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#include "libstore/ssh.hh"
#include <utility>
#include <absl/strings/match.h>
#include <absl/strings/str_split.h>
namespace nix {
SSHMaster::SSHMaster(const std::string& host, std::string keyFile,
bool useMaster, bool compress, int logFD)
: host(host),
fakeSSH(host == "localhost"),
keyFile(std::move(keyFile)),
useMaster(useMaster && !fakeSSH),
compress(compress),
logFD(logFD) {
if (host.empty() || absl::StartsWith(host, "-")) {
throw Error("invalid SSH host name '%s'", host);
}
}
void SSHMaster::addCommonSSHOpts(Strings& args) {
for (auto& i :
absl::StrSplit(getEnv("NIX_SSHOPTS"), absl::ByAnyChar(" \t\n\r"),
absl::SkipEmpty())) {
args.push_back(std::string(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;
Pipe 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, "-x", "-a"};
addCommonSSHOpts(args);
if (!socketPath.empty()) {
args.insert(args.end(), {"-S", socketPath});
}
// TODO(tazjin): Abseil verbosity flag
/*if (verbosity >= lvlChatty) {
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 = AutoCloseFD(-1);
out.writeSide = AutoCloseFD(-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 != Pid(-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,
"-M", "-N",
"-S", state->socketPath,
"-o", "LocalCommand=echo started",
"-o", "PermitLocalCommand=yes"};
// if (verbosity >= lvlChatty) { 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 = AutoCloseFD(-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;
}
} // namespace nix
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