As a first step towards DNS configuration in openvpn and a unified way
to push DNS related settings to clients in v2 and v3, this commit adds
support for parsing the new --dns option. Later commits will add support
for setting up DNS on different platforms.
For now, --dns and DNS related --dhcp-option can be used together for
smoother transition. Settings from --dns will override ones --dhcp-option
where applicable.
For detailed information about the option consult the documentation in
this commit.
Signed-off-by: Heiko Hund <he...@ist.eigentlich.net>
---
doc/man-sections/client-options.rst | 55 +++
doc/man-sections/script-options.rst | 19 +
doc/man-sections/server-options.rst | 2 +-
src/openvpn/Makefile.am | 1 +
src/openvpn/dns.c | 561 ++++++++++++++++++++++++++++
src/openvpn/dns.h | 89 +++++
src/openvpn/openvpn.vcxproj | 4 +-
src/openvpn/openvpn.vcxproj.filters | 8 +-
src/openvpn/options.c | 221 +++++++++++
src/openvpn/options.h | 7 +
src/openvpn/push.c | 4 +
src/openvpn/socket.c | 11 +
src/openvpn/socket.h | 2 +
13 files changed, 981 insertions(+), 3 deletions(-)
create mode 100644 src/openvpn/dns.c
create mode 100644 src/openvpn/dns.h
diff --git a/doc/man-sections/client-options.rst
b/doc/man-sections/client-options.rst
index 92a02e28..bdfe6aac 100644
--- a/doc/man-sections/client-options.rst
+++ b/doc/man-sections/client-options.rst
@@ -154,6 +154,61 @@ configuration.
--connect-timeout n
See ``--server-poll-timeout``.
+--dns args
+ Client DNS configuration to be used with the connection.
+
+ Valid syntaxes:
+ ::
+
+ dns search-domains domain [domain ...]
+ dns server n address addr[:port] [addr[:port]]
+ dns server n resolve-domains|exclude-domains domain [domain ...]
+ dns server n dnssec yes|optional|no
+ dns server n transport DoH|DoT|plain
+ dns server n sni server-name
+
+ The ``--dns search-domains`` directive takes one or more domain names
+ to be added as DNS domain suffixes. If it is repeated multiple times within
+ a configuration the domains are appended, thus e.g. domain names pushed by
+ a server will amend locally defined ones.
+
+ The ``--dns server`` directive is used to configure DNS server ``n``.
+ The server id ``n`` must be a value between -128 and 127. For pushed
+ DNS server options it must be between 0 and 127. The server id is used
+ to group options and also for ordering the list of configured DNS servers;
+ lower numbers come first. DNS servers being pushed to a client replace
+ already configured DNS servers with the same server id.
+
+ The ``address`` option configures the IPv4 and / or IPv6 address of
+ the DNS server. Optionally a port can be appended after a colon. IPv6
+ addresses need to be enclosed in brackets if a port is appended.
+
+ The ``resolve-domains`` and ``exclude-domains`` options take one or
+ more DNS domains which are explicitly resolved or explicitly not resolved
+ by a server. Only one of the options can be configured for a server.
+ ``resolve-domains`` is used to define a split-dns setup, where only
+ given domains are resolved by a server. ``exclude-domains`` is used to
+ define domains which will never be resolved by a server (e.g. domains
+ which can only be resolved locally). Systems which do not support fine
+ grained DNS domain configuration, will ignore these settings.
+
+ The ``dnssec`` option is used to configure validation of DNSSEC records.
+ While the exact semantics may differ for resolvers on different systems,
+ ``yes`` likely makes validation mandatory, ``no`` disables it, and
``optional``
+ uses it opportunistically.
+
+ The ``transport`` option enables DNS-over-HTTPS (``DoH``) or DNS-over-TLS
(``DoT``)
+ for a DNS server. The ``sni`` option can be used with them to specify the
+ ``server-name`` for TLS server name indication.
+
+ Each server has to have at least one address configured for a configuration
+ to be valid. All the other options can be omitted.
+
+ The ``--dns`` option will eventually obsolete the ``--dhcp-option``
directive.
+ Until then it will add configuration at the places ``--dhcp-option`` puts it
+ and will override it if both are given. So, ``--dns`` can be used today to
+ migrate from ``--dhcp-option``.
+
--explicit-exit-notify n
In UDP client mode or point-to-point mode, send server/peer an exit
notification if tunnel is restarted or OpenVPN process is exited. In
diff --git a/doc/man-sections/script-options.rst
b/doc/man-sections/script-options.rst
index 22990f4f..c81efe9e 100644
--- a/doc/man-sections/script-options.rst
+++ b/doc/man-sections/script-options.rst
@@ -586,6 +586,25 @@ instances.
netsh.exe calls which sometimes just do not work right with interface
names). Set prior to ``--up`` or ``--down`` script execution.
+:code:`dns_*`
+ The ``--dns`` configuration options will be made available to script
+ execution through this set of environment variables. Variables appear
+ only if the corresponding option has a value assigned. For the semantics
+ of each individual variable, please refer to the documentation for
``--dns``.
