ea9bf67881
Replace iface cache key with netid. Replace _mark with netid. Mark sockets used to test IPv4/IPv6 support as well as sockets used to determine source address for rfc6724 sort. Remove pid/uid mappings (functionality moved to system/netd). Do not create resolv_cache when it does not exist, but rather only when DNS configuration is supplied. Clean up unused functions. Change-Id: I9ccfda2902cc0943e87c9bc346ad9a2578accdab
2051 lines
57 KiB
C
2051 lines
57 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "resolv_cache.h"
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#include <resolv.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include "pthread.h"
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#include <errno.h>
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#include <arpa/nameser.h>
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#include <sys/system_properties.h>
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#include <net/if.h>
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#include <netdb.h>
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#include <linux/if.h>
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#include <arpa/inet.h>
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#include "resolv_private.h"
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#include "resolv_netid.h"
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#include "res_private.h"
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/* This code implements a small and *simple* DNS resolver cache.
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*
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* It is only used to cache DNS answers for a time defined by the smallest TTL
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* among the answer records in order to reduce DNS traffic. It is not supposed
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* to be a full DNS cache, since we plan to implement that in the future in a
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* dedicated process running on the system.
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*
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* Note that its design is kept simple very intentionally, i.e.:
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*
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* - it takes raw DNS query packet data as input, and returns raw DNS
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* answer packet data as output
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*
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* (this means that two similar queries that encode the DNS name
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* differently will be treated distinctly).
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*
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* the smallest TTL value among the answer records are used as the time
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* to keep an answer in the cache.
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*
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* this is bad, but we absolutely want to avoid parsing the answer packets
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* (and should be solved by the later full DNS cache process).
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*
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* - the implementation is just a (query-data) => (answer-data) hash table
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* with a trivial least-recently-used expiration policy.
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*
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* Doing this keeps the code simple and avoids to deal with a lot of things
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* that a full DNS cache is expected to do.
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*
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* The API is also very simple:
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*
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* - the client calls _resolv_cache_get() to obtain a handle to the cache.
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* this will initialize the cache on first usage. the result can be NULL
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* if the cache is disabled.
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*
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* - the client calls _resolv_cache_lookup() before performing a query
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*
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* if the function returns RESOLV_CACHE_FOUND, a copy of the answer data
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* has been copied into the client-provided answer buffer.
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*
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* if the function returns RESOLV_CACHE_NOTFOUND, the client should perform
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* a request normally, *then* call _resolv_cache_add() to add the received
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* answer to the cache.
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*
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* if the function returns RESOLV_CACHE_UNSUPPORTED, the client should
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* perform a request normally, and *not* call _resolv_cache_add()
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*
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* note that RESOLV_CACHE_UNSUPPORTED is also returned if the answer buffer
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* is too short to accomodate the cached result.
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*/
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/* the name of an environment variable that will be checked the first time
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* this code is called if its value is "0", then the resolver cache is
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* disabled.
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*/
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#define CONFIG_ENV "BIONIC_DNSCACHE"
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/* entries older than CONFIG_SECONDS seconds are always discarded.
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*/
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#define CONFIG_SECONDS (60*10) /* 10 minutes */
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/* default number of entries kept in the cache. This value has been
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* determined by browsing through various sites and counting the number
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* of corresponding requests. Keep in mind that our framework is currently
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* performing two requests per name lookup (one for IPv4, the other for IPv6)
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*
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* www.google.com 4
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* www.ysearch.com 6
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* www.amazon.com 8
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* www.nytimes.com 22
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* www.espn.com 28
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* www.msn.com 28
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* www.lemonde.fr 35
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*
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* (determined in 2009-2-17 from Paris, France, results may vary depending
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* on location)
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*
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* most high-level websites use lots of media/ad servers with different names
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* but these are generally reused when browsing through the site.
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*
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* As such, a value of 64 should be relatively comfortable at the moment.
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*
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* ******************************************
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* * NOTE - this has changed.
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* * 1) we've added IPv6 support so each dns query results in 2 responses
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* * 2) we've made this a system-wide cache, so the cost is less (it's not
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* * duplicated in each process) and the need is greater (more processes
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* * making different requests).
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* * Upping by 2x for IPv6
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* * Upping by another 5x for the centralized nature
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* *****************************************
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*/
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#define CONFIG_MAX_ENTRIES 64 * 2 * 5
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/* name of the system property that can be used to set the cache size */
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/****************************************************************************/
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/****************************************************************************/
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/***** *****/
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/***** *****/
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/***** *****/
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/****************************************************************************/
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/****************************************************************************/
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/* set to 1 to debug cache operations */
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#define DEBUG 0
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/* set to 1 to debug query data */
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#define DEBUG_DATA 0
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#undef XLOG
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#if DEBUG
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# include "private/libc_logging.h"
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# define XLOG(...) __libc_format_log(ANDROID_LOG_DEBUG,"libc",__VA_ARGS__)
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#include <stdio.h>
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#include <stdarg.h>
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/** BOUNDED BUFFER FORMATTING
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**/
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/* technical note:
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*
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* the following debugging routines are used to append data to a bounded
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* buffer they take two parameters that are:
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*
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* - p : a pointer to the current cursor position in the buffer
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* this value is initially set to the buffer's address.
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*
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* - end : the address of the buffer's limit, i.e. of the first byte
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* after the buffer. this address should never be touched.
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*
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* IMPORTANT: it is assumed that end > buffer_address, i.e.
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* that the buffer is at least one byte.
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*
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* the _bprint_() functions return the new value of 'p' after the data
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* has been appended, and also ensure the following:
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*
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* - the returned value will never be strictly greater than 'end'
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*
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* - a return value equal to 'end' means that truncation occured
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* (in which case, end[-1] will be set to 0)
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*
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* - after returning from a _bprint_() function, the content of the buffer
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* is always 0-terminated, even in the event of truncation.
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*
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* these conventions allow you to call _bprint_ functions multiple times and
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* only check for truncation at the end of the sequence, as in:
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*
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* char buff[1000], *p = buff, *end = p + sizeof(buff);
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*
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* p = _bprint_c(p, end, '"');
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* p = _bprint_s(p, end, my_string);
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* p = _bprint_c(p, end, '"');
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*
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* if (p >= end) {
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* // buffer was too small
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* }
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*
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* printf( "%s", buff );
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*/
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/* add a char to a bounded buffer */
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static char*
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_bprint_c( char* p, char* end, int c )
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{
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if (p < end) {
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if (p+1 == end)
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*p++ = 0;
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else {
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*p++ = (char) c;
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*p = 0;
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}
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}
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return p;
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}
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/* add a sequence of bytes to a bounded buffer */
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static char*
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_bprint_b( char* p, char* end, const char* buf, int len )
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{
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int avail = end - p;
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if (avail <= 0 || len <= 0)
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return p;
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if (avail > len)
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avail = len;
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memcpy( p, buf, avail );
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p += avail;
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if (p < end)
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p[0] = 0;
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else
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end[-1] = 0;
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return p;
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}
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/* add a string to a bounded buffer */
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static char*
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_bprint_s( char* p, char* end, const char* str )
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{
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return _bprint_b(p, end, str, strlen(str));
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}
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/* add a formatted string to a bounded buffer */
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static char*
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_bprint( char* p, char* end, const char* format, ... )
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{
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int avail, n;
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va_list args;
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avail = end - p;
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if (avail <= 0)
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return p;
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va_start(args, format);
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n = vsnprintf( p, avail, format, args);
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va_end(args);
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/* certain C libraries return -1 in case of truncation */
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if (n < 0 || n > avail)
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n = avail;
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p += n;
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/* certain C libraries do not zero-terminate in case of truncation */
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if (p == end)
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p[-1] = 0;
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return p;
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}
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/* add a hex value to a bounded buffer, up to 8 digits */
