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[GNUnet-SVN] [gnunet] 02/02: fix CNAME handling, caching, out-of-bounds
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From: |
gnunet |
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Subject: |
[GNUnet-SVN] [gnunet] 02/02: fix CNAME handling, caching, out-of-bounds accesses, etc. in gnunet-service-resolver |
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Date: |
Tue, 14 Aug 2018 15:30:46 +0200 |
This is an automated email from the git hooks/post-receive script.
grothoff pushed a commit to branch master
in repository gnunet.
commit 1c757482ba7ca48fa108f1613cccc5c775bd957b
Author: Christian Grothoff <address@hidden>
AuthorDate: Tue Aug 14 15:30:42 2018 +0200
fix CNAME handling, caching, out-of-bounds accesses, etc. in
gnunet-service-resolver
---
src/util/gnunet-service-resolver.c | 869 ++++++++++++++++++++++++-------------
1 file changed, 562 insertions(+), 307 deletions(-)
diff --git a/src/util/gnunet-service-resolver.c
b/src/util/gnunet-service-resolver.c
index 5b890261b..06af57509 100644
--- a/src/util/gnunet-service-resolver.c
+++ b/src/util/gnunet-service-resolver.c
@@ -11,7 +11,7 @@
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
-
+
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
@@ -28,15 +28,38 @@
#include "resolver.h"
-struct Record
+/**
+ * How long do we wait for DNS answers?
+ */
+#define DNS_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
30)
+
+/**
+ * Maximum number of hostnames we cache results for.
+ */
+#define MAX_CACHE 1024
+
+/**
+ * Entry in list of cached DNS records for a hostname.
+ */
+struct RecordListEntry
{
- struct Record *next;
+ /**
+ * This is a doubly linked list.
+ */
+ struct RecordListEntry *next;
- struct Record *prev;
+ /**
+ * This is a doubly linked list.
+ */
+ struct RecordListEntry *prev;
+ /**
+ * Cached data.
+ */
struct GNUNET_DNSPARSER_Record *record;
};
+
/**
* A cached DNS lookup result.
*/
@@ -53,30 +76,42 @@ struct ResolveCache
struct ResolveCache *prev;
/**
- * type of queried DNS record
+ * Which hostname is this cache for?
*/
- uint16_t record_type;
+ char *hostname;
/**
- * a pointer to the request_id if a query for this hostname/record_type
- * is currently pending, NULL otherwise.
+ * head of a double linked list containing the lookup results
*/
- int16_t *request_id;
+ struct RecordListEntry *records_head;
/**
- * The client that queried the records contained in this cache entry.
+ * tail of a double linked list containing the lookup results
*/
- struct GNUNET_SERVICE_Client *client;
+ struct RecordListEntry *records_tail;
+};
+
+
+/**
+ * Information about pending lookups.
+ */
+struct ActiveLookup
+{
/**
- * head of a double linked list containing the lookup results
+ * Stored in a DLL.
*/
- struct Record *records_head;
+ struct ActiveLookup *next;
/**
- * tail of a double linked list containing the lookup results
+ * Stored in a DLL.
*/
- struct Record *records_tail;
+ struct ActiveLookup *prev;
+
+ /**
+ * The client that queried the records contained in this cache entry.
+ */
+ struct GNUNET_SERVICE_Client *client;
/**
* handle for cancelling a request
@@ -88,6 +123,28 @@ struct ResolveCache
*/
struct GNUNET_SCHEDULER_Task *timeout_task;
+ /**
+ * Which hostname are we resolving?
+ */
+ char *hostname;
+
+ /**
+ * type of queried DNS record
+ */
+ uint16_t record_type;
+
+ /**
+ * Unique request ID of a client if a query for this hostname/record_type
+ * is currently pending, undefined otherwise.
+ */
+ uint16_t request_id;
+
+ /**
+ * Unique DNS request ID of a client if a query for this hostname/record_type
+ * is currently pending, undefined otherwise.
+ */
+ uint16_t dns_id;
+
};
@@ -102,69 +159,117 @@ static struct ResolveCache *cache_head;
static struct ResolveCache *cache_tail;
/**
+ * Start of the linked list of active DNS lookups.
+ */
+static struct ActiveLookup *lookup_head;
+
+/**
+ * Tail of the linked list of active DNS lookups.
+ */
+static struct ActiveLookup *lookup_tail;
+
+/**
* context of dnsstub library
*/
static struct GNUNET_DNSSTUB_Context *dnsstub_ctx;
+/**
+ * How many entries do we have in #cache_head DLL?