+
+ ::
+
+ dns_search_domain_{n}
+ dns_server_{n}_address4
+ dns_server_{n}_port4
+ dns_server_{n}_address6
+ dns_server_{n}_port6
+ dns_server_{n}_resolve_domain_{m}
+ dns_server_{n}_exclude_domain_{m}
+ dns_server_{n}_dnssec
+ dns_server_{n}_transport
+ dns_server_{n}_sni
+
:code:`foreign_option_{n}`
An option pushed via ``--push`` to a client which does not natively
support it, such as ``--dhcp-option`` on a non-Windows system, will be
diff --git a/doc/man-sections/server-options.rst
b/doc/man-sections/server-options.rst
index 8a030294..08ee7bd3 100644
--- a/doc/man-sections/server-options.rst
+++ b/doc/man-sections/server-options.rst
@@ -412,7 +412,7 @@ fast hardware. SSL/TLS authentication must be used in this
mode.
This is a partial list of options which can currently be pushed:
``--route``, ``--route-gateway``, ``--route-delay``,
- ``--redirect-gateway``, ``--ip-win32``, ``--dhcp-option``,
+ ``--redirect-gateway``, ``--ip-win32``, ``--dhcp-option``, ``--dns``,
``--inactive``, ``--ping``, ``--ping-exit``, ``--ping-restart``,
``--setenv``, ``--auth-token``, ``--persist-key``, ``--persist-tun``,
``--echo``, ``--comp-lzo``, ``--socket-flags``, ``--sndbuf``,
diff --git a/src/openvpn/Makefile.am b/src/openvpn/Makefile.am
index 5883c291..bcaf93b4 100644
--- a/src/openvpn/Makefile.am
+++ b/src/openvpn/Makefile.am
@@ -54,6 +54,7 @@ openvpn_SOURCES = \
crypto_openssl.c crypto_openssl.h \
crypto_mbedtls.c crypto_mbedtls.h \
dhcp.c dhcp.h \
+ dns.c dns.h \
env_set.c env_set.h \
errlevel.h \
error.c error.h \
diff --git a/src/openvpn/dns.c b/src/openvpn/dns.c
new file mode 100644
index 00000000..41d7b0fa
--- /dev/null
+++ b/src/openvpn/dns.c
@@ -0,0 +1,561 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2022 OpenVPN Inc <sa...@openvpn.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "dns.h"
+#include "socket.h"
+
+/**
+ * Parses a string as port and stores it
+ *
+ * @param port Pointer to in_port_t where the port value is stored
+ * @param addr Port number as string
+ * @return True if parsing was successful
+ */
+static bool
+dns_server_port_parse(in_port_t *port, char *port_str)
+{
+ char *endptr;
+ errno = 0;
+ unsigned long tmp = strtoul(port_str, &endptr, 10);
+ if (errno || *endptr != '\0' || tmp == 0 || tmp > UINT16_MAX)
+ {
+ return false;
+ }
+ *port = (in_port_t)tmp;
+ return true;
+}
+
+/**
+ * Parses a string IPv4 or IPv6 address and optional colon separated port,
+ * into a in_addr or in6_addr respectively plus a in_port_t port.
+ *
+ * @param server Pointer to DNS server the address is parsed for
+ * @param addr Address as string
+ * @return True if parsing was successful
+ */
+bool
+dns_server_addr_parse(struct dns_server *server, const char *addr)
+{
+ if (!addr)
+ {
+ return false;
+ }
+
+ char addrcopy[INET6_ADDRSTRLEN] = {0};
+ size_t copylen = 0;
+ in_port_t port = 0;
+ int af;
+
+ char *first_colon = strchr(addr, ':');
+ char *last_colon = strrchr(addr, ':');
+
+ if (!first_colon || first_colon == last_colon)
+ {
+ /* IPv4 address with optional port, e.g. 1.2.3.4 or 1.2.3.4:853 */
+ if (last_colon)
+ {
+ if (last_colon == addr || !dns_server_port_parse(&port, last_colon
+ 1))
+ {
+ return false;
+ }
+ copylen = first_colon - addr;
+ }
+ af = AF_INET;
+ }
+ else
+ {
+ /* IPv6 address with optional port, e.g. ab::cd or [ab::cd]:853 */
+ if (addr[0] == '[')
+ {
+ addr += 1;
+ char *bracket = last_colon - 1;
+ if (*bracket != ']' || bracket == addr ||
!dns_server_port_parse(&port, last_colon + 1))
+ {
+ return false;
+ }
+ copylen = bracket - addr;
+ }
+ af = AF_INET6;
+ }
+
+ /* Copy the address part into a temporary buffer and use that */
+ if (copylen)
+ {
+ if (copylen >= sizeof(addrcopy))
+ {
+ return false;
+ }
+ strncpy(addrcopy, addr, copylen);
+ addr = addrcopy;
+ }
+
+ struct addrinfo *ai = NULL;
+ if (openvpn_getaddrinfo(0, addr, NULL, 0, NULL, af, &ai) != 0)
+ {
+ return false;
+ }
+
+ if (ai->ai_family == AF_INET)
+ {
+ struct sockaddr_in *sin = (struct sockaddr_in *)ai->ai_addr;
+ server->addr4_defined = true;
+ server->addr4.s_addr = ntohl(sin->sin_addr.s_addr);
+ server->port4 = port;
+ }
+ else
+ {
+ struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)ai->ai_addr;
+ server->addr6_defined = true;
+ server->addr6 = sin6->sin6_addr;
+ server->port6 = port;
+ }
+
+ freeaddrinfo(ai);
+ return true;
+}
+
+/**
+ * Appends DNS domain parameters to a linked list.