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static char*
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_bprint_hex( char* p, char* end, unsigned value, int numDigits )
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{
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char text[sizeof(unsigned)*2];
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int nn = 0;
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while (numDigits-- > 0) {
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text[nn++] = "0123456789abcdef"[(value >> (numDigits*4)) & 15];
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}
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return _bprint_b(p, end, text, nn);
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}
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/* add the hexadecimal dump of some memory area to a bounded buffer */
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static char*
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_bprint_hexdump( char* p, char* end, const uint8_t* data, int datalen )
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{
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int lineSize = 16;
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while (datalen > 0) {
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int avail = datalen;
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int nn;
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if (avail > lineSize)
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avail = lineSize;
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for (nn = 0; nn < avail; nn++) {
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if (nn > 0)
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p = _bprint_c(p, end, ' ');
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p = _bprint_hex(p, end, data[nn], 2);
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}
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for ( ; nn < lineSize; nn++ ) {
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p = _bprint_s(p, end, " ");
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}
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p = _bprint_s(p, end, " ");
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for (nn = 0; nn < avail; nn++) {
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int c = data[nn];
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if (c < 32 || c > 127)
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c = '.';
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p = _bprint_c(p, end, c);
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}
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p = _bprint_c(p, end, '\n');
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data += avail;
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datalen -= avail;
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}
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return p;
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}
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/* dump the content of a query of packet to the log */
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static void
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XLOG_BYTES( const void* base, int len )
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{
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char buff[1024];
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char* p = buff, *end = p + sizeof(buff);
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p = _bprint_hexdump(p, end, base, len);
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XLOG("%s",buff);
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}
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#else /* !DEBUG */
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# define XLOG(...) ((void)0)
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# define XLOG_BYTES(a,b) ((void)0)
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#endif
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static time_t
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_time_now( void )
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{
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struct timeval tv;
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gettimeofday( &tv, NULL );
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return tv.tv_sec;
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}
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/* reminder: the general format of a DNS packet is the following:
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*
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* HEADER (12 bytes)
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* QUESTION (variable)
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* ANSWER (variable)
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* AUTHORITY (variable)
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* ADDITIONNAL (variable)
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*
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* the HEADER is made of:
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*
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* ID : 16 : 16-bit unique query identification field
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*
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* QR : 1 : set to 0 for queries, and 1 for responses
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* Opcode : 4 : set to 0 for queries
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* AA : 1 : set to 0 for queries
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* TC : 1 : truncation flag, will be set to 0 in queries
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* RD : 1 : recursion desired
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*
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* RA : 1 : recursion available (0 in queries)
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* Z : 3 : three reserved zero bits
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* RCODE : 4 : response code (always 0=NOERROR in queries)
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*
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* QDCount: 16 : question count
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* ANCount: 16 : Answer count (0 in queries)
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* NSCount: 16: Authority Record count (0 in queries)
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* ARCount: 16: Additionnal Record count (0 in queries)
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*
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* the QUESTION is made of QDCount Question Record (QRs)
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* the ANSWER is made of ANCount RRs
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* the AUTHORITY is made of NSCount RRs
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* the ADDITIONNAL is made of ARCount RRs
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*
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* Each Question Record (QR) is made of:
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*
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* QNAME : variable : Query DNS NAME
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* TYPE : 16 : type of query (A=1, PTR=12, MX=15, AAAA=28, ALL=255)
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* CLASS : 16 : class of query (IN=1)
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*
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* Each Resource Record (RR) is made of:
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*
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* NAME : variable : DNS NAME
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* TYPE : 16 : type of query (A=1, PTR=12, MX=15, AAAA=28, ALL=255)
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* CLASS : 16 : class of query (IN=1)
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* TTL : 32 : seconds to cache this RR (0=none)
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* RDLENGTH: 16 : size of RDDATA in bytes
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* RDDATA : variable : RR data (depends on TYPE)
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*
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* Each QNAME contains a domain name encoded as a sequence of 'labels'
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* terminated by a zero. Each label has the following format:
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*
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* LEN : 8 : lenght of label (MUST be < 64)
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* NAME : 8*LEN : label length (must exclude dots)
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*
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* A value of 0 in the encoding is interpreted as the 'root' domain and
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* terminates the encoding. So 'www.android.com' will be encoded as:
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*
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* <3>www<7>android<3>com<0>
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*
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* Where <n> represents the byte with value 'n'
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*
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* Each NAME reflects the QNAME of the question, but has a slightly more
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* complex encoding in order to provide message compression. This is achieved
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* by using a 2-byte pointer, with format:
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*
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* TYPE : 2 : 0b11 to indicate a pointer, 0b01 and 0b10 are reserved
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* OFFSET : 14 : offset to another part of the DNS packet
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*
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* The offset is relative to the start of the DNS packet and must point
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* A pointer terminates the encoding.
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*
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* The NAME can be encoded in one of the following formats:
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*
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* - a sequence of simple labels terminated by 0 (like QNAMEs)
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* - a single pointer
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* - a sequence of simple labels terminated by a pointer
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*
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* A pointer shall always point to either a pointer of a sequence of
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* labels (which can themselves be terminated by either a 0 or a pointer)
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*
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* The expanded length of a given domain name should not exceed 255 bytes.
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*
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* NOTE: we don't parse the answer packets, so don't need to deal with NAME
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* records, only QNAMEs.
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*/
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#define DNS_HEADER_SIZE 12
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#define DNS_TYPE_A "\00\01" /* big-endian decimal 1 */
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#define DNS_TYPE_PTR "\00\014" /* big-endian decimal 12 */
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#define DNS_TYPE_MX "\00\017" /* big-endian decimal 15 */
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#define DNS_TYPE_AAAA "\00\034" /* big-endian decimal 28 */
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#define DNS_TYPE_ALL "\00\0377" /* big-endian decimal 255 */
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#define DNS_CLASS_IN "\00\01" /* big-endian decimal 1 */
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typedef struct {
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const uint8_t* base;
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const uint8_t* end;
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const uint8_t* cursor;
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} DnsPacket;
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static void
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_dnsPacket_init( DnsPacket* packet, const uint8_t* buff, int bufflen )
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{
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packet->base = buff;
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packet->end = buff + bufflen;
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packet->cursor = buff;
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}
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static void
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_dnsPacket_rewind( DnsPacket* packet )
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{
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packet->cursor = packet->base;
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}
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static void
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_dnsPacket_skip( DnsPacket* packet, int count )
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{
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const uint8_t* p = packet->cursor + count;
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if (p > packet->end)
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p = packet->end;
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packet->cursor = p;
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}
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static int
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_dnsPacket_readInt16( DnsPacket* packet )
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{
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const uint8_t* p = packet->cursor;
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if (p+2 > packet->end)
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return -1;
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packet->cursor = p+2;
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return (p[0]<< 8) | p[1];
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}
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/** QUERY CHECKING
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**/
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/* check bytes in a dns packet. returns 1 on success, 0 on failure.
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* the cursor is only advanced in the case of success
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*/
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static int
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_dnsPacket_checkBytes( DnsPacket* packet, int numBytes, const void* bytes )
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{
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const uint8_t* p = packet->cursor;
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if (p + numBytes > packet->end)
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return 0;
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if (memcmp(p, bytes, numBytes) != 0)
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return 0;
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packet->cursor = p + numBytes;
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return 1;
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}
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/* parse and skip a given QNAME stored in a query packet,
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* from the current cursor position. returns 1 on success,
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* or 0 for malformed data.
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*/
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static int
|
|
_dnsPacket_checkQName( DnsPacket* packet )
|
|
{
|
|
const uint8_t* p = packet->cursor;
|
|
const uint8_t* end = packet->end;
|
|
|
|
for (;;) {
|
|
int c;
|
|
|
|
if (p >= end)
|
|
break;
|
|
|
|
c = *p++;
|
|
|
|
if (c == 0) {
|
|
packet->cursor = p;
|
|
return 1;
|
|
}
|
|
|
|
/* we don't expect label compression in QNAMEs */
|
|
if (c >= 64)
|
|
break;
|
|
|
|
p += c;
|
|
/* we rely on the bound check at the start
|
|
* of the loop here */
|
|
}
|
|
/* malformed data */
|
|
XLOG("malformed QNAME");
|
|
return 0;
|
|
}
|
|
|
|
/* parse and skip a given QR stored in a packet.
|
|
* returns 1 on success, and 0 on failure
|
|
*/
|
|
static int
|
|
_dnsPacket_checkQR( DnsPacket* packet )
|
|
{
|
|
if (!_dnsPacket_checkQName(packet))
|
|
return 0;
|
|
|
|
/* TYPE must be one of the things we support */
|
|
if (!_dnsPacket_checkBytes(packet, 2, DNS_TYPE_A) &&
|
|
!_dnsPacket_checkBytes(packet, 2, DNS_TYPE_PTR) &&
|
|
!_dnsPacket_checkBytes(packet, 2, DNS_TYPE_MX) &&
|
|
!_dnsPacket_checkBytes(packet, 2, DNS_TYPE_AAAA) &&
|
|
!_dnsPacket_checkBytes(packet, 2, DNS_TYPE_ALL))
|
|
{
|
|
XLOG("unsupported TYPE");
|
|
return 0;
|
|
}
|
|
/* CLASS must be IN */
|
|
if (!_dnsPacket_checkBytes(packet, 2, DNS_CLASS_IN)) {
|
|
XLOG("unsupported CLASS");
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* check the header of a DNS Query packet, return 1 if it is one
|
|
* type of query we can cache, or 0 otherwise
|
|
*/
|
|
static int
|
|
_dnsPacket_checkQuery( DnsPacket* packet )
|
|
{
|
|
const uint8_t* p = packet->base;
|
|
int qdCount, anCount, dnCount, arCount;
|
|
|
|
if (p + DNS_HEADER_SIZE > packet->end) {
|
|
XLOG("query packet too small");
|
|
return 0;
|
|
}
|
|
|
|
/* QR must be set to 0, opcode must be 0 and AA must be 0 */
|
|
/* RA, Z, and RCODE must be 0 */
|
|
if ((p[2] & 0xFC) != 0 || p[3] != 0) {
|
|
XLOG("query packet flags unsupported");
|
|
return 0;
|
|
}
|
|
|
|
/* Note that we ignore the TC and RD bits here for the
|
|
* following reasons:
|
|
*
|
|
* - there is no point for a query packet sent to a server
|
|
* to have the TC bit set, but the implementation might
|
|
* set the bit in the query buffer for its own needs
|
|
* between a _resolv_cache_lookup and a
|
|
* _resolv_cache_add. We should not freak out if this
|
|
* is the case.
