Add a LegacySSHStore that uses nix-store --serve

This is useful for nix-copy-closure.

src/libstore/legacy-ssh-store.cc

@@ -0,0 +1,247 @@
+#include "archive.hh"
+#include "pool.hh"
+#include "remote-store.hh"
+#include "serve-protocol.hh"
+#include "store-api.hh"
+#include "worker-protocol.hh"
+
+namespace nix {
+
+static std::string uriScheme = "legacy-ssh://";
+
+struct LegacySSHStore : public Store
+{
+    string host;
+
+    struct Connection
+    {
+        Pid sshPid;
+        AutoCloseFD out;
+        AutoCloseFD in;
+        FdSink to;
+        FdSource from;
+    };
+
+    AutoDelete tmpDir;
+
+    Path socketPath;
+
+    Pid sshMaster;
+
+    ref<Pool<Connection>> connections;
+
+    Path key;
+
+    LegacySSHStore(const string & host, const Params & params,
+        size_t maxConnections = std::numeric_limits<size_t>::max())
+        : Store(params)
+        , host(host)
+        , tmpDir(createTempDir("", "nix", true, true, 0700))
+        , socketPath((Path) tmpDir + "/ssh.sock")
+        , connections(make_ref<Pool<Connection>>(
+            maxConnections,
+            [this]() { return openConnection(); },
+            [](const ref<Connection> & r) { return true; }
+            ))
+        , key(get(params, "ssh-key", ""))
+    {
+    }
+
+    ref<Connection> openConnection()
+    {
+        if ((pid_t) sshMaster == -1) {
+            sshMaster = startProcess([&]() {
+                restoreSignals();
+                Strings args{ "ssh", "-M", "-S", socketPath, "-N", "-x", "-a", host };
+                if (!key.empty())
+                    args.insert(args.end(), {"-i", key});
+                execvp("ssh", stringsToCharPtrs(args).data());
+                throw SysError("starting SSH master connection to host ‘%s’", host);
+            });
+        }
+
+        auto conn = make_ref<Connection>();
+        Pipe in, out;
+        in.create();
+        out.create();
+        conn->sshPid = startProcess([&]() {
+            if (dup2(in.readSide.get(), STDIN_FILENO) == -1)
+                throw SysError("duping over STDIN");
+            if (dup2(out.writeSide.get(), STDOUT_FILENO) == -1)
+                throw SysError("duping over STDOUT");
+            execlp("ssh", "ssh", "-S", socketPath.c_str(), host.c_str(), "nix-store", "--serve", "--write", nullptr);
+            throw SysError("executing ‘nix-store --serve’ on remote host ‘%s’", host);
+        });
+        in.readSide = -1;
+        out.writeSide = -1;
+        conn->out = std::move(out.readSide);
+        conn->in = std::move(in.writeSide);
+        conn->to = FdSink(conn->in.get());
+        conn->from = FdSource(conn->out.get());
+
+        int remoteVersion;
+
+        try {
+            conn->to << SERVE_MAGIC_1 << SERVE_PROTOCOL_VERSION;
+            conn->to.flush();
+
+            unsigned int magic = readInt(conn->from);
+            if (magic != SERVE_MAGIC_2)
+                throw Error("protocol mismatch with ‘nix-store --serve’ on ‘%s’", host);
+            remoteVersion = readInt(conn->from);
+            if (GET_PROTOCOL_MAJOR(remoteVersion) != 0x200)
+                throw Error("unsupported ‘nix-store --serve’ protocol version on ‘%s’", host);
+
+        } catch (EndOfFile & e) {
+            throw Error("cannot connect to ‘%1%’", host);
+        }
+
+        return conn;
+    };
+
+    string getUri() override
+    {
+        return uriScheme + host;
+    }
+
+    void queryPathInfoUncached(const Path & path,
+        std::function<void(std::shared_ptr<ValidPathInfo>)> success,
+        std::function<void(std::exception_ptr exc)> failure) override
+    {
+        sync2async<std::shared_ptr<ValidPathInfo>>(success, failure, [&]() -> std::shared_ptr<ValidPathInfo> {
+            auto conn(connections->get());
+
+            debug("querying remote host ‘%s’ for info on ‘%s’", host, path);
+
+            conn->to << cmdQueryPathInfos << PathSet{path};
+            conn->to.flush();
+
+            auto info = std::make_shared<ValidPathInfo>();
+            conn->from >> info->path;
+            if (info->path.empty()) return nullptr;