+ *
+ * @param entry Address of the first list entry pointer
+ * @param domains Address of the first domain parameter
+ * @param gc The gc the new list items should be allocated in
+ */
+void
+dns_domain_list_append(struct dns_domain **entry, char **domains, struct
gc_arena *gc)
+{
+ /* Fast forward to the end of the list */
+ while (*entry)
+ {
+ entry = &((*entry)->next);
+ }
+
+ /* Append all domains to the end of the list */
+ while (*domains)
+ {
+ ALLOC_OBJ_CLEAR_GC(*entry, struct dns_domain, gc);
+ struct dns_domain *new = *entry;
+ new->name = *domains++;
+ entry = &new->next;
+ }
+}
+
+/**
+ * Parses a string DNS server priority and validates it.
+ *
+ * @param priority Pointer to where the priority should be stored
+ * @param str Priority string to parse
+ * @param pulled Whether this was pulled from a server
+ * @return True if priority in string is valid
+ */
+bool
+dns_server_priority_parse(long *priority, const char *str, bool pulled)
+{
+ char *endptr;
+ const long min = pulled ? 0 : INT8_MIN;
+ const long max = INT8_MAX;
+ long prio = strtol(str, &endptr, 10);
+ if (*endptr != '\0' || prio < min || prio > max)
+ {
+ return false;
+ }
+ *priority = prio;
+ return true;
+}
+
+/**
+ * Find or create DNS server with priority in a linked list.
+ * The list is ordered by priority.
+ *
+ * @param entry Address of the first list entry pointer
+ * @param priority Priority of the DNS server to find / create
+ * @param gc The gc new list items should be allocated in
+ */
+struct dns_server*
+dns_server_get(struct dns_server **entry, long priority, struct gc_arena *gc)
+{
+ struct dns_server *obj = *entry;
+ while (true)
+ {
+ if (!obj || obj->priority > priority)
+ {
+ ALLOC_OBJ_CLEAR_GC(*entry, struct dns_server, gc);
+ (*entry)->next = obj;
+ (*entry)->priority = priority;
+ return *entry;
+ }
+ else if (obj->priority == priority)
+ {
+ return obj;
+ }
+ entry = &obj->next;
+ obj = *entry;
+ }
+}
+
+/**
+ * Checks validity of DNS options
+ *
+ * @param msglevel The message level to log errors with
+ * @param o Pointer to the DNS options to validate
+ * @return True if no error was found
+ */
+bool
+dns_options_verify(int msglevel, const struct dns_options *o)
+{
+ const struct dns_server *server =
+ o->servers ? o->servers : o->servers_prepull;
+ while (server)
+ {
+ if (!server->addr4_defined && !server->addr6_defined)
+ {
+ msg(msglevel, "ERROR: dns server %ld does not have an address
assigned", server->priority);
+ return false;
+ }
+ server = server->next;
+ }
+ return true;
+}
+
+static struct dns_domain*
+clone_dns_domains(const struct dns_domain *domain, struct gc_arena* gc)
+{
+ struct dns_domain *new_list = NULL;
+ struct dns_domain **new_entry = &new_list;
+
+ while (domain)
+ {
+ ALLOC_OBJ_CLEAR_GC(*new_entry, struct dns_domain, gc);
+ struct dns_domain *new_domain = *new_entry;
+ *new_domain = *domain;
+ new_entry = &new_domain->next;
+ domain = domain->next;
+ }
+
+ return new_list;
+}
+
+static struct dns_server*
+clone_dns_servers(const struct dns_server *server, struct gc_arena* gc)
+{
+ struct dns_server *new_list = NULL;
+ struct dns_server **new_entry = &new_list;
+
+ while (server)
+ {
+ ALLOC_OBJ_CLEAR_GC(*new_entry, struct dns_server, gc);
+ struct dns_server *new_server = *new_entry;
+ *new_server = *server;
+ new_server->domains = clone_dns_domains(server->domains, gc);
+ new_entry = &new_server->next;
+ server = server->next;
+ }
+
+ return new_list;
+}
+
+/**
+ * Makes a deep copy of the passed DNS options.
+ *
+ * @param o Pointer to the DNS options to clone
+ * @param gc Pointer to the gc_arena to use for the clone
+ * @return The dns_options clone
+ */
+struct dns_options
+clone_dns_options(const struct dns_options o, struct gc_arena* gc)
+{
+ struct dns_options clone;
+ memset(&clone, 0, sizeof(clone));
+ clone.search_domains = clone_dns_domains(o.search_domains, gc);
+ clone.servers = clone_dns_servers(o.servers, gc);
+ clone.servers_prepull = clone_dns_servers(o.servers_prepull, gc);
+ return clone;
+}
+
+/**
+ * Saves and resets the server options, so that pulled ones don't mix in.
