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authorFlorian Weimer <fweimer@redhat.com>2017-07-01 00:53:05 +0200
committerFlorian Weimer <fweimer@redhat.com>2017-07-03 21:01:42 +0200
commit3f853f22c87f0b671c0366eb290919719fa56c0e (patch)
tree23f8835838728d4be3efca524754c1a2f5bb0396 /resolv/res_init.c
parentf30a54b21b83f254533c59ca72ad17af5249c6be (diff)
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resolv: Lift domain search list limits [BZ #19569] [BZ #21475]
This change uses the extended resolver state in struct resolv_conf to store the search list. If applications have not patched the _res object directly, this extended search list will be used by the stub resolver during name resolution.
Diffstat (limited to 'resolv/res_init.c')
-rw-r--r--resolv/res_init.c222
1 files changed, 149 insertions, 73 deletions
diff --git a/resolv/res_init.c b/resolv/res_init.c
index 659d3ea..5941d37 100644
--- a/resolv/res_init.c
+++ b/resolv/res_init.c
@@ -124,18 +124,75 @@ is_sort_mask (char ch)
return ch == '/' || ch == '&';
}
+/* 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_PREFIX search_list_
+#include <malloc/dynarray-skeleton.c>
+
+/* resolv.conf parser state and results. */
+struct resolv_conf_parser
+{
+ char *buffer; /* Temporary buffer for reading lines. */
+ char *search_list_store; /* Backing storage for search list entries. */
+ struct search_list search_list; /* Points into search_list_store. */
+};
+
+static void
+resolv_conf_parser_init (struct resolv_conf_parser *parser)
+{
+ parser->buffer = NULL;
+ parser->search_list_store = NULL;
+ search_list_init (&parser->search_list);
+}
+
+static void
+resolv_conf_parser_free (struct resolv_conf_parser *parser)
+{
+ free (parser->buffer);
+ free (parser->search_list_store);
+ search_list_free (&parser->search_list);
+}
+
+/* Try to obtain the domain name from the host name and store it in
+ *RESULT. Return false on memory allocation failure. If the domain
+ name cannot be determined for any other reason, write NULL to
+ *RESULT and return true. */
+static bool
+domain_from_hostname (char **result)
+{
+ char buf[256];
+ /* gethostbyname may not terminate the buffer. */
+ buf[sizeof (buf) - 1] = '\0';
+ if (__gethostname (buf, sizeof (buf) - 1) == 0)
+ {
+ char *dot = strchr (buf, '.');
+ if (dot != NULL)
+ {
+ *result = __strdup (dot + 1);
+ if (*result == NULL)
+ return false;
+ return true;
+ }
+ }
+ *result = NULL;
+ return true;
+}
+
/* 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, char **buffer)
+res_vinit_1 (res_state statp, bool preinit, FILE *fp,
+ struct resolv_conf_parser *parser)
{
- char *cp, **pp;
+ char *cp;
size_t buffer_size = 0;
int nserv = 0; /* Number of nameservers read from file. */
bool have_serv6 = false;
bool haveenv = false;
- bool havesearch = false;
int nsort = 0;
char *net;
@@ -162,39 +219,40 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
/* Allow user to override the local domain definition. */
if ((cp = getenv ("LOCALDOMAIN")) != NULL)
{
- strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
- statp->defdname[sizeof (statp->defdname) - 1] = '\0';
+ /* The code below splits the string in place. */
+ cp = __strdup (cp);
+ if (cp == NULL)
+ return false;
+ free (parser->search_list_store);
+ parser->search_list_store = cp;
haveenv = true;
+ /* The string will be truncated as needed below. */
+ search_list_add (&parser->search_list, cp);
+
/* Set search list to be blank-separated strings from rest of
env value. Permits users of LOCALDOMAIN to still have a
search list, and anyone to set the one that they want to use
as an individual (even more important now that the rfc1535
stuff restricts searches). */
- cp = statp->defdname;
- pp = statp->dnsrch;
- *pp++ = cp;
- for (int n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++)
+ for (bool in_name = true; *cp != '\0'; cp++)
{
if (*cp == '\n')
- break;
+ {
+ *cp = '\0';
+ break;
+ }
else if (*cp == ' ' || *cp == '\t')
{
- *cp = 0;
- n = 1;
+ *cp = '\0';
+ in_name = false;
}
- else if (n > 0)
+ else if (!in_name)
{
- *pp++ = cp;
- n = 0;
- havesearch = true;
+ search_list_add (&parser->search_list, cp);
+ in_name = true;
}
}
- /* Null terminate last domain if there are excess. */
- while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
- cp++;
- *cp = '\0';
- *pp++ = 0;
}
#define MATCH(line, name) \
@@ -210,7 +268,7 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
while (true)
{
{
- ssize_t ret = __getline (buffer, &buffer_size, fp);
+ ssize_t ret = __getline (&parser->buffer, &buffer_size, fp);
if (ret <= 0)
{
if (_IO_ferror_unlocked (fp))
@@ -221,73 +279,82 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
}
/* Skip comments. */
- if (**buffer == ';' || **buffer == '#')
+ if (*parser->buffer == ';' || *parser->buffer == '#')
continue;
/* Read default domain name. */
- if (MATCH (*buffer, "domain"))
