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/glean/NetwerkMetrics.h"
   9 #include "mozilla/net/DNSPacket.h"
  10 #include "nsIDNSService.h"
  11 #include "mozilla/Maybe.h"
  12 #include "mozilla/Atomics.h"
  13 #include "mozilla/StaticPrefs_network.h"
  14
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <netinet/in.h>
  19 #include <resolv.h>
  20 #include <poll.h>
  21 #include <dlfcn.h>
  22 #include <android/multinetwork.h>
  23
  24 namespace mozilla::net {
  25
  26 // The first call to ResolveHTTPSRecordImpl will load the library
  27 // and function pointers.
  28 static Atomic<bool> sLibLoading{false};
  29
  30 // https://developer.android.com/ndk/reference/group/networking#android_res_nquery
  31 // The function android_res_nquery is defined in <android/multinetwork.h>
  32 typedef int (*android_res_nquery_ptr)(net_handle_t network, const char* dname,
  33                                       int ns_class, int ns_type,
  34                                       uint32_t flags);
  35 static Atomic<android_res_nquery_ptr> sAndroidResNQuery;
  36
  37 #define LOG(msg, ...) \
  38   MOZ_LOG(gGetAddrInfoLog, LogLevel::Debug, ("[DNS]: " msg, ##__VA_ARGS__))
  39
  40 nsresult ResolveHTTPSRecordImpl(const nsACString& aHost,
  41                                 nsIDNSService::DNSFlags aFlags,
  42                                 TypeRecordResultType& aResult, uint32_t& aTTL) {
  43   DNSPacket packet;
  44   nsAutoCString host(aHost);
  45   nsAutoCString cname;
  46   nsresult rv;
  47
  48   if (xpc::IsInAutomation() &&
  49       !StaticPrefs::network_dns_native_https_query_in_automation()) {
  50     return NS_ERROR_UNKNOWN_HOST;
  51   }
  52
  53   if (!sLibLoading.exchange(true)) {
  54     // We're the first call here, load the library and symbols.
  55     void* handle = dlopen("libandroid.so", RTLD_LAZY | RTLD_LOCAL);
  56     if (!handle) {
  57       LOG("Error loading libandroid_net %s", dlerror());
  58       return NS_ERROR_UNKNOWN_HOST;
  59     }
  60
  61     auto x = dlsym(handle, "android_res_nquery");
  62     if (!x) {
  63       LOG("No android_res_nquery symbol");
  64     }
  65
  66     sAndroidResNQuery = (android_res_nquery_ptr)x;
  67   }
  68
  69   if (!sAndroidResNQuery) {
  70     LOG("nquery not loaded");
  71     // The library hasn't been loaded yet.
  72     return NS_ERROR_UNKNOWN_HOST;
  73   }
  74
  75   LOG("resolving %s\n", host.get());
  76   TimeStamp startTime = TimeStamp::Now();
  77   // Perform the query
  78   rv = packet.FillBuffer(
  79       [&](unsigned char response[DNSPacket::MAX_SIZE]) -> int {
  80         int fd = 0;
  81         auto closeSocket = MakeScopeExit([&] {
  82           if (fd > 0) {
  83             close(fd);
  84           }
  85         });
  86         uint32_t flags = 0;
  87         if (aFlags & nsIDNSService::RESOLVE_BYPASS_CACHE) {
  88           flags = ANDROID_RESOLV_NO_CACHE_LOOKUP;
  89         }
  90         fd = sAndroidResNQuery(0, host.get(), ns_c_in,
  91                                nsIDNSService::RESOLVE_TYPE_HTTPSSVC, flags);
  92
  93         if (fd < 0) {
  94           LOG("DNS query failed");
  95           return fd;
  96         }
  97
  98         struct pollfd fds;
  99         fds.fd = fd;
 100         fds.events = POLLIN;  // Wait for read events
 101
 102         // Wait for an event on the file descriptor
 103         int ret = poll(&fds, 1,
 104                        StaticPrefs::network_dns_native_https_timeout_android());
 105         if (ret <= 0) {
 106           LOG("poll failed %d", ret);
 107           return -1;
 108         }
 109
 110         ssize_t len = recv(fd, response, DNSPacket::MAX_SIZE - 1, 0);
 111         if (len <= 8) {
 112           LOG("size too small %zd", len);
 113           return len < 0 ? len : -1;
 114         }
 115
 116         // The first 8 bytes are UDP header.
 117         // XXX: we should consider avoiding this move somehow.
 118         for (int i = 0; i < len - 8; i++) {
 119           response[i] = response[i + 8];
 120         }
 121
 122         return len - 8;
 123       });
 124   mozilla::glean::networking::dns_native_https_call_time.AccumulateRawDuration(
 125       TimeStamp::Now() - startTime);
 126   if (NS_FAILED(rv)) {
 127     LOG("failed rv");
 128     return rv;
 129   }
 130   packet.SetNativePacket(true);
 131
 132   int32_t loopCount = 64;
 133   while (loopCount > 0 && aResult.is<Nothing>()) {
 134     loopCount--;
 135     DOHresp resp;
 136     nsClassHashtable<nsCStringHashKey, DOHresp> additionalRecords;
 137     rv = packet.Decode(host, TRRTYPE_HTTPSSVC, cname, true, resp, aResult,
 138                        additionalRecords, aTTL);
 139     if (NS_FAILED(rv)) {
 140       LOG("Decode failed %x", static_cast<uint32_t>(rv));
 141       return rv;
 142     }
 143     if (!cname.IsEmpty() && aResult.is<Nothing>()) {
 144       host = cname;
 145       cname.Truncate();
 146       continue;
 147     }
 148   }
 149
 150   if (aResult.is<Nothing>()) {
 151     LOG("Result is nothing");
 152     // The call succeeded, but no HTTPS records were found.
 153     return NS_ERROR_UNKNOWN_HOST;
 154   }
 155
 156   return NS_OK;
 157 }
 158
 159 void DNSThreadShutdown() {}
 160
 161 }  // namespace mozilla::net