| /* |
| * Copyright (C) 2008 The Android Open Source Project |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
| * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| #define LOG_TAG "resolv" |
| |
| #include "resolv_cache.h" |
| |
| #include <resolv.h> |
| #include <stdarg.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <time.h> |
| #include <mutex> |
| |
| #include <arpa/inet.h> |
| #include <arpa/nameser.h> |
| #include <errno.h> |
| #include <linux/if.h> |
| #include <net/if.h> |
| #include <netdb.h> |
| |
| #include <android-base/logging.h> |
| #include <android-base/parseint.h> |
| #include <android-base/thread_annotations.h> |
| #include <android/multinetwork.h> // ResNsendFlags |
| |
| #include <server_configurable_flags/get_flags.h> |
| |
| #include "res_state_ext.h" |
| #include "resolv_private.h" |
| |
| // NOTE: verbose logging MUST NOT be left enabled in production binaries. |
| // It floods logs at high rate, and can leak privacy-sensitive information. |
| constexpr bool kDumpData = false; |
| |
| /* This code implements a small and *simple* DNS resolver cache. |
| * |
| * It is only used to cache DNS answers for a time defined by the smallest TTL |
| * among the answer records in order to reduce DNS traffic. It is not supposed |
| * to be a full DNS cache, since we plan to implement that in the future in a |
| * dedicated process running on the system. |
| * |
| * Note that its design is kept simple very intentionally, i.e.: |
| * |
| * - it takes raw DNS query packet data as input, and returns raw DNS |
| * answer packet data as output |
| * |
| * (this means that two similar queries that encode the DNS name |
| * differently will be treated distinctly). |
| * |
| * the smallest TTL value among the answer records are used as the time |
| * to keep an answer in the cache. |
| * |
| * this is bad, but we absolutely want to avoid parsing the answer packets |
| * (and should be solved by the later full DNS cache process). |
| * |
| * - the implementation is just a (query-data) => (answer-data) hash table |
| * with a trivial least-recently-used expiration policy. |
| * |
| * Doing this keeps the code simple and avoids to deal with a lot of things |
| * that a full DNS cache is expected to do. |
| * |
| * The API is also very simple: |
| * |
| * - the client calls _resolv_cache_get() to obtain a handle to the cache. |
| * this will initialize the cache on first usage. the result can be NULL |
| * if the cache is disabled. |
| * |
| * - the client calls resolv_cache_lookup() before performing a query |
| * |
| * if the function returns RESOLV_CACHE_FOUND, a copy of the answer data |
| * has been copied into the client-provided answer buffer. |
| * |
| * if the function returns RESOLV_CACHE_NOTFOUND, the client should perform |
| * a request normally, *then* call resolv_cache_add() to add the received |
| * answer to the cache. |
| * |
| * if the function returns RESOLV_CACHE_UNSUPPORTED, the client should |
| * perform a request normally, and *not* call resolv_cache_add() |
| * |
| * note that RESOLV_CACHE_UNSUPPORTED is also returned if the answer buffer |
| * is too short to accomodate the cached result. |
| */ |
| |
| /* default number of entries kept in the cache. This value has been |
| * determined by browsing through various sites and counting the number |
| * of corresponding requests. Keep in mind that our framework is currently |
| * performing two requests per name lookup (one for IPv4, the other for IPv6) |
| * |
| * www.google.com 4 |
| * www.ysearch.com 6 |
| * www.amazon.com 8 |
| * www.nytimes.com 22 |
| * www.espn.com 28 |
| * www.msn.com 28 |
| * www.lemonde.fr 35 |
| * |
| * (determined in 2009-2-17 from Paris, France, results may vary depending |
| * on location) |
| * |
| * most high-level websites use lots of media/ad servers with different names |
| * but these are generally reused when browsing through the site. |
| * |
| * As such, a value of 64 should be relatively comfortable at the moment. |
| * |
| * ****************************************** |
| * * NOTE - this has changed. |
| * * 1) we've added IPv6 support so each dns query results in 2 responses |
| * * 2) we've made this a system-wide cache, so the cost is less (it's not |
| * * duplicated in each process) and the need is greater (more processes |
| * * making different requests). |
| * * Upping by 2x for IPv6 |
| * * Upping by another 5x for the centralized nature |
| * ***************************************** |
| */ |
| #define CONFIG_MAX_ENTRIES (64 * 2 * 5) |
| |
| /** BOUNDED BUFFER FORMATTING **/ |
| |
| /* technical note: |
| * |
| * the following debugging routines are used to append data to a bounded |
| * buffer they take two parameters that are: |
| * |
| * - p : a pointer to the current cursor position in the buffer |
| * this value is initially set to the buffer's address. |
| * |
| * - end : the address of the buffer's limit, i.e. of the first byte |
| * after the buffer. this address should never be touched. |
| * |
| * IMPORTANT: it is assumed that end > buffer_address, i.e. |
| * that the buffer is at least one byte. |
| * |
| * the bprint_x() functions return the new value of 'p' after the data |
| * has been appended, and also ensure the following: |
| * |
| * - the returned value will never be strictly greater than 'end' |
| * |
| * - a return value equal to 'end' means that truncation occurred |
| * (in which case, end[-1] will be set to 0) |
| * |
| * - after returning from a bprint_x() function, the content of the buffer |
| * is always 0-terminated, even in the event of truncation. |
| * |
| * these conventions allow you to call bprint_x() functions multiple times and |
| * only check for truncation at the end of the sequence, as in: |
| * |
| * char buff[1000], *p = buff, *end = p + sizeof(buff); |
| * |
| * p = bprint_c(p, end, '"'); |
