libexec/dma/local.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Simon 'corecode' Schubert <corecode@fs.ei.tum.de>.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/types.h>
  36 #include <sys/wait.h>
  37
  38 #include <err.h>
  39 #include <errno.h>
  40 #include <fcntl.h>
  41 #include <limits.h>
  42 #include <paths.h>
  43 #include <signal.h>
  44 #include <stdint.h>
  45 #include <stdio.h>
  46 #include <syslog.h>
  47 #include <unistd.h>
  48
  49 #include "dma.h"
  50
  51 static int
  52 create_mbox(const char *name)
  53 {
  54         struct sigaction sa, osa;
  55         pid_t child, waitchild;
  56         int status;
  57         int i;
  58         long maxfd;
  59         int e;
  60         int r = -1;
  61
  62         /*
  63          * We need to enable SIGCHLD temporarily so that waitpid works.
  64          */
  65         bzero(&sa, sizeof(sa));
  66         sa.sa_handler = SIG_DFL;
  67         sigaction(SIGCHLD, &sa, &osa);
  68
  69         do_timeout(100, 0);
  70
  71         child = fork();
  72         switch (child) {
  73         case 0:
  74                 /* child */
  75                 maxfd = sysconf(_SC_OPEN_MAX);
  76                 if (maxfd == -1)
  77                         maxfd = 1024;   /* what can we do... */
  78
  79                 for (i = 3; i <= maxfd; ++i)
  80                         close(i);
  81
  82                 execl(LIBEXEC_PATH "/dma-mbox-create", "dma-mbox-create", name, NULL);
  83                 syslog(LOG_ERR, "cannot execute "LIBEXEC_PATH"/dma-mbox-create: %m");
  84                 exit(1);
  85
  86         default:
  87                 /* parent */
  88                 waitchild = waitpid(child, &status, 0);
  89
  90                 e = errno;
  91
  92                 do_timeout(0, 0);
  93
  94                 if (waitchild == -1 && e == EINTR) {
  95                         syslog(LOG_ERR, "hung child while creating mbox `%s': %m", name);
  96                         break;
  97                 }
  98
  99                 if (waitchild == -1) {
 100                         syslog(LOG_ERR, "child disappeared while creating mbox `%s': %m", name);
 101                         break;
 102                 }
 103
 104                 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 105                         syslog(LOG_ERR, "error creating mbox `%s'", name);
 106                         break;
 107                 }
 108
 109                 /* success */
 110                 r = 0;
 111                 break;
 112
 113         case -1:
 114                 /* error */
 115                 syslog(LOG_ERR, "error creating mbox");
 116                 break;
 117         }
 118
 119         sigaction(SIGCHLD, &osa, NULL);
 120
 121         return (r);
 122 }
 123
 124 int
 125 deliver_local(struct qitem *it)
 126 {
 127         char fn[PATH_MAX+1];
 128         char line[1000];
 129         const char *sender;
 130         const char *newline = "\n";
 131         size_t linelen;
 132         int tries = 0;
 133         int mbox;
 134         int error;
 135         int hadnl = 0;
 136         off_t mboxlen;
 137         time_t now = time(NULL);
 138
 139         error = snprintf(fn, sizeof(fn), "%s/%s", _PATH_MAILDIR, it->addr);
 140         if (error < 0 || (size_t)error >= sizeof(fn)) {
 141                 syslog(LOG_NOTICE, "local delivery deferred: %m");
 142                 return (1);
 143         }
 144
 145 retry:
 146         /* wait for a maximum of 100s to get the lock to the file */
 147         do_timeout(100, 0);
 148
 149         /* don't use O_CREAT here, because we might be running as the wrong user. */
 150         mbox = open_locked(fn, O_WRONLY|O_APPEND);
 151         if (mbox < 0) {
 152                 int e = errno;
 153
 154                 do_timeout(0, 0);
 155
 156                 switch (e) {
 157                 case EACCES:
 158                 case ENOENT:
 159                         /*
 160                          * The file does not exist or we can't access it.
