Add TFTP and WPAD DHCP options

Attached is the patch to add the TFTP and WPAD DHCP options. The patch is based on openvpn 2.3.7 as I did not know how to do a windows mingw build of the git version ... The patch was tested on Windows XP 32bit and Windows 7sp1 64bit.
A 64bit windows binary can be found @ http://www.nikhef.nl/~janjust/openvpn-2.3.7-dhcp-win64.exe

@@ -692,11 +692,13 @@
  "                    DNS addr    : Set domain name server address(es)\n"
  "                    NTP         : Set NTP server address(es)\n"
  "                    NBDD        : Set NBDD server address(es)\n"
+  "                    TFTP        : Set TFTP server address(es)\n"
  "                    WINS addr   : Set WINS server address(es)\n"
  "                    NBT type    : Set NetBIOS over TCP/IP Node type\n"
  "                                  1: B, 2: P, 4: M, 8: H\n"
  "                    NBS id      : Set NetBIOS scope ID\n"
  "                    DISABLE-NBT : Disable Netbios-over-TCP/IP.\n"
+  "                    WPAD url    : Set WebProxy AutoDiscovery url\n"
  "--dhcp-renew       : Ask Windows to renew the TAP adapter lease on 

startup.\n"
"--dhcp-pre-release : Ask Windows to release the previous TAP adapter
lease on\n"
" startup.\n"
@@ -1119,6 +1121,8 @@
SHOW_STR (netbios_scope);
SHOW_INT (netbios_node_type);
SHOW_BOOL (disable_nbt);
+ SHOW_STR (tftp);
+ SHOW_STR (wpad_url);

show_dhcp_option_addrs ("DNS", o->dns, o->dns_len); show_dhcp_option_addrs ("WINS", o->wins, o->wins_len);
@@ -6153,6 +6157,14 @@

       {
         o->disable_nbt = 1;
       }

+ else if (streq (p[1], "TFTP") && p[2])
+ {
+ o->tftp = p[2];
+ }
+ else if (streq (p[1], "WPAD") && p[2])
+ {
+ o->wpad_url = p[2];
+ }
else
{
msg (msglevel, "--dhcp-option: unknown option type '%s' or
missing parameter", p[1]);

@@ -4692,6 +4692,23 @@
    buf_write_u8 (buf,  4);  /* length of the vendor specified field */
    buf_write_u32 (buf, 0x002);
  }
+
+    write_dhcp_str (buf, 66, o->tftp, &error);
+    write_dhcp_str (buf, 150, o->tftp, &error);
+
+  /* IE6 seems to requires an extra charachter at the end of the URL */
+if (o->wpad_url)
+  {
+#ifdef WIN32
+    char str[256];
+    strncpy( str, o->wpad_url, 255 );
+    strcat( str, "\r" );
+    write_dhcp_str (buf, 252, str, &error);
+#else
+    write_dhcp_str (buf, 252, o->wpad_url, &error);
+#endif
+  }
+
  return !error;

}

@@ -98,6 +98,12 @@
  /* DISABLE_NBT (43, Vendor option 001) */
  bool disable_nbt;
 
+  /* TFTP (66&150), see RFC2132: NOT an in_addr_t */
+  const char *tftp;
+
+  /* WPAD automatic proxy URL (252) */
+  const char *wpad_url;
+
  bool dhcp_renew;
  bool dhcp_pre_release;
  bool dhcp_release;

<snip>

NAK, but easy to fix (I think). Three small problems are described below.

1. Shouldn't "dhcp_option_address_parse()" be used to set o->tftp and o->wpad_url? (In the code just before this, it is used for NTP, WINS, etc.)

Hi,

nope : both options are strings, not inet addresses. You can specify a hostname for both (as the RFC states)

thx

ah, yes, will do

thx for the review,

JJK

Hi,

USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             [email protected]...
fax: +49-89-35655025                        [email protected]...

Hi,

I fully agree. Here's v2 with Jonathan's remarks addressed as well.

