Allow certain DHCP options to be used without DHCP server

Followin DHCP options:

  DOMAIN, ADAPTER_DOMAIN_SUFFIX, DNS, WINS

don't require DHCP server in order to be used.

This change allows those options to be used with dco and wintun
drivers. If an option specified which requires DHCP server and
tap-windows6 driver is not used, print a clear error message
instead of obscure reference to --ip-win32.

Reported-by: Marek Zarychta
Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Antonio Quartulli <a@unstable.cc>
Message-Id: <20230207145416.1415-1-lstipakov@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26169.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index ab1b01cf73c62e5696d9c813fa9fddf839e6696a..ce756128851c7dfcb9e33d7635b12b4d63b418e2 100644 (file)
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -1292,7 +1292,7 @@ show_tuntap_options(const struct tuntap_options *o)
     SHOW_INT(dhcp_masq_offset);
     SHOW_INT(dhcp_lease_time);
     SHOW_INT(tap_sleep);
-    SHOW_BOOL(dhcp_options);
+    SHOW_UNSIGNED(dhcp_options);
     SHOW_BOOL(dhcp_renew);
     SHOW_BOOL(dhcp_pre_release);
     SHOW_STR(domain);
@@ -2480,12 +2480,20 @@ options_postprocess_verify_ce(const struct options *options,
         msg(M_USAGE, "On Windows, --ip-win32 doesn't make sense unless --ifconfig is also used");
     }
 
-    if (options->tuntap_options.dhcp_options
-        && options->windows_driver != WINDOWS_DRIVER_WINTUN
-        && options->tuntap_options.ip_win32_type != IPW32_SET_DHCP_MASQ
-        && options->tuntap_options.ip_win32_type != IPW32_SET_ADAPTIVE)
+    if (options->tuntap_options.dhcp_options & DHCP_OPTIONS_DHCP_REQUIRED)
     {
-        msg(M_USAGE, "--dhcp-option requires --ip-win32 dynamic or adaptive");
+        const char *prefix = "Some dhcp-options require DHCP server";
+        if (options->windows_driver != WINDOWS_DRIVER_TAP_WINDOWS6)
+        {
+            msg(M_USAGE, "%s, which is not supported by selected %s driver",
+                prefix, print_windows_driver(options->windows_driver));
+        }
+        else if (options->tuntap_options.ip_win32_type != IPW32_SET_DHCP_MASQ
+                 && options->tuntap_options.ip_win32_type != IPW32_SET_ADAPTIVE)
+        {
+            msg(M_USAGE, "%s, which requires --ip-win32 dynamic or adaptive",
+                prefix);
+        }
     }
 
     if (options->windows_driver == WINDOWS_DRIVER_WINTUN && dev != DEV_TYPE_TUN)
@@ -8085,16 +8093,17 @@ add_option(struct options *options,
     {
         struct tuntap_options *o = &options->tuntap_options;
         VERIFY_PERMISSION(OPT_P_DHCPDNS);
-        bool ipv6dns = false;
 
         if ((streq(p[1], "DOMAIN") || streq(p[1], "ADAPTER_DOMAIN_SUFFIX"))
             && p[2] && !p[3])
         {
             o->domain = p[2];
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_OPTIONAL;
         }
         else if (streq(p[1], "NBS") && p[2] && !p[3])
         {
             o->netbios_scope = p[2];
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_REQUIRED;
         }
         else if (streq(p[1], "NBT") && p[2] && !p[3])
         {
@@ -8106,31 +8115,35 @@ add_option(struct options *options,
                 goto err;
             }
             o->netbios_node_type = t;
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_REQUIRED;
         }
         else if ((streq(p[1], "DNS") || streq(p[1], "DNS6")) && p[2] && !p[3]
                  && (!strstr(p[2], ":") || ipv6_addr_safe(p[2])))
         {
             if (strstr(p[2], ":"))
             {
-                ipv6dns = true;
                 dhcp_option_dns6_parse(p[2], o->dns6, &o->dns6_len, msglevel);
             }
             else
             {
                 dhcp_option_address_parse("DNS", p[2], o->dns, &o->dns_len, msglevel);
+                o->dhcp_options |= DHCP_OPTIONS_DHCP_OPTIONAL;
             }
         }
         else if (streq(p[1], "WINS") && p[2] && !p[3])
         {
             dhcp_option_address_parse("WINS", p[2], o->wins, &o->wins_len, msglevel);
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_OPTIONAL;
         }
         else if (streq(p[1], "NTP") && p[2] && !p[3])
         {
             dhcp_option_address_parse("NTP", p[2], o->ntp, &o->ntp_len, msglevel);
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_REQUIRED;
         }
         else if (streq(p[1], "NBDD") && p[2] && !p[3])
         {
             dhcp_option_address_parse("NBDD", p[2], o->nbdd, &o->nbdd_len, msglevel);
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_REQUIRED;
         }
         else if (streq(p[1], "DOMAIN-SEARCH") && p[2] && !p[3])
         {
@@ -8143,10 +8156,12 @@ add_option(struct options *options,
                 msg(msglevel, "--dhcp-option %s: maximum of %d search entries can be specified",
                     p[1], N_SEARCH_LIST_LEN);
             }
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_REQUIRED;
         }
         else if (streq(p[1], "DISABLE-NBT") && !p[2])
         {
             o->disable_nbt = 1;
+            o->dhcp_options |= DHCP_OPTIONS_DHCP_REQUIRED;
         }
 #if defined(TARGET_ANDROID)
         else if (streq(p[1], "PROXY_HTTP") && p[3] && !p[4])
@@ -8160,14 +8175,6 @@ add_option(struct options *options,
             msg(msglevel, "--dhcp-option: unknown option type '%s' or missing or unknown parameter", p[1]);
             goto err;
         }
-
-        /* flag that we have options to give to the TAP driver's DHCPv4 server
-         *  - skipped for "DNS6", as that's not a DHCPv4 option
-         */
-        if (!ipv6dns)
-        {
-            o->dhcp_options = true;
-        }
     }
 #endif /* if defined(_WIN32) || defined(TARGET_ANDROID) */
 #ifdef _WIN32

diff --git a/src/openvpn/tun.h b/src/openvpn/tun.h
index 3b0a0d249abf4a39f91f87528447530c520e26b3..e19e1a2e2e9f92fa6be18b2148cf6db2e40c9a10 100644 (file)
--- a/src/openvpn/tun.h
+++ b/src/openvpn/tun.h
@@ -62,6 +62,10 @@ enum windows_driver_type {
 #define IPW32_SET_ADAPTIVE_DELAY_WINDOW 300
 #define IPW32_SET_ADAPTIVE_TRY_NETSH    20
 
+/* bit flags for DHCP options */
+#define DHCP_OPTIONS_DHCP_OPTIONAL (1<<0)
+#define DHCP_OPTIONS_DHCP_REQUIRED (1<<1)
+
 struct tuntap_options {
     /* --ip-win32 options */
     bool ip_win32_defined;
@@ -90,7 +94,7 @@ struct tuntap_options {
 
     /* --dhcp-option options */
 
-    bool dhcp_options;
+    int dhcp_options;
 
     const char *domain;      /* DOMAIN (15) */