+ *
+ * @param o Pointer to the DNS options to modify
+ */
+void
+dns_options_preprocess_pull(struct dns_options *o)
+{
+ o->servers_prepull = o->servers;
+ o->servers = NULL;
+}
+
+/**
+ * Merges pulled DNS servers with static ones into an ordered list.
+ *
+ * @param o Pointer to the DNS options to modify
+ */
+void
+dns_options_postprocess_pull(struct dns_options *o)
+{
+ struct dns_server **entry = &o->servers;
+ struct dns_server *server = *entry;
+ struct dns_server *server_pp = o->servers_prepull;
+
+ while (server && server_pp)
+ {
+ if (server->priority > server_pp->priority)
+ {
+ /* Merge static server in front of pulled one */
+ struct dns_server *next_pp = server_pp->next;
+ server_pp->next = server;
+ *entry = server_pp;
+ server = *entry;
+ server_pp = next_pp;
+ }
+ else if (server->priority == server_pp->priority)
+ {
+ /* Pulled server overrides static one */
+ server_pp = server_pp->next;
+ }
+ entry = &server->next;
+ server = *entry;
+ }
+
+ /* Append remaining local servers */
+ if (server_pp)
+ {
+ *entry = server_pp;
+ }
+
+ o->servers_prepull = NULL;
+}
+
+static const char *
+dnssec_value(const enum dns_security dnssec)
+{
+ switch (dnssec)
+ {
+ case DNS_SECURITY_YES:
+ return "yes";
+ case DNS_SECURITY_OPTIONAL:
+ return "optional";
+ case DNS_SECURITY_NO:
+ return "no";
+ default:
+ return "unset";
+ }
+}
+
+static const char *
+transport_value(const enum dns_server_transport transport)
+{
+ switch (transport)
+ {
+ case DNS_TRANSPORT_HTTPS:
+ return "DoH";
+ case DNS_TRANSPORT_TLS:
+ return "DoT";
+ case DNS_TRANSPORT_PLAIN:
+ return "plain";
+ default:
+ return "unset";
+ }
+}
+
+/**
+ * Puts the DNS options into an environment set.
+ *
+ * @param o Pointer to the DNS options to set
+ * @param es Pointer to the env_set to set the options into
+ */
+void
+setenv_dns_options(const struct dns_options *o, struct env_set *es)
+{
+ struct gc_arena gc = gc_new();
+ const struct dns_server *s;
+ const struct dns_domain *d;
+ bool name_ok = true;
+ char env_name[64];
+ int i, j;
+
+ for (i = 1, d = o->search_domains; d != NULL; i++, d = d->next)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_search_domain_%d", i);
+ setenv_str(es, env_name, d->name);
+ }
+
+ for (i = 1, s = o->servers; s != NULL; i++, s = s->next)
+ {
+ if (s->addr4_defined)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_server_%d_address4", i);
+ setenv_str(es, env_name, print_in_addr_t(s->addr4.s_addr, 0, &gc));
+ }
+ if (s->port4)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_server_%d_port4", i);
+ setenv_str(es, env_name, print_in_port_t(s->port4, &gc));
+ }
+
+ if (s->addr6_defined)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_server_%d_address6", i);
+ setenv_str(es, env_name, print_in6_addr(s->addr6, 0, &gc));
+ }
+ if (s->port6)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_server_%d_port6", i);
+ setenv_str(es, env_name, print_in_port_t(s->port6, &gc));
+ }
+
+ if (s->domains)
+ {
+ const char* format = s->domain_type == DNS_RESOLVE_DOMAINS ?
+ "dns_server_%d_resolve_domain_%d" :
"dns_server_%d_exclude_domain_%d";
+ for (j = 1, d = s->domains; d != NULL; j++, d = d->next)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
format, i, j);
+ setenv_str(es, env_name, d->name);
+ }
+ }
+
+ if (s->dnssec)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_server_%d_dnssec", i);
+ setenv_str(es, env_name, dnssec_value(s->dnssec));
+ }
+
+ if (s->transport)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_server_%d_transport", i);
+ setenv_str(es, env_name, transport_value(s->transport));
+ }
+ if (s->sni)
+ {
+ name_ok &= openvpn_snprintf(env_name, sizeof(env_name),
"dns_server_%d_sni", i);
+ setenv_str(es, env_name, s->sni);
+ }
+ }
+
+ if (!name_ok)
+ {
+ msg(M_WARN, "WARNING: dns option setenv name buffer overflow");
+ }
+
+ gc_free(&gc);
+}
+
+/**
+ * Prints configured DNS options.
