Re: [Openvpn-devel] [PATCH v2] signal --dns support in peer info
On 13/05/2022 13:40, Arne Schwabe wrote: Am 13.05.22 um 13:22 schrieb David Sommerseth: On 13/05/2022 11:37, Heiko Hund wrote: Have clients set a bit in IV_PROTO, so that servers can make an informed decision on whether to push --dns to the client. While unknown options are ignored by clients when pushed, they generate a warning in the log. That can be circumvented by server backends by checking if bit 7 is set. Signed-off-by: Heiko Hund [...snip...] + /* support for the --dns option */ + iv_proto |= IV_PROTO_DNS_OPTION; + [...snip...] +#define IV_PROTO_DNS_OPTION (1<<6) + [...snip...] To be honest, I requested this flag but I don't think this is really what I want/need any more. I wanted to have a flag that tells me as a server that I can push --dns options instead of --dhcp-options and accept the client to evaluate them. But after some digging, I found that on platforms where dhcp-option is NOT parsed by openvpn itself (so anything but Android and Windows) and scripts are used to set DNS, these scripts will always use dhcp-options as they rely on foreign_option support. So they end up with no DNS configuration if only --dns is pushed and using --dhcp-option options if both are pushed unless the script is updated. As I remember it, this wasn't initially about Android and Windows clients. It was about the server pushing both --dhcp-option DNS and --dns at the same time, and that OpenVPN 2.5 and older clients would complain about --dns option warnings. By signalling to a server who wants to avoid this (like the Access Server), the server can chose if it wants to send --dns or --dhcp-options, based on this flag. Right? That the client side isn't parsing --dns options properly is to my understanding a different issue, which also needs a solution. And if my memory isn't completely corrupted, we had some brief talks about v2.6 clients adding some kind of "conversion" from --dns to --dhcp-options *data* for scripts/plug-ins - but only in a simplistic best-effort approach. If the strict --dhcp-option behavior is needed, that can be used with v2.6 clients for the time being if --dns causes troubles. But if both --dns and --dhcp-options are used, and the --dhcp-option provides a setting --dns support, --dns should take precedence. This should also work fine, as the --dns option is far more flexible in what it supports, while --dhcp-options are just simpler by design - and designed around a lesser dynamic Internet world. -- kind regards, David Sommerseth OpenVPN Inc OpenPGP_signature Description: OpenPGP digital signature ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
Re: [Openvpn-devel] [PATCH v2] signal --dns support in peer info
Hi, On Fri, May 13, 2022 at 01:40:07PM +0200, Arne Schwabe wrote: > So this flag doesn't really do what I expected it to promose (This > client will accept --dns and use them) So you want something that goes hand in hand with code to actually "do something with it", like +#if defined(TARGET_WINDOWS)||defined(TARGET_ANDROID) + /* we have full backend support for --dns options */ +iv_proto |= IV_PROTO_DNS_OPTION; +#endif and whenever a platform gets a "real" implementation, be it "openvpn provided --up script parsing the correct variables" or "NM plugin" or "directly implemented by magic", we add it to that list? gert -- "If was one thing all people took for granted, was conviction that if you feed honest figures into a computer, honest figures come out. Never doubted it myself till I met a computer with a sense of humor." Robert A. Heinlein, The Moon is a Harsh Mistress Gert Doering - Munich, Germany g...@greenie.muc.de signature.asc Description: PGP signature ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
Re: [Openvpn-devel] [PATCH v2] signal --dns support in peer info
Am 13.05.22 um 13:22 schrieb David Sommerseth: On 13/05/2022 11:37, Heiko Hund wrote: Have clients set a bit in IV_PROTO, so that servers can make an informed decision on whether to push --dns to the client. While unknown options are ignored by clients when pushed, they generate a warning in the log. That can be circumvented by server backends by checking if bit 7 is set. Signed-off-by: Heiko Hund --- src/openvpn/ssl.c | 3 +++ src/openvpn/ssl.h | 3 +++ 2 files changed, 6 insertions(+) diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index 61dea996..24d7f3f4 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -1940,6 +1940,9 @@ push_peer_info(struct buffer *buf, struct tls_session *session) /* support for P_DATA_V2 */ int iv_proto = IV_PROTO_DATA_V2; + /* support for the --dns option */ + iv_proto |= IV_PROTO_DNS_OPTION; + /* support for receiving push_reply before sending * push request, also signal that the client wants * to get push-reply messages without without requiring a round diff --git a/src/openvpn/ssl.h b/src/openvpn/ssl.h index 0ba86d3e..c8802707 100644 --- a/src/openvpn/ssl.h +++ b/src/openvpn/ssl.h @@ -93,6 +93,9 @@ * result. */ #define IV_PROTO_NCP_P2P (1<<5) +/** Supports the --dns option introduced in version 2.6 */ +#define IV_PROTO_DNS_OPTION (1<<6) + /* Default field in X509 to be username */ #define X509_USERNAME_FIELD_DEFAULT "CN" Only glared on the code and compile tested. LGTM. Acked-By: David Sommerseth To be honest, I requested this flag but I don't think this is really what I want/need any more. I wanted to have a flag that tells me as a server that I can push --dns options instead of --dhcp-options and accept the client to evaluate them. But after some digging, I found that on platforms where dhcp-option is NOT parsed by openvpn itself (so anything but Android and Windows) and scripts are used to set DNS, these scripts will always use dhcp-options as they rely on foreign_option support. So they end up with no DNS configuration if only --dns is pushed and using --dhcp-option options if both are pushed unless the script is updated. I think having clear preference and not knowing will make debugging logs from 3rd parties that have both --dns and --dhcp-option in them quite tedious. So this flag doesn't really do what I expected it to promose (This client will accept --dns and use them) Arne ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
Re: [Openvpn-devel] [PATCH v2] signal --dns support in peer info
On 13/05/2022 11:37, Heiko Hund wrote: Have clients set a bit in IV_PROTO, so that servers can make an informed decision on whether to push --dns to the client. While unknown options are ignored by clients when pushed, they generate a warning in the log. That can be circumvented by server backends by checking if bit 7 is set. Signed-off-by: Heiko Hund --- src/openvpn/ssl.c | 3 +++ src/openvpn/ssl.h | 3 +++ 2 files changed, 6 insertions(+) diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index 61dea996..24d7f3f4 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -1940,6 +1940,9 @@ push_peer_info(struct buffer *buf, struct tls_session *session) /* support for P_DATA_V2 */ int iv_proto = IV_PROTO_DATA_V2; +/* support for the --dns option */ +iv_proto |= IV_PROTO_DNS_OPTION; + /* support for receiving push_reply before sending * push request, also signal that the client wants * to get push-reply messages without without requiring a round diff --git a/src/openvpn/ssl.h b/src/openvpn/ssl.h index 0ba86d3e..c8802707 100644 --- a/src/openvpn/ssl.h +++ b/src/openvpn/ssl.h @@ -93,6 +93,9 @@ * result. */ #define IV_PROTO_NCP_P2P (1<<5) +/** Supports the --dns option introduced in version 2.6 */ +#define IV_PROTO_DNS_OPTION (1<<6) + /* Default field in X509 to be username */ #define X509_USERNAME_FIELD_DEFAULT "CN" Only glared on the code and compile tested. LGTM. Acked-By: David Sommerseth -- kind regards, David Sommerseth OpenVPN Inc ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
[Openvpn-devel] [PATCH v2] signal --dns support in peer info
Have clients set a bit in IV_PROTO, so that servers can make an informed decision on whether to push --dns to the client. While unknown options are ignored by clients when pushed, they generate a warning in the log. That can be circumvented by server backends by checking if bit 7 is set. Signed-off-by: Heiko Hund --- src/openvpn/ssl.c | 3 +++ src/openvpn/ssl.h | 3 +++ 2 files changed, 6 insertions(+) diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index 61dea996..24d7f3f4 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -1940,6 +1940,9 @@ push_peer_info(struct buffer *buf, struct tls_session *session) /* support for P_DATA_V2 */ int iv_proto = IV_PROTO_DATA_V2; +/* support for the --dns option */ +iv_proto |= IV_PROTO_DNS_OPTION; + /* support for receiving push_reply before sending * push request, also signal that the client wants * to get push-reply messages without without requiring a round diff --git a/src/openvpn/ssl.h b/src/openvpn/ssl.h index 0ba86d3e..c8802707 100644 --- a/src/openvpn/ssl.h +++ b/src/openvpn/ssl.h @@ -93,6 +93,9 @@ * result. */ #define IV_PROTO_NCP_P2P (1<<5) +/** Supports the --dns option introduced in version 2.6 */ +#define IV_PROTO_DNS_OPTION (1<<6) + /* Default field in X509 to be username */ #define X509_USERNAME_FIELD_DEFAULT "CN" -- 2.32.0 ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
