support --vmnet-gateway=IP, e.g., 192.168.105.1

`vde_vmnet` binary itself does not have any default value,
but the launchd plist file is updated to use 192.168.105.1
as the default, so as to avoid conflicting with VMware Fusion.

Fix #7

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

README.md

@@ -22,12 +22,10 @@ The following files will be installed:
 - `/usr/local/bin/vde_vmnet`
 - `/Library/LaunchDaemons/io.github.virtualsquare.vde-2.vde_switch.plist`
 - `/Library/LaunchDaemons/io.github.AkihiroSuda.vde_vmnet.plist`
+  - Configured to use `192.168.105.0/24`. Modifiy the file if it conflicts with your local network.
 
 See ["Testing without launchd"](#testing-without-launchd) if you don't prefer to use launchd.
 
-
-:warning: Known to conflict with VMware Fusion. See issue [#7](https://github.com/AkihiroSuda/vde_vmnet/issues/7).
-
 ## Usage
 
 ```console
@@ -75,7 +73,7 @@ vde_switch --unix /tmp/vde.ctl
 ```
 
 ```console
-sudo vde_vmnet /tmp/vde.ctl
+sudo vde_vmnet --vmnet-gateway=192.168.105.1 /tmp/vde.ctl
 ```
 
 Note: make sure to run `vde_vmnet` with root (`sudo`). See [FAQs](#FAQs) for the reason.
@@ -125,14 +123,14 @@ On the other hand, `vde_vmnet` does not require the entire QEMU process to run a
 
 - Decide a unique MAC address for the VM, e.g. `de:ad:be:ef:00:01`.
 
-- Decide a static IP address, e.g., "192.168.60.100"
+- Decide a static IP address, e.g., "192.168.105.100"
 
 - Create `/etc/bootptab` like this. Make sure not to drop the "%%" header.
 ```
 # bootptab
 %%
 # hostname      hwtype  hwaddr              ipaddr          bootfile
-tmp-vm01        1       de:ad:be:ef:00:01   192.168.60.100
+tmp-vm01        1       de:ad:be:ef:00:01   192.168.105.100
 ```
 
 - Reload the DHCP daemon.

cli.c

@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <arpa/inet.h>
 #include <getopt.h>
 
 #include <availability.h>
@@ -30,6 +31,9 @@ static void print_usage(const char *argv0) {
       "--vmnet-mode=(host|shared|bridged)  vmnet mode (default: \"shared\")\n");
   printf("--vmnet-interface=INTERFACE         interface used for "
          "--vmnet=bridged, e.g., \"en0\"\n");
+  printf("--vmnet-gateway=IP                  gateway used for "
+         "--vmnet=(host|shared), e.g., \"192.168.105.1\" (default: decided by "
+         "macOS)\n");
   printf("-h, --help                          display this help and exit\n");
   printf("-v, --version                       display version information and "
          "exit\n");
@@ -42,6 +46,7 @@ static void print_version() { puts(VERSION); }
 #define CLI_OPTIONS_ID_VDE_GROUP -42
 #define CLI_OPTIONS_ID_VMNET_MODE -43
 #define CLI_OPTIONS_ID_VMNET_INTERFACE -44
+#define CLI_OPTIONS_ID_VMNET_GATEWAY -45
 struct cli_options *cli_options_parse(int argc, char *argv[]) {
   struct cli_options *res = malloc(sizeof(*res));
   if (res == NULL) {
@@ -54,6 +59,7 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
       {"vmnet-mode", required_argument, NULL, CLI_OPTIONS_ID_VMNET_MODE},
       {"vmnet-interface", required_argument, NULL,
        CLI_OPTIONS_ID_VMNET_INTERFACE},
+      {"vmnet-gateway", required_argument, NULL, CLI_OPTIONS_ID_VMNET_GATEWAY},
       {"help", no_argument, NULL, 'h'},
       {"version", no_argument, NULL, 'v'},
       {0, 0, 0, 0},
@@ -79,6 +85,9 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
     case CLI_OPTIONS_ID_VMNET_INTERFACE:
       res->vmnet_interface = strdup(optarg);
       break;
+    case CLI_OPTIONS_ID_VMNET_GATEWAY:
+      res->vmnet_gateway = strdup(optarg);
+      break;
     case 'h':
       print_usage(argv[0]);
       cli_options_destroy(res);
@@ -115,6 +124,26 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
         "vmnet mode \"bridged\" require --vmnet-interface to be specified\n");
     goto error;
   }
+  if (res->vmnet_gateway == NULL) {
+    if (res->vmnet_mode != VMNET_BRIDGED_MODE) {
+      fprintf(stderr,
+              "WARNING: --vmnet-gateway=IP should be explicitly specified to "
+              "avoid conflicting with other applications\n");
+    }
+  } else {
+    if (res->vmnet_mode == VMNET_BRIDGED_MODE) {
+      fprintf(stderr,
+              "vmnet mode \"bridged\" conflicts with --vmnet-gateway\n");
+      goto error;
+    }
+    struct in_addr dummy;
+    if (!inet_aton(res->vmnet_gateway, &dummy)) {
+      fprintf(stderr,
+              "invalid address \"%s\" was specified for --vmnet-gateway\n",
+              res->vmnet_gateway);
+      goto error;
+    }
+  }
   return res;
 error:
   print_usage(argv[0]);
@@ -132,5 +161,7 @@ void cli_options_destroy(struct cli_options *x) {
     free(x->vde_switch);
   if (x->vmnet_interface != NULL)
     free(x->vmnet_interface);
+  if (x->vmnet_gateway != NULL)
+    free(x->vmnet_gateway);
   free(x);
 }

