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Improve SSH handling

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* Unify SSH code in SSHStore and LegacySSHStore.

* Fix a race starting the SSH master. We now wait synchronously for
  the SSH master to finish starting. This prevents the SSH clients
  from starting their own connections.

* Don't use a master if max-connections == 1.

* Add a "max-connections" store parameter.

* Add a "compress" store parameter.
This commit is contained in:
Eelco Dolstra 2017-03-03 19:05:50 +01:00
parent 7f62be1bcd
commit 577ebeaefb
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GPG key ID: 8170B4726D7198DE
7 changed files with 185 additions and 113 deletions
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60
src/libstore/legacy-ssh-store.cc
View file

@ -4,6 +4,7 @@
#include "serve-protocol.hh"
#include "store-api.hh"
#include "worker-protocol.hh"
#include "ssh.hh"
namespace nix {
@ -11,73 +12,42 @@ static std::string uriScheme = "legacy-ssh://";
struct LegacySSHStore : public Store
{
string host;
struct Connection
{
Pid sshPid;
AutoCloseFD out;
AutoCloseFD in;
std::unique_ptr<SSHMaster::Connection> sshConn;
FdSink to;
FdSource from;
};
AutoDelete tmpDir;
Path socketPath;
Pid sshMaster;
std::string host;
ref<Pool<Connection>> connections;
Path key;
SSHMaster master;
LegacySSHStore(const string & host, const Params & params,
size_t maxConnections = std::numeric_limits<size_t>::max())
LegacySSHStore(const string & host, const Params & params)
: Store(params)
, host(host)
, tmpDir(createTempDir("", "nix", true, true, 0700))
, socketPath((Path) tmpDir + "/ssh.sock")
, connections(make_ref<Pool<Connection>>(
maxConnections,
std::max(1, std::stoi(get(params, "max-connections", "1"))),
[this]() { return openConnection(); },
[](const ref<Connection> & r) { return true; }
))
, key(get(params, "ssh-key", ""))
, master(
host,
get(params, "ssh-key", ""),
// Use SSH master only if using more than 1 connection.
connections->capacity() > 1,
get(params, "compress", "") == "true")
{
}
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());
conn->sshConn = master.startCommand("nix-store --serve");
conn->to = FdSink(conn->sshConn->in.get());
conn->from = FdSource(conn->sshConn->out.get());
int remoteVersion;