Better logic + esplicitely printing when DHCP is going to be disabled

Author: pallotron

README.md

@@ -393,20 +393,13 @@ On the other hand, `socket_vmnet` does not require the entire QEMU process to ru
 
 ### How to use static IP addresses?
 
-Two options:
-
-#### By using a shorter DHCP range
 When `--vmnet-gateway=IP` is set to "192.168.105.1", the whole subnet (192.168.105.2-192.168.105.254) is used as the DHCP range.
 
 To use static IP addresses, limit the DHCP range with `--vmnet-dhcp-end=IP`.
 
 For example, `--vmnet-gateway=192.168.105.1 --vmnet-dhcp-end=192.168.105.100` allows using `192.168.105.101-192.168.105.254`
 as non-DHCP static addresses.
 
-#### By setting up network UUID (only in vmnet.host mode)
-
-When `--vmnet-mode=host` and `--vmnet-network-uuid` are set, the internal DHCP is disabled and you are free to use static IP addresses. You still need to set `--vmnet-gateway=IP` to avoid collision with other vmnet networks.
-
 ### How to reserve DHCP addresses?
 
 - Decide a unique MAC address for the VM, e.g. `de:ad:be:ef:00:01`.
@@ -443,6 +436,15 @@ sudo /usr/libexec/ApplicationFirewall/socketfilterfw --add /usr/libexec/bootpd
 /usr/libexec/ApplicationFirewall/socketfilterfw --unblock /usr/libexec/bootpd
 ```
 
+### How to setup a vmnet host network without DHCP
+
+You may need to disable the vmnet framework's DHCP to:
+- Create a host network where all VMs have static IPs.
+- Run a custom DHCP server on one VM to assign IPs to others on the same network.
+
+To disable the internal DHCP, use `--vmnet-mode=host` without `--vmnet-gateway`. This allows you to use static IP addresses for your VMs.
+You can optionally provide a `--vmnet-network-uuid`.
+
 ## Links
 
 - https://developer.apple.com/documentation/vmnet

cli.c

@@ -48,9 +48,7 @@ static void print_usage(const char *argv0) {
          "specified\n");
   printf("--vmnet-interface-id=UUID           vmnet interface ID (default: "
          "random)\n");
-  printf("--vmnet-network-uuid=UUID           vmnet network UUID (default: "
-         "random)\n");
-  printf("--vmnet-network-uuid=UUID           vmnet network UUID, if provided in \"host\" vmnet mode the\n"
+  printf("--vmnet-network-uuid=UUID           vmnet network UUID, if provided in \"host\" vmnet mode withouht --vmnet-gateway, the\n"
          "                                    internal DHCP will be disabled (default: " "random)\n");
   printf("--vmnet-nat66-prefix=PREFIX::       The IPv6 prefix to use with "
          "shared mode.\n");
@@ -207,7 +205,7 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
     goto error;
   }
   if (res->vmnet_gateway == NULL) {
-    if (res->vmnet_mode != VMNET_BRIDGED_MODE) {
+    if (res->vmnet_mode != VMNET_BRIDGED_MODE && res->vmnet_mode != VMNET_HOST_MODE) {
       WARN("--vmnet-gateway=IP should be explicitly specified to "
            "avoid conflicting with other applications");
     }

main.c

@@ -230,17 +230,23 @@ static interface_ref start(struct state *state, struct cli_options *cliopt) {
     INFOF("Using network interface \"%s\"", cliopt->vmnet_interface);
     xpc_dictionary_set_string(dict, vmnet_shared_interface_name_key, cliopt->vmnet_interface);
   }
-  if (cliopt->vmnet_gateway != NULL) {
-    xpc_dictionary_set_string(dict, vmnet_start_address_key, cliopt->vmnet_gateway);
-    xpc_dictionary_set_string(dict, vmnet_end_address_key, cliopt->vmnet_dhcp_end);
-    xpc_dictionary_set_string(dict, vmnet_subnet_mask_key, cliopt->vmnet_mask);
-  }
 
-  xpc_dictionary_set_uuid(dict, vmnet_interface_id_key, cliopt->vmnet_interface_id);
-  if (cliopt->vmnet_mode == VMNET_HOST_MODE) {
+  // no dhcp
+  if (cliopt->vmnet_mode == VMNET_HOST_MODE && cliopt->vmnet_gateway == NULL) {
     xpc_dictionary_set_uuid(dict, vmnet_network_identifier_key, cliopt->vmnet_network_uuid);
+    uuid_string_t uuid_str;
+    uuid_unparse(cliopt->vmnet_network_uuid, uuid_str);
+    INFOF("Using network identifier \"%s\" and no vmnet gateway -> NO DHCP will be enabled on this vmnet", uuid_str);
+  } else  {
+    if (cliopt->vmnet_gateway != NULL) {
+      xpc_dictionary_set_string(dict, vmnet_start_address_key, cliopt->vmnet_gateway);
+      xpc_dictionary_set_string(dict, vmnet_end_address_key, cliopt->vmnet_dhcp_end);
+      xpc_dictionary_set_string(dict, vmnet_subnet_mask_key, cliopt->vmnet_mask);
+    }
   }
 
+  xpc_dictionary_set_uuid(dict, vmnet_interface_id_key, cliopt->vmnet_interface_id);
+
   if (cliopt->vmnet_nat66_prefix != NULL) {
     xpc_dictionary_set_string(dict, vmnet_nat66_prefix_key, cliopt->vmnet_nat66_prefix);
   }