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resolv: Mirror the entire resolver configuration in struct resolv_conf

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This commit adds the remaining unchanging members (which are loaded
from /etc/resolv.conf) to struct resolv_conf.

The extended name server list is currently not used by the stub
resolver.  The switch depends on a cleanup: The _u._ext.nssocks
array stores just a single socket, and needs to be replaced with
a single socket value.

(The compatibility gethostname implementation does not use the
extended addres sort list, either.  Updating the compat code is
not worthwhile.)
This commit is contained in:
Florian Weimer
2017-06-30 20:19:10 +02:00
parent 3f853f22c8
commit a1c4eb8794
7 changed files with 572 additions and 116 deletions
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219
resolv/res_init.c
View File

@ -104,7 +104,6 @@
#include <errno.h>
#include <resolv_conf.h>
static void res_setoptions (res_state, const char *);
static uint32_t net_mask (struct in_addr);
unsigned long long int __res_initstamp;
@ -124,28 +123,70 @@ is_sort_mask (char ch)
return ch == '/' || ch == '&';
}
/* Array of name server addresses. */
#define DYNARRAY_STRUCT nameserver_list
#define DYNARRAY_ELEMENT const struct sockaddr *
#define DYNARRAY_ELEMENT_FREE(e) free ((struct sockaddr *) *(e))
#define DYNARRAY_INITIAL_SIZE 3
#define DYNARRAY_PREFIX nameserver_list_
#include <malloc/dynarray-skeleton.c>
/* Array of strings for the search array. The backing store is
managed separately. */
#define DYNARRAY_STRUCT search_list
#define DYNARRAY_ELEMENT const char *
#define DYNARRAY_INITIAL_SIZE 4
#define DYNARRAY_INITIAL_SIZE 6
#define DYNARRAY_PREFIX search_list_
#include <malloc/dynarray-skeleton.c>
/* Array of name server addresses. */
#define DYNARRAY_STRUCT sort_list
#define DYNARRAY_ELEMENT struct resolv_sortlist_entry
#define DYNARRAY_INITIAL_SIZE 0
#define DYNARRAY_PREFIX sort_list_
#include <malloc/dynarray-skeleton.c>
/* resolv.conf parser state and results. */
struct resolv_conf_parser
{
char *buffer; /* Temporary buffer for reading lines. */
struct nameserver_list nameserver_list; /* Nameserver addresses. */
char *search_list_store; /* Backing storage for search list entries. */
struct search_list search_list; /* Points into search_list_store. */
struct sort_list sort_list; /* Address preference sorting list. */
/* Configuration template. The non-array elements are filled in
directly. The array elements are updated prior to the call to
__resolv_conf_attach. */
struct resolv_conf template;
};
static void
resolv_conf_parser_init (struct resolv_conf_parser *parser)
resolv_conf_parser_init (struct resolv_conf_parser *parser,
const struct __res_state *preinit)
{
parser->buffer = NULL;
parser->search_list_store = NULL;
nameserver_list_init (&parser->nameserver_list);
search_list_init (&parser->search_list);
sort_list_init (&parser->sort_list);
if (preinit != NULL)
{
parser->template.retrans = preinit->retrans;
parser->template.retry = preinit->retry;
parser->template.options = preinit->options | RES_INIT;
}
else
{
parser->template.retrans = RES_TIMEOUT;
parser->template.retry = RES_DFLRETRY;
parser->template.options = RES_DEFAULT | RES_INIT;
}
parser->template.ndots = 1;
}
static void
@ -153,7 +194,23 @@ resolv_conf_parser_free (struct resolv_conf_parser *parser)
{
free (parser->buffer);
free (parser->search_list_store);
nameserver_list_free (&parser->nameserver_list);
search_list_free (&parser->search_list);
sort_list_free (&parser->sort_list);
}
/* Allocate a struct sockaddr_in object on the heap, with the
specified address and port. */
static struct sockaddr *
allocate_address_v4 (struct in_addr a, uint16_t port)
{
struct sockaddr_in *sa4 = malloc (sizeof (*sa4));
if (sa4 == NULL)
return NULL;
sa4->sin_family = AF_INET;
