Friedman is setting up his desk

agent/command.c

@@ -0,0 +1,229 @@
+/* command.c - gpg-agent command handler
+ *	Copyright (C) 2001 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+/* FIXME: we should not use the default assuan buffering but setup
+   some buffering in secure mempory to protect session keys etc. */
+
+#include <config.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+
+#include "agent.h"
+#include "../assuan/assuan.h"
+
+#define set_error(e,t) assuan_set_error (ctx, ASSUAN_ ## e, (t))
+#define digitp(a) ((a) >= '0' && (a) <= '9')
+#define hexdigitp(a) (digitp (a)                     \
+                      || ((a) >= 'A' && (a) <= 'F')  \
+                      || ((a) >= 'a' && (a) <= 'f'))
+#define atoi_1(p)   (*(p) - '0' )
+#define atoi_2(p)   ((atoi_1(p) * 10) + atoi_1((p)+1))
+/* assumes ASCII and pre-checked values */
+#define xtoi_1(p)   (*(p) <= '9'? (*(p)- '0'): \
+                     *(p) <= 'F'? (*(p)-'A'+10):(*(p)-'a'+10))
+#define xtoi_2(p)   ((xtoi_1(p) * 16) + xtoi_1((p)+1))
+
+/* Data used to associate an Assuan context with local server data */
+struct server_local_s {
+  ASSUAN_CONTEXT assuan_ctx;
+  int message_fd;
+};
+
+/* SETHASH <hexstring>
+
+  The client can use this command to tell the server about the data
+  (which usually is a hash) to be signed. */
+static int
+cmd_sethash (ASSUAN_CONTEXT ctx, char *line)
+{
+  int n;
+  char *p;
+  CTRL ctrl = assuan_get_pointer (ctx);
+  unsigned char *buf;
+
+  /* parse the hash value */
+  for (p=line,n=0; hexdigitp (*p); p++, n++)
+    ;
+  if (*p)
+    return set_error (Parameter_Error, "invalid hexstring");
+  if ((n&1))
+    return set_error (Parameter_Error, "odd number of digits");
+  n /= 2;
+  if (n != 16 && n != 20 && n != 24 && n != 32)
+    return set_error (Parameter_Error, "unsupported length of hash");
+  if (n > MAX_DIGEST_LEN)
+    return set_error (Parameter_Error, "hash value to long");
+
+  buf = ctrl->digest.value;
+  ctrl->digest.valuelen = n;
+  for (p=line, n=0; n < ctrl->digest.valuelen; p += 2, n++)
+    buf[n] = xtoi_2 (p);
+  for (; n < ctrl->digest.valuelen; n++)
+    buf[n] = 0;
+  return 0;
+}
+
+
+/* PKSIGN <options>
+
+   Perform the actual sign operation. Neither input nor output are
+   sensitive to to eavesdropping */
+static int
+cmd_pksign (ASSUAN_CONTEXT ctx, char *line)
+{
+  int rc;
+  CTRL ctrl = assuan_get_pointer (ctx);
+
+  /* fixme: check that all required data is available */
+  rc = agent_pksign (ctrl, assuan_get_data_fp (ctx));
+  /* fixme: return an error */
+  return 0;
+}
+
+
+/* MESSAGE FD=<n>
+
+   Set the file descriptor to read a message which is used with
+   detached signatures */
+static int 
+cmd_message (ASSUAN_CONTEXT ctx, char *line)
+{
+#if 0
+  char *endp;
+  int fd;
+  CTRL ctrl = assuan_get_pointer (ctx);
+
+  if (strncmp (line, "FD=", 3))
+    return set_error (Syntax_Error, "FD=<n> expected");
+  line += 3;
+  if (!digitp (*line))
+    return set_error (Syntax_Error, "number required");
+  fd = strtoul (line, &endp, 10);
+  if (*endp)
+    return set_error (Syntax_Error, "garbage found");
+  if (fd == -1)
+    return set_error (No_Input, NULL);
+
+  ctrl->server_local->message_fd = fd;
+  return 0;
+#endif
+  return set_error (Not_Implemented, NULL);
+}
+
+
+
+/* Tell the assuan library about our commands */
+static int
+register_commands (ASSUAN_CONTEXT ctx)
+{
+  static struct {
+    const char *name;
+    int cmd_id;
+    int (*handler)(ASSUAN_CONTEXT, char *line);
+  } table[] = {
+    { "SETHASH",    0,  cmd_sethash },
+    { "PKSIGN",     0,  cmd_pksign },
+    { "",     ASSUAN_CMD_INPUT, NULL }, 
+    { "",     ASSUAN_CMD_OUTPUT, NULL }, 
+    { "MESSAGE",    0,  cmd_message },
+    { NULL }
+  };
+  int i, j, rc;
+
+  for (i=j=0; table[i].name; i++)
+    {
+      rc = assuan_register_command (ctx,
+                                    table[i].cmd_id? table[i].cmd_id
+                                                   : (ASSUAN_CMD_USER + j++),
+                                    table[i].name, table[i].handler);
+      if (rc)
+        return rc;
+    } 
+  return 0;
+}
+
+
+/* Startup the server */
+void
+start_command_handler (void)
+{
+  int rc;
+  int filedes[2];
+  ASSUAN_CONTEXT ctx;
+  struct server_control_s ctrl;
+
+  memset (&ctrl, 0, sizeof ctrl);
+
+  /* For now we use a simple pipe based server so that we can work
+     from scripts.  We will later add options to run as a daemon and
+     wait for requests on a Unix domain socket */
+  filedes[0] = 0;
+  filedes[1] = 1;
+  rc = assuan_init_pipe_server (&ctx, filedes);
+  if (rc)
+    {
+      log_error ("failed to initialize the server: %s\n",
+                 assuan_strerror(rc));
+      agent_exit (2);
+    }
+  rc = register_commands (ctx);
+  if (rc)
+    {
+      log_error ("failed to the register commands with Assuan: %s\n",
+                 assuan_strerror(rc));
+      agent_exit (2);
+    }
+
+  assuan_set_pointer (ctx, &ctrl);
+  ctrl.server_local = xcalloc (1, sizeof *ctrl.server_local);
+  ctrl.server_local->assuan_ctx = ctx;
+  ctrl.server_local->message_fd = -1;
+
+  log_info ("Assuan started\n");
+  for (;;)
+    {
+      rc = assuan_accept (ctx);
+      if (rc == -1)
+        {
+          log_info ("Assuan terminated\n");
+          break;
+        }
+      else if (rc)
+        {
+          log_info ("Assuan accept problem: %s\n", assuan_strerror (rc));
+          break;
+        }
+      
+      rc = assuan_process (ctx);
+      if (rc)
+        {
+          log_info ("Assuan processing failed: %s\n", assuan_strerror (rc));
+          continue;
+        }
+    }
+
+
+  assuan_deinit_pipe_server (ctx);
+}
+