+ */
+static unsigned int cache_size;
-void free_cache_entry (struct ResolveCache *entry)
+/**
+ * Remove @a entry from cache.
+ *
+ * @param rc entry to free
+ */
+static void
+free_cache_entry (struct ResolveCache *rc)
{
- struct Record *pos;
- struct Record *next;
-
- next = entry->records_head;
- while (NULL != (pos = next))
+ struct RecordListEntry *pos;
+
+ while (NULL != (pos = rc->records_head))
{
- next = pos->next;
- GNUNET_CONTAINER_DLL_remove (entry->records_head,
- entry->records_tail,
+ GNUNET_CONTAINER_DLL_remove (rc->records_head,
+ rc->records_tail,
pos);
- if (NULL != pos->record)
- {
- GNUNET_DNSPARSER_free_record (pos->record);
- GNUNET_free (pos->record);
- }
+ GNUNET_DNSPARSER_free_record (pos->record);
+ GNUNET_free (pos->record);
GNUNET_free (pos);
}
- if (NULL != entry->resolve_handle)
+ GNUNET_free_non_null (rc->hostname);
+ GNUNET_CONTAINER_DLL_remove (cache_head,
+ cache_tail,
+ rc);
+ cache_size--;
+ GNUNET_free (rc);
+}
+
+
+/**
+ * Release resources associated with @a al
+ *
+ * @param al an active lookup
+ */
+static void
+free_active_lookup (struct ActiveLookup *al)
+{
+ GNUNET_CONTAINER_DLL_remove (lookup_head,
+ lookup_tail,
+ al);
+ if (NULL != al->resolve_handle)
{
- GNUNET_DNSSTUB_resolve_cancel (entry->resolve_handle);
- entry->resolve_handle = NULL;
+ GNUNET_DNSSTUB_resolve_cancel (al->resolve_handle);
+ al->resolve_handle = NULL;
}
- if (NULL != entry->timeout_task)
+ if (NULL != al->timeout_task)
{
- GNUNET_SCHEDULER_cancel (entry->timeout_task);
- entry->timeout_task = NULL;
+ GNUNET_SCHEDULER_cancel (al->timeout_task);
+ al->timeout_task = NULL;
}
- GNUNET_free_non_null (entry->request_id);
- GNUNET_free (entry);
+ GNUNET_free_non_null (al->hostname);
+ GNUNET_free (al);
}
-static char*
-extract_dns_server (const char* line, size_t line_len)
+
+/**
+ * Find out if the configuration file line contains a string
+ * starting with "nameserver ", and if so, return a copy of
+ * the nameserver's IP.
+ *
+ * @param line line to parse
+ * @param line_len number of characters in @a line
+ * @return NULL if no nameserver is configured in this @a line
+ */
+static char *
+extract_dns_server (const char* line,
+ size_t line_len)
{
- if (0 == strncmp (line, "nameserver ", 11))
- return GNUNET_strndup (line + 11, line_len - 11);
+ if (0 == strncmp (line,
+ "nameserver ",
+ strlen ("nameserver ")))
+ return GNUNET_strndup (line + strlen ("nameserver "),
+ line_len - strlen ("nameserver "));
return NULL;
}
-
+
/**
- * reads the list of nameservers from /etc/resolve.conf
+ * Reads the list of nameservers from /etc/resolve.conf
*
* @param server_addrs[out] a list of null-terminated server address strings
* @return the number of server addresses in @server_addrs, -1 on error
*/
-static ssize_t
+static int
lookup_dns_servers (char ***server_addrs)
{
struct GNUNET_DISK_FileHandle *fh;
char buf[2048];
ssize_t bytes_read;
- size_t read_offset = 0;
- unsigned int num_dns_servers = 0;
-
+ size_t read_offset;
+ unsigned int num_dns_servers;
+
fh = GNUNET_DISK_file_open ("/etc/resolv.conf",
GNUNET_DISK_OPEN_READ,
GNUNET_DISK_PERM_NONE);
@@ -179,41 +284,51 @@ lookup_dns_servers (char ***server_addrs)
buf,
sizeof (buf));
*server_addrs = NULL;
+ read_offset = 0;
+ num_dns_servers = 0;
while (read_offset < bytes_read)
{
- char *newline;
+ const char *newline;
size_t line_len;
char *dns_server;
-
- newline = strchr (buf + read_offset, '\n');
+
+ newline = strchr (buf + read_offset,
+ '\n');
if (NULL == newline)
- {
break;
- }
line_len = newline - buf - read_offset;
- dns_server = extract_dns_server (buf + read_offset, line_len);
+ dns_server = extract_dns_server (buf + read_offset,
+ line_len);
if (NULL != dns_server)
- {
GNUNET_array_append (*server_addrs,
num_dns_servers,
dns_server);
- }
read_offset += line_len + 1;
}
GNUNET_DISK_file_close (fh);
- return num_dns_servers;
+ return (int) num_dns_servers;
}
+/**
+ * Compute name to use for DNS reverse lookups from @a ip.
