netwerk/dns/PlatformDNSAndroid.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=4 sw=2 sts=2 et cin: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "GetAddrInfo.h"
   8 #include "mozilla/net/DNSPacket.h"
   9 #include "nsIDNSService.h"
  10 #include "mozilla/Maybe.h"
  11 #include "mozilla/Atomics.h"
  12 #include "mozilla/StaticPrefs_network.h"
  13
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <netinet/in.h>
  18 #include <resolv.h>
  19 #include <poll.h>
  20 #include <dlfcn.h>
  21 #include <android/multinetwork.h>
  22
  23 namespace mozilla::net {
  24
  25 // The first call to ResolveHTTPSRecordImpl will load the library
  26 // and function pointers.
  27 static Atomic<bool> sLibLoading{false};
  28
  29 // https://developer.android.com/ndk/reference/group/networking#android_res_nquery
  30 // The function android_res_nquery is defined in <android/multinetwork.h>
  31 typedef int (*android_res_nquery_ptr)(net_handle_t network, const char* dname,
  32                                       int ns_class, int ns_type,
  33                                       uint32_t flags);
  34 static Atomic<android_res_nquery_ptr> sAndroidResNQuery;
  35
  36 #define LOG(msg, ...) \
  37   MOZ_LOG(gGetAddrInfoLog, LogLevel::Debug, ("[DNS]: " msg, ##__VA_ARGS__))
  38
  39 nsresult ResolveHTTPSRecordImpl(const nsACString& aHost, uint16_t aFlags,
  40                                 TypeRecordResultType& aResult, uint32_t& aTTL) {
  41   DNSPacket packet;
  42   nsAutoCString host(aHost);
  43   nsAutoCString cname;
  44   nsresult rv;
  45
  46   if (xpc::IsInAutomation() &&
  47       !StaticPrefs::network_dns_native_https_query_in_automation()) {
  48     return NS_ERROR_UNKNOWN_HOST;
  49   }
  50
  51   if (!sLibLoading.exchange(true)) {
  52     // We're the first call here, load the library and symbols.
  53     void* handle = dlopen("libandroid.so", RTLD_LAZY | RTLD_LOCAL);
  54     if (!handle) {
  55       LOG("Error loading libandroid_net %s", dlerror());
  56       return NS_ERROR_UNKNOWN_HOST;
  57     }
  58
  59     auto x = dlsym(handle, "android_res_nquery");
  60     if (!x) {
  61       LOG("No android_res_nquery symbol");
  62     }
  63
  64     sAndroidResNQuery = (android_res_nquery_ptr)x;
  65   }
  66
  67   if (!sAndroidResNQuery) {
  68     LOG("nquery not loaded");
  69     // The library hasn't been loaded yet.
  70     return NS_ERROR_UNKNOWN_HOST;
  71   }
  72
  73   LOG("resolving %s\n", host.get());
  74   // Perform the query
  75   rv = packet.FillBuffer(
  76       [&](unsigned char response[DNSPacket::MAX_SIZE]) -> int {
  77         int fd = 0;
  78         auto closeSocket = MakeScopeExit([&] {
  79           if (fd > 0) {
  80             close(fd);
  81           }
  82         });
  83         uint32_t flags = 0;
  84         if (aFlags & nsIDNSService::RESOLVE_BYPASS_CACHE) {
  85           flags = ANDROID_RESOLV_NO_CACHE_LOOKUP;
  86         }
  87         fd = sAndroidResNQuery(0, host.get(), ns_c_in,
  88                                nsIDNSService::RESOLVE_TYPE_HTTPSSVC, flags);
  89
  90         if (fd < 0) {
  91           LOG("DNS query failed");
  92           return fd;
  93         }
  94
  95         struct pollfd fds;
  96         fds.fd = fd;
  97         fds.events = POLLIN;  // Wait for read events
  98
  99         // Wait for an event on the file descriptor
 100         int ret = poll(&fds, 1,
 101                        StaticPrefs::network_dns_native_https_timeout_android());
 102         if (ret <= 0) {
 103           LOG("poll failed %d", ret);
 104           return -1;
 105         }
 106
 107         ssize_t len = recv(fd, response, DNSPacket::MAX_SIZE - 1, 0);
 108         if (len <= 8) {
 109           LOG("size too small %zd", len);
 110           return len < 0 ? len : -1;
 111         }
 112
 113         // The first 8 bytes are UDP header.
 114         // XXX: we should consider avoiding this move somehow.
 115         for (int i = 0; i < len - 8; i++) {
 116           response[i] = response[i + 8];
 117         }
 118
 119         return len - 8;
 120       });
 121   if (NS_FAILED(rv)) {
 122     LOG("failed rv");
 123     return rv;
 124   }
 125   packet.SetNativePacket(true);
 126
 127   int32_t loopCount = 64;
 128   while (loopCount > 0 && aResult.is<Nothing>()) {
 129     loopCount--;
 130     DOHresp resp;
 131     nsClassHashtable<nsCStringHashKey, DOHresp> additionalRecords;
 132     rv = packet.Decode(host, TRRTYPE_HTTPSSVC, cname, true, resp, aResult,
 133                        additionalRecords, aTTL);
 134     if (NS_FAILED(rv)) {
 135       LOG("Decode failed %x", static_cast<uint32_t>(rv));
 136       return rv;
 137     }
 138     if (!cname.IsEmpty() && aResult.is<Nothing>()) {
 139       host = cname;
 140       cname.Truncate();
 141       continue;
 142     }
 143   }
 144
 145   if (aResult.is<Nothing>()) {
 146     LOG("Result is nothing");
 147     // The call succeeded, but no HTTPS records were found.
 148     return NS_ERROR_UNKNOWN_HOST;
 149   }
 150
 151   return NS_OK;
 152 }
 153
 154 void DNSThreadShutdown() {}
 155
 156 }  // namespace mozilla::net