+            assert(path == info->path);
+
+            PathSet references;
+            conn->from >> info->deriver;
+            info->references = readStorePaths<PathSet>(*this, conn->from);
+            readLongLong(conn->from); // download size
+            info->narSize = readLongLong(conn->from);
+
+            auto s = readString(conn->from);
+            assert(s == "");
+
+            return info;
+        });
+    }
+
+    void addToStore(const ValidPathInfo & info, const ref<std::string> & nar,
+        bool repair, bool dontCheckSigs,
+        std::shared_ptr<FSAccessor> accessor) override
+    {
+        debug("adding path ‘%s’ to remote host ‘%s’", info.path, host);
+
+        auto conn(connections->get());
+
+        conn->to
+            << cmdImportPaths
+            << 1;
+        conn->to(*nar);
+        conn->to
+            << exportMagic
+            << info.path
+            << info.references
+            << info.deriver
+            << 0
+            << 0;
+        conn->to.flush();
+
+        if (readInt(conn->from) != 1)
+            throw Error("failed to add path ‘%s’ to remote host ‘%s’, info.path, host");
+
+    }
+
+    void narFromPath(const Path & path, Sink & sink) override
+    {
+        auto conn(connections->get());
+
+        conn->to << cmdDumpStorePath << path;
+        conn->to.flush();
+
+        /* FIXME: inefficient. */
+        ParseSink parseSink; /* null sink; just parse the NAR */
+        SavingSourceAdapter savedNAR(conn->from);
+        parseDump(parseSink, savedNAR);
+        sink(savedNAR.s);
+    }
+
+    /* Unsupported methods. */
+    [[noreturn]] void unsupported()
+    {
+        throw Error("operation not supported on SSH stores");
+    }
+
+    PathSet queryAllValidPaths() override { unsupported(); }
+
+    void queryReferrers(const Path & path, PathSet & referrers) override
+    { unsupported(); }
+
+    PathSet queryDerivationOutputs(const Path & path) override
+    { unsupported(); }
+
+    StringSet queryDerivationOutputNames(const Path & path) override
+    { unsupported(); }
+
+    Path queryPathFromHashPart(const string & hashPart) override
+    { unsupported(); }
+
+    Path addToStore(const string & name, const Path & srcPath,
+        bool recursive, HashType hashAlgo,
+        PathFilter & filter, bool repair) override
+    { unsupported(); }
+
+    Path addTextToStore(const string & name, const string & s,
+        const PathSet & references, bool repair) override
+    { unsupported(); }
+
+    void buildPaths(const PathSet & paths, BuildMode buildMode) override
+    { unsupported(); }
+
+    BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
+        BuildMode buildMode) override
+    { unsupported(); }
+
+    void ensurePath(const Path & path) override
+    { unsupported(); }
+
+    void addTempRoot(const Path & path) override
+    { unsupported(); }
+
+    void addIndirectRoot(const Path & path) override
+    { unsupported(); }
+
+    Roots findRoots() override
+    { unsupported(); }
+
+    void collectGarbage(const GCOptions & options, GCResults & results) override
+    { unsupported(); }
+
+    ref<FSAccessor> getFSAccessor()
+    { unsupported(); }
+
+    void addSignatures(const Path & storePath, const StringSet & sigs) override
+    { unsupported(); }
+
+    bool isTrusted() override
+    { return true; }
+
+};
+
+static RegisterStoreImplementation regStore([](
+    const std::string & uri, const Store::Params & params)
+    -> std::shared_ptr<Store>
+{
+    if (std::string(uri, 0, uriScheme.size()) != uriScheme) return 0;
+    return std::make_shared<LegacySSHStore>(std::string(uri, uriScheme.size()), params);
+});
+
+}

src/libstore/remote-store.cc

@@ -37,6 +37,7 @@ template<class T> T readStorePaths(Store & store, Source & from)
 }
 
 template PathSet readStorePaths(Store & store, Source & from);
+template Paths readStorePaths(Store & store, Source & from);
 
 /* TODO: Separate these store impls into different files, give them better names */
 RemoteStore::RemoteStore(const Params & params, size_t maxConnections)