cli.h

@@ -4,10 +4,16 @@
 #include <vmnet/vmnet.h>
 
 struct cli_options {
-  char *vde_group;              // --vde-group
-  operating_modes_t vmnet_mode; // --vmnet-mode
-  char *vmnet_interface;        // --vmnet-interface
-  char *vde_switch;             // arg
+  // --vde-group
+  char *vde_group;
+  // --vmnet-mode, corresponds to vmnet_operation_mode_key
+  operating_modes_t vmnet_mode;
+  // --vmnet-interface, corresponds to vmnet_shared_interface_name_key
+  char *vmnet_interface;
+  // --vmnet-gateway, corresponds to vmnet_start_address_key
+  char *vmnet_gateway;
+  // arg
+  char *vde_switch;
 };
 
 struct cli_options *cli_options_parse(int argc, char *argv[]);

launchd/io.github.AkihiroSuda.vde_vmnet.plist

@@ -9,6 +9,7 @@
 		<key>ProgramArguments</key>
 		<array>
 			<string>/usr/local/bin/vde_vmnet</string>
+			<string>--vmnet-gateway=192.168.105.1</string>
 			<string>/var/run/vde.ctl</string>
 		</array>
 		<key>StandardErrorPath</key>
@@ -28,4 +29,4 @@
 			</dict>
 		</dict>
 	</dict>
-</plist>
+</plist>

main.c

@@ -3,6 +3,8 @@
 #include <stdlib.h>
 #include <sys/uio.h>
 
+#include <arpa/inet.h>
+
 #include <vmnet/vmnet.h>
 
 #include <libvdeplug.h>
@@ -159,6 +161,32 @@ static interface_ref start(VDECONN *vdeconn, struct cli_options *cliopt) {
     xpc_dictionary_set_string(dict, vmnet_shared_interface_name_key,
                               cliopt->vmnet_interface);
   }
+  if (cliopt->vmnet_gateway != NULL) {
+    /* Set vmnet_start_address_key */
+    xpc_dictionary_set_string(dict, vmnet_start_address_key,
+                              cliopt->vmnet_gateway);
+
+    /* Set vmnet_end_address_key with .254 */
+    struct in_addr sin;
+    if (!inet_aton(cliopt->vmnet_gateway, &sin)) {
+      perror("inet_aton(cliopt->vmnet_gateway)");
+      return NULL;
+    }
+    uint32_t h = ntohl(sin.s_addr);
+    h &= 0xFFFFFF00;
+    h |= 0x000000FE;
+    sin.s_addr = htonl(h);
+
+    const char *end = inet_ntoa(sin); /* static storage, do not free */
+    if (end == NULL) {
+      perror("inet_ntoa");
+      return NULL;
+    }
+    xpc_dictionary_set_string(dict, vmnet_end_address_key, end);
+
+    /* Set vmnet_subnet_mask_key */
+    xpc_dictionary_set_string(dict, vmnet_subnet_mask_key, "255.255.255.0");
+  }
 
   uuid_t uuid;
   // TODO: support deterministic UUID and MAC address

test/test.ipxe

@@ -10,6 +10,12 @@ show netmask
 show dns
 show dhcp-server
 echo </vde_vmnet:iPXE-testing>
-# sleep for flushing the serial console
+
+echo [testing Internet connection]
+imgfetch http://google.com/
+
+echo [sleeping for flushing the serial console]
 sleep 1
+
+echo [exiting]
 reboot

test/test.sh

@@ -29,9 +29,14 @@ if ! grep -q "net0/mac:hex = 52:54:00:12:34:56" serial.log; then
 	exit 1
 fi
 
-if ! grep -q "net0.dhcp/ip:ipv4 = 192.168." serial.log; then
+if ! grep -q "net0.dhcp/ip:ipv4 = 192.168.105." serial.log; then
 	echo >&2 "ERROR: net0.dhcp/ip:ipv4 not found"
 	exit 1
 fi
 
+if ! grep -q "net0.dhcp/gateway:ipv4 = 192.168.105.1" serial.log; then
+	echo >&2 "ERROR: net0.dhcp/gateway:ipv4 not found"
+	exit 1
+fi
+
 rm -f serial.log