@@ -692,11 +692,13 @@
  "                    DNS addr    : Set domain name server address(es)\n"
  "                    NTP         : Set NTP server address(es)\n"
  "                    NBDD        : Set NBDD server address(es)\n"
+  "                    TFTP        : Set TFTP server address(es)\n"
  "                    WINS addr   : Set WINS server address(es)\n"
  "                    NBT type    : Set NetBIOS over TCP/IP Node type\n"
  "                                  1: B, 2: P, 4: M, 8: H\n"
  "                    NBS id      : Set NetBIOS scope ID\n"
  "                    DISABLE-NBT : Disable Netbios-over-TCP/IP.\n"
+  "                    WPAD url    : Set WebProxy AutoDiscovery url\n"
  "--dhcp-renew       : Ask Windows to renew the TAP adapter lease on 

startup.\n"
"--dhcp-pre-release : Ask Windows to release the previous TAP adapter
lease on\n"
" startup.\n"
@@ -1119,6 +1121,8 @@
SHOW_STR (netbios_scope);
SHOW_INT (netbios_node_type);
SHOW_BOOL (disable_nbt);
+ SHOW_STR (tftp);
+ SHOW_STR (wpad_url);

show_dhcp_option_addrs ("DNS", o->dns, o->dns_len); show_dhcp_option_addrs ("WINS", o->wins, o->wins_len);
@@ -6153,6 +6157,14 @@

       {
         o->disable_nbt = 1;
       }

+ else if (streq (p[1], "TFTP") && p[2])
+ {
+ o->tftp = p[2];
+ }
+ else if (streq (p[1], "WPAD") && p[2])
+ {
+ o->wpad_url = p[2];
+ }
else
{
msg (msglevel, "--dhcp-option: unknown option type '%s' or
missing parameter", p[1]);

@@ -4692,6 +4692,27 @@
    buf_write_u8 (buf,  4);  /* length of the vendor specified field */
    buf_write_u32 (buf, 0x002);
  }
+
+  /* Set both the RFC2132 and Cisco DHCP options for a TFTP server */
+  if (o->tftp)
+  {
+    write_dhcp_str (buf, 66, o->tftp, &error);
+    write_dhcp_str (buf, 150, o->tftp, &error);
+  }
+
+  /* IE6 seems to requires an extra character at the end of the URL */
+if (o->wpad_url)
+  {
+#ifdef WIN32
+    char str[256];
+    strncpy( str, o->wpad_url, 255 );
+    strcat( str, "\r" );
+    write_dhcp_str (buf, 252, str, &error);
+#else
+    write_dhcp_str (buf, 252, o->wpad_url, &error);
+#endif
+  }
+
  return !error;

}

@@ -98,6 +98,12 @@
  /* DISABLE_NBT (43, Vendor option 001) */
  bool disable_nbt;
 
+  /* TFTP (66&150), see RFC2132: NOT an in_addr_t */
+  const char *tftp;
+
+  /* WPAD automatic proxy URL (252) */
+  const char *wpad_url;
+
  bool dhcp_renew;
  bool dhcp_pre_release;
  bool dhcp_release;

@@ -5413,6 +5413,14 @@

to a non-windows client, the option will be saved in the client's environment before the up script is called, under
the name "foreign_option_{n}".
+
+.B TFTP hostname|address --
+Set TFTP server hostname or address (Trivial File Transer Protocol). +This option sets both the RFC2132 DHCP option (66) and the Cisco option (150). +
+.B WPAD url --
+Set the WPAD url (Windows Proxy Auto Detection) for proxy autodetection. +The URL should be of the format "http://example.org/wpad.dat". .\"*********************************************************
.TP
.B \-\-tap\-sleep n

ACK as to my concerns, thanks!

One way to build a git version on openvpn-build is this:

$ git clone <url>
$ mv openvpn openvpn-2.3_git
$ cd openvpn
$ autoreconf -vi
$ cd ..
$ tar -zcf openvpn-2.3_git.tar.gz openvpn-2.3_git

Then copy openvpn-2.3_git.tar.gz to a webserver and set openvpn version to "2.3_git" in generic/build.vars. Renaming the directory is needed due to how openvpn-build moves around in the build directories.

Samuli

Just a stupid question ... instead of the 'tar' command, why not just run 'make dist' ?

kind regards,

David Sommerseth

Hi,

I just discovered that my patch does not set the (poorly documented) Cisco TFTP options; I'm working on rev3 which does set them correctly (at least, Wireshark says I am setting them now correctly). Stay tuned :)

