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#include "ssh.hh"
namespace nix {
SSHMaster::SSHMaster(const std::string & host, const std::string & keyFile, bool useMaster, bool compress, int logFD)
: host(host)
, fakeSSH(host == "localhost")
, keyFile(keyFile)
, useMaster(useMaster && !fakeSSH)
, compress(compress)
, logFD(logFD)
{
if (host == "" || hasPrefix(host, "-"))
throw Error("invalid SSH host name '%s'", host);
}
void SSHMaster::addCommonSSHOpts(Strings & args)
{
for (auto & i : tokenizeString<Strings>(getEnv("NIX_SSHOPTS").value_or("")))
args.push_back(i);
if (!keyFile.empty())
args.insert(args.end(), {"-i", keyFile});
if (compress)
args.push_back("-C");
}
std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string & command)
{
Path socketPath = startMaster();
Pipe in, out;
in.create();
out.create();
auto conn = std::make_unique<Connection>();
ProcessOptions options;
options.dieWithParent = false;
conn->sshPid = startProcess([&]() {
restoreSignals();
close(in.writeSide.get());
close(out.readSide.get());
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");
if (logFD != -1 && dup2(logFD, STDERR_FILENO) == -1)
throw SysError("duping over stderr");
Strings args;
if (fakeSSH) {
args = { "bash", "-c" };
} else {
args = { "ssh", host.c_str(), "-x", "-a" };
addCommonSSHOpts(args);
if (socketPath != "")
args.insert(args.end(), {"-S", socketPath});
if (verbosity >= Verbosity::Chatty)
args.push_back("-v");
}
args.push_back(command);
execvp(args.begin()->c_str(), stringsToCharPtrs(args).data());
// could not exec ssh/bash
throw SysError("unable to execute '%s'", args.front());
}, options);
in.readSide = -1;
out.writeSide = -1;
conn->out = std::move(out.readSide);
conn->in = std::move(in.writeSide);
return conn;
}
Path SSHMaster::startMaster()
{
if (!useMaster) return "";
auto state(state_.lock());
if (state->sshMaster != -1) return state->socketPath;
state->tmpDir = std::make_unique<AutoDelete>(createTempDir("", "nix", true, true, 0700));
state->socketPath = (Path) *state->tmpDir + "/ssh.sock";
Pipe out;
out.create();
ProcessOptions options;
options.dieWithParent = false;
state->sshMaster = startProcess([&]() {
restoreSignals();
close(out.readSide.get());
if (dup2(out.writeSide.get(), STDOUT_FILENO) == -1)
throw SysError("duping over stdout");
Strings args =
{ "ssh", host.c_str(), "-M", "-N", "-S", state->socketPath
, "-o", "LocalCommand=echo started"
, "-o", "PermitLocalCommand=yes"
};
if (verbosity >= Verbosity::Chatty)
args.push_back("-v");
addCommonSSHOpts(args);
execvp(args.begin()->c_str(), stringsToCharPtrs(args).data());
throw SysError("unable to execute '%s'", args.front());
}, options);
out.writeSide = -1;
std::string reply;
try {
reply = readLine(out.readSide.get());
} catch (EndOfFile & e) { }
if (reply != "started")
throw Error("failed to start SSH master connection to '%s'", host);
return state->socketPath;
}
}
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