 161                          * Call dma-mbox-create to create it and fix permissions.
 162                          */
 163                         if (tries > 0 || create_mbox(it->addr) != 0) {
 164                                 syslog(LOG_ERR, "local delivery deferred: can not create `%s'", fn);
 165                                 return (1);
 166                         }
 167                         ++tries;
 168                         goto retry;
 169
 170                 case EINTR:
 171                         syslog(LOG_NOTICE, "local delivery deferred: can not lock `%s'", fn);
 172                         break;
 173
 174                 default:
 175                         syslog(LOG_NOTICE, "local delivery deferred: can not open `%s': %m", fn);
 176                         break;
 177                 }
 178                 return (1);
 179         }
 180         do_timeout(0, 0);
 181
 182         mboxlen = lseek(mbox, 0, SEEK_END);
 183
 184         /* New mails start with \nFrom ...., unless we're at the beginning of the mbox */
 185         if (mboxlen == 0)
 186                 newline = "";
 187
 188         /* If we're bouncing a message, claim it comes from MAILER-DAEMON */
 189         sender = it->sender;
 190         if (strcmp(sender, "") == 0)
 191                 sender = "MAILER-DAEMON";
 192
 193         if (fseek(it->mailf, 0, SEEK_SET) != 0) {
 194                 syslog(LOG_NOTICE, "local delivery deferred: can not seek: %m");
 195                 goto out;
 196         }
 197
 198         error = snprintf(line, sizeof(line), "%sFrom %s\t%s", newline, sender, ctime(&now));
 199         if (error < 0 || (size_t)error >= sizeof(line)) {
 200                 syslog(LOG_NOTICE, "local delivery deferred: can not write header: %m");
 201                 goto out;
 202         }
 203         if (write(mbox, line, error) != error)
 204                 goto wrerror;
 205
 206         while (!feof(it->mailf)) {
 207                 if (fgets(line, sizeof(line), it->mailf) == NULL)
 208                         break;
 209                 linelen = strlen(line);
 210                 if (linelen == 0 || line[linelen - 1] != '\n') {
 211                         syslog(LOG_CRIT, "local delivery failed: corrupted queue file");
 212                         snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
 213                         error = -1;
 214                         goto chop;
 215                 }
 216
 217                 /*
 218                  * mboxro processing:
 219                  * - escape lines that start with "From " with a > sign.
 220                  * - be reversable by escaping lines that contain an arbitrary
 221                  *   number of > signs, followed by "From ", i.e. />*From / in regexp.
 222                  * - strict mbox processing only requires escaping after empty lines,
 223                  *   yet most MUAs seem to relax this requirement and will treat any
 224                  *   line starting with "From " as the beginning of a new mail.
 225                  */
 226                 if ((!MBOX_STRICT || hadnl) &&
 227                     strncmp(&line[strspn(line, ">")], "From ", 5) == 0) {
 228                         const char *gt = ">";
 229
 230                         if (write(mbox, gt, 1) != 1)
 231                                 goto wrerror;
 232                         hadnl = 0;
 233                 } else if (strcmp(line, "\n") == 0) {
 234                         hadnl = 1;
 235                 } else {
 236                         hadnl = 0;
 237                 }
 238                 if ((size_t)write(mbox, line, linelen) != linelen)
 239                         goto wrerror;
 240         }
 241         close(mbox);
 242         return (0);
 243
 244 wrerror:
 245         syslog(LOG_ERR, "local delivery failed: write error: %m");
 246         error = 1;
 247 chop:
 248         if (ftruncate(mbox, mboxlen) != 0)
 249                 syslog(LOG_WARNING, "error recovering mbox `%s': %m", fn);
 250 out:
 251         close(mbox);
 252         return (error);
 253 }