feat: Allow specifying vmnet network UUID to disable DHCP (when in Host mode)

README.md

@@ -12,27 +12,28 @@ Unlike `vde_vmnet`, `socket_vmnet` does not depend on VDE.
 <!-- START doctoc generated TOC please keep comment here to allow auto update -->
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 
-- [Install](#install)
-  - [From binary](#from-binary)
-  - [From source](#from-source)
-  - [From Homebrew](#from-homebrew)
-  - [From MacPorts](#from-macports)
-- [Usage](#usage)
-  - [QEMU](#qemu)
-  - [Lima](#lima)
-- [Advanced usage](#advanced-usage)
-  - [Multi VM](#multi-vm)
-  - [Bridged mode](#bridged-mode)
-- [FAQs](#faqs)
-  - [Why does `socket_vmnet` require root?](#why-does-socket_vmnet-require-root)
-  - [Is it possible to run `socket_vmnet` with SETUID?](#is-it-possible-to-run-socket_vmnet-with-setuid)
+  - [Install](#install)
+    - [From binary](#from-binary)
+    - [From source](#from-source)
+    - [From Homebrew](#from-homebrew)
+    - [From MacPorts](#from-macports)
+  - [Usage](#usage)
+    - [QEMU](#qemu)
+    - [Lima](#lima)
+  - [Advanced usage](#advanced-usage)
+    - [Multi VM](#multi-vm)
+    - [Bridged mode](#bridged-mode)
+  - [FAQs](#faqs)
+    - [Why does `socket_vmnet` require root?](#why-does-socket_vmnet-require-root)
+    - [Is it possible to run `socket_vmnet` with SETUID?](#is-it-possible-to-run-socket_vmnet-with-setuid)
   - [How is socket_vmnet related to vde_vmnet?](#how-is-socket_vmnet-related-to-vde_vmnet)
-  - [How is socket_vmnet related to QEMU-builtin vmnet support?](#how-is-socket_vmnet-related-to-qemu-builtin-vmnet-support)
-  - [How to use static IP addresses?](#how-to-use-static-ip-addresses)
-  - [How to reserve DHCP addresses?](#how-to-reserve-dhcp-addresses)
-  - [IP address is not assigned](#ip-address-is-not-assigned)
-- [Links](#links)
-- [Troubleshooting](#troubleshooting)
+    - [How is socket_vmnet related to QEMU-builtin vmnet support?](#how-is-socket_vmnet-related-to-qemu-builtin-vmnet-support)
+    - [How to use static IP addresses?](#how-to-use-static-ip-addresses)
+    - [How to reserve DHCP addresses?](#how-to-reserve-dhcp-addresses)
+    - [IP address is not assigned](#ip-address-is-not-assigned)
+    - [How to setup a vmnet host network without DHCP?](#how-to-setup-a-vmnet-host-network-without-dhcp)
+  - [Links](#links)
+  - [Troubleshooting](#troubleshooting)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
@@ -430,6 +431,20 @@ 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?
+
+Some users may need to disable the vmnet framework's DHCP for various scenarios, such as:
+
+- 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.
+
+Disabling macOS DHCP only works in `--vmnet-mode=host` if you provide a `--vmnet-network-identifier`.
+For example, to create a host network without DHCP on `socket_vmnet`:
+
+```bash
+sudo /opt/socket_vmnet/bin/socket_vmnet --vmnet-mode=host --vmnet-network-identifier=$(uuidgen)
+```
+
 ## Links
 
 - https://developer.apple.com/documentation/vmnet

cli.c

@@ -48,6 +48,16 @@ static void print_usage(const char *argv0) {
          "specified\n");
   printf("--vmnet-interface-id=UUID           vmnet interface ID (default: "
          "random)\n");
+  printf(
+      "--vmnet-network-identifier=UUID     The identifier(uuid) to uniquely identify the network. "
+      "\n"
+      "                                    This property is only applicable to a vmnet_interface\n"
+      "                                    in VMNET_HOST_MODE.\n"
+      "                                    If this property is set, the vmnet_interface is added "
+      "to \n"
+      "                                    an isolated network with the specified\n"
+      "                                    identifier. No DHCP service is provided on this "
+      "network.\n");
   printf("--vmnet-nat66-prefix=PREFIX::       The IPv6 prefix to use with "
          "shared mode.\n");
   printf("                                    The prefix must be a ULA i.e. "
@@ -72,6 +82,7 @@ enum {
   CLI_OPT_VMNET_MASK,
   CLI_OPT_VMNET_INTERFACE_ID,
   CLI_OPT_VMNET_NAT66_PREFIX,
+  CLI_OPT_VMNET_NETWORK_IDENTIFIER,
 };
 
