Message-ID: <55A3DBF8.5010003@...1147...> Date: Mon, 13 Jul 2015 17:40:40 +0200 From: Jan Just Keijser MIME-Version: 1.0 References: <55950ACC.1000909@...1147...> <20150702123852.GS382@...1296...> <55953B78.8090904@...1147...> <559D4FD9.4090006@...1147...> In-Reply-To: <559D4FD9.4090006@...1147...> Subject: Re: [Openvpn-devel] [PATCH v2] Add TFTP and WPAD DHCP options List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: "openvpn-devel@lists.sourceforge.net" Jan Just Keijser wrote: > Jan Just Keijser wrote: >> Gert Doering wrote: >>> On Thu, Jul 02, 2015 at 11:56:28AM +0200, Jan Just Keijser wrote: >>> >>>> + write_dhcp_str (buf, 66, o->tftp, &error); >>>> + write_dhcp_str (buf, 150, o->tftp, &error); >>>> >>> >>> This does not look safe to me (or I'm overlooking something) - if >>> o->tftp is not set, it will do "strlen(o->tftp)" inside >>> write_dhcp_str()... >>> >>> (And we generally shouldn't set options that we do not have anything >>> to say for :) ). >>> >>> >> I fully agree. Here's v2 with Jonathan's remarks addressed as well. > > 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 :) here's rev3 of the patch; this time the Cisco DHCP options are fully understood by Whireshark ;) share and enjoy, JJK --- openvpn-2.3.7/src/openvpn/options.c 2015-06-02 10:01:24.000000000 +0200 +++ /tmp/build-x86_64/openvpn-2.3.7/src/openvpn/options.c 2015-07-13 14:55:43.805931105 +0200 @@ -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]); --- openvpn-2.3.7/src/openvpn/tun.h 2015-06-02 10:01:24.000000000 +0200 +++ /tmp/build-x86_64/openvpn-2.3.7/src/openvpn/tun.h 2015-07-13 14:55:43.806930944 +0200 @@ -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; --- openvpn-2.3.7/src/openvpn/tun.c 2015-06-08 08:16:35.000000000 +0200 +++ /tmp/build-x86_64/openvpn-2.3.7/src/openvpn/tun.c 2015-07-13 14:55:43.807930787 +0200 @@ -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; } --- openvpn-2.3.7/doc/openvpn.8 2015-06-02 10:01:34.000000000 +0200 +++ /tmp/build-x86_64/openvpn-2.3.7/doc/openvpn.8 2015-07-13 14:56:51.148556280 +0200 @@ -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