1 /* $NetBSD: resolv.h,v 1.31 2005/12/26 19:01:47 perry Exp $ */ 2 3 /* 4 * Copyright (c) 1983, 1987, 1989 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 34 * Portions Copyright (c) 1996-1999 by Internet Software Consortium. 35 * 36 * Permission to use, copy, modify, and distribute this software for any 37 * purpose with or without fee is hereby granted, provided that the above 38 * copyright notice and this permission notice appear in all copies. 39 * 40 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 41 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 42 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 43 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 44 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 45 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 46 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 47 */ 48 49 #pragma once 50 51 #include <android-base/logging.h> 52 #include <android-base/unique_fd.h> 53 #include <private/android_filesystem_config.h> // AID_DNS 54 55 #include <net/if.h> 56 #include <time.h> 57 #include <span> 58 #include <string> 59 #include <vector> 60 61 #include "DnsResolver.h" 62 #include "netd_resolv/resolv.h" 63 #include "params.h" 64 #include "stats.pb.h" 65 66 // Linux defines MAXHOSTNAMELEN as 64, while the domain name limit in 67 // RFC 1034 and RFC 1035 is 255 octets. 68 #ifdef MAXHOSTNAMELEN 69 #undef MAXHOSTNAMELEN 70 #endif 71 #define MAXHOSTNAMELEN 256 72 73 /* 74 * Global defines and variables for resolver stub. 75 */ 76 #define RES_TIMEOUT 5000 /* min. milliseconds between retries */ 77 #define RES_DFLRETRY 2 /* Default #/tries. */ 78 79 // Flags for ResState::flags 80 #define RES_F_VC 0x00000001 // socket is TCP 81 #define RES_F_EDNS0ERR 0x00000004 // EDNS0 caused errors 82 #define RES_F_MDNS 0x00000008 // MDNS packet 83 84 // Holds either a sockaddr_in or a sockaddr_in6. 85 union sockaddr_union { 86 struct sockaddr sa; 87 struct sockaddr_in sin; 88 struct sockaddr_in6 sin6; 89 }; 90 constexpr int MAXPACKET = 8 * 1024; 91 92 struct ResState { ResStateResState93 ResState(const android_net_context* netcontext, android::net::NetworkDnsEventReported* dnsEvent) 94 : netid(netcontext->dns_netid), 95 uid(netcontext->uid), 96 pid(netcontext->pid), 97 mark(netcontext->dns_mark), 98 event(dnsEvent), 99 netcontext_flags(netcontext->flags) {} 100 101 ResState clone(android::net::NetworkDnsEventReported* dnsEvent = nullptr) { 102 // TODO: Separate non-copyable members to other structures and let default copy 103 // constructor do its work for below copyable members. 104 ResState copy; 105 copy.netid = netid; 106 copy.uid = uid; 107 copy.pid = pid; 108 copy.search_domains = search_domains; 109 copy.nsaddrs = nsaddrs; 110 copy.udpsocks_ts = udpsocks_ts; 111 copy.ndots = ndots; 112 copy.mark = mark; 113 copy.tcp_nssock_ts = tcp_nssock_ts; 114 copy.flags = flags; 115 copy.event = (dnsEvent == nullptr) ? event : dnsEvent; 116 copy.netcontext_flags = netcontext_flags; 117 copy.tc_mode = tc_mode; 118 copy.enforce_dns_uid = enforce_dns_uid; 119 copy.sort_nameservers = sort_nameservers; 120 return copy; 121 } closeSocketsResState122 void closeSockets() { 123 tcp_nssock.reset(); 124 flags &= ~RES_F_VC; 125 126 for (auto& sock : udpsocks) { 127 sock.reset(); 128 } 129 } 130 nameserverCountResState131 int nameserverCount() { return nsaddrs.size(); } 132 133 // clang-format off 134 unsigned netid; // NetId: cache key and socket mark 135 uid_t uid; // uid of the app that sent the DNS lookup 136 pid_t pid; // pid of the app that sent the DNS lookup 137 std::vector<std::string> search_domains{}; // domains to search 138 std::vector<android::netdutils::IPSockAddr> nsaddrs; 139 std::array<timespec, MAXNS> udpsocks_ts; // The creation time of the UDP sockets 140 android::base::unique_fd udpsocks[MAXNS]; // UDP sockets to nameservers 141 unsigned ndots : 4 = 1; // threshold for initial abs. query 142 unsigned mark; // Socket mark to be used by all DNS query sockets 143 android::base::unique_fd tcp_nssock; // TCP socket (but why not one per nameserver?) 144 timespec tcp_nssock_ts = {}; // The creation time of the TCP socket 145 uint32_t flags = 0; // See RES_F_* defines below 146 android::net::NetworkDnsEventReported* event; 147 uint32_t netcontext_flags; 148 int tc_mode = 0; 149 bool enforce_dns_uid = false; 150 bool sort_nameservers = false; // True if nsaddrs has been sorted. 