|
|
*
|
|
* - we consider that the result from a RD=0 or a RD=1
|
|
* query might be different, hence that the RD bit
|
|
* should be used to differentiate cached result.
|
|
*
|
|
* this implies that RD is checked when hashing or
|
|
* comparing query packets, but not TC
|
|
*/
|
|
|
|
/* ANCOUNT, DNCOUNT and ARCOUNT must be 0 */
|
|
qdCount = (p[4] << 8) | p[5];
|
|
anCount = (p[6] << 8) | p[7];
|
|
dnCount = (p[8] << 8) | p[9];
|
|
arCount = (p[10]<< 8) | p[11];
|
|
|
|
if (anCount != 0 || dnCount != 0 || arCount != 0) {
|
|
XLOG("query packet contains non-query records");
|
|
return 0;
|
|
}
|
|
|
|
if (qdCount == 0) {
|
|
XLOG("query packet doesn't contain query record");
|
|
return 0;
|
|
}
|
|
|
|
/* Check QDCOUNT QRs */
|
|
packet->cursor = p + DNS_HEADER_SIZE;
|
|
|
|
for (;qdCount > 0; qdCount--)
|
|
if (!_dnsPacket_checkQR(packet))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/** QUERY DEBUGGING
|
|
**/
|
|
#if DEBUG
|
|
static char*
|
|
_dnsPacket_bprintQName(DnsPacket* packet, char* bp, char* bend)
|
|
{
|
|
const uint8_t* p = packet->cursor;
|
|
const uint8_t* end = packet->end;
|
|
int first = 1;
|
|
|
|
for (;;) {
|
|
int c;
|
|
|
|
if (p >= end)
|
|
break;
|
|
|
|
c = *p++;
|
|
|
|
if (c == 0) {
|
|
packet->cursor = p;
|
|
return bp;
|
|
}
|
|
|
|
/* we don't expect label compression in QNAMEs */
|
|
if (c >= 64)
|
|
break;
|
|
|
|
if (first)
|
|
first = 0;
|
|
else
|
|
bp = _bprint_c(bp, bend, '.');
|
|
|
|
bp = _bprint_b(bp, bend, (const char*)p, c);
|
|
|
|
p += c;
|
|
/* we rely on the bound check at the start
|
|
* of the loop here */
|
|
}
|
|
/* malformed data */
|
|
bp = _bprint_s(bp, bend, "<MALFORMED>");
|
|
return bp;
|
|
}
|
|
|
|
static char*
|
|
_dnsPacket_bprintQR(DnsPacket* packet, char* p, char* end)
|
|
{
|
|
#define QQ(x) { DNS_TYPE_##x, #x }
|
|
static const struct {
|
|
const char* typeBytes;
|
|
const char* typeString;
|
|
} qTypes[] =
|
|
{
|
|
QQ(A), QQ(PTR), QQ(MX), QQ(AAAA), QQ(ALL),
|
|
{ NULL, NULL }
|
|
};
|
|
int nn;
|
|
const char* typeString = NULL;
|
|
|
|
/* dump QNAME */
|
|
p = _dnsPacket_bprintQName(packet, p, end);
|
|
|
|
/* dump TYPE */
|
|
p = _bprint_s(p, end, " (");
|
|
|
|
for (nn = 0; qTypes[nn].typeBytes != NULL; nn++) {
|
|
if (_dnsPacket_checkBytes(packet, 2, qTypes[nn].typeBytes)) {
|
|
typeString = qTypes[nn].typeString;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (typeString != NULL)
|
|
p = _bprint_s(p, end, typeString);
|
|
else {
|
|
int typeCode = _dnsPacket_readInt16(packet);
|
|
p = _bprint(p, end, "UNKNOWN-%d", typeCode);
|
|
}
|
|
|
|
p = _bprint_c(p, end, ')');
|
|
|
|
/* skip CLASS */
|
|
_dnsPacket_skip(packet, 2);
|
|
return p;
|
|
}
|
|
|
|
/* this function assumes the packet has already been checked */
|
|
static char*
|
|
_dnsPacket_bprintQuery( DnsPacket* packet, char* p, char* end )
|
|
{
|
|
int qdCount;
|
|
|
|
if (packet->base[2] & 0x1) {
|
|
p = _bprint_s(p, end, "RECURSIVE ");
|
|
}
|
|
|
|
_dnsPacket_skip(packet, 4);
|
|
qdCount = _dnsPacket_readInt16(packet);
|
|
_dnsPacket_skip(packet, 6);
|
|
|
|
for ( ; qdCount > 0; qdCount-- ) {
|
|
p = _dnsPacket_bprintQR(packet, p, end);
|
|
}
|
|
return p;
|
|
}
|
|
#endif
|
|
|
|
|
|
/** QUERY HASHING SUPPORT
|
|
**
|
|
** THE FOLLOWING CODE ASSUMES THAT THE INPUT PACKET HAS ALREADY
|
|
** BEEN SUCCESFULLY CHECKED.
|
|
**/
|
|
|
|
/* use 32-bit FNV hash function */
|
|
#define FNV_MULT 16777619U
|
|
#define FNV_BASIS 2166136261U
|
|
|
|
static unsigned
|
|
_dnsPacket_hashBytes( DnsPacket* packet, int numBytes, unsigned hash )
|
|
{
|
|
const uint8_t* p = packet->cursor;
|
|
const uint8_t* end = packet->end;
|
|
|
|
while (numBytes > 0 && p < end) {
|
|
hash = hash*FNV_MULT ^ *p++;
|
|
}
|
|
packet->cursor = p;
|
|
return hash;
|
|
}
|
|
|
|
|
|
static unsigned
|
|
_dnsPacket_hashQName( DnsPacket* packet, unsigned hash )
|
|
{
|
|
const uint8_t* p = packet->cursor;
|
|
const uint8_t* end = packet->end;
|
|
|
|
for (;;) {
|
|
int c;
|
|
|
|
if (p >= end) { /* should not happen */
|
|
XLOG("%s: INTERNAL_ERROR: read-overflow !!\n", __FUNCTION__);
|
|
break;
|
|
}
|
|
|
|
c = *p++;
|
|
|
|
if (c == 0)
|
|
break;
|
|
|
|
if (c >= 64) {
|
|
XLOG("%s: INTERNAL_ERROR: malformed domain !!\n", __FUNCTION__);
|
|
break;
|
|
}
|
|
if (p + c >= end) {
|
|
XLOG("%s: INTERNAL_ERROR: simple label read-overflow !!\n",
|
|
__FUNCTION__);
|
|
break;
|
|
}
|
|
while (c > 0) {
|
|
hash = hash*FNV_MULT ^ *p++;
|
|
c -= 1;
|
|
}
|
|
}
|
|
packet->cursor = p;
|
|
return hash;
|
|
}
|
|
|
|
static unsigned
|
|
_dnsPacket_hashQR( DnsPacket* packet, unsigned hash )
|
|
{
|
|
hash = _dnsPacket_hashQName(packet, hash);
|
|
hash = _dnsPacket_hashBytes(packet, 4, hash); /* TYPE and CLASS */
|
|
return hash;
|
|
}
|
|
|
|
static unsigned
|
|
_dnsPacket_hashQuery( DnsPacket* packet )
|
|
{
|
|
unsigned hash = FNV_BASIS;
|
|
int count;
|
|
_dnsPacket_rewind(packet);
|
|
|
|
/* we ignore the TC bit for reasons explained in
|
|
* _dnsPacket_checkQuery().
|
|
*
|
|
* however we hash the RD bit to differentiate
|
|
* between answers for recursive and non-recursive
|
|
* queries.
