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364 lines
9.0 KiB
C
364 lines
9.0 KiB
C
/* command.c - gpg-agent command handler
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* Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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/* FIXME: we should not use the default assuan buffering but setup
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some buffering in secure mempory to protect session keys etc. */
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#include <config.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <unistd.h>
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#include "agent.h"
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#include "../assuan/assuan.h"
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/* maximum allowed size of the inquired ciphertext */
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#define MAXLEN_CIPHERTEXT 4096
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/* maximum allowed size of the key parameters */
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#define MAXLEN_KEYPARAM 1024
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#define set_error(e,t) assuan_set_error (ctx, ASSUAN_ ## e, (t))
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#if MAX_DIGEST_LEN < 20
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#error MAX_DIGEST_LEN shorter than keygrip
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#endif
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/* Data used to associate an Assuan context with local server data */
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struct server_local_s {
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ASSUAN_CONTEXT assuan_ctx;
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int message_fd;
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};
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static void
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reset_notify (ASSUAN_CONTEXT ctx)
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{
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CTRL ctrl = assuan_get_pointer (ctx);
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memset (ctrl->keygrip, 0, 20);
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ctrl->have_keygrip = 0;
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ctrl->digest.valuelen = 0;
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}
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/* SIGKEY <hexstring_with_keygrip>
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SETKEY <hexstring_with_keygrip>
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Set the key used for a sign or decrypt operation */
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static int
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cmd_sigkey (ASSUAN_CONTEXT ctx, char *line)
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{
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int n;
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char *p;
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CTRL ctrl = assuan_get_pointer (ctx);
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unsigned char *buf;
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/* parse the hash value */
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for (p=line,n=0; hexdigitp (p); p++, n++)
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;
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if (*p)
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return set_error (Parameter_Error, "invalid hexstring");
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if ((n&1))
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return set_error (Parameter_Error, "odd number of digits");
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n /= 2;
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if (n != 20)
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return set_error (Parameter_Error, "invalid length of keygrip");
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buf = ctrl->keygrip;
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for (p=line, n=0; n < 20; p += 2, n++)
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buf[n] = xtoi_2 (p);
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ctrl->have_keygrip = 1;
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return 0;
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}
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/* SETHASH <algonumber> <hexstring>
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The client can use this command to tell the server about the data
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(which usually is a hash) to be signed. */
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static int
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cmd_sethash (ASSUAN_CONTEXT ctx, char *line)
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{
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int n;
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char *p;
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CTRL ctrl = assuan_get_pointer (ctx);
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unsigned char *buf;
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char *endp;
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int algo;
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/* parse the algo number and check it */
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algo = (int)strtoul (line, &endp, 10);
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for (line = endp; *line == ' ' || *line == '\t'; line++)
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;
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if (!algo || gcry_md_test_algo (algo))
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return set_error (Unsupported_Algorithm, NULL);
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ctrl->digest.algo = algo;
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/* parse the hash value */
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for (p=line,n=0; hexdigitp (p); p++, n++)
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;
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if (*p)
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return set_error (Parameter_Error, "invalid hexstring");
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if ((n&1))
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return set_error (Parameter_Error, "odd number of digits");
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n /= 2;
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if (n != 16 && n != 20 && n != 24 && n != 32)
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return set_error (Parameter_Error, "unsupported length of hash");
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if (n > MAX_DIGEST_LEN)
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return set_error (Parameter_Error, "hash value to long");
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buf = ctrl->digest.value;
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ctrl->digest.valuelen = n;
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for (p=line, n=0; n < ctrl->digest.valuelen; p += 2, n++)
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buf[n] = xtoi_2 (p);
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for (; n < ctrl->digest.valuelen; n++)
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buf[n] = 0;
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return 0;
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}
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/* PKSIGN <options>
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Perform the actual sign operation. Neither input nor output are
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sensitive to eavesdropping */
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static int
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cmd_pksign (ASSUAN_CONTEXT ctx, char *line)
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{
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int rc;
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CTRL ctrl = assuan_get_pointer (ctx);
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rc = agent_pksign (ctrl, assuan_get_data_fp (ctx));
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return map_to_assuan_status (rc);
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}
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/* PKDECRYPT <options>
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Perform the actual decrypt operation. Input is not
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sensitive to eavesdropping */
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static int
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cmd_pkdecrypt (ASSUAN_CONTEXT ctx, char *line)
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{
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int rc;
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CTRL ctrl = assuan_get_pointer (ctx);
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char *value;
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size_t valuelen;
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/* First inquire the data to decrypt */
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rc = assuan_inquire (ctx, "CIPHERTEXT",
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&value, &valuelen, MAXLEN_CIPHERTEXT);
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if (rc)
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return rc;
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rc = agent_pkdecrypt (ctrl, value, valuelen, assuan_get_data_fp (ctx));
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xfree (value);
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return map_to_assuan_status (rc);
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}
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/* GENKEY
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Generate a new key, store the secret part and return the public
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part. Here is an example transaction:
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C: GENKEY
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S: INQUIRE KEYPARM
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C: D (genkey (rsa (nbits 1024)))
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C: END
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S: D (public-key
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S: D (rsa (n 326487324683264) (e 10001)))
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S OK key created
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*/
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static int
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cmd_genkey (ASSUAN_CONTEXT ctx, char *line)
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{
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CTRL ctrl = assuan_get_pointer (ctx);
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int rc;
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char *value;
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size_t valuelen;
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/* First inquire the parameters */
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rc = assuan_inquire (ctx, "KEYPARAM", &value, &valuelen, MAXLEN_KEYPARAM);
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if (rc)
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return rc;
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rc = agent_genkey (ctrl, value, valuelen, assuan_get_data_fp (ctx));
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xfree (value);
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return map_to_assuan_status (rc);
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}
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/* GET_PASSPHRASE <cache_id> [<error_message> <prompt> <description>]
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This function is usually used to ask for a passphrase to be used
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for conventional encryption, but may aslo be used by programs which
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need specal handling of passphrases. This command uses a syntax
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which helps clients to use the agent with minimum effort. The
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agent either returns with an error or with a OK followed by the hex
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encoded passphrase. Note that the length of the strings is
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implicitly limited by the maximum length of a command.
