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#include "current-process.hh"
#include "environment-variables.hh"
#include "ssh.hh"
#include "finally.hh"
#include "logging.hh"
#include "strings.hh"
namespace nix {
SSHMaster::SSHMaster(const std::string & host, const std::string & keyFile, const std::string & sshPublicHostKey, bool useMaster, bool compress, int logFD)
: host(host)
, fakeSSH(host == "localhost")
, keyFile(keyFile)
, sshPublicHostKey(sshPublicHostKey)
, useMaster(useMaster && !fakeSSH)
, compress(compress)
, logFD(logFD)
{
if (host == "" || host.starts_with("-"))
throw Error("invalid SSH host name '%s'", host);
auto state(state_.lock());
state->tmpDir = std::make_unique<AutoDelete>(createTempDir("", "nix", true, true, 0700));
}
void SSHMaster::addCommonSSHOpts(Strings & args)
{
auto state(state_.lock());
for (auto & i : tokenizeString<Strings>(getEnv("NIX_SSHOPTS").value_or("")))
args.push_back(i);
if (!keyFile.empty())
args.insert(args.end(), {"-i", keyFile});
if (!sshPublicHostKey.empty()) {
Path fileName = (Path) *state->tmpDir + "/host-key";
auto p = host.rfind("@");
std::string thost = p != std::string::npos ? std::string(host, p + 1) : host;
writeFile(fileName, thost + " " + base64Decode(sshPublicHostKey) + "\n");
args.insert(args.end(), {"-oUserKnownHostsFile=" + fileName});
}
if (compress)
args.push_back("-C");
args.push_back("-oPermitLocalCommand=yes");
args.push_back("-oLocalCommand=echo started");
}
bool SSHMaster::isMasterRunning() {
Strings args = {"-O", "check", host};
addCommonSSHOpts(args);
auto res = runProgram(RunOptions {.program = "ssh", .args = args, .mergeStderrToStdout = true});
return res.first == 0;
}
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;
std::optional<Finally<std::function<void()>>> resumeLoggerDefer;
if (!fakeSSH && !useMaster) {
logger->pause();
resumeLoggerDefer.emplace([&]() { logger->resume(); });
}
conn->sshPid = startProcess([&]() {
restoreProcessContext();
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" };
addCommonSSHOpts(args);
if (socketPath != "")
args.insert(args.end(), {"-S", socketPath});
}
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.reset();
out.writeSide.reset();
// Wait for the SSH connection to be established,
// So that we don't overwrite the password prompt with our progress bar.
if (!fakeSSH && !useMaster && !isMasterRunning()) {
std::string reply;
try {
reply = readLine(out.readSide.get());
} catch (EndOfFile & e) { }
if (reply != "started") {
warn("SSH to '%s' failed, stdout first line: '%s'", host, reply);
throw Error("failed to start SSH connection to '%s'", host);
}
}
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) return state->socketPath;
state->socketPath = (Path) *state->tmpDir + "/ssh.sock";
Pipe out;
out.create();
ProcessOptions options;
options.dieWithParent = false;
logger->pause();
Finally cleanup = [&]() { logger->resume(); };
if (isMasterRunning())
return state->socketPath;
state->sshMaster = startProcess([&]() {
restoreProcessContext();
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 };
addCommonSSHOpts(args);
execvp(args.begin()->c_str(), stringsToCharPtrs(args).data());
throw SysError("unable to execute '%s'", args.front());
}, options);
out.writeSide.reset();
std::string reply;
try {
reply = readLine(out.readSide.get());
} catch (EndOfFile & e) { }
if (reply != "started") {
printTalkative("SSH master stdout first line: %s", reply);
throw Error("failed to start SSH master connection to '%s'", host);
}
return state->socketPath;
}
}
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