|
|
*/
|
|
hash = hash*FNV_MULT ^ (packet->base[2] & 1);
|
|
|
|
/* assume: other flags are 0 */
|
|
_dnsPacket_skip(packet, 4);
|
|
|
|
/* read QDCOUNT */
|
|
count = _dnsPacket_readInt16(packet);
|
|
|
|
/* assume: ANcount, NScount, ARcount are 0 */
|
|
_dnsPacket_skip(packet, 6);
|
|
|
|
/* hash QDCOUNT QRs */
|
|
for ( ; count > 0; count-- )
|
|
hash = _dnsPacket_hashQR(packet, hash);
|
|
|
|
return hash;
|
|
}
|
|
|
|
|
|
/** QUERY COMPARISON
|
|
**
|
|
** THE FOLLOWING CODE ASSUMES THAT THE INPUT PACKETS HAVE ALREADY
|
|
** BEEN SUCCESFULLY CHECKED.
|
|
**/
|
|
|
|
static int
|
|
_dnsPacket_isEqualDomainName( DnsPacket* pack1, DnsPacket* pack2 )
|
|
{
|
|
const uint8_t* p1 = pack1->cursor;
|
|
const uint8_t* end1 = pack1->end;
|
|
const uint8_t* p2 = pack2->cursor;
|
|
const uint8_t* end2 = pack2->end;
|
|
|
|
for (;;) {
|
|
int c1, c2;
|
|
|
|
if (p1 >= end1 || p2 >= end2) {
|
|
XLOG("%s: INTERNAL_ERROR: read-overflow !!\n", __FUNCTION__);
|
|
break;
|
|
}
|
|
c1 = *p1++;
|
|
c2 = *p2++;
|
|
if (c1 != c2)
|
|
break;
|
|
|
|
if (c1 == 0) {
|
|
pack1->cursor = p1;
|
|
pack2->cursor = p2;
|
|
return 1;
|
|
}
|
|
if (c1 >= 64) {
|
|
XLOG("%s: INTERNAL_ERROR: malformed domain !!\n", __FUNCTION__);
|
|
break;
|
|
}
|
|
if ((p1+c1 > end1) || (p2+c1 > end2)) {
|
|
XLOG("%s: INTERNAL_ERROR: simple label read-overflow !!\n",
|
|
__FUNCTION__);
|
|
break;
|
|
}
|
|
if (memcmp(p1, p2, c1) != 0)
|
|
break;
|
|
p1 += c1;
|
|
p2 += c1;
|
|
/* we rely on the bound checks at the start of the loop */
|
|
}
|
|
/* not the same, or one is malformed */
|
|
XLOG("different DN");
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
_dnsPacket_isEqualBytes( DnsPacket* pack1, DnsPacket* pack2, int numBytes )
|
|
{
|
|
const uint8_t* p1 = pack1->cursor;
|
|
const uint8_t* p2 = pack2->cursor;
|
|
|
|
if ( p1 + numBytes > pack1->end || p2 + numBytes > pack2->end )
|
|
return 0;
|
|
|
|
if ( memcmp(p1, p2, numBytes) != 0 )
|
|
return 0;
|
|
|
|
pack1->cursor += numBytes;
|
|
pack2->cursor += numBytes;
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
_dnsPacket_isEqualQR( DnsPacket* pack1, DnsPacket* pack2 )
|
|
{
|
|
/* compare domain name encoding + TYPE + CLASS */
|
|
if ( !_dnsPacket_isEqualDomainName(pack1, pack2) ||
|
|
!_dnsPacket_isEqualBytes(pack1, pack2, 2+2) )
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
_dnsPacket_isEqualQuery( DnsPacket* pack1, DnsPacket* pack2 )
|
|
{
|
|
int count1, count2;
|
|
|
|
/* compare the headers, ignore most fields */
|
|
_dnsPacket_rewind(pack1);
|
|
_dnsPacket_rewind(pack2);
|
|
|
|
/* compare RD, ignore TC, see comment in _dnsPacket_checkQuery */
|
|
if ((pack1->base[2] & 1) != (pack2->base[2] & 1)) {
|
|
XLOG("different RD");
|
|
return 0;
|
|
}
|
|
|
|
/* assume: other flags are all 0 */
|
|
_dnsPacket_skip(pack1, 4);
|
|
_dnsPacket_skip(pack2, 4);
|
|
|
|
/* compare QDCOUNT */
|
|
count1 = _dnsPacket_readInt16(pack1);
|
|
count2 = _dnsPacket_readInt16(pack2);
|
|
if (count1 != count2 || count1 < 0) {
|
|
XLOG("different QDCOUNT");
|
|
return 0;
|
|
}
|
|
|
|
/* assume: ANcount, NScount and ARcount are all 0 */
|
|
_dnsPacket_skip(pack1, 6);
|
|
_dnsPacket_skip(pack2, 6);
|
|
|
|
/* compare the QDCOUNT QRs */
|
|
for ( ; count1 > 0; count1-- ) {
|
|
if (!_dnsPacket_isEqualQR(pack1, pack2)) {
|
|
XLOG("different QR");
|
|
return 0;
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/****************************************************************************/
|
|
/****************************************************************************/
|
|
/***** *****/
|
|
/***** *****/
|
|
/***** *****/
|
|
/****************************************************************************/
|
|
/****************************************************************************/
|
|
|
|
/* cache entry. for simplicity, 'hash' and 'hlink' are inlined in this
|
|
* structure though they are conceptually part of the hash table.
|
|
*
|
|
* similarly, mru_next and mru_prev are part of the global MRU list
|
|
*/
|
|
typedef struct Entry {
|
|
unsigned int hash; /* hash value */
|
|
struct Entry* hlink; /* next in collision chain */
|
|
struct Entry* mru_prev;
|
|
struct Entry* mru_next;
|
|
|
|
const uint8_t* query;
|
|
int querylen;
|
|
const uint8_t* answer;
|
|
int answerlen;
|
|
time_t expires; /* time_t when the entry isn't valid any more */
|
|
int id; /* for debugging purpose */
|
|
} Entry;
|
|
|
|
/**
|
|
* Find the TTL for a negative DNS result. This is defined as the minimum
|
|
* of the SOA records TTL and the MINIMUM-TTL field (RFC-2308).
|
|
*
|
|
* Return 0 if not found.
|
|
*/
|
|
static u_long
|
|
answer_getNegativeTTL(ns_msg handle) {
|
|
int n, nscount;
|
|
u_long result = 0;
|
|
ns_rr rr;
|
|
|
|
nscount = ns_msg_count(handle, ns_s_ns);
|
|
for (n = 0; n < nscount; n++) {
|
|
if ((ns_parserr(&handle, ns_s_ns, n, &rr) == 0) && (ns_rr_type(rr) == ns_t_soa)) {
|
|
const u_char *rdata = ns_rr_rdata(rr); // find the data
|
|
const u_char *edata = rdata + ns_rr_rdlen(rr); // add the len to find the end
|
|
int len;
|
|
u_long ttl, rec_result = ns_rr_ttl(rr);
|
|
|
|
// find the MINIMUM-TTL field from the blob of binary data for this record
|
|
// skip the server name
|
|
len = dn_skipname(rdata, edata);
|
|
if (len == -1) continue; // error skipping
|
|
rdata += len;
|
|
|
|
// skip the admin name
|
|
len = dn_skipname(rdata, edata);
|
|
if (len == -1) continue; // error skipping
|
|
rdata += len;
|
|
|
|
if (edata - rdata != 5*NS_INT32SZ) continue;
|
|
// skip: serial number + refresh interval + retry interval + expiry
|
|
rdata += NS_INT32SZ * 4;
|
|
// finally read the MINIMUM TTL
|
|
ttl = ns_get32(rdata);
|
|
if (ttl < rec_result) {
|
|
rec_result = ttl;
|
|
}
|
|
// Now that the record is read successfully, apply the new min TTL
|
|
if (n == 0 || rec_result < result) {
|
|
result = rec_result;
|
|
}
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Parse the answer records and find the appropriate
|
|
* smallest TTL among the records. This might be from
|
|
* the answer records if found or from the SOA record
|
|
* if it's a negative result.
|
|
*
|
|
* The returned TTL is the number of seconds to
|
|
* keep the answer in the cache.
|
|
*
|
|
* In case of parse error zero (0) is returned which
|
|
* indicates that the answer shall not be cached.
|
|
*/
|
|
static u_long
|
|
answer_getTTL(const void* answer, int answerlen)
|
|
{
|
|
ns_msg handle;
|
|
int ancount, n;
|
|
u_long result, ttl;
|
|
ns_rr rr;
|
|
|
|
result = 0;
|
|
if (ns_initparse(answer, answerlen, &handle) >= 0) {
|
|
// get number of answer records
|
|
ancount = ns_msg_count(handle, ns_s_an);
|
|
|
|
if (ancount == 0) {
|
|
// a response with no answers? Cache this negative result.