+ *
+ * @param o Pointer to the DNS options to print
+ */
+void
+show_dns_options(const struct dns_options *o)
+{
+ struct gc_arena gc = gc_new();
+
+ int i = 1;
+ struct dns_server *server = o->servers_prepull ? o->servers_prepull :
o->servers;
+ while (server)
+ {
+ msg(D_SHOW_PARMS, " DNS server #%d:", i++);
+
+ if (server->addr4_defined)
+ {
+ const char *addr = print_in_addr_t(server->addr4.s_addr, 0, &gc);
+ if (server->port4)
+ {
+ const char *port = print_in_port_t(server->port4, &gc);
+ msg(D_SHOW_PARMS, " address4 = %s:%s", addr, port);
+ }
+ else
+ {
+ msg(D_SHOW_PARMS, " address4 = %s", addr);
+ }
+ }
+ if (server->addr6_defined)
+ {
+ const char *addr = print_in6_addr(server->addr6, 0, &gc);
+ if (server->port6)
+ {
+ const char *port = print_in_port_t(server->port6, &gc);
+ msg(D_SHOW_PARMS, " address6 = [%s]:%s", addr, port);
+ }
+ else
+ {
+ msg(D_SHOW_PARMS, " address6 = %s", addr);
+ }
+ }
+
+ if (server->dnssec)
+ {
+ msg(D_SHOW_PARMS, " dnssec = %s", dnssec_value(server->dnssec));
+ }
+
+ if (server->transport)
+ {
+ msg(D_SHOW_PARMS, " transport = %s",
transport_value(server->transport));
+ }
+ if (server->sni)
+ {
+ msg(D_SHOW_PARMS, " sni = %s", server->sni);
+ }
+
+ struct dns_domain *domain = server->domains;
+ if (domain)
+ {
+ if (server->domain_type == DNS_RESOLVE_DOMAINS)
+ {
+ msg(D_SHOW_PARMS, " resolve domains:");
+ }
+ else
+ {
+ msg(D_SHOW_PARMS, " exclude domains:");
+ }
+ while(domain)
+ {
+ msg(D_SHOW_PARMS, " %s", domain->name);
+ domain = domain->next;
+ }
+ }
+
+ server = server->next;
+ }
+
+ struct dns_domain *search_domain = o->search_domains;
+ if (search_domain)
+ {
+ msg(D_SHOW_PARMS, " DNS search domains:");
+ while(search_domain)
+ {
+ msg(D_SHOW_PARMS, " %s", search_domain->name);
+ search_domain = search_domain->next;
+ }
+ }
+
+ gc_free(&gc);
+}
diff --git a/src/openvpn/dns.h b/src/openvpn/dns.h
new file mode 100644
index 00000000..5248d345
--- /dev/null
+++ b/src/openvpn/dns.h
@@ -0,0 +1,89 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2022 OpenVPN Inc <sa...@openvpn.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef DNS_H
+#define DNS_H
+
+#include "buffer.h"
+#include "env_set.h"
+
+enum dns_domain_type {
+ DNS_DOMAINS_UNSET,
+ DNS_RESOLVE_DOMAINS,
+ DNS_EXCLUDE_DOMAINS
+};
+
+enum dns_security {
+ DNS_SECURITY_UNSET,
+ DNS_SECURITY_NO,
+ DNS_SECURITY_YES,
+ DNS_SECURITY_OPTIONAL
+};
+
+enum dns_server_transport {
+ DNS_TRANSPORT_UNSET,
+ DNS_TRANSPORT_PLAIN,
+ DNS_TRANSPORT_HTTPS,
+ DNS_TRANSPORT_TLS
+};
+
+struct dns_domain {
+ struct dns_domain *next;
+ const char *name;
+};
+
+struct dns_server {
+ struct dns_server *next;
+ long priority;
+ bool addr4_defined;
+ bool addr6_defined;
+ struct in_addr addr4;
+ struct in6_addr addr6;
+ in_port_t port4;
+ in_port_t port6;
+ struct dns_domain *domains;
+ enum dns_domain_type domain_type;
+ enum dns_security dnssec;
+ enum dns_server_transport transport;
+ char *sni;
+};
+
+struct dns_options {
+ struct dns_domain *search_domains;
+ struct dns_server *servers_prepull;
+ struct dns_server *servers;
+ struct gc_arena gc;
+};
+
+bool dns_server_priority_parse(long *priority, const char *str, bool pulled);
+struct dns_server* dns_server_get(struct dns_server **entry, long priority,
struct gc_arena *gc);
+void dns_domain_list_append(struct dns_domain **entry, char **domains, struct
gc_arena *gc);
+bool dns_server_addr_parse(struct dns_server *server, const char *addr);
+bool dns_options_verify(int msglevel, const struct dns_options *o);
+struct dns_options clone_dns_options(const struct dns_options o, struct
gc_arena *gc);
+void dns_options_preprocess_pull(struct dns_options *o);