+ *
+ * @param ip IP address to resolve, in binary format, network byte order
+ * @param af address family of @a ip, AF_INET or AF_INET6
+ */
static char *
-make_reverse_hostname (const void *ip, int af)
+make_reverse_hostname (const void *ip,
+ int af)
{
- char *buf = GNUNET_new_array (80, char);
+ char *buf = GNUNET_new_array (80,
+ char);
int pos = 0;
+
if (AF_INET == af)
{
struct in_addr *addr = (struct in_addr *)ip;
uint32_t ip_int = addr->s_addr;
+
for (int i = 3; i >= 0; i--)
{
int n = GNUNET_snprintf (buf + pos,
@@ -227,21 +342,29 @@ make_reverse_hostname (const void *ip, int af)
}
pos += n;
}
- pos += GNUNET_snprintf (buf + pos, 80 - pos, "in-addr.arpa");
+ pos += GNUNET_snprintf (buf + pos,
+ 80 - pos,
+ "in-addr.arpa");
}
else if (AF_INET6 == af)
{
struct in6_addr *addr = (struct in6_addr *)ip;
for (int i = 15; i >= 0; i--)
{
- int n = GNUNET_snprintf (buf + pos, 80 - pos, "%x.", addr->s6_addr[i] &
0xf);
+ int n = GNUNET_snprintf (buf + pos,
+ 80 - pos,
+ "%x.",
+ addr->s6_addr[i] & 0xf);
if (n < 0)
{
GNUNET_free (buf);
return NULL;
}
pos += n;
- n = GNUNET_snprintf (buf + pos, 80 - pos, "%x.", addr->s6_addr[i] >> 4);
+ n = GNUNET_snprintf (buf + pos,
+ 80 - pos,
+ "%x.",
+ addr->s6_addr[i] >> 4);
if (n < 0)
{
GNUNET_free (buf);
@@ -249,45 +372,70 @@ make_reverse_hostname (const void *ip, int af)
}
pos += n;
}
- pos += GNUNET_snprintf (buf + pos, 80 - pos, "ip6.arpa");
+ pos += GNUNET_snprintf (buf + pos,
+ 80 - pos,
+ "ip6.arpa");
}
buf[pos] = '\0';
return buf;
}
-static void
+/**
+ * Send DNS @a record back to our @a client.
+ *
+ * @param record information to transmit
+ * @param record_type requested record type from client
+ * @param request_id to which request are we responding
+ * @param client where to send @a record
+ * @return #GNUNET_YES if we sent a reply,
+ * #GNUNET_NO if the record type is not understood or
+ * does not match @a record_type
+ */
+static int
send_reply (struct GNUNET_DNSPARSER_Record *record,
+ uint16_t record_type,
uint16_t request_id,
struct GNUNET_SERVICE_Client *client)
{
struct GNUNET_RESOLVER_ResponseMessage *msg;
struct GNUNET_MQ_Envelope *env;
- void *payload;
+ const void *payload;
size_t payload_len;
switch (record->type)
{
- case GNUNET_DNSPARSER_TYPE_PTR:
- {
- char *hostname = record->data.hostname;
- payload = hostname;
- payload_len = strlen (hostname) + 1;
- break;
- }
- case GNUNET_DNSPARSER_TYPE_A:
- case GNUNET_DNSPARSER_TYPE_AAAA:
- {
- payload = record->data.raw.data;
- payload_len = record->data.raw.data_len;
- break;
- }
- default:
- {
- GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
- "Cannot handle DNS response type: unimplemented\n");
- return;
- }
+ case GNUNET_DNSPARSER_TYPE_CNAME:
+ if (GNUNET_DNSPARSER_TYPE_CNAME != record_type)
+ return GNUNET_NO;
+ payload = record->data.hostname;
+ payload_len = strlen (record->data.hostname) + 1;
+ break;
+ case GNUNET_DNSPARSER_TYPE_PTR:
+ if (GNUNET_DNSPARSER_TYPE_PTR != record_type)
+ return GNUNET_NO;
