Allow the machines file to specify host public keys

It's easier for the Hydra provisioner to put host public keys in the
machines file than to separately manage the known_hosts file
(especially when the provisioner runs on a different machine).

configure.ac

@@ -10,7 +10,7 @@ AC_PROG_LN_S
 AC_PROG_LIBTOOL
 AC_PROG_CXX
 
-CXXFLAGS+=" -std=c++0x"
+CXXFLAGS+=" -std=c++11"
 
 dnl Optional dependencies to build the manual, normally not needed
 dnl since the tarball comes with the PDF and HTML manuals.

src/hydra-queue-runner/build-remote.cc

@@ -26,8 +26,7 @@ static void append(Strings & dst, const Strings & src)
 }
 
 
-static void openConnection(const string & sshName, const string & sshKey,
+static void openConnection(Machine::ptr machine, Path tmpDir, int stderrFD, Child & child)
-    int stderrFD, Child & child)
 {
     Pipe to, from;
     to.create();
@@ -45,11 +44,18 @@ static void openConnection(const string & sshName, const string & sshKey,
             throw SysError("cannot dup stderr");
 
         Strings argv;
-        if (sshName == "localhost")
+        if (machine->sshName == "localhost")
             argv = {"nix-store", "--serve", "--write"};
         else {
-            argv = {"ssh", sshName};
+            argv = {"ssh", machine->sshName};
-            if (sshKey != "" && sshKey != "-") append(argv, {"-i", sshKey});
+            if (machine->sshKey != "") append(argv, {"-i", machine->sshKey});
+            if (machine->sshPublicHostKey != "") {
+                Path fileName = tmpDir + "/host-key";
+                auto p = machine->sshName.find("@");
+                string host = p != string::npos ? string(machine->sshName, p + 1) : machine->sshName;
+                writeFile(fileName, host + " " + machine->sshPublicHostKey + "\n");
+                append(argv, {"-oUserKnownHostsFile=" + fileName});
+            }
             append(argv,
                 { "-x", "-a", "-oBatchMode=yes", "-oConnectTimeout=60", "-oTCPKeepAlive=yes"
                 , "--", "nix-store", "--serve", "--write" });
@@ -136,8 +142,11 @@ void State::buildRemote(std::shared_ptr<StoreAPI> store,
     AutoCloseFD logFD(open(result.logFile.c_str(), O_CREAT | O_TRUNC | O_WRONLY, 0666));
     if (logFD == -1) throw SysError(format("creating log file ‘%1%’") % result.logFile);
 
+    nix::Path tmpDir = createTempDir();
+    AutoDelete tmpDirDel(tmpDir, true);
+
     Child child;
-    openConnection(machine->sshName, machine->sshKey, logFD, child);
+    openConnection(machine, tmpDir, logFD, child);
 
     logFD.close();
 
@@ -277,5 +286,4 @@ void State::buildRemote(std::shared_ptr<StoreAPI> store,
     /* Shut down the connection. */
     child.to.close();
     child.pid.wait(true);
-
 }

src/hydra-queue-runner/hydra-queue-runner.cc

@@ -40,12 +40,12 @@ void State::parseMachines(const std::string & contents)
         line = trim(string(line, 0, line.find('#')));
         auto tokens = tokenizeString<std::vector<std::string>>(line);
         if (tokens.size() < 3) continue;
-        tokens.resize(7);
+        tokens.resize(8);
 
         auto machine = std::make_shared<Machine>();
         machine->sshName = tokens[0];
         machine->systemTypes = tokenizeString<StringSet>(tokens[1], ",");
-        machine->sshKey = tokens[2];
+        machine->sshKey = tokens[2] == "-" ? string("") : tokens[2];
         if (tokens[3] != "")
             string2Int(tokens[3], machine->maxJobs);
         else
@@ -57,6 +57,8 @@ void State::parseMachines(const std::string & contents)
         machine->mandatoryFeatures = tokenizeString<StringSet>(tokens[6], ",");
         for (auto & f : machine->mandatoryFeatures)
             machine->supportedFeatures.insert(f);
+        if (tokens[7] != "" && tokens[7] != "-")
+            machine->sshPublicHostKey = base64Decode(tokens[7]);
 
         /* Re-use the State object of the previous machine with the
            same name. */

src/hydra-queue-runner/state.hh

@@ -205,6 +205,7 @@ struct Machine
     std::set<std::string> systemTypes, supportedFeatures, mandatoryFeatures;
     unsigned int maxJobs = 1;
     float speedFactor = 1.0;
+    std::string sshPublicHostKey;
 
     struct State {
         typedef std::shared_ptr<State> ptr;