agent: Support ssh-agent extensions for environment variables.

* common/session-env.c (session_env_list_stdenvnames): Extend to allow
return all names as one string.
* agent/command-ssh.c (SSH_REQUEST_EXTENSION): New.
(SSH_RESPONSE_EXTENSION_FAILURE): New.
(request_specs): Add handler for the extension command.
(ssh_handler_extension): New.
--

The extension mechanism is specified in
https://tools.ietf.org/html/draft-miller-ssh-agent-04

Signed-off-by: Werner Koch <[email protected]>

1 files changed, 35 insertions, 3 deletions

diff --git a/common/session-env.c b/common/session-env.c
index 1df2c4431..5d6b66dd6 100644
--- a/common/session-env.c
+++ b/common/session-env.c
@@ -98,13 +98,45 @@ static size_t lastallocatedarraysize;
 
 /* Return the names of standard environment variables one after the
    other.  The caller needs to set the value at the address of
-   ITERATOR initially to 0 and then call this function until it returns
-   NULL.  */
+   ITERATOR initially to 0 and then call this function until it
+   returns NULL.  If ITERATOR is NULL, a single comma delimited string
+   with the names is returned; NULL is never returned in this case and
+   R_ASSNAME is ignored.  */
 const char *
 session_env_list_stdenvnames (int *iterator, const char **r_assname)
 {
-  int idx = *iterator;
+  int idx;
+  static char *commastring;
+
+  if (!iterator)
+    {
+      if (!commastring)
+        {
+          size_t len = 0;
+          char *p;
+
+          for (idx = 0; idx < DIM (stdenvnames); idx++)
+            len += strlen (stdenvnames[idx].name) + 1;
+          commastring = xtrymalloc (len);
+          if (!commastring)
+            {
+              log_error ("%s: error allocating string: %s\n", __func__,
+                         gpg_strerror (gpg_error_from_syserror ()));
+              return "GPG_TTY,TERM,DISPLAY";
+            }
+          p = commastring;
+          for (idx = 0; idx < DIM (stdenvnames); idx++)
+            {
+              if (idx)
+                *p++ = ',';
+              p = stpcpy (p, stdenvnames[idx].name);
+            }
+          gpgrt_annotate_leaked_object (commastring);
+        }
+      return commastring;
+    }
 
+  idx = *iterator;
   if (idx < 0 || idx >= DIM (stdenvnames))
     return NULL;
   *iterator = idx + 1;