+ if (MATCH (parser->buffer, "domain"))
{
if (haveenv)
/* LOCALDOMAIN overrides the configuration file. */
continue;
- cp = *buffer + sizeof ("domain") - 1;
+ cp = parser->buffer + sizeof ("domain") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp == '\0') || (*cp == '\n'))
continue;
- strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
- statp->defdname[sizeof (statp->defdname) - 1] = '\0';
- if ((cp = strpbrk (statp->defdname, " \t\n")) != NULL)
+
+ cp = __strdup (cp);
+ if (cp == NULL)
+ return false;
+ free (parser->search_list_store);
+ parser->search_list_store = cp;
+ search_list_clear (&parser->search_list);
+ search_list_add (&parser->search_list, cp);
+ /* Replace trailing whitespace. */
+ if ((cp = strpbrk (cp, " \t\n")) != NULL)
*cp = '\0';
- havesearch = false;
continue;
}
/* Set search list. */
- if (MATCH (*buffer, "search"))
+ if (MATCH (parser->buffer, "search"))
{
if (haveenv)
/* LOCALDOMAIN overrides the configuration file. */
continue;
- cp = *buffer + sizeof ("search") - 1;
+ cp = parser->buffer + sizeof ("search") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp == '\0') || (*cp == '\n'))
continue;
- strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
- statp->defdname[sizeof (statp->defdname) - 1] = '\0';
- if ((cp = strchr (statp->defdname, '\n')) != NULL)
- *cp = '\0';
+
+ {
+ char *p = strchr (cp, '\n');
+ if (p != NULL)
+ *p = '\0';
+ }
+ cp = __strdup (cp);
+ if (cp == NULL)
+ return false;
+ free (parser->search_list_store);
+ parser->search_list_store = cp;
+
+ /* The string is truncated below. */
+ search_list_clear (&parser->search_list);
+ search_list_add (&parser->search_list, cp);
+
/* Set search list to be blank-separated strings on rest
of line. */
- cp = statp->defdname;
- pp = statp->dnsrch;
- *pp++ = cp;
- for (int n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++)
+ for (bool in_name = true; *cp != '\0'; cp++)
{
if (*cp == ' ' || *cp == '\t')
{
- *cp = 0;
- n = 1;
+ *cp = '\0';
+ in_name = false;
}
- else if (n)
+ else if (!in_name)
{
- *pp++ = cp;
- n = 0;
+ search_list_add (&parser->search_list, cp);
+ in_name = true;
}
}
- /* Null terminate last domain if there are excess. */
- while (*cp != '\0' && *cp != ' ' && *cp != '\t')
- cp++;
- *cp = '\0';
- *pp++ = 0;
- havesearch = true;
continue;
}
/* Read nameservers to query. */
- if (MATCH (*buffer, "nameserver") && nserv < MAXNS)
+ if (MATCH (parser->buffer, "nameserver") && nserv < MAXNS)
{
struct in_addr a;
- cp = *buffer + sizeof ("nameserver") - 1;
+ cp = parser->buffer + sizeof ("nameserver") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
@@ -335,11 +402,11 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
}
continue;
}
- if (MATCH (*buffer, "sortlist"))
+ if (MATCH (parser->buffer, "sortlist"))
{
struct in_addr a;
- cp = *buffer + sizeof ("sortlist") - 1;
+ cp = parser->buffer + sizeof ("sortlist") - 1;
while (nsort < MAXRESOLVSORT)
{
while (*cp == ' ' || *cp == '\t')
@@ -379,9 +446,9 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
}
continue;
}
- if (MATCH (*buffer, "options"))
+ if (MATCH (parser->buffer, "options"))
{
- res_setoptions (statp, *buffer + sizeof ("options") - 1);
+ res_setoptions (statp, parser->buffer + sizeof ("options") - 1);
continue;
}
}
@@ -399,25 +466,29 @@ res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
statp->nsaddr.sin_port = htons (NAMESERVER_PORT);
statp->nscount = 1;
}
- if (statp->defdname[0] == 0)
- {
- char buf[sizeof (statp->defdname)];
- if (__gethostname (buf, sizeof (statp->defdname) - 1) == 0
- && (cp = strchr (buf, '.')) != NULL)
- strcpy (statp->defdname, cp + 1);
- }
- /* Find components of local domain that might be searched. */
- if (!havesearch)
+ if (search_list_size (&parser->search_list) == 0)
{
- pp = statp->dnsrch;
- *pp++ = statp->defdname;
- *pp = NULL;
-
+ char *domain;
+ if (!domain_from_hostname (&domain))
+ return false;
+ if (domain != NULL)
+ {
+ free (parser->search_list_store);
+ parser->search_list_store = domain;
+ search_list_add (&parser->search_list, domain);
+ }
}
if ((cp = getenv ("RES_OPTIONS")) != NULL)
res_setoptions (statp, cp);
+
+ if (search_list_has_failed (&parser->search_list))
+ {
+ __set_errno (ENOMEM);
+ return false;
+ }
+
statp->options |= RES_INIT;
return true;
}
@@ -453,13 +524,17 @@ __res_vinit (res_state statp, int preinit)
return -1;
}
- char *buffer = NULL;
- bool ok = res_vinit_1 (statp, preinit, fp, &buffer);
- free (buffer);
+ struct resolv_conf_parser parser;
+ resolv_conf_parser_init (&parser);
+ bool ok = res_vinit_1 (statp, preinit, fp, &parser);
if (ok)
{
- struct resolv_conf init = { 0 }; /* No data yet. */
+ 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);
if (conf == NULL)
ok = false;
@@ -469,6 +544,7 @@ __res_vinit (res_state statp, int preinit)
__resolv_conf_put (conf);
}
}
+ resolv_conf_parser_free (&parser);
if (!ok)
{