sa4->sin_addr = a;
sa4->sin_port = htons (port);
return (struct sockaddr *) sa4;
}
/* Try to obtain the domain name from the host name and store it in
@ -181,40 +238,17 @@ domain_from_hostname (char **result)
return true;
}
static void res_setoptions (struct resolv_conf_parser *, const char *options);
/* Internal helper function for __res_vinit, to aid with resource
deallocation and error handling. Return true on success, false on
failure. */
static bool
res_vinit_1 (res_state statp, bool preinit, FILE *fp,
struct resolv_conf_parser *parser)
res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
{
char *cp;
size_t buffer_size = 0;
int nserv = 0; /* Number of nameservers read from file. */
bool have_serv6 = false;
bool haveenv = false;
int nsort = 0;
char *net;
if (!preinit)
{
statp->retrans = RES_TIMEOUT;
statp->retry = RES_DFLRETRY;
statp->options = RES_DEFAULT;
statp->id = res_randomid ();
}
statp->nscount = 0;
statp->defdname[0] = '\0';
statp->ndots = 1;
statp->pfcode = 0;
statp->_vcsock = -1;
statp->_flags = 0;
statp->__glibc_unused_qhook = NULL;
statp->__glibc_unused_rhook = NULL;
statp->_u._ext.nscount = 0;
for (int n = 0; n < MAXNS; n++)
statp->_u._ext.nsaddrs[n] = NULL;
/* Allow user to override the local domain definition. */
if ((cp = getenv ("LOCALDOMAIN")) != NULL)
@ -350,19 +384,19 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp,
continue;
}
/* Read nameservers to query. */
if (MATCH (parser->buffer, "nameserver") && nserv < MAXNS)
if (MATCH (parser->buffer, "nameserver"))
{
struct in_addr a;
cp = parser->buffer + sizeof ("nameserver") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
struct sockaddr *sa;
if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
{
statp->nsaddr_list[nserv].sin_addr = a;
statp->nsaddr_list[nserv].sin_family = AF_INET;
statp->nsaddr_list[nserv].sin_port = htons (NAMESERVER_PORT);
nserv++;
sa = allocate_address_v4 (a, NAMESERVER_PORT);
if (sa == NULL)
return false;
}
else
{
@ -392,13 +426,18 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp,
compatibility. */
__inet6_scopeid_pton
(&a6, el + 1, &sa6->sin6_scope_id);
statp->nsaddr_list[nserv].sin_family = 0;
statp->_u._ext.nsaddrs[nserv] = sa6;
statp->_u._ext.nssocks[nserv] = -1;
have_serv6 = true;
nserv++;
sa = (struct sockaddr *) sa6;
}
else
/* IPv6 address parse failure. */
sa = NULL;
}
if (sa != NULL)
{
const struct sockaddr **p = nameserver_list_emplace
(&parser->nameserver_list);
if (p != NULL)
*p = sa;
}
continue;
}
@ -407,21 +446,22 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp,
struct in_addr a;
cp = parser->buffer + sizeof ("sortlist") - 1;
while (nsort < MAXRESOLVSORT)
while (true)
{
while (*cp == ' ' || *cp == '\t')
cp++;
if (*cp == '\0' || *cp == '\n' || *cp == ';')
break;
net = cp;
char *net = cp;
while (*cp && !is_sort_mask (*cp) && *cp != ';'
&& isascii (*cp) && !isspace (*cp))
cp++;
char separator = *cp;
*cp = 0;
struct resolv_sortlist_entry e;
if (__inet_aton (net, &a))
{
statp->sort_list[nsort].addr = a;
e.addr = a;
if (is_sort_mask (separator))
{
*cp++ = separator;
@ -432,15 +472,13 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp,
separator = *cp;
*cp = 0;
if (__inet_aton (net, &a))
statp->sort_list[nsort].mask = a.s_addr;
e.mask = a.s_addr;
else
statp->sort_list[nsort].mask
= net_mask (statp->sort_list[nsort].addr);
e.mask = net_mask (e.addr);
}
else
statp->sort_list[nsort].mask
= net_mask (statp->sort_list[nsort].addr);
nsort++;
e.mask = net_mask (e.addr);
sort_list_add (&parser->sort_list, e);
}
*cp = separator;
}
@ -448,23 +486,22 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp,
}
if (MATCH (parser->buffer, "options"))
{
res_setoptions (statp, parser->buffer + sizeof ("options") - 1);
res_setoptions (parser, parser->buffer + sizeof ("options") - 1);
continue;
}
}
statp->nscount = nserv;
if (have_serv6)