151 // clang-format on 152 153 private: ResStateResState154 ResState() {} 155 }; 156 157 /* End of stats related definitions */ 158 159 /* 160 * Error code extending h_errno codes defined in bionic/libc/include/netdb.h. 161 * 162 * This error code, including legacy h_errno, is returned from res_nquery(), res_nsearch(), 163 * res_nquerydomain(), res_queryN_parallel(), res_searchN() and res_querydomainN() for DNS metrics. 164 * 165 * TODO: Consider mapping legacy and extended h_errno into a unified resolver error code mapping. 166 */ 167 #define NETD_RESOLV_H_ERRNO_EXT_TIMEOUT RCODE_TIMEOUT 168 169 extern const char* const _res_opcodes[]; 170 171 int res_nameinquery(const char*, int, int, const uint8_t*, const uint8_t*); 172 int res_queriesmatch(const uint8_t*, const uint8_t*, const uint8_t*, const uint8_t*); 173 174 int res_nquery(ResState*, const char*, int, int, std::span<uint8_t>, int*); 175 int res_nsearch(ResState*, const char*, int, int, std::span<uint8_t>, int*); 176 int res_nquerydomain(ResState*, const char*, const char*, int, int, std::span<uint8_t>, int*); 177 int res_nmkquery(int op, const char* qname, int cl, int type, std::span<const uint8_t> data, 178 std::span<uint8_t> msg, int netcontext_flags); 179 int res_nsend(ResState* statp, std::span<const uint8_t> msg, std::span<uint8_t> ans, int* rcode, 180 uint32_t flags, std::chrono::milliseconds sleepTimeMs = {}); 181 int res_nopt(ResState*, int, std::span<uint8_t>, int); 182 183 int getaddrinfo_numeric(const char* hostname, const char* servname, addrinfo hints, 184 addrinfo** result); 185 186 // Helper function for converting h_errno to the error codes visible to netd 187 int herrnoToAiErrno(int herrno); 188 189 // Helper function to enable MDNS resolution. 190 void setMdnsFlag(std::string_view hostname, unsigned netid, uint32_t* flags); 191 192 // Helper function for checking MDNS resolution is enabled or not. 193 bool isMdnsResolution(uint32_t flags); 194 195 // switch resolver log severity 196 android::base::LogSeverity logSeverityStrToEnum(const std::string& logSeverityStr); 197 198 template <typename Dest> saturate_cast(int64_t x)199 Dest saturate_cast(int64_t x) { 200 using DestLimits = std::numeric_limits<Dest>; 201 if (x > DestLimits::max()) return DestLimits::max(); 202 if (x < DestLimits::min()) return DestLimits::min(); 203 return static_cast<Dest>(x); 204 } 205 is_power_of_2(size_t n)206 constexpr bool is_power_of_2(size_t n) { 207 return n != 0 && (n & (n - 1)) == 0; 208 } 209 210 // Rounds up a pointer to a char buffer |p| to a multiple of |Alignment| bytes. 211 // Requirements: 212 // |p| must be a pointer to a byte-sized type (e.g.: uint8_t) 213 // |Alignment| must be a power of 2 214 template<uintptr_t Alignment = sizeof(void*), typename T> is_power_of_2(Alignment)215 requires (sizeof(T) == 1) && (is_power_of_2(Alignment)) 216 constexpr T* align_ptr(T* const p) { 217 // Written this way to sidestep the performance-no-int-to-ptr clang-tidy warning. 218 constexpr uintptr_t mask = Alignment - 1; 219 const uintptr_t uintptr = reinterpret_cast<uintptr_t>(p); 220 const uintptr_t aligned = (uintptr + mask) & ~mask; 221 const uintptr_t bias = aligned - uintptr; 222 return p + bias; 223 } 224 225 // Testcases for align_ptr() 226 // TODO: enable when libc++ has std::bit_cast - reinterpret_cast isn't allowed in consteval context 227 // static_assert(align_ptr((char*)1000) == (char*)1000); 228 // static_assert(align_ptr((char*)1001) == (char*)1000 + sizeof(void*)); 229 // static_assert(align_ptr((char*)1003) == (char*)1000 + sizeof(void*)); 230 // static_assert(align_ptr<sizeof(uint32_t)>((char*)1004) == (char*)1004); 231 // static_assert(align_ptr<sizeof(uint64_t)>((char*)1004) == (char*)1008); 232 233 android::net::NsType getQueryType(std::span<const uint8_t> msg); 234 235 android::net::IpVersion ipFamilyToIPVersion(int ipFamily); 236 resolv_tag_socket(int sock,uid_t uid,pid_t pid)237 inline void resolv_tag_socket(int sock, uid_t uid, pid_t pid) { 238 // This is effectively equivalent to testing for R+ 239 if (android::net::gResNetdCallbacks.tagSocket != nullptr) { 240 if (int err = android::net::gResNetdCallbacks.tagSocket(sock, TAG_SYSTEM_DNS, uid, pid)) { 241 LOG(WARNING) << "Failed to tag socket: " << strerror(-err); 242 } 243 } 244 245 // fchown() apps' uid only in R+, since it's incompatible with Q's ebpf vpn isolation feature. 246 if (fchown(sock, (android::net::gApiLevel >= 30) ? uid : AID_DNS, -1) == -1) { 247 PLOG(WARNING) << "Failed to chown socket"; 248 } 249 } 250