| * p = bprint_s(p, end, my_string); |
| * p = bprint_c(p, end, '"'); |
| * |
| * if (p >= end) { |
| * // buffer was too small |
| * } |
| * |
| * printf( "%s", buff ); |
| */ |
| |
| /* Defaults used for initializing res_params */ |
| |
| // If successes * 100 / total_samples is less than this value, the server is considered failing |
| #define SUCCESS_THRESHOLD 75 |
| // Sample validity in seconds. Set to -1 to disable skipping failing servers. |
| #define NSSAMPLE_VALIDITY 1800 |
| |
| /* add a char to a bounded buffer */ |
| static char* bprint_c(char* p, char* end, int c) { |
| if (p < end) { |
| if (p + 1 == end) |
| *p++ = 0; |
| else { |
| *p++ = (char) c; |
| *p = 0; |
| } |
| } |
| return p; |
| } |
| |
| /* add a sequence of bytes to a bounded buffer */ |
| static char* bprint_b(char* p, char* end, const char* buf, int len) { |
| int avail = end - p; |
| |
| if (avail <= 0 || len <= 0) return p; |
| |
| if (avail > len) avail = len; |
| |
| memcpy(p, buf, avail); |
| p += avail; |
| |
| if (p < end) |
| p[0] = 0; |
| else |
| end[-1] = 0; |
| |
| return p; |
| } |
| |
| /* add a string to a bounded buffer */ |
| static char* bprint_s(char* p, char* end, const char* str) { |
| return bprint_b(p, end, str, strlen(str)); |
| } |
| |
| /* add a formatted string to a bounded buffer */ |
| static char* bprint(char* p, char* end, const char* format, ...) { |
| int avail, n; |
| va_list args; |
| |
| avail = end - p; |
| |
| if (avail <= 0) return p; |
| |
| va_start(args, format); |
| n = vsnprintf(p, avail, format, args); |
| va_end(args); |
| |
| /* certain C libraries return -1 in case of truncation */ |
| if (n < 0 || n > avail) n = avail; |
| |
| p += n; |
| /* certain C libraries do not zero-terminate in case of truncation */ |
| if (p == end) p[-1] = 0; |
| |
| return p; |
| } |
| |
| /* add a hex value to a bounded buffer, up to 8 digits */ |
| static char* bprint_hex(char* p, char* end, unsigned value, int numDigits) { |
| char text[sizeof(unsigned) * 2]; |
| int nn = 0; |
| |
| while (numDigits-- > 0) { |
| text[nn++] = "0123456789abcdef"[(value >> (numDigits * 4)) & 15]; |
| } |
| return bprint_b(p, end, text, nn); |
| } |
| |
| /* add the hexadecimal dump of some memory area to a bounded buffer */ |
| static char* bprint_hexdump(char* p, char* end, const uint8_t* data, int datalen) { |
| int lineSize = 16; |
| |
| while (datalen > 0) { |
| int avail = datalen; |
| int nn; |
| |
| if (avail > lineSize) avail = lineSize; |
| |
| for (nn = 0; nn < avail; nn++) { |
| if (nn > 0) p = bprint_c(p, end, ' '); |
| p = bprint_hex(p, end, data[nn], 2); |
| } |
| for (; nn < lineSize; nn++) { |
| p = bprint_s(p, end, " "); |
| } |
| p = bprint_s(p, end, " "); |
| |
| for (nn = 0; nn < avail; nn++) { |
| int c = data[nn]; |
| |
| if (c < 32 || c > 127) c = '.'; |
| |
| p = bprint_c(p, end, c); |
| } |
| p = bprint_c(p, end, '\n'); |
| |
| data += avail; |
| datalen -= avail; |
| } |
| return p; |
| } |
| |
| /* dump the content of a query of packet to the log */ |
| static void dump_bytes(const uint8_t* base, int len) { |
| if (!kDumpData) return; |
| |
| char buff[1024]; |
| char *p = buff, *end = p + sizeof(buff); |
| |
| p = bprint_hexdump(p, end, base, len); |
| LOG(INFO) << __func__ << ": " << buff; |
| } |
| |
| static time_t _time_now(void) { |
| struct timeval tv; |
| |
| gettimeofday(&tv, NULL); |
| return tv.tv_sec; |
| } |
| |
| /* reminder: the general format of a DNS packet is the following: |
| * |
| * HEADER (12 bytes) |
| * QUESTION (variable) |
| * ANSWER (variable) |
| * AUTHORITY (variable) |
| * ADDITIONNAL (variable) |
| * |
| * the HEADER is made of: |
| * |
| * ID : 16 : 16-bit unique query identification field |
| * |
| * QR : 1 : set to 0 for queries, and 1 for responses |
| * Opcode : 4 : set to 0 for queries |
| * AA : 1 : set to 0 for queries |
| * TC : 1 : truncation flag, will be set to 0 in queries |
| * RD : 1 : recursion desired |
| * |
| * RA : 1 : recursion available (0 in queries) |
| * Z : 3 : three reserved zero bits |
| * RCODE : 4 : response code (always 0=NOERROR in queries) |
| * |
| * QDCount: 16 : question count |
| * ANCount: 16 : Answer count (0 in queries) |
| * NSCount: 16: Authority Record count (0 in queries) |
| * ARCount: 16: Additionnal Record count (0 in queries) |
| * |
| * the QUESTION is made of QDCount Question Record (QRs) |
| * the ANSWER is made of ANCount RRs |
| * the AUTHORITY is made of NSCount RRs |
| * the ADDITIONNAL is made of ARCount RRs |
| * |
| * Each Question Record (QR) is made of: |
| * |
| * QNAME : variable : Query DNS NAME |
| * TYPE : 16 : type of query (A=1, PTR=12, MX=15, AAAA=28, ALL=255) |
| * CLASS : 16 : class of query (IN=1) |
| * |
| * Each Resource Record (RR) is made of: |
| * |
| * NAME : variable : DNS NAME |
| * TYPE : 16 : type of query (A=1, PTR=12, MX=15, AAAA=28, ALL=255) |
| * CLASS : 16 : class of query (IN=1) |
| * TTL : 32 : seconds to cache this RR (0=none) |
| * RDLENGTH: 16 : size of RDDATA in bytes |
| * RDDATA : variable : RR data (depends on TYPE) |
| * |
| * Each QNAME contains a domain name encoded as a sequence of 'labels' |
| * terminated by a zero. Each label has the following format: |
| * |
| * LEN : 8 : lenght of label (MUST be < 64) |
| * NAME : 8*LEN : label length (must exclude dots) |
| * |
| * A value of 0 in the encoding is interpreted as the 'root' domain and |
| * terminates the encoding. So 'www.android.com' will be encoded as: |
| * |
| * <3>www<7>android<3>com<0> |
| * |
| * Where <n> represents the byte with value 'n' |
| * |
| * Each NAME reflects the QNAME of the question, but has a slightly more |
| * complex encoding in order to provide message compression. This is achieved |
| * by using a 2-byte pointer, with format: |
| * |
| * TYPE : 2 : 0b11 to indicate a pointer, 0b01 and 0b10 are reserved |
