From 4e7d5f660cec6da3a432c726dfe7a579c7581c79 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 3 Aug 2018 18:12:28 +0200
Subject: [PATCH] SSHMaster: Bypass SSH when connecting to localhost

This is primarily useful for testing since it removes the need to have
SSH working.
---
 src/libstore/ssh.cc | 22 +++++++++++++++-------
 src/libstore/ssh.hh |  1 +
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/libstore/ssh.cc b/src/libstore/ssh.cc
index 033c58093..5e0e44935 100644
--- a/src/libstore/ssh.cc
+++ b/src/libstore/ssh.cc
@@ -4,8 +4,9 @@ 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)
+    , useMaster(useMaster && !fakeSSH)
     , compress(compress)
     , logFD(logFD)
 {
@@ -45,12 +46,19 @@ std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string
         if (logFD != -1 && dup2(logFD, STDERR_FILENO) == -1)
             throw SysError("duping over stderr");
 
-        Strings args = { "ssh", host.c_str(), "-x", "-a" };
-        addCommonSSHOpts(args);
-        if (socketPath != "")
-            args.insert(args.end(), {"-S", socketPath});
-        if (verbosity >= lvlChatty)
-            args.push_back("-v");
+        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 >= lvlChatty)
+                args.push_back("-v");
+        }
+
         args.push_back(command);
         execvp(args.begin()->c_str(), stringsToCharPtrs(args).data());
 
diff --git a/src/libstore/ssh.hh b/src/libstore/ssh.hh
index 1268e6d00..4f0f0bd29 100644
--- a/src/libstore/ssh.hh
+++ b/src/libstore/ssh.hh
@@ -10,6 +10,7 @@ class SSHMaster
 private:
 
     const std::string host;
+    bool fakeSSH;
     const std::string keyFile;
     const bool useMaster;
     const bool compress;