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gnupg/agent/command.c
2001-11-24 18:52:02 +00:00

230 lines
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/* 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);
}