| * OFFSET : 14 : offset to another part of the DNS packet |
| * |
| * The offset is relative to the start of the DNS packet and must point |
| * A pointer terminates the encoding. |
| * |
| * The NAME can be encoded in one of the following formats: |
| * |
| * - a sequence of simple labels terminated by 0 (like QNAMEs) |
| * - a single pointer |
| * - a sequence of simple labels terminated by a pointer |
| * |
| * A pointer shall always point to either a pointer of a sequence of |
| * labels (which can themselves be terminated by either a 0 or a pointer) |
| * |
| * The expanded length of a given domain name should not exceed 255 bytes. |
| * |
| * NOTE: we don't parse the answer packets, so don't need to deal with NAME |
| * records, only QNAMEs. |
| */ |
| |
| #define DNS_HEADER_SIZE 12 |
| |
| #define DNS_TYPE_A "\00\01" /* big-endian decimal 1 */ |
| #define DNS_TYPE_PTR "\00\014" /* big-endian decimal 12 */ |
| #define DNS_TYPE_MX "\00\017" /* big-endian decimal 15 */ |
| #define DNS_TYPE_AAAA "\00\034" /* big-endian decimal 28 */ |
| #define DNS_TYPE_ALL "\00\0377" /* big-endian decimal 255 */ |
| |
| #define DNS_CLASS_IN "\00\01" /* big-endian decimal 1 */ |
| |
| typedef struct { |
| const uint8_t* base; |
| const uint8_t* end; |
| const uint8_t* cursor; |
| } DnsPacket; |
| |
| static void _dnsPacket_init(DnsPacket* packet, const uint8_t* buff, int bufflen) { |
| packet->base = buff; |
| packet->end = buff + bufflen; |
| packet->cursor = buff; |
| } |
| |
| static void _dnsPacket_rewind(DnsPacket* packet) { |
| packet->cursor = packet->base; |
| } |
| |
| static void _dnsPacket_skip(DnsPacket* packet, int count) { |
| const uint8_t* p = packet->cursor + count; |
| |
| if (p > packet->end) p = packet->end; |
| |
| packet->cursor = p; |
| } |
| |
| static int _dnsPacket_readInt16(DnsPacket* packet) { |
| const uint8_t* p = packet->cursor; |
| |
| if (p + 2 > packet->end) return -1; |
| |
| packet->cursor = p + 2; |
| return (p[0] << 8) | p[1]; |
| } |
| |
| /** QUERY CHECKING **/ |
| |
| /* check bytes in a dns packet. returns 1 on success, 0 on failure. |
| * the cursor is only advanced in the case of success |
| */ |
| static int _dnsPacket_checkBytes(DnsPacket* packet, int numBytes, const void* bytes) { |
| const uint8_t* p = packet->cursor; |
| |
| if (p + numBytes > packet->end) return 0; |
| |
| if (memcmp(p, bytes, numBytes) != 0) return 0; |
| |
| packet->cursor = p + numBytes; |
| return 1; |
| } |
| |
| /* parse and skip a given QNAME stored in a query packet, |
| * from the current cursor position. returns 1 on success, |
| * or 0 for malformed data. |
| */ |
| 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 */ |
| LOG(INFO) << __func__ << ": 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)) { |
| LOG(INFO) << __func__ << ": unsupported TYPE"; |
| return 0; |
| } |
| /* CLASS must be IN */ |
| if (!_dnsPacket_checkBytes(packet, 2, DNS_CLASS_IN)) { |
| LOG(INFO) << __func__ << ": 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) { |
| LOG(INFO) << __func__ << ": 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] & 0xCF) != 0) { |
| LOG(INFO) << __func__ << ": query packet flags unsupported"; |
| return 0; |
| } |
| |
| /* Note that we ignore the TC, RD, CD, and AD 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 query might depend on |
| * the RD, AD, and CD bits, so these bits |
| * should be used to differentiate cached result. |
| * |
| * this implies that these bits are 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 > 1) { |
| LOG(INFO) << __func__ << ": query packet contains non-query records"; |
| return 0; |
| } |
| |
| if (qdCount == 0) { |
| LOG(INFO) << __func__ << ": 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 **/ |
| 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; |
| } |
| |
| /** 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 */ |
| LOG(INFO) << __func__ << ": INTERNAL_ERROR: read-overflow"; |
| break; |
| } |
| |
| c = *p++; |
| |
| if (c == 0) break; |
| |
| if (c >= 64) { |
| LOG(INFO) << __func__ << ": INTERNAL_ERROR: malformed domain"; |
| break; |
| } |
| if (p + c >= end) { |
| LOG(INFO) << __func__ << ": INTERNAL_ERROR: simple label read-overflow"; |
| 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_hashRR(DnsPacket* packet, unsigned hash) { |
| int rdlength; |
| hash = _dnsPacket_hashQR(packet, hash); |
| hash = _dnsPacket_hashBytes(packet, 4, hash); /* TTL */ |
| rdlength = _dnsPacket_readInt16(packet); |
| hash = _dnsPacket_hashBytes(packet, rdlength, hash); /* RDATA */ |
| return hash; |
| } |
| |
| static unsigned _dnsPacket_hashQuery(DnsPacket* packet) { |
| unsigned hash = FNV_BASIS; |
| int count, arcount; |
| _dnsPacket_rewind(packet); |
| |
| /* ignore the ID */ |
| _dnsPacket_skip(packet, 2); |
| |
| /* 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); |
| |
| /* mark the first header byte as processed */ |
| _dnsPacket_skip(packet, 1); |
| |
| /* process the second header byte */ |
| hash = _dnsPacket_hashBytes(packet, 1, hash); |
| |
| /* read QDCOUNT */ |
| count = _dnsPacket_readInt16(packet); |
| |
| /* assume: ANcount and NScount are 0 */ |
| _dnsPacket_skip(packet, 4); |
| |
| /* read ARCOUNT */ |
| arcount = _dnsPacket_readInt16(packet); |
| |
| /* hash QDCOUNT QRs */ |
| for (; count > 0; count--) hash = _dnsPacket_hashQR(packet, hash); |
| |
| /* hash ARCOUNT RRs */ |
| for (; arcount > 0; arcount--) hash = _dnsPacket_hashRR(packet, hash); |
| |
| return hash; |
| } |
| |
| /** QUERY COMPARISON |
| ** |
| ** THE FOLLOWING CODE ASSUMES THAT THE INPUT PACKETS HAVE ALREADY |
| ** BEEN SUCCESSFULLY 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) { |
| LOG(INFO) << __func__ << ": INTERNAL_ERROR: read-overflow"; |
| break; |
| } |
| c1 = *p1++; |
| c2 = *p2++; |
| if (c1 != c2) break; |
| |
| if (c1 == 0) { |
| pack1->cursor = p1; |
| pack2->cursor = p2; |