+ payload = record->data.hostname;
+ payload_len = strlen (record->data.hostname) + 1;
+ break;
+ case GNUNET_DNSPARSER_TYPE_A:
+ if ( (GNUNET_DNSPARSER_TYPE_A != record_type) &&
+ (GNUNET_DNSPARSER_TYPE_ALL != record_type) )
+ return GNUNET_NO;
+ payload = record->data.raw.data;
+ payload_len = record->data.raw.data_len;
+ break;
+ case GNUNET_DNSPARSER_TYPE_AAAA:
+ if ( (GNUNET_DNSPARSER_TYPE_AAAA != record_type) &&
+ (GNUNET_DNSPARSER_TYPE_ALL != record_type) )
+ return GNUNET_NO;
+ payload = record->data.raw.data;
+ payload_len = record->data.raw.data_len;
+ break;
+ default:
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+ "Cannot handle DNS response type %u: not supported here\n",
+ record->type);
+ return GNUNET_NO;
}
env = GNUNET_MQ_msg_extra (msg,
payload_len,
@@ -298,9 +446,17 @@ send_reply (struct GNUNET_DNSPARSER_Record *record,
payload_len);
GNUNET_MQ_send (GNUNET_SERVICE_client_get_mq (client),
env);
+ return GNUNET_YES;
}
+/**
+ * Send message to @a client that we transmitted all
+ * responses for @a request_id
+ *
+ * @param request_id to which request are we responding
+ * @param client where to send @a record
+ */
static void
send_end_msg (uint16_t request_id,
struct GNUNET_SERVICE_Client *client)
@@ -309,7 +465,7 @@ send_end_msg (uint16_t request_id,
struct GNUNET_MQ_Envelope *env;
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "Sending end message\n");
+ "Sending END message\n");
env = GNUNET_MQ_msg (msg,
GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
msg->id = request_id;
@@ -318,102 +474,263 @@ send_end_msg (uint16_t request_id,
}
+/**
+ * Remove expired entries from @a rc
+ *
+ * @param rc entry in resolver cache
+ * @return #GNUNET_YES if @a rc was completely expired
+ * #GNUNET_NO if some entries are left
+ */
+static int
+remove_expired (struct ResolveCache *rc)
+{
+ struct GNUNET_TIME_Absolute now = GNUNET_TIME_absolute_get ();
+ struct RecordListEntry *n;
+
+ for (struct RecordListEntry *pos = rc->records_head;
+ NULL != pos;
+ pos = n)
+ {
+ n = pos->next;
+ if (now.abs_value_us > pos->record->expiration_time.abs_value_us)
+ GNUNET_CONTAINER_DLL_remove (rc->records_head,
+ rc->records_tail,
+ pos);
+ }
+ if (NULL == rc->records_head)
+ {
+ free_cache_entry (rc);
+ return GNUNET_YES;
+ }
+ return GNUNET_NO;
+}
+
+
+/**
+ * Process DNS request for @a hostname with request ID @a request_id
+ * from @a client demanding records of type @a record_type.
+ *
+ * @param hostname DNS name to resolve
+ * @param record_type desired record type
+ * @param request_id client's request ID
+ * @param client who should get the result?
+ */
+static void
+process_get (const char *hostname,
+ uint16_t record_type,
+ uint16_t request_id,
+ struct GNUNET_SERVICE_Client *client);
+
+
+/**
+ * Get an IP address as a string (works for both IPv4 and IPv6). Note
+ * that the resolution happens asynchronously and that the first call
+ * may not immediately result in the FQN (but instead in a
+ * human-readable IP address).
