ssh/session.scm (make-session): Fix "#:config" handling

This patch fixes "make-session" procedure to make it handle "#:config" option
according to the Guile-SSH documentation.  That is, passing "#f" as the
"#:config" value disables reading the default SSH documentation.

Reported by graywolf in
<#38>

* modules/ssh/session.scm (make-session): Fix "#:config" handling: disable
default configuration reading when set to "#f" as per Guile-SSH documentation.
Use "#t" as the default value to keep the backward compatibility.
* libguile-ssh/session-func.c (session_options): Add
SSH_OPTIONS_PROCESS_CONFIG.
(set_option): Handle SSH_OPTIONS_PROCESS_CONFIG.
* doc/api-sessions.texi: Update.
* NEWS: Update.

NEWS

@@ -20,6 +20,15 @@ This change affects the following procedures from =(ssh popen)=:
 
 Reported by graywolf in
 <https://github.com/artyom-poptsov/guile-ssh/issues/39>
+** =make-session= now handles =#:config= set to =#f= properly
+Now =make-session= disables reading the default SSH configuration files when
+=#:config= is set to =#f= (as per Guile-SSH documentation.)
+
+When =#:config= is set to =#t= then the default SSH configuration files are
+read.  This is by default to keep the backward compatibility.
+
+Reported by graywolf in
+<https://github.com/artyom-poptsov/guile-ssh/issues/38>
 ** New simplified version of the project logo
 Thanks to Darya Sev. <sdarsy@ya.ru> for very helpful design advices for the
 new simplified version of the project logo.

doc/api-sessions.texi

@@ -244,6 +244,13 @@ be ``yes'', ``no'' or a specific algorithm name if needed ("zlib",
 @verb{|"zlib@openssh.com"|}, "none").
 
 Expected type of @var{value}: string.
+@item process-config?
+Set it to @code{#f} to disable automatic processing of per-user and
+system-wide OpenSSH configuration files.  LibSSH automatically uses these
+configuration files unless you provide it with this option or with different
+file.
+
+Expected type of @var{value}: boolean.
 @item proxycommand
 Set the command to be executed in order to connect to server.
 

libguile-ssh/session-func.c

@@ -67,6 +67,7 @@ static gssh_symbol_t session_options[] = {
   { "stricthostkeycheck", SSH_OPTIONS_STRICTHOSTKEYCHECK },
   { "compression",        SSH_OPTIONS_COMPRESSION        },
   { "compression-level",  SSH_OPTIONS_COMPRESSION_LEVEL  },
+  { "process-config?",    SSH_OPTIONS_PROCESS_CONFIG     },
 
 #if HAVE_LIBSSH_0_8_1
   { "nodelay",            SSH_OPTIONS_NODELAY            },
@@ -384,6 +385,7 @@ set_option (SCM scm_session, gssh_session_t* sd, int type, SCM value)
     case SSH_OPTIONS_SSH1:
     case SSH_OPTIONS_SSH2:
     case SSH_OPTIONS_STRICTHOSTKEYCHECK:
+    case SSH_OPTIONS_PROCESS_CONFIG:
 #if HAVE_LIBSSH_0_8_1
     case SSH_OPTIONS_NODELAY:
 #endif

modules/ssh/session.scm

@@ -74,25 +74,27 @@
                        knownhosts timeout timeout-usec ssh1 ssh2 log-verbosity
                        ciphers-c-s ciphers-s-c compression-c-s compression-s-c
                        proxycommand stricthostkeycheck compression
-                       compression-level nodelay callbacks config
+                       compression-level nodelay callbacks (config #t)
                        public-key-accepted-types)
   "Make a new SSH session with specified configuration.\n
 Return a new SSH session."
   (let ((session (%make-session)))
 
     (session-set-if-specified! host)
 
-    (when config
-      (or host
-          (throw 'guile-ssh-error
-                 "'config' is specified, but 'host' option is missed."))
-      (cond
-       ((string? config)
-        (%gssh-session-parse-config! session config))
-       ((boolean? config)
-        (%gssh-session-parse-config! session #f))
-       (else
-        (throw 'guile-ssh-error "Wrong 'config' value" config))))
+    (if config
+        (begin
+          (or host
+              (throw 'guile-ssh-error
+                     "'config' is specified, but 'host' option is missed."))
+          (cond
+           ((string? config)
+            (%gssh-session-parse-config! session config))
+           ((boolean? config)
+            (%gssh-session-parse-config! session #f))
+           (else
+            (throw 'guile-ssh-error "Wrong 'config' value" config))))
+        (session-set! session 'process-config? #f))
 
     (session-set-if-specified! port)
     (session-set-if-specified! user)