| return 1; |
| } |
| if (c1 >= 64) { |
| LOG(INFO) << __func__ << ": INTERNAL_ERROR: malformed domain"; |
| break; |
| } |
| if ((p1 + c1 > end1) || (p2 + c1 > end2)) { |
| LOG(INFO) << __func__ << ": INTERNAL_ERROR: simple label read-overflow"; |
| 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 */ |
| LOG(INFO) << __func__ << ": 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_isEqualRR(DnsPacket* pack1, DnsPacket* pack2) { |
| int rdlength1, rdlength2; |
| /* compare query + TTL */ |
| if (!_dnsPacket_isEqualQR(pack1, pack2) || !_dnsPacket_isEqualBytes(pack1, pack2, 4)) return 0; |
| |
| /* compare RDATA */ |
| rdlength1 = _dnsPacket_readInt16(pack1); |
| rdlength2 = _dnsPacket_readInt16(pack2); |
| if (rdlength1 != rdlength2 || !_dnsPacket_isEqualBytes(pack1, pack2, rdlength1)) return 0; |
| |
| return 1; |
| } |
| |
| static int _dnsPacket_isEqualQuery(DnsPacket* pack1, DnsPacket* pack2) { |
| int count1, count2, arcount1, arcount2; |
| |
| /* 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)) { |
| LOG(INFO) << __func__ << ": different RD"; |
| return 0; |
| } |
| |
| if (pack1->base[3] != pack2->base[3]) { |
| LOG(INFO) << __func__ << ": different CD or AD"; |
| return 0; |
| } |
| |
| /* mark ID and header bytes as compared */ |
| _dnsPacket_skip(pack1, 4); |
| _dnsPacket_skip(pack2, 4); |
| |
| /* compare QDCOUNT */ |
| count1 = _dnsPacket_readInt16(pack1); |
| count2 = _dnsPacket_readInt16(pack2); |
| if (count1 != count2 || count1 < 0) { |
| LOG(INFO) << __func__ << ": different QDCOUNT"; |
| return 0; |
| } |
| |
| /* assume: ANcount and NScount are 0 */ |
| _dnsPacket_skip(pack1, 4); |
| _dnsPacket_skip(pack2, 4); |
| |
| /* compare ARCOUNT */ |
| arcount1 = _dnsPacket_readInt16(pack1); |
| arcount2 = _dnsPacket_readInt16(pack2); |
| if (arcount1 != arcount2 || arcount1 < 0) { |
| LOG(INFO) << __func__ << ": different ARCOUNT"; |
| return 0; |
| } |
| |
| /* compare the QDCOUNT QRs */ |
| for (; count1 > 0; count1--) { |
| if (!_dnsPacket_isEqualQR(pack1, pack2)) { |
| LOG(INFO) << __func__ << ": different QR"; |
| return 0; |
| } |
| } |
| |
| /* compare the ARCOUNT RRs */ |
| for (; arcount1 > 0; arcount1--) { |
| if (!_dnsPacket_isEqualRR(pack1, pack2)) { |
| LOG(INFO) << __func__ << ": different additional RR"; |
| 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 = ntohl(*reinterpret_cast<const uint32_t*>(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((const uint8_t*) 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 { |
| PLOG(INFO) << __func__ << ": ns_parserr failed ancount no = " << n; |
| } |
| } |
| } |
| } else { |
| PLOG(INFO) << __func__ << ": ns_initparse failed"; |
| } |
| |
| LOG(INFO) << __func__ << ": TTL = " << result; |
| return result; |
| } |
| |
| static void entry_free(Entry* e) { |
| /* everything is allocated in a single memory block */ |
| if (e) { |
| free(e); |
| } |
| } |
| |
| static void entry_mru_remove(Entry* e) { |
| e->mru_prev->mru_next = e->mru_next; |
| e->mru_next->mru_prev = e->mru_prev; |
| } |
| |
| static 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 = (const uint8_t*) query; |
| e->querylen = querylen; |
| e->hash = entry_hash(e); |
| |
| _dnsPacket_init(pack, e->query, e->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 = (Entry*) 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 */ |
| constexpr int PENDING_REQUEST_TIMEOUT = 20; |
| |
| typedef struct resolv_cache { |
| int max_entries; |
| int num_entries; |
| Entry mru_list; |
| int last_id; |
| Entry* entries; |
| struct pending_req_info { |
| unsigned int hash; |
| struct pending_req_info* next; |
| } pending_requests; |
| } Cache; |
| |
| struct resolv_cache_info { |
| unsigned netid; |
| Cache* cache; |
| struct resolv_cache_info* next; |
| int nscount; |
| char* nameservers[MAXNS]; |
| struct addrinfo* nsaddrinfo[MAXNS]; |
| int revision_id; // # times the nameservers have been replaced |
| res_params params; |
| struct res_stats nsstats[MAXNS]; |
| char defdname[MAXDNSRCHPATH]; |
| int dnsrch_offset[MAXDNSRCH + 1]; // offsets into defdname |
| int wait_for_pending_req_timeout_count; |
| }; |
| |
| // A helper class for the Clang Thread Safety Analysis to deal with |
| // std::unique_lock. |
| class SCOPED_CAPABILITY ScopedAssumeLocked { |
| public: |
| ScopedAssumeLocked(std::mutex& mutex) ACQUIRE(mutex) {} |
| ~ScopedAssumeLocked() RELEASE() {} |
| }; |
| |
| // lock protecting everything in the resolve_cache_info structs (next ptr, etc) |
| static std::mutex cache_mutex; |
| static std::condition_variable cv; |
| |
| /* gets cache associated with a network, or NULL if none exists */ |
| static resolv_cache* find_named_cache_locked(unsigned netid) REQUIRES(cache_mutex); |
| static int resolv_create_cache_for_net_locked(unsigned netid) REQUIRES(cache_mutex); |
| |
| static void cache_flush_pending_requests_locked(struct resolv_cache* cache) { |
| resolv_cache::pending_req_info *ri, *tmp; |
| if (!cache) return; |
| |
| ri = cache->pending_requests.next; |
| |
| while (ri) { |
| tmp = ri; |
| ri = ri->next; |
| free(tmp); |
| } |
| |
| cache->pending_requests.next = NULL; |
| cv.notify_all(); |
| } |
| |
| // Return true - if there is a pending request in |cache| matching |key|. |
| // Return false - if no pending request is found matching the key. Optionally |
| // link a new one if parameter append_if_not_found is true. |
| static bool cache_has_pending_request_locked(resolv_cache* cache, const Entry* key, |
| bool append_if_not_found) { |
| if (!cache || !key) return false; |
| |
| resolv_cache::pending_req_info* ri = cache->pending_requests.next; |
| resolv_cache::pending_req_info* prev = &cache->pending_requests; |
| while (ri) { |
| if (ri->hash == key->hash) { |
| return true; |
| } |
| prev = ri; |
| ri = ri->next; |
| } |
| |
| if (append_if_not_found) { |
