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/GleanMetrics.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, uint16_t aFlags,
  41                                 TypeRecordResultType& aResult, uint32_t& aTTL) {
  42   DNSPacket packet;
  43   nsAutoCString host(aHost);
  44   nsAutoCString cname;
  45   nsresult rv;
  46
  47   if (xpc::IsInAutomation() &&
  48       !StaticPrefs::network_dns_native_https_query_in_automation()) {
  49     return NS_ERROR_UNKNOWN_HOST;
  50   }
  51
  52   if (!sLibLoading.exchange(true)) {
  53     // We're the first call here, load the library and symbols.
  54     void* handle = dlopen("libandroid.so", RTLD_LAZY | RTLD_LOCAL);
  55     if (!handle) {
  56       LOG("Error loading libandroid_net %s", dlerror());
  57       return NS_ERROR_UNKNOWN_HOST;
  58     }
  59
  60     auto x = dlsym(handle, "android_res_nquery");
  61     if (!x) {
  62       LOG("No android_res_nquery symbol");
  63     }
  64
  65     sAndroidResNQuery = (android_res_nquery_ptr)x;
  66   }
  67
  68   if (!sAndroidResNQuery) {
  69     LOG("nquery not loaded");
  70     // The library hasn't been loaded yet.
  71     return NS_ERROR_UNKNOWN_HOST;
  72   }
  73
  74   LOG("resolving %s\n", host.get());
  75   TimeStamp startTime = TimeStamp::Now();
  76   // Perform the query
  77   rv = packet.FillBuffer(
  78       [&](unsigned char response[DNSPacket::MAX_SIZE]) -> int {
  79         int fd = 0;
  80         auto closeSocket = MakeScopeExit([&] {
  81           if (fd > 0) {
  82             close(fd);
  83           }
  84         });
  85         uint32_t flags = 0;
  86         if (aFlags & nsIDNSService::RESOLVE_BYPASS_CACHE) {
  87           flags = ANDROID_RESOLV_NO_CACHE_LOOKUP;
  88         }
  89         fd = sAndroidResNQuery(0, host.get(), ns_c_in,
  90                                nsIDNSService::RESOLVE_TYPE_HTTPSSVC, flags);
  91
  92         if (fd < 0) {
  93           LOG("DNS query failed");
  94           return fd;
  95         }
  96
  97         struct pollfd fds;
  98         fds.fd = fd;
  99         fds.events = POLLIN;  // Wait for read events
 100
 101         // Wait for an event on the file descriptor
 102         int ret = poll(&fds, 1,
 103                        StaticPrefs::network_dns_native_https_timeout_android());
 104         if (ret <= 0) {
 105           LOG("poll failed %d", ret);
 106           return -1;
 107         }
 108
 109         ssize_t len = recv(fd, response, DNSPacket::MAX_SIZE - 1, 0);
 110         if (len <= 8) {
 111           LOG("size too small %zd", len);
 112           return len < 0 ? len : -1;
 113         }
 114
 115         // The first 8 bytes are UDP header.
 116         // XXX: we should consider avoiding this move somehow.
 117         for (int i = 0; i < len - 8; i++) {
 118           response[i] = response[i + 8];
 119         }
 120
 121         return len - 8;
 122       });
 123   mozilla::glean::networking::dns_native_https_call_time.AccumulateRawDuration(
 124       TimeStamp::Now() - startTime);
 125   if (NS_FAILED(rv)) {
 126     LOG("failed rv");
 127     return rv;
 128   }
 129   packet.SetNativePacket(true);
 130
 131   int32_t loopCount = 64;
 132   while (loopCount > 0 && aResult.is<Nothing>()) {
 133     loopCount--;
 134     DOHresp resp;
 135     nsClassHashtable<nsCStringHashKey, DOHresp> additionalRecords;
 136     rv = packet.Decode(host, TRRTYPE_HTTPSSVC, cname, true, resp, aResult,
 137                        additionalRecords, aTTL);
 138     if (NS_FAILED(rv)) {
 139       LOG("Decode failed %x", static_cast<uint32_t>(rv));
 140       return rv;
 141     }
 142     if (!cname.IsEmpty() && aResult.is<Nothing>()) {
 143       host = cname;
 144       cname.Truncate();
 145       continue;
 146     }
 147   }
 148
 149   if (aResult.is<Nothing>()) {
 150     LOG("Result is nothing");
 151     // The call succeeded, but no HTTPS records were found.
 152     return NS_ERROR_UNKNOWN_HOST;
 153   }
 154
 155   return NS_OK;
 156 }
 157
 158 void DNSThreadShutdown() {}
 159
 160 }  // namespace mozilla::net