+void dns_options_postprocess_pull(struct dns_options *o);
+void setenv_dns_options(const struct dns_options *o, struct env_set *es);
+void show_dns_options(const struct dns_options *o);
+
+#endif
diff --git a/src/openvpn/openvpn.vcxproj b/src/openvpn/openvpn.vcxproj
index 65ee6839..f6ec17bf 100644
--- a/src/openvpn/openvpn.vcxproj
+++ b/src/openvpn/openvpn.vcxproj
@@ -255,6 +255,7 @@
<ClCompile Include="cryptoapi.c" />
<ClCompile Include="env_set.c" />
<ClCompile Include="dhcp.c" />
+ <ClCompile Include="dns.c" />
<ClCompile Include="error.c" />
<ClCompile Include="event.c" />
<ClCompile Include="fdmisc.c" />
@@ -336,6 +337,7 @@
<ClInclude Include="crypto_openssl.h" />
<ClInclude Include="cryptoapi.h" />
<ClInclude Include="dhcp.h" />
+ <ClInclude Include="dns.h" />
<ClInclude Include="env_set.h" />
<ClInclude Include="errlevel.h" />
<ClInclude Include="error.h" />
@@ -427,4 +429,4 @@
<Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
<ImportGroup Label="ExtensionTargets">
</ImportGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/src/openvpn/openvpn.vcxproj.filters
b/src/openvpn/openvpn.vcxproj.filters
index f5fdfcd7..97bca54b 100644
--- a/src/openvpn/openvpn.vcxproj.filters
+++ b/src/openvpn/openvpn.vcxproj.filters
@@ -39,6 +39,9 @@
<ClCompile Include="dhcp.c">
<Filter>Source Files</Filter>
</ClCompile>
+ <ClCompile Include="dns.c">
+ <Filter>Source Files</Filter>
+ </ClCompile>
<ClCompile Include="error.c">
<Filter>Source Files</Filter>
</ClCompile>
@@ -290,6 +293,9 @@
<ClInclude Include="dhcp.h">
<Filter>Header Files</Filter>
</ClInclude>
+ <ClInclude Include="dns.h">
+ <Filter>Header Files</Filter>
+ </ClInclude>
<ClInclude Include="errlevel.h">
<Filter>Header Files</Filter>
</ClInclude>
@@ -526,4 +532,4 @@
<Filter>Resource Files</Filter>
</Manifest>
</ItemGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index bf8e7759..457c70c1 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -496,6 +496,16 @@ static const char usage_message[] =
" ignore or reject causes the option to be allowed,
removed or\n"
" rejected with error. May be specified multiple times,
and\n"
" each filter is applied in the order of appearance.\n"
+ "--dns server <n> <option> <value> [value ...] : Configure option for DNS
server #n\n"
+ " Valid options are :\n"
+ " address <addr[:port]> [addr[:port]] : server address
4/6\n"
+ " resolve-domains <domain> [domain ...] : split domains\n"
+ " exclude-domains <domain> [domain ...] : domains not to
resolve\n"
+ " dnssec <yes|no|optional> : option to use DNSSEC\n"
+ " type <DoH|DoT> : query server over HTTPS / TLS\n"
+ " sni <domain> : DNS server name indication\n"
+ "--dns search-domains <domain> [domain ...]:\n"
+ " Add domains to DNS domain search list\n"
"--auth-retry t : How to handle auth failures. Set t to\n"
" none (default), interact, or nointeract.\n"
"--static-challenge t e : Enable static challenge/response protocol
using\n"
@@ -783,6 +793,7 @@ init_options(struct options *o, const bool init_gc)
if (init_gc)
{
gc_init(&o->gc);
+ gc_init(&o->dns_options.gc);
o->gc_owned = true;
}
o->mode = MODE_POINT_TO_POINT;
@@ -886,6 +897,7 @@ uninit_options(struct options *o)
if (o->gc_owned)
{
gc_free(&o->gc);
+ gc_free(&o->dns_options.gc);
}
}
@@ -988,6 +1000,11 @@ setenv_settings(struct env_set *es, const struct options
*o)
{
setenv_connection_entry(es, &o->ce, 1);
}
+
+ if (!o->pull)
+ {
+ setenv_dns_options(&o->dns_options, es);
+ }
}
static in_addr_t
@@ -1262,6 +1279,64 @@ dhcp_option_address_parse(const char *name, const char
*parm, in_addr_t *array,
}
}
+/*
+ * If DNS options are set use these for TUN/TAP options as well.
+ * Applies to DNS, DNS6 and DOMAIN-SEARCH.
+ * Existing options will be discarded.