| ri = (resolv_cache::pending_req_info*)calloc(1, sizeof(resolv_cache::pending_req_info)); |
| if (ri) { |
| ri->hash = key->hash; |
| prev->next = ri; |
| } |
| } |
| return false; |
| } |
| |
| // Notify all threads that the cache entry |key| has become available |
| static void _cache_notify_waiting_tid_locked(struct resolv_cache* cache, const Entry* key) { |
| if (!cache || !key) return; |
| |
| resolv_cache::pending_req_info* ri = cache->pending_requests.next; |
| resolv_cache::pending_req_info* prev = &cache->pending_requests; |
| while (ri) { |
| if (ri->hash == key->hash) { |
| // remove item from list and destroy |
| prev->next = ri->next; |
| free(ri); |
| cv.notify_all(); |
| return; |
| } |
| prev = ri; |
| ri = ri->next; |
| } |
| } |
| |
| void _resolv_cache_query_failed(unsigned netid, const void* query, int querylen, uint32_t flags) { |
| // We should not notify with these flags. |
| if (flags & (ANDROID_RESOLV_NO_CACHE_STORE | ANDROID_RESOLV_NO_CACHE_LOOKUP)) { |
| return; |
| } |
| Entry key[1]; |
| Cache* cache; |
| |
| if (!entry_init_key(key, query, querylen)) return; |
| |
| std::lock_guard guard(cache_mutex); |
| |
| cache = find_named_cache_locked(netid); |
| |
| if (cache) { |
| _cache_notify_waiting_tid_locked(cache, key); |
| } |
| } |
| |
| 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; |
| |
| LOG(INFO) << __func__ << ": *** DNS CACHE FLUSHED ***"; |
| } |
| |
| static resolv_cache* resolv_cache_create() { |
| struct resolv_cache* cache; |
| |
| cache = (struct resolv_cache*) calloc(sizeof(*cache), 1); |
| if (cache) { |
| cache->max_entries = CONFIG_MAX_ENTRIES; |
| cache->entries = (Entry*) calloc(sizeof(*cache->entries), cache->max_entries); |
| if (cache->entries) { |
| cache->mru_list.mru_prev = cache->mru_list.mru_next = &cache->mru_list; |
| LOG(INFO) << __func__ << ": cache created"; |
| } else { |
| free(cache); |
| cache = NULL; |
| } |
| } |
| return cache; |
| } |
| |
| static void dump_query(const uint8_t* query, int querylen) { |
| if (!WOULD_LOG(VERBOSE)) return; |
| |
| char temp[256], *p = temp, *end = p + sizeof(temp); |
| DnsPacket pack[1]; |
| |
| _dnsPacket_init(pack, query, querylen); |
| p = dnsPacket_bprintQuery(pack, p, end); |
| LOG(VERBOSE) << __func__ << ": " << 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); |
| |
| LOG(INFO) << __func__ << ": " << temp; |
| } |
| |
| /* 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; |
| |
| LOG(INFO) << __func__ << ": entry " << e->id << " added (count=" << 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; |
| |
| LOG(INFO) << __func__ << ": entry " << e->id << " removed (count=" << 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 */ |
| LOG(INFO) << __func__ << ": OLDEST NOT IN HTABLE ?"; |
| return; |
| } |
| LOG(INFO) << __func__ << ": Cache full - removing oldest"; |
| dump_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 */ |
| LOG(INFO) << __func__ << ": ENTRY NOT IN HTABLE ?"; |
| return; |
| } |
| e = e->mru_next; |
| _cache_remove_p(cache, lookup); |
| } else { |
| e = e->mru_next; |
| } |
| } |
| } |
| |
| // gets a resolv_cache_info associated with a network, or NULL if not found |
| static resolv_cache_info* find_cache_info_locked(unsigned netid) REQUIRES(cache_mutex); |
| |
| ResolvCacheStatus resolv_cache_lookup(unsigned netid, const void* query, int querylen, void* answer, |
| int answersize, int* answerlen, uint32_t flags) { |
| // Skip cache lookup, return RESOLV_CACHE_NOTFOUND directly so that it is |
| // possible to cache the answer of this query. |
| // If ANDROID_RESOLV_NO_CACHE_STORE is set, return RESOLV_CACHE_SKIP to skip possible cache |
| // storing. |
| if (flags & ANDROID_RESOLV_NO_CACHE_LOOKUP) { |
| return flags & ANDROID_RESOLV_NO_CACHE_STORE ? RESOLV_CACHE_SKIP : RESOLV_CACHE_NOTFOUND; |
| } |
| Entry key; |
| Entry** lookup; |
| Entry* e; |
| time_t now; |
| Cache* cache; |
| |
| LOG(INFO) << __func__ << ": lookup"; |
| dump_query((u_char*) query, querylen); |
| |
| /* we don't cache malformed queries */ |
| if (!entry_init_key(&key, query, querylen)) { |
| LOG(INFO) << __func__ << ": unsupported query"; |
| return RESOLV_CACHE_UNSUPPORTED; |
| } |
| /* lookup cache */ |
| std::unique_lock lock(cache_mutex); |
| ScopedAssumeLocked assume_lock(cache_mutex); |
| cache = find_named_cache_locked(netid); |
| if (cache == nullptr) { |
| return RESOLV_CACHE_UNSUPPORTED; |
| } |
| |
| /* 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) { |
| LOG(INFO) << __func__ << ": NOT IN CACHE"; |
| // If it is no-cache-store mode, we won't wait for possible query. |
| if (flags & ANDROID_RESOLV_NO_CACHE_STORE) { |
| return RESOLV_CACHE_SKIP; |
| } |
| |
| if (!cache_has_pending_request_locked(cache, &key, true)) { |
| return RESOLV_CACHE_NOTFOUND; |
| |
| } else { |
| LOG(INFO) << __func__ << ": Waiting for previous request"; |
| // wait until (1) timeout OR |
| // (2) cv is notified AND no pending request matching the |key| |
| // (cv notifier should delete pending request before sending notification.) |
| bool ret = cv.wait_for(lock, std::chrono::seconds(PENDING_REQUEST_TIMEOUT), |
| [netid, &cache, &key]() REQUIRES(cache_mutex) { |
| // Must update cache as it could have been deleted |
| cache = find_named_cache_locked(netid); |
| return !cache_has_pending_request_locked(cache, &key, false); |
| }); |
| if (!cache) { |
| return RESOLV_CACHE_NOTFOUND; |
| } |
| if (ret == false) { |
| resolv_cache_info* info = find_cache_info_locked(netid); |
| if (info != NULL) { |
| info->wait_for_pending_req_timeout_count++; |
| } |
| } |
| lookup = _cache_lookup_p(cache, &key); |
| e = *lookup; |
| if (e == NULL) { |
| return RESOLV_CACHE_NOTFOUND; |
| } |
| } |
| } |
| |
| now = _time_now(); |
| |
| /* remove stale entries here */ |
| if (now >= e->expires) { |
| LOG(INFO) << __func__ << ": NOT IN CACHE (STALE ENTRY " << *lookup << "DISCARDED)"; |