/* We try IPv6 servers again. */
statp->ipv6_unavail = false;
statp->nsort = nsort;
fclose (fp);
}
if (__glibc_unlikely (statp->nscount == 0))
if (__glibc_unlikely (nameserver_list_size (&parser->nameserver_list) == 0))
{
statp->nsaddr.sin_addr = __inet_makeaddr (IN_LOOPBACKNET, 1);
statp->nsaddr.sin_family = AF_INET;
statp->nsaddr.sin_port = htons (NAMESERVER_PORT);
statp->nscount = 1;
const struct sockaddr **p
= nameserver_list_emplace (&parser->nameserver_list);
if (p == NULL)
return false;
*p = allocate_address_v4 (__inet_makeaddr (IN_LOOPBACKNET, 1),
NAMESERVER_PORT);
if (*p == NULL)
return false;
}
if (search_list_size (&parser->search_list) == 0)
@ -481,15 +518,16 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp,
}
if ((cp = getenv ("RES_OPTIONS")) != NULL)
res_setoptions (statp, cp);
res_setoptions (parser, cp);
if (search_list_has_failed (&parser->search_list))
if (nameserver_list_has_failed (&parser->nameserver_list)
|| search_list_has_failed (&parser->search_list)
|| sort_list_has_failed (&parser->sort_list))
{
__set_errno (ENOMEM);
return false;
}
statp->options |= RES_INIT;
return true;
}
@ -525,17 +563,27 @@ __res_vinit (res_state statp, int preinit)
}
struct resolv_conf_parser parser;
resolv_conf_parser_init (&parser);
bool ok = res_vinit_1 (statp, preinit, fp, &parser);
if (preinit)
{
resolv_conf_parser_init (&parser, statp);
statp->id = res_randomid ();
}
else
resolv_conf_parser_init (&parser, NULL);
bool ok = res_vinit_1 (fp, &parser);
if (ok)
{
struct resolv_conf init =
{
.search_list = search_list_begin (&parser.search_list),
.search_list_size = search_list_size (&parser.search_list),
};
struct resolv_conf *conf = __resolv_conf_allocate (&init);
parser.template.nameserver_list
= nameserver_list_begin (&parser.nameserver_list);
parser.template.nameserver_list_size
= nameserver_list_size (&parser.nameserver_list);
parser.template.search_list = search_list_begin (&parser.search_list);
parser.template.search_list_size
= search_list_size (&parser.search_list);
parser.template.sort_list = sort_list_begin (&parser.sort_list);
parser.template.sort_list_size = sort_list_size (&parser.sort_list);
struct resolv_conf *conf = __resolv_conf_allocate (&parser.template);
if (conf == NULL)
ok = false;
else
@ -547,18 +595,13 @@ __res_vinit (res_state statp, int preinit)
resolv_conf_parser_free (&parser);
if (!ok)
{
/* Deallocate the name server addresses which have been
allocated. */
for (int n = 0; n < MAXNS; n++)
free (statp->_u._ext.nsaddrs[n]);
return -1;
}
return 0;
return -1;
else
return 0;
}
static void
res_setoptions (res_state statp, const char *options)
res_setoptions (struct resolv_conf_parser *parser, const char *options)
{
const char *cp = options;
@ -572,25 +615,25 @@ res_setoptions (res_state statp, const char *options)
{
int i = atoi (cp + sizeof ("ndots:") - 1);
if (i <= RES_MAXNDOTS)
statp->ndots = i;
parser->template.ndots = i;
else
statp->ndots = RES_MAXNDOTS;
parser->template.ndots = RES_MAXNDOTS;
}
else if (!strncmp (cp, "timeout:", sizeof ("timeout:") - 1))
{
int i = atoi (cp + sizeof ("timeout:") - 1);
if (i <= RES_MAXRETRANS)
statp->retrans = i;
parser->template.retrans = i;
else
statp->retrans = RES_MAXRETRANS;
parser->template.retrans = RES_MAXRETRANS;
}
else if (!strncmp (cp, "attempts:", sizeof ("attempts:") - 1))
{
int i = atoi (cp + sizeof ("attempts:") - 1);
if (i <= RES_MAXRETRY)
statp->retry = i;
parser->template.retry = i;
else
statp->retry = RES_MAXRETRY;
parser->template.retry = RES_MAXRETRY;
}
else
{
@ -616,9 +659,9 @@ res_setoptions (res_state statp, const char *options)
if (strncmp (cp, options[i].str, options[i].len) == 0)
{
if (options[i].clear)
statp->options &= options[i].flag;
parser->template.options &= options[i].flag;
else
statp->options |= options[i].flag;
parser->template.options |= options[i].flag;
break;
}
}