+ *
+ * @param hostname what hostname was to be resolved
+ * @param record_type what type of record was requested
+ * @param request_id unique identification of the client's request
+ * @param client handle to the client making the request (for sending the
reply)
+ */
+static int
+try_cache (const char *hostname,
+ uint16_t record_type,
+ uint16_t request_id,
+ struct GNUNET_SERVICE_Client *client)
+{
+ struct ResolveCache *pos;
+ struct ResolveCache *next;
+ int found;
+
+ next = cache_head;
+ for (pos = next; NULL != pos; pos = next)
+ {
+ next = pos->next;
+ if (GNUNET_YES == remove_expired (pos))
+ continue;
+ if (0 == strcmp (pos->hostname,
+ hostname))
+ break;
+ }
+ if (NULL == pos)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+ "No cache entry for '%s'\n",
+ hostname);
+ return GNUNET_NO;
+ }
+ if (cache_head != pos)
+ {
+ /* move result to head to achieve LRU for cache eviction */
+ GNUNET_CONTAINER_DLL_remove (cache_head,
+ cache_tail,
+ pos);
+ GNUNET_CONTAINER_DLL_insert (cache_head,
+ cache_tail,
+ pos);
+ }
+ found = GNUNET_NO;
+ for (struct RecordListEntry *rle = pos->records_head;
+ NULL != rle;
+ rle = rle->next)
+ {
+ const struct GNUNET_DNSPARSER_Record *record = rle->record;
+
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+ "Found cache entry for '%s', record type '%u'\n",
+ hostname,
+ record_type);
+ if ( (GNUNET_DNSPARSER_TYPE_CNAME == record->type) &&
+ (GNUNET_DNSPARSER_TYPE_CNAME != record_type) &&
+ (GNUNET_NO == found) )
+ {
+ const char *hostname = record->data.hostname;
+
+ process_get (hostname,
+ record_type,
+ request_id,
+ client);
+ return GNUNET_YES; /* counts as a cache "hit" */
+ }
+ found |= send_reply (rle->record,
+ record_type,
+ request_id,
+ client);
+ }
+ if (GNUNET_NO == found)
+ return GNUNET_NO; /* had records, but none matched! */
+ send_end_msg (request_id,
+ client);
+ return GNUNET_YES;
+}
+
+
+/**
+ * We got a result from DNS. Add it to the cache and
+ * see if we can make our client happy...
+ *
+ * @param cls the `struct ActiveLookup`
+ * @param dns the DNS response
+ * @param dns_len number of bytes in @a dns
+ */
static void
handle_resolve_result (void *cls,
const struct GNUNET_TUN_DnsHeader *dns,
size_t dns_len)
{
- struct ResolveCache *cache = cls;
+ struct ActiveLookup *al = cls;
struct GNUNET_DNSPARSER_Packet *parsed;
- uint16_t request_id = *cache->request_id;
- struct GNUNET_SERVICE_Client *client = cache->client;
+ struct ResolveCache *rc;
parsed = GNUNET_DNSPARSER_parse ((const char *)dns,
dns_len);
if (NULL == parsed)
{
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
- "Failed to parse DNS reply (request ID %u\n",
- request_id);
+ "Failed to parse DNS reply (hostname %s, request ID %u)\n",
+ al->hostname,
+ al->dns_id);
return;
}
- if (request_id != ntohs (parsed->id))
+ if (al->dns_id != ntohs (parsed->id))
{
- GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Request ID in DNS reply does not match\n");
+ GNUNET_DNSPARSER_free_packet (parsed);
return;
}
- else if (0 == parsed->num_answers)
+ if (0 == parsed->num_answers)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "DNS reply (request ID %u) contains no answers\n",
- request_id);
- GNUNET_CONTAINER_DLL_remove (cache_head,
- cache_tail,
- cache);
- free_cache_entry (cache);
- cache = NULL;
- }
- else
- {
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "Got reply for request ID %u\n",
- request_id);
- for (unsigned int i = 0; i != parsed->num_answers; i++)
- {
- struct Record *cache_entry = GNUNET_new (struct Record);
- struct GNUNET_DNSPARSER_Record *record = &parsed->answers[i];
- cache_entry->record = GNUNET_DNSPARSER_duplicate_record (record);
- GNUNET_CONTAINER_DLL_insert (cache->records_head,
- cache->records_tail,
- cache_entry);
- send_reply (cache_entry->record,
- request_id,
- cache->client);
- }
- GNUNET_free_non_null (cache->request_id);
- cache->request_id = NULL;
+ "DNS reply (hostname %s, request ID %u) contains no answers\n",
+ al->hostname,
+ al->request_id);
+ GNUNET_DNSPARSER_free_packet (parsed);
+ send_end_msg (al->request_id,
+ al->client);
+ free_active_lookup (al);
+ return;
}
- send_end_msg (request_id,
- client);
- if (NULL != cache)
- cache->client = NULL;
- if (NULL != cache)