| dump_query(e->query, e->querylen); |
| _cache_remove_p(cache, lookup); |
| return RESOLV_CACHE_NOTFOUND; |
| } |
| |
| *answerlen = e->answerlen; |
| if (e->answerlen > answersize) { |
| /* NOTE: we return UNSUPPORTED if the answer buffer is too short */ |
| LOG(INFO) << __func__ << ": ANSWER TOO LONG"; |
| return RESOLV_CACHE_UNSUPPORTED; |
| } |
| |
| 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); |
| } |
| |
| LOG(INFO) << __func__ << ": FOUND IN CACHE entry=" << e; |
| return RESOLV_CACHE_FOUND; |
| } |
| |
| int resolv_cache_add(unsigned netid, const void* query, int querylen, const void* answer, |
| int answerlen) { |
| Entry key[1]; |
| Entry* e; |
| Entry** lookup; |
| u_long ttl; |
| Cache* cache = NULL; |
| |
| /* don't assume that the query has already been cached |
| */ |
| if (!entry_init_key(key, query, querylen)) { |
| LOG(INFO) << __func__ << ": passed invalid query?"; |
| return -EINVAL; |
| } |
| |
| std::lock_guard guard(cache_mutex); |
| |
| cache = find_named_cache_locked(netid); |
| if (cache == nullptr) { |
| return -ENONET; |
| } |
| |
| LOG(INFO) << __func__ << ": query:"; |
| dump_query((u_char*)query, querylen); |
| res_pquery((u_char*)answer, answerlen); |
| if (kDumpData) { |
| LOG(INFO) << __func__ << ": answer:"; |
| dump_bytes((u_char*)answer, answerlen); |
| } |
| |
| lookup = _cache_lookup_p(cache, key); |
| e = *lookup; |
| |
| // Should only happen on ANDROID_RESOLV_NO_CACHE_LOOKUP |
| if (e != NULL) { |
| LOG(INFO) << __func__ << ": ALREADY IN CACHE (" << e << ") ? IGNORING ADD"; |
| _cache_notify_waiting_tid_locked(cache, key); |
| return -EEXIST; |
| } |
| |
| if (cache->num_entries >= cache->max_entries) { |
| _cache_remove_expired(cache); |
| if (cache->num_entries >= cache->max_entries) { |
| _cache_remove_oldest(cache); |
| } |
| // TODO: It looks useless, remove below code after having test to prove it. |
| lookup = _cache_lookup_p(cache, key); |
| e = *lookup; |
| if (e != NULL) { |
| LOG(INFO) << __func__ << ": ALREADY IN CACHE (" << e << ") ? IGNORING ADD"; |
| _cache_notify_waiting_tid_locked(cache, key); |
| return -EEXIST; |
| } |
| } |
| |
| 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); |
| } |
| } |
| |
| cache_dump_mru(cache); |
| _cache_notify_waiting_tid_locked(cache, key); |
| |
| return 0; |
| } |
| |
| // Head of the list of caches. |
| static struct resolv_cache_info res_cache_list GUARDED_BY(cache_mutex); |
| |
| // insert resolv_cache_info into the list of resolv_cache_infos |
| static void insert_cache_info_locked(resolv_cache_info* cache_info); |
| // creates a resolv_cache_info |
| static resolv_cache_info* create_cache_info(); |
| // empty the nameservers set for the named cache |
| static void free_nameservers_locked(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(resolv_cache_info* cache_info, const char** servers, |
| int numservers); |
| // clears the stats samples contained withing the given cache_info |
| static void res_cache_clear_stats_locked(resolv_cache_info* cache_info); |
| |
| // public API for netd to query if name server is set on specific netid |
| bool resolv_has_nameservers(unsigned netid) { |
| std::lock_guard guard(cache_mutex); |
| resolv_cache_info* info = find_cache_info_locked(netid); |
| return (info != nullptr) && (info->nscount > 0); |
| } |
| |
| static int resolv_create_cache_for_net_locked(unsigned netid) { |
| resolv_cache* cache = find_named_cache_locked(netid); |
| // Should not happen |
| if (cache) { |
| LOG(ERROR) << __func__ << ": Cache is already created, netId: " << netid; |
| return -EEXIST; |
| } |
| |
| resolv_cache_info* cache_info = create_cache_info(); |
| if (!cache_info) return -ENOMEM; |
| cache = resolv_cache_create(); |
| if (!cache) { |
| free(cache_info); |
| return -ENOMEM; |
| } |
| cache_info->cache = cache; |
| cache_info->netid = netid; |
| insert_cache_info_locked(cache_info); |
| |
| return 0; |
| } |
| |
| int resolv_create_cache_for_net(unsigned netid) { |
| std::lock_guard guard(cache_mutex); |
| return resolv_create_cache_for_net_locked(netid); |
| } |
| |
| void resolv_delete_cache_for_net(unsigned netid) { |
| std::lock_guard guard(cache_mutex); |
| |
| struct resolv_cache_info* prev_cache_info = &res_cache_list; |
| |
| while (prev_cache_info->next) { |
| struct resolv_cache_info* cache_info = prev_cache_info->next; |
| |
| if (cache_info->netid == netid) { |
| prev_cache_info->next = cache_info->next; |
| cache_flush_locked(cache_info->cache); |
| free(cache_info->cache->entries); |
| free(cache_info->cache); |
| free_nameservers_locked(cache_info); |
| free(cache_info); |
| break; |
| } |
| |
| prev_cache_info = prev_cache_info->next; |
| } |
| } |
| |
| std::vector<unsigned> resolv_list_caches() { |
| std::lock_guard guard(cache_mutex); |
| struct resolv_cache_info* cache_info = res_cache_list.next; |
| std::vector<unsigned> result; |
| while (cache_info) { |
| result.push_back(cache_info->netid); |
| cache_info = cache_info->next; |
| } |
| return result; |
| } |
| |
| static resolv_cache_info* create_cache_info() { |
| return (struct resolv_cache_info*) calloc(sizeof(struct resolv_cache_info), 1); |
| } |
| |
| // TODO: convert this to a simple and efficient C++ container. |
| 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 resolv_cache* find_named_cache_locked(unsigned netid) { |
| resolv_cache_info* info = find_cache_info_locked(netid); |
| if (info != nullptr) return info->cache; |
| return nullptr; |
| } |
| |
| static 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; |
| } |
| |
| static void resolv_set_default_params(res_params* params) { |
| params->sample_validity = NSSAMPLE_VALIDITY; |
| params->success_threshold = SUCCESS_THRESHOLD; |
| params->min_samples = 0; |
| params->max_samples = 0; |
| params->base_timeout_msec = 0; // 0 = legacy algorithm |
| params->retry_count = 0; |
| } |