+ */
+static void
+tuntap_options_copy_dns(struct options *o)
+{
+ struct tuntap_options *tt = &o->tuntap_options;
+ struct dns_options *dns = &o->dns_options;
+
+ if (dns->search_domains)
+ {
+ tt->domain_search_list_len = 0;
+ const struct dns_domain *domain = dns->search_domains;
+ while (domain && tt->domain_search_list_len < N_SEARCH_LIST_LEN)
+ {
+ tt->domain_search_list[tt->domain_search_list_len++] =
domain->name;
+ domain = domain->next;
+ }
+ if (domain)
+ {
+ msg(M_WARN, "WARNING: couldn't copy all --dns search-domains to
--dhcp-option");
+ }
+ }
+
+ if (dns->servers)
+ {
+ tt->dns_len = 0;
+ tt->dns6_len = 0;
+ bool overflow = false;
+ const struct dns_server *server = dns->servers;
+ while (server)
+ {
+ if (server->addr4_defined && tt->dns_len < N_DHCP_ADDR)
+ {
+ tt->dns[tt->dns_len++] = server->addr4.s_addr;
+ }
+ else
+ {
+ overflow = true;
+ }
+ if (server->addr6_defined && tt->dns6_len < N_DHCP_ADDR)
+ {
+ tt->dns6[tt->dns6_len++] = server->addr6;
+ }
+ else
+ {
+ overflow = true;
+ }
+ server = server->next;
+ }
+ if (overflow)
+ {
+ msg(M_WARN, "WARNING: couldn't copy all --dns server addresses to
--dhcp-option");
+ }
+ }
+}
#endif /* if defined(_WIN32) || defined(TARGET_ANDROID) */
static const char *
@@ -1690,6 +1765,8 @@ show_settings(const struct options *o)
print_client_nat_list(o->client_nat, D_SHOW_PARMS);
}
+ show_dns_options(&o->dns_options);
+
#ifdef ENABLE_MANAGEMENT
SHOW_STR(management_addr);
SHOW_STR(management_port);
@@ -3069,6 +3146,8 @@ options_postprocess_verify(const struct options *o)
{
options_postprocess_verify_ce(o, &o->ce);
}
+
+ dns_options_verify(M_FATAL, &o->dns_options);
}
/**
@@ -3311,6 +3390,16 @@ options_postprocess_mutate(struct options *o)
* Save certain parms before modifying options during connect, especially
* when using --pull
*/
+ if (o->pull)
+ {
+ dns_options_preprocess_pull(&o->dns_options);
+ }
+#if defined(_WIN32) || defined(TARGET_ANDROID)
+ else
+ {
+ tuntap_options_copy_dns(o);
+ }
+#endif
pre_connect_save(o);
}
@@ -3655,6 +3744,25 @@ options_postprocess(struct options *options)
#endif /* !ENABLE_SMALL */
}
+/*
+ * Sanity check on options after more options were pulled from server.
+ * Also time to modify some options based on other options.
+ */
+bool
+options_postprocess_pull(struct options *o, struct env_set *es)
+{
+ bool success = dns_options_verify(D_PUSH_ERRORS, &o->dns_options);
+ if (success)
+ {
+ dns_options_postprocess_pull(&o->dns_options);
+ setenv_dns_options(&o->dns_options, es);
+#if defined(_WIN32) || defined(TARGET_ANDROID)
+ tuntap_options_copy_dns(o);
+#endif
+ }
+ return success;
+}
+
/*
* Save/Restore certain option defaults before --pull is applied.
*/
@@ -3686,6 +3794,8 @@ pre_connect_save(struct options *o)
o->pre_connect->route_default_gateway = o->route_default_gateway;
o->pre_connect->route_ipv6_default_gateway = o->route_ipv6_default_gateway;
+ o->pre_connect->dns_options = clone_dns_options(o->dns_options, &o->gc);
+
/* NCP related options that can be overwritten by a push */
o->pre_connect->ciphername = o->ciphername;
o->pre_connect->authname = o->authname;
@@ -3736,6 +3846,12 @@ pre_connect_restore(struct options *o, struct gc_arena
*gc)
o->route_default_gateway = pp->route_default_gateway;
o->route_ipv6_default_gateway = pp->route_ipv6_default_gateway;
+ /* Free DNS options and reset them to pre-pull state */
+ gc_free(&o->dns_options.gc);
+ struct gc_arena dns_gc = gc_new();;
+ o->dns_options = clone_dns_options(pp->dns_options, &dns_gc);
+ o->dns_options.gc = dns_gc;
+
if (pp->client_nat_defined)
{
cnol_check_alloc(o);
@@ -7485,6 +7601,111 @@ add_option(struct options *options,
to->ip_win32_defined = true;
}
#endif /* ifdef _WIN32 */
+ else if (streq(p[0], "dns") && p[1])
+ {
+ VERIFY_PERMISSION(OPT_P_DEFAULT);
+
+ if (streq(p[1], "search-domains") && p[2])
+ {
+ dns_domain_list_append(&options->dns_options.search_domains,
&p[2], &options->dns_options.gc);
+ }
+ else if (streq(p[1], "server") && p[2] && p[3] && p[4])
+ {
+ long priority;
+ if (!dns_server_priority_parse(&priority, p[2], pull_mode)) {
+ msg(msglevel, "--dns server: invalid priority value '%s'",
p[2]);
+ goto err;
+ }
+
+ struct dns_server *server =
dns_server_get(&options->dns_options.servers, priority,
&options->dns_options.gc);
+
+ if (streq(p[3], "address") && !p[6])
+ {
+ for (int i = 4; p[i]; i++)
+ {
+ if(!dns_server_addr_parse(server, p[i]))
+ {
+ msg(msglevel, "--dns server %ld: malformed or
duplicate address '%s'", priority, p[i]);
