mirror of git://git.gnupg.org/gnupg.git
419 lines
11 KiB
C
419 lines
11 KiB
C
/* trustlist.c - Maintain the list of trusted keys
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* Copyright (C) 2002, 2004 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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* USA.
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*/
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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 <assert.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include "agent.h"
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#include <assuan.h> /* fixme: need a way to avoid assuan calls here */
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#include "i18n.h"
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static const char headerblurb[] =
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"# This is the list of trusted keys. Comment lines, like this one, as\n"
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"# well as empty lines are ignored. The entire file may be integrity\n"
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"# protected by the use of a MAC, so changing the file does not make\n"
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"# sense without the knowledge of the MAC key. Lines do have a length\n"
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"# limit but this is not serious limitation as the format of the\n"
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"# entries is fixed and checked by gpg-agent: A non-comment line starts\n"
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"# with optional white spaces, followed by the SHA-1 fingerpint in hex,\n"
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"# optionally followed by a flag character which my either be 'P', 'S'\n"
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"# or '*'. Additional data, delimited by white space, is ignored.\n"
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"#\n"
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"# NOTE: You should give the gpg-agent a HUP after editing this file.\n"
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"\n";
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static FILE *trustfp;
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static int trustfp_used; /* Counter to track usage of TRUSTFP. */
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static int reload_trustlist_pending;
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static int
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open_list (int append)
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{
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char *fname;
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fname = make_filename (opt.homedir, "trustlist.txt", NULL);
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trustfp = fopen (fname, append? "a+":"r");
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if (!trustfp && errno == ENOENT)
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{
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trustfp = fopen (fname, "wx");
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if (!trustfp)
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{
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gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno));
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log_error ("can't create `%s': %s\n", fname, strerror (errno));
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xfree (fname);
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return tmperr;
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}
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fputs (headerblurb, trustfp);
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fclose (trustfp);
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trustfp = fopen (fname, append? "a+":"r");
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}
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if (!trustfp)
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{
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gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno));
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log_error ("can't open `%s': %s\n", fname, strerror (errno));
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xfree (fname);
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return tmperr;
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}
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/*FIXME: check the MAC */
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return 0;
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}
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/* Read the trustlist and return entry by entry. KEY must point to a
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buffer of at least 41 characters. KEYFLAG does return either 'P',
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'S' or '*'.
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Reading a valid entry returns 0, EOF returns -1 any other error
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returns the appropriate error code. */
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static int
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read_list (char *key, int *keyflag)
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{
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int rc;
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int c, i, j;
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char *p, line[256];
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if (!trustfp)
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{
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rc = open_list (0);
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if (rc)
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return rc;
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}
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do
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{
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if (!fgets (line, DIM(line)-1, trustfp) )
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{
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if (feof (trustfp))
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return -1;
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return gpg_error (gpg_err_code_from_errno (errno));
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}
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if (!*line || line[strlen(line)-1] != '\n')
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{
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/* eat until end of line */
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while ( (c=getc (trustfp)) != EOF && c != '\n')
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;
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return gpg_error (*line? GPG_ERR_LINE_TOO_LONG
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: GPG_ERR_INCOMPLETE_LINE);
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}
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/* Allow for empty lines and spaces */
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for (p=line; spacep (p); p++)
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;
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}
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while (!*p || *p == '\n' || *p == '#');
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for (i=j=0; (p[i] == ':' || hexdigitp (p+i)) && j < 40; i++)
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if ( p[i] != ':' )
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key[j++] = p[i] >= 'a'? (p[i] & 0xdf): p[i];
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key[j] = 0;
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if (j!=40 || !(spacep (p+i) || p[i] == '\n'))
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{
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log_error ("invalid formatted fingerprint in trustlist\n");
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return gpg_error (GPG_ERR_BAD_DATA);
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}
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assert (p[i]);
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if (p[i] == '\n')
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*keyflag = '*';
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else
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{
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i++;
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if ( p[i] == 'P' || p[i] == 'p')
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*keyflag = 'P';
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else if ( p[i] == 'S' || p[i] == 's')
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*keyflag = 'S';
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else if ( p[i] == '*')
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*keyflag = '*';
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else
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{
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log_error ("invalid keyflag in trustlist\n");
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return gpg_error (GPG_ERR_BAD_DATA);
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}
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i++;
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if ( !(spacep (p+i) || p[i] == '\n'))
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{
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log_error ("invalid keyflag in trustlist\n");
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return gpg_error (GPG_ERR_BAD_DATA);
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}
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}
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return 0;
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}
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/* Check whether the given fpr is in our trustdb. We expect FPR to be
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an all uppercase hexstring of 40 characters. */
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int
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agent_istrusted (const char *fpr)
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{
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int rc;
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static char key[41];
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int keyflag;
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trustfp_used++;
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if (trustfp)
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rewind (trustfp);
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while (!(rc=read_list (key, &keyflag)))
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{
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if (!strcmp (key, fpr))
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{
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trustfp_used--;
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return 0;
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}
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}
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if (rc != -1)
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{
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/* Error in the trustdb - close it to give the user a chance for
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correction */
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if (trustfp)
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fclose (trustfp);
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trustfp = NULL;
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}
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trustfp_used--;
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return rc;
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}
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/* Write all trust entries to FP. */
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int
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agent_listtrusted (void *assuan_context)
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{
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int rc;
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static char key[51];
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int keyflag;
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trustfp_used++;
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if (trustfp)
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rewind (trustfp);
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while (!(rc=read_list (key, &keyflag)))
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{
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key[40] = ' ';
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key[41] = keyflag;
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key[42] = '\n';
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assuan_send_data (assuan_context, key, 43);
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assuan_send_data (assuan_context, NULL, 0); /* flush */
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}
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if (rc == -1)
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rc = 0;
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if (rc)
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{
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/* Error in the trustdb - close it to give the user a chance for
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correction */
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if (trustfp)
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fclose (trustfp);
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trustfp = NULL;
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}
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trustfp_used--;
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return rc;
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}
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/* Insert the given fpr into our trustdb. We expect FPR to be an all
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uppercase hexstring of 40 characters. FLAG is either 'P' or 'C'.