| |
| static void resolv_set_experiment_params(res_params* params) { |
| using android::base::ParseInt; |
| using server_configurable_flags::GetServerConfigurableFlag; |
| |
| if (params->retry_count == 0) { |
| params->retry_count = RES_DFLRETRY; |
| ParseInt(GetServerConfigurableFlag("netd_native", "retry_count", ""), ¶ms->retry_count); |
| } |
| |
| if (params->base_timeout_msec == 0) { |
| params->base_timeout_msec = RES_TIMEOUT; |
| ParseInt(GetServerConfigurableFlag("netd_native", "retransmission_time_interval", ""), |
| ¶ms->base_timeout_msec); |
| } |
| } |
| |
| int resolv_set_nameservers_for_net(unsigned netid, const char** servers, const int numservers, |
| const char* domains, const res_params* params) { |
| char* cp; |
| int* offset; |
| struct addrinfo* nsaddrinfo[MAXNS]; |
| |
| if (numservers > MAXNS) { |
| LOG(ERROR) << __func__ << ": numservers=" << numservers << ", MAXNS=" << MAXNS; |
| return E2BIG; |
| } |
| |
| // Parse the addresses before actually locking or changing any state, in case there is an error. |
| // As a side effect this also reduces the time the lock is kept. |
| char sbuf[NI_MAXSERV]; |
| snprintf(sbuf, sizeof(sbuf), "%u", NAMESERVER_PORT); |
| for (int i = 0; i < numservers; i++) { |
| // The addrinfo structures allocated here are freed in free_nameservers_locked(). |
| const addrinfo hints = { |
| .ai_family = AF_UNSPEC, .ai_socktype = SOCK_DGRAM, .ai_flags = AI_NUMERICHOST}; |
| int rt = getaddrinfo_numeric(servers[i], sbuf, hints, &nsaddrinfo[i]); |
| if (rt != 0) { |
| for (int j = 0; j < i; j++) { |
| freeaddrinfo(nsaddrinfo[j]); |
| } |
| LOG(INFO) << __func__ << ": getaddrinfo_numeric(" << servers[i] |
| << ") = " << gai_strerror(rt); |
| return EINVAL; |
| } |
| } |
| |
| std::lock_guard guard(cache_mutex); |
| |
| resolv_cache_info* cache_info = find_cache_info_locked(netid); |
| |
| if (cache_info == NULL) return ENONET; |
| |
| uint8_t old_max_samples = cache_info->params.max_samples; |
| if (params != NULL) { |
| cache_info->params = *params; |
| } else { |
| resolv_set_default_params(&cache_info->params); |
| } |
| resolv_set_experiment_params(&cache_info->params); |
| if (!resolv_is_nameservers_equal_locked(cache_info, servers, numservers)) { |
| // free current before adding new |
| free_nameservers_locked(cache_info); |
| for (int i = 0; i < numservers; i++) { |
| cache_info->nsaddrinfo[i] = nsaddrinfo[i]; |
| cache_info->nameservers[i] = strdup(servers[i]); |
| LOG(INFO) << __func__ << ": netid = " << netid << ", addr = " << servers[i]; |
| } |
| cache_info->nscount = numservers; |
| |
| // Clear the NS statistics because the mapping to nameservers might have changed. |
| res_cache_clear_stats_locked(cache_info); |
| |
| // increment the revision id to ensure that sample state is not written back if the |
| // servers change; in theory it would suffice to do so only if the servers or |
| // max_samples actually change, in practice the overhead of checking is higher than the |
| // cost, and overflows are unlikely |
| ++cache_info->revision_id; |
| } else { |
| if (cache_info->params.max_samples != old_max_samples) { |
| // If the maximum number of samples changes, the overhead of keeping the most recent |
| // samples around is not considered worth the effort, so they are cleared instead. |
| // All other parameters do not affect shared state: Changing these parameters does |
| // not invalidate the samples, as they only affect aggregation and the conditions |
| // under which servers are considered usable. |
| res_cache_clear_stats_locked(cache_info); |
| ++cache_info->revision_id; |
| } |
| for (int j = 0; j < numservers; j++) { |
| freeaddrinfo(nsaddrinfo[j]); |
| } |
| } |
| |
| // Always update the search paths, since determining whether they actually changed is |
| // complex due to the zero-padding, and probably not worth the effort. Cache-flushing |
| // however is not necessary, since the stored cache entries do contain the domain, not |
| // just the host name. |
| strlcpy(cache_info->defdname, domains, sizeof(cache_info->defdname)); |
| if ((cp = strchr(cache_info->defdname, '\n')) != NULL) *cp = '\0'; |
| LOG(INFO) << __func__ << ": domains=\"" << cache_info->defdname << "\""; |
| |
| 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 */ |
| |
| return 0; |
| } |
| |
| static int resolv_is_nameservers_equal_locked(resolv_cache_info* cache_info, const char** servers, |
| int numservers) { |
| if (cache_info->nscount != numservers) { |
| return 0; |
| } |
| |
| // Compare each name server against current name servers. |
| // TODO: this is incorrect if the list of current or previous nameservers |
| // contains duplicates. This does not really matter because the framework |
| // filters out duplicates, but we should probably fix it. It's also |
| // insensitive to the order of the nameservers; we should probably fix that |
| // too. |
| for (int i = 0; i < numservers; i++) { |
| for (int j = 0;; j++) { |
| if (j >= numservers) { |
| return 0; |
| } |
| if (strcmp(cache_info->nameservers[i], servers[j]) == 0) { |
| break; |
| } |
| } |
| } |
| |
| return 1; |
| } |
| |
| static void free_nameservers_locked(resolv_cache_info* cache_info) { |
| int i; |
| for (i = 0; i < cache_info->nscount; 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; |
| } |
| cache_info->nsstats[i].sample_count = cache_info->nsstats[i].sample_next = 0; |
| } |
| cache_info->nscount = 0; |
| res_cache_clear_stats_locked(cache_info); |
| ++cache_info->revision_id; |
| } |
| |
| void _resolv_populate_res_for_net(res_state statp) { |
| if (statp == NULL) { |
| return; |
| } |
| LOG(INFO) << __func__ << ": netid=" << statp->netid; |
| |
| std::lock_guard guard(cache_mutex); |
| resolv_cache_info* info = find_cache_info_locked(statp->netid); |
| if (info != NULL) { |
| int nserv; |
| struct addrinfo* ai; |