+ goto err;
+ }
+ }
+ }
+ else if (streq(p[3], "resolve-domains"))
+ {
+ if (server->domain_type == DNS_EXCLUDE_DOMAINS)
+ {
+ msg(msglevel, "--dns server %ld: cannot use
resolve-domains and exclude-domains", priority);
+ goto err;
+ }
+ server->domain_type = DNS_RESOLVE_DOMAINS;
+ dns_domain_list_append(&server->domains, &p[4],
&options->dns_options.gc);
+ }
+ else if (streq(p[3], "exclude-domains"))
+ {
+ if (server->domain_type == DNS_RESOLVE_DOMAINS)
+ {
+ msg(msglevel, "--dns server %ld: cannot use
exclude-domains and resolve-domains", priority);
+ goto err;
+ }
+ server->domain_type = DNS_EXCLUDE_DOMAINS;
+ dns_domain_list_append(&server->domains, &p[4],
&options->dns_options.gc);
+ }
+ else if (streq(p[3], "dnssec") && !p[5])
+ {
+ if (streq(p[4], "yes"))
+ {
+ server->dnssec = DNS_SECURITY_YES;
+ }
+ else if (streq(p[4], "no"))
+ {
+ server->dnssec = DNS_SECURITY_NO;
+ }
+ else if (streq(p[4], "optional"))
+ {
+ server->dnssec = DNS_SECURITY_OPTIONAL;
+ }
+ else
+ {
+ msg(msglevel, "--dns server %ld: malformed dnssec value
'%s'", priority, p[4]);
+ goto err;
+ }
+ }
+ else if (streq(p[3], "transport") && !p[5])
+ {
+ if (streq(p[4], "plain"))
+ {
+ server->transport = DNS_TRANSPORT_PLAIN;
+ }
+ else if (streq(p[4], "DoH"))
+ {
+ server->transport = DNS_TRANSPORT_HTTPS;
+ }
+ else if (streq(p[4], "DoT"))
+ {
+ server->transport = DNS_TRANSPORT_TLS;
+ }
+ else
+ {
+ msg(msglevel, "--dns server %ld: malformed transport value
'%s'", priority, p[4]);
+ goto err;
+ }
+ }
+ else if (streq(p[3], "sni") && !p[5])
+ {
+ server->sni = p[4];
+ }
+ else
+ {
+ msg(msglevel, "--dns server %ld: unknown option type '%s' or
missing or unknown parameter", priority, p[3]);
+ goto err;
+ }
+ }
+ else
+ {
+ msg(msglevel, "--dns: unknown option type '%s' or missing or
unknown parameter", p[1]);
+ goto err;
+ }
+ }
#if defined(_WIN32) || defined(TARGET_ANDROID)
else if (streq(p[0], "dhcp-option") && p[1])
{
diff --git a/src/openvpn/options.h b/src/openvpn/options.h
index d4f41cd7..c06fcbf1 100644
--- a/src/openvpn/options.h
+++ b/src/openvpn/options.h
@@ -42,6 +42,7 @@
#include "pushlist.h"
#include "clinat.h"
#include "crypto_backend.h"
+#include "dns.h"
/*
@@ -76,6 +77,8 @@ struct options_pre_connect
bool client_nat_defined;
struct client_nat_option_list *client_nat;
+ struct dns_options dns_options;
+
const char* ciphername;
const char* authname;
@@ -272,6 +275,8 @@ struct options
struct remote_host_store *rh_store;
+ struct dns_options dns_options;
+
bool remote_random;
const char *ipchange;
const char *dev;
@@ -802,6 +807,8 @@ char *options_string_extract_option(const char
*options_string,
void options_postprocess(struct options *options);
+bool options_postprocess_pull(struct options *o, struct env_set *es);
+
void pre_connect_save(struct options *o);
void pre_connect_restore(struct options *o, struct gc_arena *gc);
diff --git a/src/openvpn/push.c b/src/openvpn/push.c
index f9343b42..43716500 100644
--- a/src/openvpn/push.c
+++ b/src/openvpn/push.c
@@ -459,6 +459,10 @@ incoming_push_message(struct context *c, const struct
buffer *buffer)
/* delay bringing tun/tap up until --push parms received from remote */
if (status == PUSH_MSG_REPLY)
{
+ if (!options_postprocess_pull(&c->options, c->c2.es))
+ {
+ goto error;
+ }
if (!do_up(c, true, c->options.push_option_types_found))
{
msg(D_PUSH_ERRORS, "Failed to open tun/tap interface");
diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index df736746..d00cd4ac 100644
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -2906,6 +2906,17 @@ print_in6_addr(struct in6_addr a6, unsigned int flags,
struct gc_arena *gc)
return BSTR(&out);
}
+/*
+ * Convert an in_port_t in host byte order to a string
+ */
+const char *
+print_in_port_t(in_port_t port, struct gc_arena *gc)
+{
+ struct buffer buffer = alloc_buf_gc(8, gc);
+ buf_printf(&buffer, "%hu", port);
+ return BSTR(&buffer);
+}
+
#ifndef UINT8_MAX
#define UINT8_MAX 0xff
#endif
diff --git a/src/openvpn/socket.h b/src/openvpn/socket.h
index cc1e0c36..deaa41a2 100644
--- a/src/openvpn/socket.h
+++ b/src/openvpn/socket.h
@@ -360,6 +360,8 @@ const char *print_in_addr_t(in_addr_t addr, unsigned int
flags, struct gc_arena
const char *print_in6_addr(struct in6_addr addr6, unsigned int flags, struct
gc_arena *gc);
+const char *print_in_port_t(in_port_t port, struct gc_arena *gc);
+
struct in6_addr add_in6_addr( struct in6_addr base, uint32_t add );
#define SA_IP_PORT (1<<0)
--
2.32.0
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