test: Tweak tests, add alloc failure test

test/ares-test-live.cc

@@ -246,7 +246,7 @@ TEST_F(DefaultChannelTest, LiveSearchSRV) {
 
 TEST_F(DefaultChannelTest, LiveSearchANY) {
   SearchResult result;
-  ares_search(channel_, "facebook.com.", ns_c_in, ns_t_any,
+  ares_search(channel_, "google.com.", ns_c_in, ns_t_any,
               SearchCallback, &result);
   Process();
   EXPECT_TRUE(result.done_);

test/ares-test-mock.cc

@@ -78,6 +78,50 @@ TEST_F(MockChannelTest, SearchDomains) {
   EXPECT_EQ("{'www.third.gov' aliases=[] addrs=[2.3.4.5]}", ss.str());
 }
 
+TEST_F(MockChannelTest, SearchDomainsAllocFail) {
+  DNSPacket nofirst;
+  nofirst.set_response().set_aa().set_rcode(ns_r_nxdomain)
+    .add_question(new DNSQuestion("www.first.com", ns_t_a));
+  ON_CALL(server_, OnRequest("www.first.com", ns_t_a))
+    .WillByDefault(SetReply(&server_, &nofirst));
+  DNSPacket nosecond;
+  nosecond.set_response().set_aa().set_rcode(ns_r_nxdomain)
+    .add_question(new DNSQuestion("www.second.org", ns_t_a));
+  ON_CALL(server_, OnRequest("www.second.org", ns_t_a))
+    .WillByDefault(SetReply(&server_, &nosecond));
+  DNSPacket yesthird;
+  yesthird.set_response().set_aa()
+    .add_question(new DNSQuestion("www.third.gov", ns_t_a))
+    .add_answer(new DNSARR("www.third.gov", 0x0200, {2, 3, 4, 5}));
+  ON_CALL(server_, OnRequest("www.third.gov", ns_t_a))
+    .WillByDefault(SetReply(&server_, &yesthird));
+
+  // Fail a variety of different memory allocations, and confirm
+  // that the operation either fails with ENOMEM or succeeds
+  // with the expected result.
+  const int kCount = 34;
+  HostResult results[kCount];
+  for (int ii = 1; ii <= kCount; ii++) {
+    HostResult* result = &(results[ii - 1]);
+    ClearFails();
+    SetAllocFail(ii);
+    ares_gethostbyname(channel_, "www", AF_INET, HostCallback, result);
+    Process();
+    EXPECT_TRUE(result->done_);
+    if (result->status_ != ARES_ENOMEM) {
+      std::stringstream ss;
+      ss << result->host_;
+      EXPECT_EQ("{'www.third.gov' aliases=[] addrs=[2.3.4.5]}", ss.str()) << " failed alloc #" << ii;
+      if (verbose) std::cerr << "Succeeded despite failure of alloc #" << ii << std::endl;
+    }
+  }
+
+  // Explicitly destroy the channel now, so that the HostResult objects
+  // are still valid (in case any pending work refers to them).
+  ares_destroy(channel_);
+  channel_ = nullptr;
+}
+
 TEST_F(MockChannelTest, Resend) {
   std::vector<byte> nothing;
   DNSPacket reply;

test/ares-test.cc

@@ -174,6 +174,10 @@ void MockServer::Process(int fd) {
   char *name = nullptr;
   long enclen;
   ares_expand_name(question, buffer, len, &name, &enclen);
+  if (!name) {
+    std::cerr << "Failed to retrieve name" << std::endl;
+    return;
+  }
   qlen -= enclen;
   question += enclen;
   std::string namestr(name);
@@ -287,9 +291,11 @@ std::ostream& operator<<(std::ostream& os, const HostResult& result) {
   return os;
 }
 
-HostEnt::HostEnt(const struct hostent *hostent) {
-  if (!hostent) return;
-  if (hostent->h_name) name_ = hostent->h_name;
+HostEnt::HostEnt(const struct hostent *hostent) : addrtype_(-1) {
+  if (!hostent)
+    return;
+  if (hostent->h_name)
+    name_ = hostent->h_name;
   if (hostent->h_aliases) {
     char** palias = hostent->h_aliases;
     while (*palias != nullptr) {
@@ -326,6 +332,7 @@ std::ostream& operator<<(std::ostream& os, const HostEnt& host) {
   os << '}';
   return os;
 }
+
 void HostCallback(void *data, int status, int timeouts,
                   struct hostent *hostent) {
   EXPECT_NE(nullptr, data);

test/dns-proto.cc

@@ -233,6 +233,10 @@ std::string QuestionToString(const std::vector<byte>& packet,
   char *name = nullptr;
   long enclen;
   ares_expand_name(*data, packet.data(), packet.size(), &name, &enclen);
+  if (enclen > *len) {
+    ss << "(error, encoded name len " << enclen << "bigger than remaining data " << *len << " bytes)";
+    return ss.str();
+  }
   *len -= enclen;
   *data += enclen;
   ss << "'" << name << "' ";
@@ -261,6 +265,10 @@ std::string RRToString(const std::vector<byte>& packet,
   char *name = nullptr;
   long enclen;
   ares_expand_name(*data, packet.data(), packet.size(), &name, &enclen);
+  if (enclen > *len) {
+    ss << "(error, encoded name len " << enclen << "bigger than remaining data " << *len << " bytes)";
+    return ss.str();
+  }
   *len -= enclen;
   *data += enclen;
   ss << "'" << name << "' ";