| 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 { |
| LOG(INFO) << __func__ << ": found too long addrlen"; |
| } |
| } |
| 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 |
| // WARNING: Don't use str*cpy() here, this string contains zeroes. |
| memcpy(statp->defdname, info->defdname, sizeof(statp->defdname)); |
| char** pp = statp->dnsrch; |
| int* p = info->dnsrch_offset; |
| while (pp < statp->dnsrch + MAXDNSRCH && *p != -1) { |
| *pp++ = &statp->defdname[0] + *p++; |
| } |
| } |
| } |
| |
| /* Resolver reachability statistics. */ |
| |
| static void _res_cache_add_stats_sample_locked(res_stats* stats, const res_sample* sample, |
| int max_samples) { |
| // Note: This function expects max_samples > 0, otherwise a (harmless) modification of the |
| // allocated but supposedly unused memory for samples[0] will happen |
| LOG(INFO) << __func__ << ": adding sample to stats, next = " << unsigned(stats->sample_next) |
| << ", count = " << unsigned(stats->sample_count); |
| stats->samples[stats->sample_next] = *sample; |
| if (stats->sample_count < max_samples) { |
| ++stats->sample_count; |
| } |
| if (++stats->sample_next >= max_samples) { |
| stats->sample_next = 0; |
| } |
| } |
| |
| static void res_cache_clear_stats_locked(resolv_cache_info* cache_info) { |
| if (cache_info) { |
| for (int i = 0; i < MAXNS; ++i) { |
| cache_info->nsstats->sample_count = cache_info->nsstats->sample_next = 0; |
| } |
| } |
| } |
| |
| int android_net_res_stats_get_info_for_net(unsigned netid, int* nscount, |
| struct sockaddr_storage servers[MAXNS], int* dcount, |
| char domains[MAXDNSRCH][MAXDNSRCHPATH], |
| res_params* params, struct res_stats stats[MAXNS], |
| int* wait_for_pending_req_timeout_count) { |
| int revision_id = -1; |
| std::lock_guard guard(cache_mutex); |
| |
| resolv_cache_info* info = find_cache_info_locked(netid); |
| if (info) { |
| if (info->nscount > MAXNS) { |
| LOG(INFO) << __func__ << ": nscount " << info->nscount << " > MAXNS " << MAXNS; |
| errno = EFAULT; |
| return -1; |
| } |
| int i; |
| for (i = 0; i < info->nscount; i++) { |
| // Verify that the following assumptions are held, failure indicates corruption: |
| // - getaddrinfo() may never return a sockaddr > sockaddr_storage |
| // - all addresses are valid |
| // - there is only one address per addrinfo thanks to numeric resolution |
| int addrlen = info->nsaddrinfo[i]->ai_addrlen; |
| if (addrlen < (int) sizeof(struct sockaddr) || addrlen > (int) sizeof(servers[0])) { |
| LOG(INFO) << __func__ << ": nsaddrinfo[" << i << "].ai_addrlen == " << addrlen; |
| errno = EMSGSIZE; |
| return -1; |
| } |
| if (info->nsaddrinfo[i]->ai_addr == NULL) { |
| LOG(INFO) << __func__ << ": nsaddrinfo[" << i << "].ai_addr == NULL"; |
| errno = ENOENT; |
| return -1; |
| } |
| if (info->nsaddrinfo[i]->ai_next != NULL) { |
| LOG(INFO) << __func__ << ": nsaddrinfo[" << i << "].ai_next != NULL"; |
| errno = ENOTUNIQ; |
| return -1; |
| } |
| } |
| *nscount = info->nscount; |
| for (i = 0; i < info->nscount; i++) { |
| memcpy(&servers[i], info->nsaddrinfo[i]->ai_addr, info->nsaddrinfo[i]->ai_addrlen); |
| stats[i] = info->nsstats[i]; |
| } |
| for (i = 0; i < MAXDNSRCH; i++) { |
| const char* cur_domain = info->defdname + info->dnsrch_offset[i]; |
| // dnsrch_offset[i] can either be -1 or point to an empty string to indicate the end |
| // of the search offsets. Checking for < 0 is not strictly necessary, but safer. |
| // TODO: Pass in a search domain array instead of a string to |
| // resolv_set_nameservers_for_net() and make this double check unnecessary. |
| if (info->dnsrch_offset[i] < 0 || |
| ((size_t) info->dnsrch_offset[i]) >= sizeof(info->defdname) || !cur_domain[0]) { |
| break; |
| } |
| strlcpy(domains[i], cur_domain, MAXDNSRCHPATH); |
| } |
| *dcount = i; |
| *params = info->params; |
| revision_id = info->revision_id; |
| *wait_for_pending_req_timeout_count = info->wait_for_pending_req_timeout_count; |
| } |
| |
| return revision_id; |
| } |
| |
| int resolv_cache_get_resolver_stats(unsigned netid, res_params* params, res_stats stats[MAXNS]) { |
| std::lock_guard guard(cache_mutex); |
| resolv_cache_info* info = find_cache_info_locked(netid); |
| if (info) { |
| memcpy(stats, info->nsstats, sizeof(info->nsstats)); |
| *params = info->params; |
| return info->revision_id; |
| } |
| |
| return -1; |
| } |
| |
| void _resolv_cache_add_resolver_stats_sample(unsigned netid, int revision_id, int ns, |
| const res_sample* sample, int max_samples) { |
| if (max_samples <= 0) return; |
| |
| std::lock_guard guard(cache_mutex); |
| resolv_cache_info* info = find_cache_info_locked(netid); |
| |
| if (info && info->revision_id == revision_id) { |
| _res_cache_add_stats_sample_locked(&info->nsstats[ns], sample, max_samples); |
| } |
| } |
| |
| bool has_named_cache(unsigned netid) { |
| std::lock_guard guard(cache_mutex); |
| return find_named_cache_locked(netid) != nullptr; |
| } |
| |
| int resolv_cache_get_expiration(unsigned netid, const std::vector<char> query, time_t* expiration) { |
| Entry key; |
| Entry** lookup; |
| Entry* e; |
| Cache* cache; |
| *expiration = -1; |
| |
| // A malfored query is not allowed. |
| if (!entry_init_key(&key, query.data(), query.size())) { |
| LOG(WARNING) << __func__ << ": unsupported query"; |
| return -EINVAL; |
| } |
| |
| // lookup cache. |
| std::lock_guard guard(cache_mutex); |
| if (cache = find_named_cache_locked(netid); cache == nullptr) { |
| LOG(WARNING) << __func__ << ": cache not created in the network " << netid; |
| return -ENONET; |
| } |
| lookup = _cache_lookup_p(cache, &key); |
| e = *lookup; |
| if (e == NULL) { |
| LOG(WARNING) << __func__ << ": not in cache"; |
| return -ENODATA; |
| } |
| |
| if (_time_now() >= e->expires) { |
| LOG(WARNING) << __func__ << ": entry expired"; |
| return -ENODATA; |
| } |
| |
| *expiration = e->expires; |
| return 0; |
| } |