1 files changed, 159 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/ssh.cc b/third_party/nix/src/libstore/ssh.cc
new file mode 100644
index 000000000000..1b09eb42c6b9
--- /dev/null
+++ b/third_party/nix/src/libstore/ssh.cc
@@ -0,0 +1,159 @@
+#include "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"))) {
+    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 = -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,
+                        "-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 = -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