tolling client repay protection

src/tpm.c

@@ -687,6 +687,50 @@ static void rsu_handle_recv(facilities_t* facilities, TPM_t* tpm_rx, void* secur
         tpm->tpm->referencePosition.positionConfidenceEllipse.semiMajorOrientation = 900;
     }
 
+    // Client management
+    for (int i = 0 ; i < tolling->station.rsu.clients_len; ++i) {
+        if (itss_time_get() > tolling->station.rsu.clients[i]->ts + TOLLING_CLIENT_LIFETIME_MS) {
+            free(tolling->station.rsu.clients[i]);
+            tolling->station.rsu.clients[i] = NULL;
+            for (int j = i; j < tolling->station.rsu.clients_len-1; ++j) {
+               tolling->station.rsu.clients[j] = tolling->station.rsu.clients[j+1];
+            }
+            --tolling->station.rsu.clients_len;
+        }
+    }
+
+    // Find client
+    toll_client_t* client = NULL;
+    for (int i = 0; i < tolling->station.rsu.clients_len; ++i) {
+        if (tolling->station.rsu.clients[i]->id == client_id) {
+            client = tolling->station.rsu.clients[i];
+        }
+    } 
+
+    // Create client
+    if (!client) {
+        if (tolling->station.rsu.clients_len-1 >= TOLLING_MAX_CLIENTS) {
+            syslog_err("[facilities] [tolling] max clients reached");
+            goto cleanup;
+        }
+        tolling->station.rsu.clients[tolling->station.rsu.clients_len] = malloc(sizeof(toll_client_t));
+        client = tolling->station.rsu.clients[tolling->station.rsu.clients_len];
+        client->id = client_id;
+        client->station_id = tpm_rx->header.stationID;
+        client->ts = itss_time_get();
+        client->accepted = -1;
+    }
+
+    uint8_t confirmation_code = TollingConfirmationCode_rejected;
+    if (itss_time_get() > client->ts + TOLLING_PAYMENT_MIN_PERIOD_MS ||
+        client->accepted == -1) {
+        confirmation_code = TollingConfirmationCode_accepted;
+        client->accepted = true;
+    } else if (client->accepted && 
+               itss_time_get() < client->ts + TOLLING_PAYMENT_MIN_PERIOD_MS) {
+        confirmation_code = TollingConfirmationCode_alreadyAccepted;
+    }
+
     tpm->tpm->tollingType = calloc(1, sizeof(TollingType_t));
     switch (tpm_rx->tpm->tollingType->present) {
         case TollingType_PR_entry:
@@ -695,7 +739,7 @@ static void rsu_handle_recv(facilities_t* facilities, TPM_t* tpm_rx, void* secur
             tpm->tpm->tollingType->choice.entry.choice.reply.clientId = client_id;
             tpm->tpm->tollingType->choice.entry.choice.reply.infoId = info_id;
             tpm->tpm->tollingType->choice.entry.choice.reply.transactionNonce = nonce;
-            tpm->tpm->tollingType->choice.entry.choice.reply.confirmationCode = TollingConfirmationCode_accepted;
+            tpm->tpm->tollingType->choice.entry.choice.reply.confirmationCode = confirmation_code;
             break;
         case TollingType_PR_exit:
             tpm->tpm->tollingType->present = TollingType_PR_exit;
@@ -704,7 +748,7 @@ static void rsu_handle_recv(facilities_t* facilities, TPM_t* tpm_rx, void* secur
             tpm->tpm->tollingType->choice.exit->choice.reply.clientId = client_id;
             tpm->tpm->tollingType->choice.exit->choice.reply.infoId = info_id;
             tpm->tpm->tollingType->choice.exit->choice.reply.transactionNonce = nonce;
-            tpm->tpm->tollingType->choice.exit->choice.reply.confirmationCode = TollingConfirmationCode_accepted;
+            tpm->tpm->tollingType->choice.exit->choice.reply.confirmationCode = confirmation_code;
             break;
         case TollingType_PR_single:
             tpm->tpm->tollingType->present = TollingType_PR_single;
@@ -712,7 +756,7 @@ static void rsu_handle_recv(facilities_t* facilities, TPM_t* tpm_rx, void* secur
             tpm->tpm->tollingType->choice.single.choice.reply.clientId = client_id;
             tpm->tpm->tollingType->choice.single.choice.reply.infoId = info_id;
             tpm->tpm->tollingType->choice.single.choice.reply.transactionNonce = nonce;
-            tpm->tpm->tollingType->choice.single.choice.reply.confirmationCode = TollingConfirmationCode_accepted;
+            tpm->tpm->tollingType->choice.single.choice.reply.confirmationCode = confirmation_code;
             break;
         default:
             break;
@@ -1290,6 +1334,9 @@ int tolling_init(tolling_t* tolling, void* zmq_ctx, char* security_address, uint
 
     switch (station_type) {
         case 15:
+            for (int i = 0; i < TOLLING_MAX_CLIENTS; ++i) {
+                tolling->station.rsu.clients[i] = NULL;
+            }
             break;
         default:
             tolling->station.obu.toll_type = -1;

src/tpm.h

@@ -12,6 +12,8 @@
 #define TOLLING_CONN_TIMEOUT_MS 10000
 #define TOLLING_RT_PERIOD_MS 400
 #define TOLLING_RT_TIMEOUT_MS 10000
+#define TOLLING_MAX_CLIENTS 256
+#define TOLLING_CLIENT_LIFETIME_MS 300000
 
 typedef enum TOLLING_PROTOCOL {
     TOLLING_PROTOCOL_SIMPLE,
@@ -41,6 +43,13 @@ typedef struct tlsc {
     uint16_t nmsg;
 } tlsc_t;
 
+typedef struct toll_client {
+    uint64_t station_id;
+    uint64_t id;
+    uint64_t ts;
+    int8_t accepted;
+} toll_client_t;
+
 typedef struct tolling {
     bool enabled;
     pthread_mutex_t lock;
@@ -63,6 +72,8 @@ typedef struct tolling {
     union {
         // RSU
         struct {
+            toll_client_t* clients[TOLLING_MAX_CLIENTS];
+            uint16_t clients_len;
         } rsu;
 
         // OBU