+ /* LRU-based cache eviction: we remove from tail */
+ while (cache_size > MAX_CACHE)
+ free_cache_entry (cache_tail);
+
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+ "Got reply for hostname %s and request ID %u\n",
+ al->hostname,
+ al->request_id);
+ /* add to cache */
+ for (unsigned int i = 0; i != parsed->num_answers; i++)
{
- if (NULL != cache->timeout_task)
- {
- GNUNET_SCHEDULER_cancel (cache->timeout_task);
- cache->timeout_task = NULL;
- }
- if (NULL != cache->resolve_handle)
+ struct GNUNET_DNSPARSER_Record *record = &parsed->answers[i];
+ struct RecordListEntry *rle;
+
+ for (rc = cache_head; NULL != rc; rc = rc->next)
+ if (0 == strcasecmp (rc->hostname,
+ record->name))
+ break;
+ if (NULL == rc)
{
- GNUNET_DNSSTUB_resolve_cancel (cache->resolve_handle);
- cache->resolve_handle = NULL;
+ rc = GNUNET_new (struct ResolveCache);
+ rc->hostname = GNUNET_strdup (record->name);
+ GNUNET_CONTAINER_DLL_insert (cache_head,
+ cache_tail,
+ rc);
+ cache_size++;
}
+ /* TODO: ought to check first if we have this exact record
+ already in the cache! */
+ rle = GNUNET_new (struct RecordListEntry);
+ rle->record = GNUNET_DNSPARSER_duplicate_record (record);
+ GNUNET_CONTAINER_DLL_insert (rc->records_head,
+ rc->records_tail,
+ rle);
}
+
+ /* resume by trying again from cache */
+ if (GNUNET_NO ==
+ try_cache (al->hostname,
+ al->record_type,
+ al->request_id,
+ al->client))
+ /* cache failed, tell client we could not get an answer */
+ send_end_msg (al->request_id,
+ al->client);
+ free_active_lookup (al);
GNUNET_DNSPARSER_free_packet (parsed);
}
+/**
+ * We encountered a timeout trying to perform a
+ * DNS lookup.
+ *
+ * @param cls a `struct ActiveLookup`
+ */
static void
handle_resolve_timeout (void *cls)
{
- struct ResolveCache *cache = cls;
+ struct ActiveLookup *al = cls;
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "timeout!\n");
- if (NULL != cache->resolve_handle)
- {
- GNUNET_DNSSTUB_resolve_cancel (cache->resolve_handle);
- cache->resolve_handle = NULL;
- }
- GNUNET_CONTAINER_DLL_remove (cache_head,
- cache_tail,
- cache);
- free_cache_entry (cache);
+ al->timeout_task = NULL;
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+ "DNS lookup timeout!\n");
+ send_end_msg (al->request_id,
+ al->client);
+ free_active_lookup (al);
}
+/**
+ * Initiate an active lookup, then cache the result and
+ * try to then complete the resolution.
+ *
+ * @param hostname DNS name to resolve
+ * @param record_type record type to locate
+ * @param request_id client request ID
+ * @param client handle to the client
+ */
static int
resolve_and_cache (const char* hostname,
uint16_t record_type,
@@ -424,10 +741,11 @@ resolve_and_cache (const char* hostname,
size_t packet_size;
struct GNUNET_DNSPARSER_Query query;
struct GNUNET_DNSPARSER_Packet packet;
- struct ResolveCache *cache;
- struct GNUNET_TIME_Relative timeout =
- GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5);
+ struct ActiveLookup *al;
+ uint16_t dns_id;
+ dns_id =(uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
+ UINT16_MAX);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"resolve_and_cache\n");
query.name = (char *)hostname;
@@ -438,9 +756,9 @@ resolve_and_cache (const char* hostname,
sizeof (packet));
packet.num_queries = 1;
packet.queries = &query;
- packet.id = htons (request_id);
+ packet.id = htons (dns_id);
packet.flags.recursion_desired = 1;
- if (GNUNET_OK !=
+ if (GNUNET_OK !=
GNUNET_DNSPARSER_pack (&packet,
UINT16_MAX,
&packet_buf,
@@ -450,136 +768,67 @@ resolve_and_cache (const char* hostname,
"Failed to pack query for hostname `%s'\n",
hostname);
return GNUNET_SYSERR;
-
+
}
- cache = GNUNET_malloc (sizeof (struct ResolveCache));
- cache->record_type = record_type;
- cache->request_id = GNUNET_memdup (&request_id, sizeof (request_id));
- cache->client = client;
- cache->timeout_task = GNUNET_SCHEDULER_add_delayed (timeout,
- &handle_resolve_timeout,
- cache);
- cache->resolve_handle =
+ al = GNUNET_new (struct ActiveLookup);
+ al->hostname = GNUNET_strdup (hostname);
+ al->record_type = record_type;
+ al->request_id = request_id;
+ al->dns_id = dns_id;
+ al->client = client;
+ al->timeout_task = GNUNET_SCHEDULER_add_delayed (DNS_TIMEOUT,
