Return value of _modbus_tcp_pi_connect() on failure (closes #61)

src/modbus-tcp.c

@@ -349,8 +349,9 @@ static int _modbus_tcp_pi_connect(modbus_t *ctx)
                      &ai_hints, &ai_list);
     if (rc != 0) {
         if (ctx->debug) {
-            printf("Error returned by getaddrinfo: %d\n", rc);
+            fprintf(stderr, "Error returned by getaddrinfo: %s\n", gai_strerror(rc));
         }
+        errno = ECONNREFUSED;
         return -1;
     }
 
@@ -518,8 +519,13 @@ int modbus_tcp_pi_listen(modbus_t *ctx, int nb_connection)
 
     ai_list = NULL;
     rc = getaddrinfo(node, service, &ai_hints, &ai_list);
-    if (rc != 0)
+    if (rc != 0) {
+        if (ctx->debug) {
+            fprintf(stderr, "Error returned by getaddrinfo: %s\n", gai_strerror(rc));
+        }
+        errno = ECONNREFUSED;
         return -1;
+    }
 
     new_socket = -1;
     for (ai_ptr = ai_list; ai_ptr != NULL; ai_ptr = ai_ptr->ai_next) {

tests/unit-test-client.c

@@ -82,8 +82,7 @@ int main(int argc, char *argv[])
     }
 
     if (modbus_connect(ctx) == -1) {
-        fprintf(stderr, "Connection failed: %s\n",
-                modbus_strerror(errno));
+        fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
         modbus_free(ctx);
         return -1;
     }