|
|
result = answer_getNegativeTTL(handle);
|
|
} else {
|
|
for (n = 0; n < ancount; n++) {
|
|
if (ns_parserr(&handle, ns_s_an, n, &rr) == 0) {
|
|
ttl = ns_rr_ttl(rr);
|
|
if (n == 0 || ttl < result) {
|
|
result = ttl;
|
|
}
|
|
} else {
|
|
XLOG("ns_parserr failed ancount no = %d. errno = %s\n", n, strerror(errno));
|
|
}
|
|
}
|
|
}
|
|
} else {
|
|
XLOG("ns_parserr failed. %s\n", strerror(errno));
|
|
}
|
|
|
|
XLOG("TTL = %d\n", result);
|
|
|
|
return result;
|
|
}
|
|
|
|
static void
|
|
entry_free( Entry* e )
|
|
{
|
|
/* everything is allocated in a single memory block */
|
|
if (e) {
|
|
free(e);
|
|
}
|
|
}
|
|
|
|
static __inline__ void
|
|
entry_mru_remove( Entry* e )
|
|
{
|
|
e->mru_prev->mru_next = e->mru_next;
|
|
e->mru_next->mru_prev = e->mru_prev;
|
|
}
|
|
|
|
static __inline__ void
|
|
entry_mru_add( Entry* e, Entry* list )
|
|
{
|
|
Entry* first = list->mru_next;
|
|
|
|
e->mru_next = first;
|
|
e->mru_prev = list;
|
|
|
|
list->mru_next = e;
|
|
first->mru_prev = e;
|
|
}
|
|
|
|
/* compute the hash of a given entry, this is a hash of most
|
|
* data in the query (key) */
|
|
static unsigned
|
|
entry_hash( const Entry* e )
|
|
{
|
|
DnsPacket pack[1];
|
|
|
|
_dnsPacket_init(pack, e->query, e->querylen);
|
|
return _dnsPacket_hashQuery(pack);
|
|
}
|
|
|
|
/* initialize an Entry as a search key, this also checks the input query packet
|
|
* returns 1 on success, or 0 in case of unsupported/malformed data */
|
|
static int
|
|
entry_init_key( Entry* e, const void* query, int querylen )
|
|
{
|
|
DnsPacket pack[1];
|
|
|
|
memset(e, 0, sizeof(*e));
|
|
|
|
e->query = query;
|
|
e->querylen = querylen;
|
|
e->hash = entry_hash(e);
|
|
|
|
_dnsPacket_init(pack, query, querylen);
|
|
|
|
return _dnsPacket_checkQuery(pack);
|
|
}
|
|
|
|
/* allocate a new entry as a cache node */
|
|
static Entry*
|
|
entry_alloc( const Entry* init, const void* answer, int answerlen )
|
|
{
|
|
Entry* e;
|
|
int size;
|
|
|
|
size = sizeof(*e) + init->querylen + answerlen;
|
|
e = calloc(size, 1);
|
|
if (e == NULL)
|
|
return e;
|
|
|
|
e->hash = init->hash;
|
|
e->query = (const uint8_t*)(e+1);
|
|
e->querylen = init->querylen;
|
|
|
|
memcpy( (char*)e->query, init->query, e->querylen );
|
|
|
|
e->answer = e->query + e->querylen;
|
|
e->answerlen = answerlen;
|
|
|
|
memcpy( (char*)e->answer, answer, e->answerlen );
|
|
|
|
return e;
|
|
}
|
|
|
|
static int
|
|
entry_equals( const Entry* e1, const Entry* e2 )
|
|
{
|
|
DnsPacket pack1[1], pack2[1];
|
|
|
|
if (e1->querylen != e2->querylen) {
|
|
return 0;
|
|
}
|
|
_dnsPacket_init(pack1, e1->query, e1->querylen);
|
|
_dnsPacket_init(pack2, e2->query, e2->querylen);
|
|
|
|
return _dnsPacket_isEqualQuery(pack1, pack2);
|
|
}
|
|
|
|
/****************************************************************************/
|
|
/****************************************************************************/
|
|
/***** *****/
|
|
/***** *****/
|
|
/***** *****/
|
|
/****************************************************************************/
|
|
/****************************************************************************/
|
|
|
|
/* We use a simple hash table with external collision lists
|
|
* for simplicity, the hash-table fields 'hash' and 'hlink' are
|
|
* inlined in the Entry structure.
|
|
*/
|
|
|
|
/* Maximum time for a thread to wait for an pending request */
|
|
#define PENDING_REQUEST_TIMEOUT 20;
|
|
|
|
typedef struct pending_req_info {
|
|
unsigned int hash;
|
|
pthread_cond_t cond;
|
|
struct pending_req_info* next;
|
|
} PendingReqInfo;
|
|
|
|
typedef struct resolv_cache {
|
|
int max_entries;
|
|
int num_entries;
|
|
Entry mru_list;
|
|
pthread_mutex_t lock;
|
|
int last_id;
|
|
Entry* entries;
|
|
PendingReqInfo pending_requests;
|
|
} Cache;
|
|
|
|
struct resolv_cache_info {
|
|
unsigned netid;
|
|
Cache* cache;
|
|
struct resolv_cache_info* next;
|
|
char* nameservers[MAXNS +1];
|
|
struct addrinfo* nsaddrinfo[MAXNS + 1];
|
|
char defdname[256];
|
|
int dnsrch_offset[MAXDNSRCH+1]; // offsets into defdname
|
|
};
|
|
|
|
#define HTABLE_VALID(x) ((x) != NULL && (x) != HTABLE_DELETED)
|
|
|
|
static void
|
|
_cache_flush_pending_requests_locked( struct resolv_cache* cache )
|
|
{
|
|
struct pending_req_info *ri, *tmp;
|
|
if (cache) {
|
|
ri = cache->pending_requests.next;
|
|
|
|
while (ri) {
|
|
tmp = ri;
|
|
ri = ri->next;
|
|
pthread_cond_broadcast(&tmp->cond);
|
|
|
|
pthread_cond_destroy(&tmp->cond);
|
|
free(tmp);
|
|
}
|
|
|
|
cache->pending_requests.next = NULL;
|
|
}
|
|
}
|
|
|
|
/* return 0 if no pending request is found matching the key
|
|
* if a matching request is found the calling thread will wait
|
|
* and return 1 when released */
|
|
static int
|
|
_cache_check_pending_request_locked( struct resolv_cache* cache, Entry* key )
|
|
{
|
|
struct pending_req_info *ri, *prev;
|
|
int exist = 0;
|
|
|
|
if (cache && key) {
|
|
ri = cache->pending_requests.next;
|
|
prev = &cache->pending_requests;
|
|
while (ri) {
|
|
if (ri->hash == key->hash) {
|
|
exist = 1;
|
|
break;
|
|
}
|
|
prev = ri;
|
|
ri = ri->next;
|
|
}
|
|
|
|
if (!exist) {
|
|
ri = calloc(1, sizeof(struct pending_req_info));
|
|
if (ri) {
|
|
ri->hash = key->hash;
|
|
pthread_cond_init(&ri->cond, NULL);
|
|
prev->next = ri;
|
|
}
|
|
} else {
|
|
struct timespec ts = {0,0};
|
|
XLOG("Waiting for previous request");
|
|
ts.tv_sec = _time_now() + PENDING_REQUEST_TIMEOUT;
|
|
pthread_cond_timedwait(&ri->cond, &cache->lock, &ts);
|
|
}
|
|
}
|
|
|
|
return exist;
|
|
}
|
|
|
|
/* notify any waiting thread that waiting on a request
|
|
* matching the key has been added to the cache */
|
|
static void
|
|
_cache_notify_waiting_tid_locked( struct resolv_cache* cache, Entry* key )
|
|
{
|
|
struct pending_req_info *ri, *prev;
|
|
|
|
if (cache && key) {
|
|
ri = cache->pending_requests.next;
|
|
prev = &cache->pending_requests;
|
|
while (ri) {
|
|
if (ri->hash == key->hash) {
|
|
pthread_cond_broadcast(&ri->cond);
|
|
break;
|
|
}
|
|
prev = ri;
|
|
ri = ri->next;
|
|
}
|
|
|
|
// remove item from list and destroy
|
|
if (ri) {
|
|
prev->next = ri->next;
|
|
pthread_cond_destroy(&ri->cond);
|
|
free(ri);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* notify the cache that the query failed */
|
|
void
|
|
_resolv_cache_query_failed( struct resolv_cache* cache,
|
|
const void* query,
|
|
int querylen)
|
|
{
|
|
Entry key[1];
|
|
|
|
if (cache && entry_init_key(key, query, querylen)) {
|
|
pthread_mutex_lock(&cache->lock);
|
|
_cache_notify_waiting_tid_locked(cache, key);
|
|
pthread_mutex_unlock(&cache->lock);
|
|
}
|
|
}
|
|
|
|
static void
|
|
_cache_flush_locked( Cache* cache )
|
|
{
|
|
int nn;
|
|
|
|
for (nn = 0; nn < cache->max_entries; nn++)
|
|
{
|
|
Entry** pnode = (Entry**) &cache->entries[nn];
|
|
|
|
while (*pnode != NULL) {
|
|
Entry* node = *pnode;
|
|
*pnode = node->hlink;
|
|
entry_free(node);
|
|
}
|
|
}
|
|
|
|
// flush pending request
|
|
_cache_flush_pending_requests_locked(cache);
|
|
|
|
cache->mru_list.mru_next = cache->mru_list.mru_prev = &cache->mru_list;
|
|
cache->num_entries = 0;
|
|
cache->last_id = 0;
|
|
|
|
XLOG("*************************\n"
|
|
"*** DNS CACHE FLUSHED ***\n"
|
|
"*************************");
|
|
}
|
|
|
|
static int
|
|
_res_cache_get_max_entries( void )
|
|
{
|
|
int cache_size = CONFIG_MAX_ENTRIES;
|
|
|
|
const char* cache_mode = getenv("ANDROID_DNS_MODE");
|
|
if (cache_mode == NULL || strcmp(cache_mode, "local") != 0) {
|
|
// Don't use the cache in local mode. This is used by the proxy itself.