JJK

here's rev3 of the patch; this time the Cisco DHCP options are fully understood by Whireshark ;)

share and enjoy,

JJK

@@ -692,11 +692,13 @@
  "                    DNS addr    : Set domain name server address(es)\n"
  "                    NTP         : Set NTP server address(es)\n"
  "                    NBDD        : Set NBDD server address(es)\n"
+  "                    TFTP        : Set TFTP server address(es)\n"
  "                    WINS addr   : Set WINS server address(es)\n"
  "                    NBT type    : Set NetBIOS over TCP/IP Node type\n"
  "                                  1: B, 2: P, 4: M, 8: H\n"
  "                    NBS id      : Set NetBIOS scope ID\n"
  "                    DISABLE-NBT : Disable Netbios-over-TCP/IP.\n"
+  "                    WPAD url    : Set WebProxy AutoDiscovery url\n"
  "--dhcp-renew       : Ask Windows to renew the TAP adapter lease on 

startup.\n"
"--dhcp-pre-release : Ask Windows to release the previous TAP adapter
lease on\n"
" startup.\n"
@@ -1119,6 +1121,8 @@
SHOW_STR (netbios_scope);
SHOW_INT (netbios_node_type);
SHOW_BOOL (disable_nbt);
+ SHOW_STR (tftp);
+ SHOW_STR (wpad_url);

show_dhcp_option_addrs ("DNS", o->dns, o->dns_len); show_dhcp_option_addrs ("WINS", o->wins, o->wins_len);
@@ -5354,7 +5358,11 @@

       {
         if (ip_or_dns_addr_safe (p[1], options->allow_pull_fqdn) || 
is_special_addr (p[1])) /* FQDN -- may be DNS name */
           {
+             struct tuntap_options *o = &options->tuntap_options;
+
             options->route_default_gateway = p[1];
+        +             dhcp_option_address_parse ("GW", p[1], o->gw, &o->gw_len, msglevel);
           }
         else
           {
@@ -6153,6 +6161,14 @@
       {
         o->disable_nbt = 1;
       }

+ else if (streq (p[1], "TFTP") && p[2])
+ {
+ dhcp_option_address_parse ("TFTP", p[2], o->tftp, &o->tftp_len, msglevel);
+ }
+ else if (streq (p[1], "WPAD") && p[2])
+ {
+ o->wpad_url = p[2];
+ }
else
{
msg (msglevel, "--dhcp-option: unknown option type '%s' or
missing parameter", p[1]);

@@ -78,7 +78,6 @@
 

#define N_DHCP_ADDR 4        /* Max # of addresses allowed for
                               DNS, WINS, etc. */

-
/* DNS (6) */
in_addr_t dns[N_DHCP_ADDR];
int dns_len;
@@ -98,6 +97,14 @@
/* DISABLE_NBT (43, Vendor option 001) */
bool disable_nbt;

+ /* TFTP (66&150), RFC2132 states that it does not have to be an in_addr_t
+ but option 150 (Cisco) *does* */
+ in_addr_t tftp[N_DHCP_ADDR];
+ int tftp_len;
+
+ /* WPAD automatic proxy URL (252) */
+ const char *wpad_url;
+
bool dhcp_renew;
bool dhcp_pre_release;
bool dhcp_release;

@@ -4662,6 +4662,11 @@

build_dhcp_options_string (struct buffer *buf, const struct tuntap_options *o) {
bool error = false;
+ const char *tftp_str = NULL;
+ int i;
+
+ struct gc_arena gc = gc_new ();
+
if (o->domain)

    write_dhcp_str (buf, 15, o->domain, &error);

@@ -4692,6 +4697,30 @@
buf_write_u8 (buf, 4); /* length of the vendor specified field */ buf_write_u32 (buf, 0x002);
}
+

+  /* Set both the RFC2132 and Cisco DHCP options for a TFTP server */
+  if (o->tftp_len > 0)
+  {

+ tftp_str = print_in_addr_t (o->tftp[0], 0, &gc);
+ write_dhcp_str (buf, 66, tftp_str, &error);
+ }
+ write_dhcp_u32_array (buf, 150, (uint32_t*)o->tftp, o->tftp_len, &error);
+ + /* IE6 seems to requires an extra character at the end of the URL */
+ if (o->wpad_url)
+ {
+#ifdef WIN32

+    char str[256];
+    strncpy( str, o->wpad_url, 255 );
+    strcat( str, "\r" );
+    write_dhcp_str (buf, 252, str, &error);

+#else
+ write_dhcp_str (buf, 252, o->wpad_url, &error);
+#endif
+ }
+
+ gc_free (&gc);
+
return !error;
}

@@ -5413,6 +5413,14 @@

to a non-windows client, the option will be saved in the client's environment before the up script is called, under
the name "foreign_option_{n}".
+
+.B TFTP addr --
+Set TFTP server address (Trivial File Transer Protocol).
+This option sets both the RFC2132 DHCP option (66) and the Cisco option (150). +
+.B WPAD url --
+Set the WPAD url (Windows Proxy Auto Detection) for proxy autodetection. +The URL should be of the format "http://example.org/wpad.dat". .\"*********************************************************
.TP
.B \-\-tap\-sleep n