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This function does first check whether that key has alreay been put
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into the trustdb and returns success in this case. Before a FPR
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actually gets inserted, the user is asked by means of the pin-entry
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whether this is actual wants he want to do.
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*/
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int
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agent_marktrusted (ctrl_t ctrl, const char *name, const char *fpr, int flag)
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{
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int rc;
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static char key[41];
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int keyflag;
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char *desc;
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char *fname;
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/* Check whether we are at all allowed to modify the trustlist.
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This is useful so that the trustlist may be a symlink to a global
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trustlist with only admin priviliges to modify it. Of course
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this is not a secure way of denying access, but it avoids the
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usual clicking on an Okay buttun thing most users are used to. */
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fname = make_filename (opt.homedir, "trustlist.txt", NULL);
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rc = access (fname, W_OK);
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if (rc && errno != ENOENT)
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{
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xfree (fname);
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return gpg_error (GPG_ERR_EPERM);
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}
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xfree (fname);
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trustfp_used++;
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if (trustfp)
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rewind (trustfp);
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while (!(rc=read_list (key, &keyflag)))
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{
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if (!strcmp (key, fpr))
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return 0;
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}
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if (trustfp)
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fclose (trustfp);
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trustfp = NULL;
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if (rc != -1)
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{
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trustfp_used--;
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return rc; /* Error in the trustlist. */
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}
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/* This feature must explicitly been enabled. */
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if (!opt.allow_mark_trusted)
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{
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trustfp_used--;
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return gpg_error (GPG_ERR_NOT_SUPPORTED);
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}
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/* Insert a new one. */
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if (asprintf (&desc,
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/* TRANSLATORS: This prompt is shown by the Pinentry
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and has one special property: A "%%0A" is used by
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Pinentry to insert a line break. The double
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percent sign is actually needed because it is also
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a printf format string. If you need to insert a
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plain % sign, you need to encode it as "%%25". The
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second "%s" gets replaced by a hexdecimal
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fingerprint string whereas the first one receives
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the name as store in the certificate. */
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_("Please verify that the certificate identified as:%%0A"
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" \"%s\"%%0A"
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"has the fingerprint:%%0A"
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" %s"), name, fpr) < 0 )
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{
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trustfp_used--;
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return out_of_core ();
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}
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/* TRANSLATORS: "Correct" is the label of a button and intended to
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be hit if the fingerprint matches the one of the CA. The other
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button is "the default "Cancel" of the Pinentry. */
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rc = agent_get_confirmation (ctrl, desc, _("Correct"), NULL);
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free (desc);
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if (rc)
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{
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trustfp_used--;
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return rc;
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}
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if (asprintf (&desc,
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/* TRANSLATORS: This prompt is shown by the Pinentry
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and has one special property: A "%%0A" is used by
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Pinentry to insert a line break. The double
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percent sign is actually needed because it is also
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a printf format string. If you need to insert a
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plain % sign, you need to encode it as "%%25". The
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"%s" gets replaced by the name as store in the
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certificate. */
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_("Do you ultimately trust%%0A"
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" \"%s\"%%0A"
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"to correctly certify user certificates?"),
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name) < 0 )
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{
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trustfp_used--;
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return out_of_core ();
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}
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rc = agent_get_confirmation (ctrl, desc, _("Yes"), _("No"));
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free (desc);
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if (rc)
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{
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trustfp_used--;
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return rc;
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}
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/* Now check again to avoid duplicates. Also open in append mode now. */
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rc = open_list (1);
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if (rc)
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{
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trustfp_used--;
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return rc;
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}
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rewind (trustfp);
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while (!(rc=read_list (key, &keyflag)))
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{
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if (!strcmp (key, fpr))
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{
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trustfp_used--;
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return 0;
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}
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}
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if (rc != -1)
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{
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if (trustfp)
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fclose (trustfp);
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trustfp = NULL;
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trustfp_used--;
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return rc; /* Error in the trustlist. */
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}
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rc = 0;
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/* Append the key. */
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fflush (trustfp);
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fputs ("\n# ", trustfp);
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print_sanitized_string (trustfp, name, 0);
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fprintf (trustfp, "\n%s %c\n", fpr, flag);
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if (ferror (trustfp))
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rc = gpg_error (gpg_err_code_from_errno (errno));
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/* close because we are in append mode */
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if (fclose (trustfp))
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rc = gpg_error (gpg_err_code_from_errno (errno));
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trustfp = NULL;
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trustfp_used--;
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return rc;
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}
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void
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agent_trustlist_housekeeping (void)
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{
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if (reload_trustlist_pending && !trustfp_used)
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{
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if (trustfp)
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{
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fclose (trustfp);
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trustfp = NULL;
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}
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reload_trustlist_pending = 0;
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}
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}
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/* Not all editors are editing files in place, thus a changes
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trustlist.txt won't be recognozed if we keep the file descriptor
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open. This function may be used to explicitly close that file
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descriptor, which will force a reopen in turn. */
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void
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agent_reload_trustlist (void)
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{
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reload_trustlist_pending = 1;
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agent_trustlist_housekeeping ();
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}
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