diff mbox series

[Openvpn-devel,release/2.6] Allow certain DHCP options to be used without DHCP server

Message ID 20230207085339.1492-1-lstipakov@gmail.com
State Superseded
Headers show
Series [Openvpn-devel,release/2.6] Allow certain DHCP options to be used without DHCP server | expand

Commit Message

Lev Stipakov Feb. 7, 2023, 8:53 a.m. UTC 
From: Lev Stipakov <lev@openvpn.net>

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.

Signed-off-by: Lev Stipakov <lev@openvpn.net>
---
 src/openvpn/options.c | 39 +++++++++++++++++++++++----------------
 src/openvpn/tun.h     | 13 ++++++++++++-
 2 files changed, 35 insertions(+), 17 deletions(-)
diff mbox series

Patch

diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index 6ae3faf8..9c05217c 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -1290,7 +1290,7 @@  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_INT(dhcp_options);
     SHOW_BOOL(dhcp_renew);
     SHOW_BOOL(dhcp_pre_release);
     SHOW_STR(domain);
@@ -2478,12 +2478,20 @@  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)
@@ -8083,16 +8091,17 @@  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])
         {
@@ -8104,31 +8113,35 @@  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])
         {
@@ -8141,10 +8154,12 @@  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])
@@ -8158,14 +8173,6 @@  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 3b0a0d24..66604c19 100644
--- a/src/openvpn/tun.h
+++ b/src/openvpn/tun.h
@@ -62,6 +62,17 @@  enum windows_driver_type {
 #define IPW32_SET_ADAPTIVE_DELAY_WINDOW 300
 #define IPW32_SET_ADAPTIVE_TRY_NETSH    20
 
+/* this is a bitmask */
+enum dhcp_options_type {
+    DHCP_OPTIONS_NONE = 0,
+
+    /* option doesn't require DHCP server */
+    DHCP_OPTIONS_DHCP_OPTIONAL = 1,
+
+    /* option requires DHCP server */
+    DHCP_OPTIONS_DHCP_REQUIRED = 2
+};
+
 struct tuntap_options {
     /* --ip-win32 options */
     bool ip_win32_defined;
@@ -90,7 +101,7 @@  struct tuntap_options {
 
     /* --dhcp-option options */
 
-    bool dhcp_options;
+    enum dhcp_options_type dhcp_options;
 
     const char *domain;      /* DOMAIN (15) */