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*/
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static int
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cmd_get_passphrase (ASSUAN_CONTEXT ctx, char *line)
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{
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int rc;
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char *response;
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char *desc, *prompt, *errtext;
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/* FIXME: Parse that stuff */
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desc = "We need a passphrase";
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prompt = NULL;
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errtext = "try again";
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rc = agent_get_passphrase (&response, desc, prompt, errtext);
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if (!rc)
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{
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rc = assuan_set_okay_line (ctx, response);
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xfree (response);
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}
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return map_to_assuan_status (rc);
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}
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/* CLEAR_PASSPHRASE <cache_id>
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may be used to invalidate the cache entry for a passphrase. The
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function returns with OK even when ther eis no cached passphrase.
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*/
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static int
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cmd_clear_passphrase (ASSUAN_CONTEXT ctx, char *line)
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{
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int rc;
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/* fixme: no caching yet. so return with OK */
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rc = 0;
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return map_to_assuan_status (rc);
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}
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/* Tell the assuan library about our commands */
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static int
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register_commands (ASSUAN_CONTEXT ctx)
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{
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static struct {
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const char *name;
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int cmd_id;
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int (*handler)(ASSUAN_CONTEXT, char *line);
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} table[] = {
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{ "SIGKEY", 0, cmd_sigkey },
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{ "SETKEY", 0, cmd_sigkey },
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{ "SETHASH", 0, cmd_sethash },
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{ "PKSIGN", 0, cmd_pksign },
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{ "PKDECRYPT", 0, cmd_pkdecrypt },
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{ "GENKEY", 0, cmd_genkey },
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{ "GET_PASSPHRASE",0, cmd_get_passphrase },
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{ "CLEAR_PASSPHRASE",0, cmd_clear_passphrase },
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{ "", ASSUAN_CMD_INPUT, NULL },
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{ "", ASSUAN_CMD_OUTPUT, NULL },
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{ NULL }
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};
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int i, j, rc;
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for (i=j=0; table[i].name; i++)
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{
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rc = assuan_register_command (ctx,
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table[i].cmd_id? table[i].cmd_id
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: (ASSUAN_CMD_USER + j++),
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table[i].name, table[i].handler);
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if (rc)
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return rc;
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}
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assuan_register_reset_notify (ctx, reset_notify);
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return 0;
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}
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/* Startup the server */
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void
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start_command_handler (void)
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{
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int rc;
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int filedes[2];
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ASSUAN_CONTEXT ctx;
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struct server_control_s ctrl;
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memset (&ctrl, 0, sizeof ctrl);
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/* For now we use a simple pipe based server so that we can work
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from scripts. We will later add options to run as a daemon and
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wait for requests on a Unix domain socket */
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filedes[0] = 0;
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filedes[1] = 1;
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rc = assuan_init_pipe_server (&ctx, filedes);
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if (rc)
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{
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log_error ("failed to initialize the server: %s\n",
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assuan_strerror(rc));
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agent_exit (2);
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}
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rc = register_commands (ctx);
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if (rc)
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{
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log_error ("failed to the register commands with Assuan: %s\n",
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assuan_strerror(rc));
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agent_exit (2);
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}
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assuan_set_pointer (ctx, &ctrl);
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ctrl.server_local = xcalloc (1, sizeof *ctrl.server_local);
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ctrl.server_local->assuan_ctx = ctx;
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ctrl.server_local->message_fd = -1;
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for (;;)
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{
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rc = assuan_accept (ctx);
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if (rc == -1)
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{
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break;
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}
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else if (rc)
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{
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log_info ("Assuan accept problem: %s\n", assuan_strerror (rc));
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break;
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}
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rc = assuan_process (ctx);
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if (rc)
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{
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log_info ("Assuan processing failed: %s\n", assuan_strerror (rc));
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continue;
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}
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}
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assuan_deinit_pipe_server (ctx);
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}
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