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