|
|
cache_size = 0;
|
|
}
|
|
|
|
XLOG("cache size: %d", cache_size);
|
|
return cache_size;
|
|
}
|
|
|
|
static struct resolv_cache*
|
|
_resolv_cache_create( void )
|
|
{
|
|
struct resolv_cache* cache;
|
|
|
|
cache = calloc(sizeof(*cache), 1);
|
|
if (cache) {
|
|
cache->max_entries = _res_cache_get_max_entries();
|
|
cache->entries = calloc(sizeof(*cache->entries), cache->max_entries);
|
|
if (cache->entries) {
|
|
pthread_mutex_init( &cache->lock, NULL );
|
|
cache->mru_list.mru_prev = cache->mru_list.mru_next = &cache->mru_list;
|
|
XLOG("%s: cache created\n", __FUNCTION__);
|
|
} else {
|
|
free(cache);
|
|
cache = NULL;
|
|
}
|
|
}
|
|
return cache;
|
|
}
|
|
|
|
|
|
#if DEBUG
|
|
static void
|
|
_dump_query( const uint8_t* query, int querylen )
|
|
{
|
|
char temp[256], *p=temp, *end=p+sizeof(temp);
|
|
DnsPacket pack[1];
|
|
|
|
_dnsPacket_init(pack, query, querylen);
|
|
p = _dnsPacket_bprintQuery(pack, p, end);
|
|
XLOG("QUERY: %s", temp);
|
|
}
|
|
|
|
static void
|
|
_cache_dump_mru( Cache* cache )
|
|
{
|
|
char temp[512], *p=temp, *end=p+sizeof(temp);
|
|
Entry* e;
|
|
|
|
p = _bprint(temp, end, "MRU LIST (%2d): ", cache->num_entries);
|
|
for (e = cache->mru_list.mru_next; e != &cache->mru_list; e = e->mru_next)
|
|
p = _bprint(p, end, " %d", e->id);
|
|
|
|
XLOG("%s", temp);
|
|
}
|
|
|
|
static void
|
|
_dump_answer(const void* answer, int answerlen)
|
|
{
|
|
res_state statep;
|
|
FILE* fp;
|
|
char* buf;
|
|
int fileLen;
|
|
|
|
fp = fopen("/data/reslog.txt", "w+");
|
|
if (fp != NULL) {
|
|
statep = __res_get_state();
|
|
|
|
res_pquery(statep, answer, answerlen, fp);
|
|
|
|
//Get file length
|
|
fseek(fp, 0, SEEK_END);
|
|
fileLen=ftell(fp);
|
|
fseek(fp, 0, SEEK_SET);
|
|
buf = (char *)malloc(fileLen+1);
|
|
if (buf != NULL) {
|
|
//Read file contents into buffer
|
|
fread(buf, fileLen, 1, fp);
|
|
XLOG("%s\n", buf);
|
|
free(buf);
|
|
}
|
|
fclose(fp);
|
|
remove("/data/reslog.txt");
|
|
}
|
|
else {
|
|
errno = 0; // else debug is introducing error signals
|
|
XLOG("%s: can't open file\n", __FUNCTION__);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#if DEBUG
|
|
# define XLOG_QUERY(q,len) _dump_query((q), (len))
|
|
# define XLOG_ANSWER(a, len) _dump_answer((a), (len))
|
|
#else
|
|
# define XLOG_QUERY(q,len) ((void)0)
|
|
# define XLOG_ANSWER(a,len) ((void)0)
|
|
#endif
|
|
|
|
/* This function tries to find a key within the hash table
|
|
* In case of success, it will return a *pointer* to the hashed key.
|
|
* In case of failure, it will return a *pointer* to NULL
|
|
*
|
|
* So, the caller must check '*result' to check for success/failure.
|
|
*
|
|
* The main idea is that the result can later be used directly in
|
|
* calls to _resolv_cache_add or _resolv_cache_remove as the 'lookup'
|
|
* parameter. This makes the code simpler and avoids re-searching
|
|
* for the key position in the htable.
|
|
*
|
|
* The result of a lookup_p is only valid until you alter the hash
|
|
* table.
|
|
*/
|
|
static Entry**
|
|
_cache_lookup_p( Cache* cache,
|
|
Entry* key )
|
|
{
|
|
int index = key->hash % cache->max_entries;
|
|
Entry** pnode = (Entry**) &cache->entries[ index ];
|
|
|
|
while (*pnode != NULL) {
|
|
Entry* node = *pnode;
|
|
|
|
if (node == NULL)
|
|
break;
|
|
|
|
if (node->hash == key->hash && entry_equals(node, key))
|
|
break;
|
|
|
|
pnode = &node->hlink;
|
|
}
|
|
return pnode;
|
|
}
|
|
|
|
/* Add a new entry to the hash table. 'lookup' must be the
|
|
* result of an immediate previous failed _lookup_p() call
|
|
* (i.e. with *lookup == NULL), and 'e' is the pointer to the
|
|
* newly created entry
|
|
*/
|
|
static void
|
|
_cache_add_p( Cache* cache,
|
|
Entry** lookup,
|
|
Entry* e )
|
|
{
|
|
*lookup = e;
|
|
e->id = ++cache->last_id;
|
|
entry_mru_add(e, &cache->mru_list);
|
|
cache->num_entries += 1;
|
|
|
|
XLOG("%s: entry %d added (count=%d)", __FUNCTION__,
|
|
e->id, cache->num_entries);
|
|
}
|
|
|
|
/* Remove an existing entry from the hash table,
|
|
* 'lookup' must be the result of an immediate previous
|
|
* and succesful _lookup_p() call.
|
|
*/
|
|
static void
|
|
_cache_remove_p( Cache* cache,
|
|
Entry** lookup )
|
|
{
|
|
Entry* e = *lookup;
|
|
|
|
XLOG("%s: entry %d removed (count=%d)", __FUNCTION__,
|
|
e->id, cache->num_entries-1);
|
|
|
|
entry_mru_remove(e);
|
|
*lookup = e->hlink;
|
|
entry_free(e);
|
|
cache->num_entries -= 1;
|
|
}
|
|
|
|
/* Remove the oldest entry from the hash table.
|
|
*/
|
|
static void
|
|
_cache_remove_oldest( Cache* cache )
|
|
{
|
|
Entry* oldest = cache->mru_list.mru_prev;
|
|
Entry** lookup = _cache_lookup_p(cache, oldest);
|
|
|
|
if (*lookup == NULL) { /* should not happen */
|
|
XLOG("%s: OLDEST NOT IN HTABLE ?", __FUNCTION__);
|
|
return;
|
|
}
|
|
if (DEBUG) {
|
|
XLOG("Cache full - removing oldest");
|
|
XLOG_QUERY(oldest->query, oldest->querylen);
|
|
}
|
|
_cache_remove_p(cache, lookup);
|
|
}
|
|
|
|
/* Remove all expired entries from the hash table.
|
|
*/
|
|
static void _cache_remove_expired(Cache* cache) {
|
|
Entry* e;
|
|
time_t now = _time_now();
|
|
|
|
for (e = cache->mru_list.mru_next; e != &cache->mru_list;) {
|
|
// Entry is old, remove
|
|
if (now >= e->expires) {
|
|
Entry** lookup = _cache_lookup_p(cache, e);
|
|
if (*lookup == NULL) { /* should not happen */
|
|
XLOG("%s: ENTRY NOT IN HTABLE ?", __FUNCTION__);
|
|
return;
|
|
}
|
|
e = e->mru_next;
|
|
_cache_remove_p(cache, lookup);
|
|
} else {
|
|
e = e->mru_next;
|
|
}
|
|
}
|
|
}
|
|
|
|
ResolvCacheStatus
|
|
_resolv_cache_lookup( struct resolv_cache* cache,
|
|
const void* query,
|
|
int querylen,
|
|
void* answer,
|
|
int answersize,
|
|
int *answerlen )
|
|
{
|
|
Entry key[1];
|
|
Entry** lookup;
|
|
Entry* e;
|
|
time_t now;
|
|
|
|
ResolvCacheStatus result = RESOLV_CACHE_NOTFOUND;
|
|
|
|
XLOG("%s: lookup", __FUNCTION__);
|
|
XLOG_QUERY(query, querylen);
|
|
|
|
/* we don't cache malformed queries */
|
|
if (!entry_init_key(key, query, querylen)) {
|
|
XLOG("%s: unsupported query", __FUNCTION__);
|
|
return RESOLV_CACHE_UNSUPPORTED;
|
|
}
|
|
/* lookup cache */
|
|
pthread_mutex_lock( &cache->lock );
|
|
|
|
/* see the description of _lookup_p to understand this.
