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resolve: Try to maintain the order of DNS servers if using resolvconf

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Since 17fd304e60 ("resolve: Don't install individual servers via
resolvconf"), DNS servers were sorted if getting installed via resolvconf.
In some setups the order might be important (even though relying on it
isn't a good idea in general as stub resolvers are free to use all of
the servers as they please).
This commit is contained in:
Tobias Brunner
2023-06-19 14:56:24 +02:00
parent 2d1006963e
commit 6440975bb4
1 changed files with 36 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libcharon/plugins/resolve/resolve_handler.c
+36 -34
View File
@@ -1,5 +1,5 @@
/*
* Copyright (C) 2012-2022 Tobias Brunner
* Copyright (C) 2012-2023 Tobias Brunner
* Copyright (C) 2009 Martin Willi
*
* Copyright (C) secunet Security Networks AG
@@ -23,7 +23,7 @@
#include <utils/debug.h>
#include <utils/process.h>
#include <collections/array.h>
#include <collections/hashtable.h>
#include <threading/mutex.h>
/* path to resolvconf executable */
@@ -67,7 +67,7 @@ struct private_resolve_handler_t {
/**
* Reference counting for DNS servers dns_server_t
*/
array_t *servers;
hashtable_t *servers;
};
/**
@@ -88,24 +88,21 @@ typedef struct {
} dns_server_t;
/**
* Compare a server and a stored reference
* Hash DNS server address
*/
static int dns_server_find(const void *a, const void *b)
static u_int dns_server_hash(const void *key)
{
host_t *server = (host_t*)a;
dns_server_t *item = (dns_server_t*)b;
return chunk_compare(server->get_address(server),
item->server->get_address(item->server));
host_t *host = (host_t*)key;
return chunk_hash(host->get_address(host));
}
/**
* Sort references by DNS server
* Compare two DNS server addresses
*/
static int dns_server_sort(const void *a, const void *b, void *user)
static bool dns_server_equals(const void *a, const void *b)
{
const dns_server_t *da = a, *db = b;
return chunk_compare(da->server->get_address(da->server),
db->server->get_address(db->server));
host_t *ha = (host_t*)a, *hb = (host_t*)b;
return chunk_equals(ha->get_address(ha), hb->get_address(hb));
}
/**
@@ -184,33 +181,37 @@ static void remove_nameserver(private_resolve_handler_t *this, host_t *addr)
}
/**
* Install the given nameservers by invoking resolvconf. If the array is empty,
* Install the given nameservers by invoking resolvconf. If the table is empty,
* remove the config.
*/
static bool invoke_resolvconf(private_resolve_handler_t *this, array_t *servers)
static bool invoke_resolvconf(private_resolve_handler_t *this,
hashtable_t *servers)
{
process_t *process;
enumerator_t *enumerator;
dns_server_t *dns;
FILE *shell;
int in, out, retval, i;
int in, out, retval;
bool install = servers->get_count(servers);
process = process_start_shell(NULL, array_count(servers) ? &in : NULL, &out,
NULL, "2>&1 %s %s %s", this->resolvconf,
array_count(servers) ? "-a" : "-d", this->iface);
process = process_start_shell(NULL, install ? &in : NULL, &out,
NULL, "2>&1 %s %s %s", this->resolvconf,
install ? "-a" : "-d", this->iface);
if (!process)
{
return FALSE;
}
if (array_count(servers))
if (install)
{
shell = fdopen(in, "w");
if (shell)
{
for (i = 0; i < array_count(servers); i++)
enumerator = servers->create_enumerator(servers);
while (enumerator->enumerate(enumerator, NULL, &dns))
{
array_get(servers, i, &dns);
fprintf(shell, "nameserver %H\n", dns->server);
}
enumerator->destroy(enumerator);
fclose(shell);
}
else
@@ -263,7 +264,7 @@ METHOD(attribute_handler_t, handle, bool,
private_resolve_handler_t *this, ike_sa_t *ike_sa,
configuration_attribute_type_t type, chunk_t data)
{
dns_server_t *found = NULL;
dns_server_t *found;
host_t *addr;
bool handled;
@@ -286,14 +287,14 @@ METHOD(attribute_handler_t, handle, bool,
}
this->mutex->lock(this->mutex);
if (array_bsearch(this->servers, addr, dns_server_find, &found) == -1)
found = this->servers->get(this->servers, addr);
if (!found)
{
INIT(found,
.server = addr->clone(addr),
.refcount = 1,
);
array_insert_create(&this->servers, ARRAY_TAIL, found);
array_sort(this->servers, dns_server_sort, NULL);
this->servers->put(this->servers, found->server, found);
if (this->resolvconf)
{
@@ -306,7 +307,7 @@ METHOD(attribute_handler_t, handle, bool,
}
if (!handled)
{
array_remove(this->servers, ARRAY_TAIL, NULL);
this->servers->remove(this->servers, found->server);
found->server->destroy(found->server);
free(found);
}
@@ -332,9 +333,9 @@ METHOD(attribute_handler_t, release, void,
private_resolve_handler_t *this, ike_sa_t *ike_sa,
configuration_attribute_type_t type, chunk_t data)
{
dns_server_t *found = NULL;
dns_server_t *found;
host_t *addr;
int family, idx;
int family;
switch (type)
{
@@ -350,8 +351,8 @@ METHOD(attribute_handler_t, release, void,
addr = host_create_from_chunk(family, data, 0);
this->mutex->lock(this->mutex);
idx = array_bsearch(this->servers, addr, dns_server_find, &found);
if (idx != -1)
found = this->servers->get(this->servers, addr);
if (found)
{
if (--found->refcount > 0)
{
@@ -360,7 +361,7 @@ METHOD(attribute_handler_t, release, void,
}
else
{
array_remove(this->servers, idx, NULL);
this->servers->remove(this->servers, found->server);
found->server->destroy(found->server);
free(found);
@@ -460,7 +461,7 @@ METHOD(attribute_handler_t, create_attribute_enumerator, enumerator_t*,
METHOD(resolve_handler_t, destroy, void,
private_resolve_handler_t *this)
{
array_destroy(this->servers);
this->servers->destroy(this->servers);
this->mutex->destroy(this->mutex);
free(this);
}
@@ -483,6 +484,7 @@ resolve_handler_t *resolve_handler_create()
.destroy = _destroy,
},
.mutex = mutex_create(MUTEX_TYPE_DEFAULT),
.servers = hashtable_create(dns_server_hash, dns_server_equals, 4),
.file = lib->settings->get_str(lib->settings,
"%s.plugins.resolve.file", RESOLV_CONF, lib->ns),
.resolvconf = lib->settings->get_str(lib->settings,