+ &handle_resolve_timeout,
+ al);
+ al->resolve_handle =
GNUNET_DNSSTUB_resolve (dnsstub_ctx,
packet_buf,
packet_size,
&handle_resolve_result,
- cache);
- GNUNET_CONTAINER_DLL_insert (cache_head,
- cache_tail,
- cache);
+ al);
+ GNUNET_free (packet_buf);
+ GNUNET_CONTAINER_DLL_insert (lookup_head,
+ lookup_tail,
+ al);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "resolve %s, request_id = %u\n",
+ "Resolving %s, request_id = %u, dns_id = %u\n",
hostname,
- request_id);
- GNUNET_free (packet_buf);
+ (unsigned int) request_id,
+ (unsigned int) dns_id);
return GNUNET_OK;
}
-static const char *
-get_hostname (struct ResolveCache *cache_entry)
-{
- if (NULL != cache_entry->records_head)
- {
- GNUNET_assert (NULL != cache_entry->records_head);
- GNUNET_assert (NULL != cache_entry->records_head->record);
- GNUNET_assert (NULL != cache_entry->records_head->record->name);
- return cache_entry->records_head->record->name;
- }
- return NULL;
-}
-
-
-static const uint16_t *
-get_record_type (struct ResolveCache *cache_entry)
-{
- if (NULL != cache_entry->records_head)
- return &cache_entry->record_type;
- return NULL;
-}
-
-
-static const struct GNUNET_TIME_Absolute *
-get_expiration_time (struct ResolveCache *cache_entry)
-{
- if (NULL != cache_entry->records_head)
- return &cache_entry->records_head->record->expiration_time;
- return NULL;
-}
-
-
-static int
-remove_if_expired (struct ResolveCache *cache_entry)
-{
- struct GNUNET_TIME_Absolute now = GNUNET_TIME_absolute_get ();
-
- if ( (NULL != cache_entry->records_head) &&
- (now.abs_value_us > get_expiration_time (cache_entry)->abs_value_us) )
- {
- GNUNET_CONTAINER_DLL_remove (cache_head,
- cache_tail,
- cache_entry);
- free_cache_entry (cache_entry);
- return GNUNET_YES;
- }
- return GNUNET_NO;
-}
-
-
/**
- * Get an IP address as a string (works for both IPv4 and IPv6). Note
- * that the resolution happens asynchronously and that the first call
- * may not immediately result in the FQN (but instead in a
- * human-readable IP address).
+ * Process DNS request for @a hostname with request ID @a request_id
+ * from @a client demanding records of type @a record_type.
*
- * @param client handle to the client making the request (for sending the
reply)
- * @param af AF_INET or AF_INET6
- * @param ip `struct in_addr` or `struct in6_addr`
+ * @param hostname DNS name to resolve
+ * @param record_type desired record type
+ * @param request_id client's request ID
+ * @param client who should get the result?
*/
-static int
-try_cache (const char *hostname,
- uint16_t record_type,
- uint16_t request_id,
- struct GNUNET_SERVICE_Client *client)
+static void
+process_get (const char *hostname,
+ uint16_t record_type,
+ uint16_t request_id,
+ struct GNUNET_SERVICE_Client *client)
{
- struct ResolveCache *pos;
- struct ResolveCache *next;
-
- next = cache_head;
- while ( (NULL != (pos = next)) &&
- ( (NULL == pos->records_head) ||
- (0 != strcmp (get_hostname (pos), hostname)) ||
- (*get_record_type (pos) != record_type) ) )
+ if (GNUNET_NO ==
+ try_cache (hostname,
+ record_type,
+ request_id,
+ client))
{
- next = pos->next;
- remove_if_expired (pos);
- }
- if (NULL != pos)
- {
- if (GNUNET_NO == remove_if_expired (pos))
+ if (GNUNET_OK !=
+ resolve_and_cache (hostname,
+ record_type,
+ request_id,
+ client))
{
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "found cache entry for '%s', record type '%u'\n",
- hostname,
- record_type);
- struct Record *cache_pos = pos->records_head;
- while (NULL != cache_pos)
- {
- send_reply (cache_pos->record,
- request_id,
- client);
- cache_pos = cache_pos->next;
- }
send_end_msg (request_id,
- client);
- return GNUNET_YES;
+ client);
}
}
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "no cache entry for '%s'\n",
- hostname);
- return GNUNET_NO;
}
@@ -639,23 +888,6 @@ check_get (void *cls,
}
-static void
-process_get (const char *hostname,
- uint16_t record_type,
- uint16_t request_id,
- struct GNUNET_SERVICE_Client *client)
-{
- if (GNUNET_NO == try_cache (hostname, record_type, request_id, client))
- {
- int result = resolve_and_cache (hostname,
- record_type,
- request_id,
- client);
- GNUNET_assert (GNUNET_OK == result);
- }
-}
-
-
/**
* Handle GET-message.