|
|
* the function always return a non-NULL pointer.
|
|
*/
|
|
lookup = _cache_lookup_p(cache, key);
|
|
e = *lookup;
|
|
|
|
if (e == NULL) {
|
|
XLOG( "NOT IN CACHE");
|
|
// calling thread will wait if an outstanding request is found
|
|
// that matching this query
|
|
if (!_cache_check_pending_request_locked(cache, key)) {
|
|
goto Exit;
|
|
} else {
|
|
lookup = _cache_lookup_p(cache, key);
|
|
e = *lookup;
|
|
if (e == NULL) {
|
|
goto Exit;
|
|
}
|
|
}
|
|
}
|
|
|
|
now = _time_now();
|
|
|
|
/* remove stale entries here */
|
|
if (now >= e->expires) {
|
|
XLOG( " NOT IN CACHE (STALE ENTRY %p DISCARDED)", *lookup );
|
|
XLOG_QUERY(e->query, e->querylen);
|
|
_cache_remove_p(cache, lookup);
|
|
goto Exit;
|
|
}
|
|
|
|
*answerlen = e->answerlen;
|
|
if (e->answerlen > answersize) {
|
|
/* NOTE: we return UNSUPPORTED if the answer buffer is too short */
|
|
result = RESOLV_CACHE_UNSUPPORTED;
|
|
XLOG(" ANSWER TOO LONG");
|
|
goto Exit;
|
|
}
|
|
|
|
memcpy( answer, e->answer, e->answerlen );
|
|
|
|
/* bump up this entry to the top of the MRU list */
|
|
if (e != cache->mru_list.mru_next) {
|
|
entry_mru_remove( e );
|
|
entry_mru_add( e, &cache->mru_list );
|
|
}
|
|
|
|
XLOG( "FOUND IN CACHE entry=%p", e );
|
|
result = RESOLV_CACHE_FOUND;
|
|
|
|
Exit:
|
|
pthread_mutex_unlock( &cache->lock );
|
|
return result;
|
|
}
|
|
|
|
|
|
void
|
|
_resolv_cache_add( struct resolv_cache* cache,
|
|
const void* query,
|
|
int querylen,
|
|
const void* answer,
|
|
int answerlen )
|
|
{
|
|
Entry key[1];
|
|
Entry* e;
|
|
Entry** lookup;
|
|
u_long ttl;
|
|
|
|
/* don't assume that the query has already been cached
|
|
*/
|
|
if (!entry_init_key( key, query, querylen )) {
|
|
XLOG( "%s: passed invalid query ?", __FUNCTION__);
|
|
return;
|
|
}
|
|
|
|
pthread_mutex_lock( &cache->lock );
|
|
|
|
XLOG( "%s: query:", __FUNCTION__ );
|
|
XLOG_QUERY(query,querylen);
|
|
XLOG_ANSWER(answer, answerlen);
|
|
#if DEBUG_DATA
|
|
XLOG( "answer:");
|
|
XLOG_BYTES(answer,answerlen);
|
|
#endif
|
|
|
|
lookup = _cache_lookup_p(cache, key);
|
|
e = *lookup;
|
|
|
|
if (e != NULL) { /* should not happen */
|
|
XLOG("%s: ALREADY IN CACHE (%p) ? IGNORING ADD",
|
|
__FUNCTION__, e);
|
|
goto Exit;
|
|
}
|
|
|
|
if (cache->num_entries >= cache->max_entries) {
|
|
_cache_remove_expired(cache);
|
|
if (cache->num_entries >= cache->max_entries) {
|
|
_cache_remove_oldest(cache);
|
|
}
|
|
/* need to lookup again */
|
|
lookup = _cache_lookup_p(cache, key);
|
|
e = *lookup;
|
|
if (e != NULL) {
|
|
XLOG("%s: ALREADY IN CACHE (%p) ? IGNORING ADD",
|
|
__FUNCTION__, e);
|
|
goto Exit;
|
|
}
|
|
}
|
|
|
|
ttl = answer_getTTL(answer, answerlen);
|
|
if (ttl > 0) {
|
|
e = entry_alloc(key, answer, answerlen);
|
|
if (e != NULL) {
|
|
e->expires = ttl + _time_now();
|
|
_cache_add_p(cache, lookup, e);
|
|
}
|
|
}
|
|
#if DEBUG
|
|
_cache_dump_mru(cache);
|
|
#endif
|
|
Exit:
|
|
_cache_notify_waiting_tid_locked(cache, key);
|
|
pthread_mutex_unlock( &cache->lock );
|
|
}
|
|
|
|
/****************************************************************************/
|
|
/****************************************************************************/
|
|
/***** *****/
|
|
/***** *****/
|
|
/***** *****/
|
|
/****************************************************************************/
|
|
/****************************************************************************/
|
|
|
|
static pthread_once_t _res_cache_once = PTHREAD_ONCE_INIT;
|
|
|
|
// Head of the list of caches. Protected by _res_cache_list_lock.
|
|
static struct resolv_cache_info _res_cache_list;
|
|
|
|
// lock protecting everything in the _resolve_cache_info structs (next ptr, etc)
|
|
static pthread_mutex_t _res_cache_list_lock;
|
|
|
|
/* insert resolv_cache_info into the list of resolv_cache_infos */
|
|
static void _insert_cache_info_locked(struct resolv_cache_info* cache_info);
|
|
/* creates a resolv_cache_info */
|
|
static struct resolv_cache_info* _create_cache_info( void );
|
|
/* gets cache associated with a network, or NULL if none exists */
|
|
static struct resolv_cache* _find_named_cache_locked(unsigned netid);
|
|
/* gets a resolv_cache_info associated with a network, or NULL if not found */
|
|
static struct resolv_cache_info* _find_cache_info_locked(unsigned netid);
|
|
/* look up the named cache, and creates one if needed */
|
|
static struct resolv_cache* _get_res_cache_for_net_locked(unsigned netid);
|
|
/* empty the named cache */
|
|
static void _flush_cache_for_net_locked(unsigned netid);
|
|
/* empty the nameservers set for the named cache */
|
|
static void _free_nameservers_locked(struct resolv_cache_info* cache_info);
|
|
/* return 1 if the provided list of name servers differs from the list of name servers
|
|
* currently attached to the provided cache_info */
|
|
static int _resolv_is_nameservers_equal_locked(struct resolv_cache_info* cache_info,
|
|
const char** servers, int numservers);
|
|
|
|
static void
|
|
_res_cache_init(void)
|
|
{
|
|
const char* env = getenv(CONFIG_ENV);
|
|
|
|
if (env && atoi(env) == 0) {
|
|
/* the cache is disabled */
|
|
return;
|
|
}
|
|
|
|
memset(&_res_cache_list, 0, sizeof(_res_cache_list));
|
|
pthread_mutex_init(&_res_cache_list_lock, NULL);
|
|
}
|
|
|
|
struct resolv_cache*
|
|
__get_res_cache(unsigned netid)
|
|
{
|
|
struct resolv_cache *cache;
|
|
|
|
pthread_once(&_res_cache_once, _res_cache_init);
|
|
pthread_mutex_lock(&_res_cache_list_lock);
|
|
|
|
/* Does NOT create a cache if it does not exist. */
|
|
cache = _find_named_cache_locked(netid);
|
|
|
|
pthread_mutex_unlock(&_res_cache_list_lock);
|
|
XLOG("%s: netid=%u, cache=%p\n", __FUNCTION__, netid, cache);
|
|
return cache;
|
|
}
|
|
|
|
static struct resolv_cache*
|
|
_get_res_cache_for_net_locked(unsigned netid)
|
|
{
|
|
struct resolv_cache* cache = _find_named_cache_locked(netid);
|
|
if (!cache) {
|
|
struct resolv_cache_info* cache_info = _create_cache_info();
|
|
if (cache_info) {
|
|
cache = _resolv_cache_create();
|
|
if (cache) {
|
|
cache_info->cache = cache;
|
|
cache_info->netid = netid;
|
|
_insert_cache_info_locked(cache_info);
|
|
} else {
|
|
free(cache_info);
|
|
}
|
|
}
|
|
}
|
|
return cache;
|
|
}
|
|
|
|
void
|
|
_resolv_flush_cache_for_net(unsigned netid)