 struct cli_options *cli_options_parse(int argc, char *argv[]) {
@@ -82,18 +93,19 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
   }
 
   const struct option longopts[] = {
-      {"socket-group",       required_argument, NULL, CLI_OPT_SOCKET_GROUP      },
-      {"vmnet-mode",         required_argument, NULL, CLI_OPT_VMNET_MODE        },
-      {"vmnet-interface",    required_argument, NULL, CLI_OPT_VMNET_INTERFACE   },
-      {"vmnet-gateway",      required_argument, NULL, CLI_OPT_VMNET_GATEWAY     },
-      {"vmnet-dhcp-end",     required_argument, NULL, CLI_OPT_VMNET_DHCP_END    },
-      {"vmnet-mask",         required_argument, NULL, CLI_OPT_VMNET_MASK        },
-      {"vmnet-interface-id", required_argument, NULL, CLI_OPT_VMNET_INTERFACE_ID},
-      {"vmnet-nat66-prefix", required_argument, NULL, CLI_OPT_VMNET_NAT66_PREFIX},
-      {"pidfile",            required_argument, NULL, 'p'                       },
-      {"help",               no_argument,       NULL, 'h'                       },
-      {"version",            no_argument,       NULL, 'v'                       },
-      {0,                    0,                 0,    0                         },
+      {"socket-group",             required_argument, NULL, CLI_OPT_SOCKET_GROUP            },
+      {"vmnet-mode",               required_argument, NULL, CLI_OPT_VMNET_MODE              },
+      {"vmnet-interface",          required_argument, NULL, CLI_OPT_VMNET_INTERFACE         },
+      {"vmnet-gateway",            required_argument, NULL, CLI_OPT_VMNET_GATEWAY           },
+      {"vmnet-dhcp-end",           required_argument, NULL, CLI_OPT_VMNET_DHCP_END          },
+      {"vmnet-mask",               required_argument, NULL, CLI_OPT_VMNET_MASK              },
+      {"vmnet-interface-id",       required_argument, NULL, CLI_OPT_VMNET_INTERFACE_ID      },
+      {"vmnet-nat66-prefix",       required_argument, NULL, CLI_OPT_VMNET_NAT66_PREFIX      },
+      {"vmnet-network-identifier", required_argument, NULL, CLI_OPT_VMNET_NETWORK_IDENTIFIER},
+      {"pidfile",                  required_argument, NULL, 'p'                             },
+      {"help",                     no_argument,       NULL, 'h'                             },
+      {"version",                  no_argument,       NULL, 'v'                             },
+      {0,                          0,                 0,    0                               },
   };
   int opt = 0;
   while ((opt = getopt_long(argc, argv, "hvp:", longopts, NULL)) != -1) {
@@ -134,6 +146,12 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
     case CLI_OPT_VMNET_NAT66_PREFIX:
       res->vmnet_nat66_prefix = strdup(optarg);
       break;
+    case CLI_OPT_VMNET_NETWORK_IDENTIFIER:
+      if (uuid_parse(optarg, res->vmnet_network_identifier) < 0) {
+        ERRORF("Failed to parse network identifier UUID \"%s\"", optarg);
+        goto error;
+      }
+      break;
     case 'p':
       res->pidfile = strdup(optarg);
       break;
@@ -191,7 +209,7 @@ 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");
     }

cli.h

@@ -20,6 +20,8 @@ struct cli_options {
   char *vmnet_mask;
   // --vmnet-interface-id, corresponds to vmnet_interface_id_key
   uuid_t vmnet_interface_id;
+  // --vmnet-network-identifier, corresponds to vmnet_network_identifier_key
+  uuid_t vmnet_network_identifier;
   // --vmnet-nat66-prefix, corresponds to vmnet_nat66_prefix_key
   char *vmnet_nat66_prefix;
   // -p, --pidfile; writes pidfile using permissions of socket_vmnet

main.c

@@ -230,6 +230,11 @@ 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 (!uuid_is_null(cliopt->vmnet_network_identifier)) {
+    xpc_dictionary_set_uuid(dict, vmnet_network_identifier_key, cliopt->vmnet_network_identifier);
+  }
+
   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);