*
@@ -670,7 +902,7 @@ handle_get (void *cls,
int direction;
int af;
uint16_t request_id;
- const char *hostname;
+ char *hostname;
direction = ntohl (msg->direction);
af = ntohl (msg->af);
@@ -683,17 +915,26 @@ handle_get (void *cls,
{
case AF_UNSPEC:
{
- process_get (hostname, GNUNET_DNSPARSER_TYPE_ALL, request_id, client);
+ process_get (hostname,
+ GNUNET_DNSPARSER_TYPE_ALL,
+ request_id,
+ client);
break;
}
case AF_INET:
{
- process_get (hostname, GNUNET_DNSPARSER_TYPE_A, request_id, client);
+ process_get (hostname,
+ GNUNET_DNSPARSER_TYPE_A,
+ request_id,
+ client);
break;
}
case AF_INET6:
{
- process_get (hostname, GNUNET_DNSPARSER_TYPE_AAAA, request_id, client);
+ process_get (hostname,
+ GNUNET_DNSPARSER_TYPE_AAAA,
+ request_id,
+ client);
break;
}
default:
@@ -708,50 +949,63 @@ handle_get (void *cls,
else
{
/* hostname from IP */
- hostname = make_reverse_hostname (&msg[1], af);
- process_get (hostname, GNUNET_DNSPARSER_TYPE_PTR, request_id, client);
+ hostname = make_reverse_hostname (&msg[1],
+ af);
+ process_get (hostname,
+ GNUNET_DNSPARSER_TYPE_PTR,
+ request_id,
+ client);
}
- GNUNET_free_non_null ((char *)hostname);
+ GNUNET_free_non_null (hostname);
GNUNET_SERVICE_client_continue (client);
}
-static void
+/**
+ * Service is shutting down, clean up.
+ *
+ * @param cls NULL, unused
+ */
+static void
shutdown_task (void *cls)
{
(void) cls;
- struct ResolveCache *pos;
- while (NULL != (pos = cache_head))
- {
- GNUNET_CONTAINER_DLL_remove (cache_head,
- cache_tail,
- pos);
- free_cache_entry (pos);
- }
+ while (NULL != lookup_head)
+ free_active_lookup (lookup_head);
+ while (NULL != cache_head)
+ free_cache_entry (cache_head);
GNUNET_DNSSTUB_stop (dnsstub_ctx);
}
+/**
+ * Service is starting, initialize everything.
+ *
+ * @param cls NULL, unused
+ * @param cfg our configuration
+ * @param sh service handle
+ */
static void
init_cb (void *cls,
const struct GNUNET_CONFIGURATION_Handle *cfg,
struct GNUNET_SERVICE_Handle *sh)
{
+ char **dns_servers;
+ int num_dns_servers;
+
(void) cfg;
(void) sh;
-
GNUNET_SCHEDULER_add_shutdown (&shutdown_task,
cls);
dnsstub_ctx = GNUNET_DNSSTUB_start (128);
- char **dns_servers;
- ssize_t num_dns_servers = lookup_dns_servers (&dns_servers);
- if (0 == num_dns_servers)
+ num_dns_servers = lookup_dns_servers (&dns_servers);
+ if (0 >= num_dns_servers)
{
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
- "no DNS server available. DNS resolution will not be
possible.\n");
+ _("No DNS server available. DNS resolution will not be
possible.\n"));
}
- for (int i = 0; i != num_dns_servers; i++)
+ for (int i = 0; i < num_dns_servers; i++)
{
int result = GNUNET_DNSSTUB_add_dns_ip (dnsstub_ctx, dns_servers[i]);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
@@ -796,18 +1050,19 @@ disconnect_cb (void *cls,
struct GNUNET_SERVICE_Client *c,
void *internal_cls)
{
+ struct ActiveLookup *n;
(void) cls;
- struct ResolveCache *pos = cache_head;
- while (NULL != pos)
+ GNUNET_assert (c == internal_cls);
+ n = lookup_head;
+ for (struct ActiveLookup *al = n;
+ NULL != al;
+ al = n)
{
- if (pos->client == c)
- {
- pos->client = NULL;
- }
- pos = pos->next;
+ n = al->next;
+ if (al->client == c)
+ free_active_lookup (al);
}
- GNUNET_assert (c == internal_cls);
}
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