|
|
{
|
|
pthread_once(&_res_cache_once, _res_cache_init);
|
|
pthread_mutex_lock(&_res_cache_list_lock);
|
|
|
|
_flush_cache_for_net_locked(netid);
|
|
|
|
pthread_mutex_unlock(&_res_cache_list_lock);
|
|
}
|
|
|
|
static void
|
|
_flush_cache_for_net_locked(unsigned netid)
|
|
{
|
|
struct resolv_cache* cache = _find_named_cache_locked(netid);
|
|
if (cache) {
|
|
pthread_mutex_lock(&cache->lock);
|
|
_cache_flush_locked(cache);
|
|
pthread_mutex_unlock(&cache->lock);
|
|
}
|
|
}
|
|
|
|
static struct resolv_cache_info*
|
|
_create_cache_info(void)
|
|
{
|
|
struct resolv_cache_info* cache_info;
|
|
|
|
cache_info = calloc(sizeof(*cache_info), 1);
|
|
return cache_info;
|
|
}
|
|
|
|
static void
|
|
_insert_cache_info_locked(struct resolv_cache_info* cache_info)
|
|
{
|
|
struct resolv_cache_info* last;
|
|
|
|
for (last = &_res_cache_list; last->next; last = last->next);
|
|
|
|
last->next = cache_info;
|
|
|
|
}
|
|
|
|
static struct resolv_cache*
|
|
_find_named_cache_locked(unsigned netid) {
|
|
|
|
struct resolv_cache_info* info = _find_cache_info_locked(netid);
|
|
|
|
if (info != NULL) return info->cache;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct resolv_cache_info*
|
|
_find_cache_info_locked(unsigned netid)
|
|
{
|
|
struct resolv_cache_info* cache_info = _res_cache_list.next;
|
|
|
|
while (cache_info) {
|
|
if (cache_info->netid == netid) {
|
|
break;
|
|
}
|
|
|
|
cache_info = cache_info->next;
|
|
}
|
|
return cache_info;
|
|
}
|
|
|
|
void
|
|
_resolv_set_nameservers_for_net(unsigned netid, const char** servers, int numservers,
|
|
const char *domains)
|
|
{
|
|
int i, rt, index;
|
|
struct addrinfo hints;
|
|
char sbuf[NI_MAXSERV];
|
|
register char *cp;
|
|
int *offset;
|
|
|
|
pthread_once(&_res_cache_once, _res_cache_init);
|
|
pthread_mutex_lock(&_res_cache_list_lock);
|
|
|
|
// creates the cache if not created
|
|
_get_res_cache_for_net_locked(netid);
|
|
|
|
struct resolv_cache_info* cache_info = _find_cache_info_locked(netid);
|
|
|
|
if (cache_info != NULL &&
|
|
!_resolv_is_nameservers_equal_locked(cache_info, servers, numservers)) {
|
|
// free current before adding new
|
|
_free_nameservers_locked(cache_info);
|
|
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = PF_UNSPEC;
|
|
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
|
|
hints.ai_flags = AI_NUMERICHOST;
|
|
sprintf(sbuf, "%u", NAMESERVER_PORT);
|
|
|
|
index = 0;
|
|
for (i = 0; i < numservers && i < MAXNS; i++) {
|
|
rt = getaddrinfo(servers[i], sbuf, &hints, &cache_info->nsaddrinfo[index]);
|
|
if (rt == 0) {
|
|
cache_info->nameservers[index] = strdup(servers[i]);
|
|
index++;
|
|
XLOG("%s: netid = %u, addr = %s\n", __FUNCTION__, netid, servers[i]);
|
|
} else {
|
|
cache_info->nsaddrinfo[index] = NULL;
|
|
}
|
|
}
|
|
|
|
// code moved from res_init.c, load_domain_search_list
|
|
strlcpy(cache_info->defdname, domains, sizeof(cache_info->defdname));
|
|
if ((cp = strchr(cache_info->defdname, '\n')) != NULL)
|
|
*cp = '\0';
|
|
cp = cache_info->defdname;
|
|
offset = cache_info->dnsrch_offset;
|
|
while (offset < cache_info->dnsrch_offset + MAXDNSRCH) {
|
|
while (*cp == ' ' || *cp == '\t') /* skip leading white space */
|
|
cp++;
|
|
if (*cp == '\0') /* stop if nothing more to do */
|
|
break;
|
|
*offset++ = cp - cache_info->defdname; /* record this search domain */
|
|
while (*cp) { /* zero-terminate it */
|
|
if (*cp == ' '|| *cp == '\t') {
|
|
*cp++ = '\0';
|
|
break;
|
|
}
|
|
cp++;
|
|
}
|
|
}
|
|
*offset = -1; /* cache_info->dnsrch_offset has MAXDNSRCH+1 items */
|
|
|
|
// flush cache since new settings
|
|
_flush_cache_for_net_locked(netid);
|
|
|
|
}
|
|
|
|
pthread_mutex_unlock(&_res_cache_list_lock);
|
|
}
|
|
|
|
static int
|
|
_resolv_is_nameservers_equal_locked(struct resolv_cache_info* cache_info,
|
|
const char** servers, int numservers)
|
|
{
|
|
int i;
|
|
char** ns;
|
|
int equal = 1;
|
|
|
|
// compare each name server against current name servers
|
|
if (numservers > MAXNS) numservers = MAXNS;
|
|
for (i = 0; i < numservers && equal; i++) {
|
|
ns = cache_info->nameservers;
|
|
equal = 0;
|
|
while(*ns) {
|
|
if (strcmp(*ns, servers[i]) == 0) {
|
|
equal = 1;
|
|
break;
|
|
}
|
|
ns++;
|
|
}
|
|
}
|
|
|
|
return equal;
|
|
}
|
|
|
|
static void
|
|
_free_nameservers_locked(struct resolv_cache_info* cache_info)
|
|
{
|
|
int i;
|
|
for (i = 0; i <= MAXNS; i++) {
|
|
free(cache_info->nameservers[i]);
|
|
cache_info->nameservers[i] = NULL;
|
|
if (cache_info->nsaddrinfo[i] != NULL) {
|
|
freeaddrinfo(cache_info->nsaddrinfo[i]);
|
|
cache_info->nsaddrinfo[i] = NULL;
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
_resolv_populate_res_for_net(res_state statp)
|
|
{
|
|
if (statp == NULL) {
|
|
return;
|
|
}
|
|
|
|
pthread_once(&_res_cache_once, _res_cache_init);
|
|
pthread_mutex_lock(&_res_cache_list_lock);
|
|
|
|
struct resolv_cache_info* info = _find_cache_info_locked(statp->netid);
|
|
if (info != NULL) {
|
|
int nserv;
|
|
struct addrinfo* ai;
|
|
XLOG("%s: %u\n", __FUNCTION__, statp->netid);
|
|
for (nserv = 0; nserv < MAXNS; nserv++) {
|
|
ai = info->nsaddrinfo[nserv];
|
|
if (ai == NULL) {
|
|
break;
|
|
}
|
|
|
|
if ((size_t) ai->ai_addrlen <= sizeof(statp->_u._ext.ext->nsaddrs[0])) {
|
|
if (statp->_u._ext.ext != NULL) {
|
|
memcpy(&statp->_u._ext.ext->nsaddrs[nserv], ai->ai_addr, ai->ai_addrlen);
|
|
statp->nsaddr_list[nserv].sin_family = AF_UNSPEC;
|
|
} else {
|
|
if ((size_t) ai->ai_addrlen
|
|
<= sizeof(statp->nsaddr_list[0])) {
|
|
memcpy(&statp->nsaddr_list[nserv], ai->ai_addr,
|
|
ai->ai_addrlen);
|
|
} else {
|
|
statp->nsaddr_list[nserv].sin_family = AF_UNSPEC;
|
|
}
|
|
}
|
|
} else {
|
|
XLOG("%s: found too long addrlen", __FUNCTION__);
|
|
}
|
|
}
|
|
statp->nscount = nserv;
|
|
// now do search domains. Note that we cache the offsets as this code runs alot
|
|
// but the setting/offset-computer only runs when set/changed
|
|
strlcpy(statp->defdname, info->defdname, sizeof(statp->defdname));
|
|
register char **pp = statp->dnsrch;
|
|
register int *p = info->dnsrch_offset;
|
|
while (pp < statp->dnsrch + MAXDNSRCH && *p != -1) {
|
|
*pp++ = &statp->defdname + *p++;
|
|
}
|
|
}
|
|
pthread_mutex_unlock(&_res_cache_list_lock);
|
|
}
|