libexec/dma/local.c

   1 /*
   2  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
   3  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to The DragonFly Project
   6  * by Simon Schubert <2@0x2c.org>.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  * 3. Neither the name of The DragonFly Project nor the names of its
  19  *    contributors may be used to endorse or promote products derived
  20  *    from this software without specific, prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <sys/types.h>
  37 #include <sys/wait.h>
  38
  39 #include <err.h>
  40 #include <errno.h>
  41 #include <fcntl.h>
  42 #include <limits.h>
  43 #include <paths.h>
  44 #include <signal.h>
  45 #include <stdint.h>
  46 #include <stdio.h>
  47 #include <strings.h>
  48 #include <string.h>
  49 #include <syslog.h>
  50 #include <unistd.h>
  51
  52 #include "dma.h"
  53
  54 static int
  55 create_mbox(const char *name)
  56 {
  57         struct sigaction sa, osa;
  58         pid_t child, waitchild;
  59         int status;
  60         int i;
  61         long maxfd;
  62         int e;
  63         int r = -1;
  64
  65         /*
  66          * We need to enable SIGCHLD temporarily so that waitpid works.
  67          */
  68         bzero(&sa, sizeof(sa));
  69         sa.sa_handler = SIG_DFL;
  70         sigaction(SIGCHLD, &sa, &osa);
  71
  72         do_timeout(100, 0);
  73
  74         child = fork();
  75         switch (child) {
  76         case 0:
  77                 /* child */
  78                 maxfd = sysconf(_SC_OPEN_MAX);
  79                 if (maxfd == -1)
  80                         maxfd = 1024;   /* what can we do... */
  81
  82                 for (i = 3; i <= maxfd; ++i)
  83                         close(i);
  84
  85                 execl(LIBEXEC_PATH "/dma-mbox-create", "dma-mbox-create", name, (char *)NULL);
  86                 syslog(LOG_ERR, "cannot execute "LIBEXEC_PATH"/dma-mbox-create: %m");
  87                 exit(EX_SOFTWARE);
  88
  89         default:
  90                 /* parent */
  91                 waitchild = waitpid(child, &status, 0);
  92
  93                 e = errno;
  94
  95                 do_timeout(0, 0);
  96
  97                 if (waitchild == -1 && e == EINTR) {
  98                         syslog(LOG_ERR, "hung child while creating mbox `%s': %m", name);
  99                         break;
 100                 }
 101
 102                 if (waitchild == -1) {
 103                         syslog(LOG_ERR, "child disappeared while creating mbox `%s': %m", name);
 104                         break;
 105                 }
 106
 107                 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 108                         syslog(LOG_ERR, "error creating mbox `%s'", name);
 109                         break;
 110                 }
 111
 112                 /* success */
 113                 r = 0;
 114                 break;
 115
 116         case -1:
 117                 /* error */
 118                 syslog(LOG_ERR, "error creating mbox");
 119                 break;
 120         }
 121
 122         sigaction(SIGCHLD, &osa, NULL);
 123
 124         return (r);
 125 }
 126
 127 int
 128 deliver_local(struct qitem *it)
 129 {
 130         char fn[PATH_MAX+1];
 131         char line[1000];
 132         const char *sender;
 133         const char *newline = "\n";
 134         size_t linelen;
 135         int tries = 0;
 136         int mbox;
 137         int error;
 138         int hadnl = 0;
 139         off_t mboxlen;
 140         time_t now = time(NULL);
 141
 142         error = snprintf(fn, sizeof(fn), "%s/%s", _PATH_MAILDIR, it->addr);
 143         if (error < 0 || (size_t)error >= sizeof(fn)) {
 144                 syslog(LOG_NOTICE, "local delivery deferred: %m");
 145                 return (1);
 146         }
 147
 148 retry:
 149         /* wait for a maximum of 100s to get the lock to the file */
 150         do_timeout(100, 0);
 151
 152         /* don't use O_CREAT here, because we might be running as the wrong user. */
 153         mbox = open_locked(fn, O_WRONLY|O_APPEND);
 154         if (mbox < 0) {
 155                 int e = errno;
 156
 157                 do_timeout(0, 0);
 158
 159                 switch (e) {
 160                 case EACCES:
 161                 case ENOENT:
 162                         /*
 163                          * The file does not exist or we can't access it.
 164                          * Call dma-mbox-create to create it and fix permissions.
 165                          */
 166                         if (tries > 0 || create_mbox(it->addr) != 0) {
 167                                 syslog(LOG_ERR, "local delivery deferred: can not create `%s'", fn);
 168                                 return (1);
 169                         }
 170                         ++tries;
 171                         goto retry;
 172
 173                 case EINTR:
 174                         syslog(LOG_NOTICE, "local delivery deferred: can not lock `%s'", fn);
 175                         break;
 176
 177                 default:
 178                         syslog(LOG_NOTICE, "local delivery deferred: can not open `%s': %m", fn);
 179                         break;
 180                 }
 181                 return (1);
 182         }
 183         do_timeout(0, 0);
 184
 185         mboxlen = lseek(mbox, 0, SEEK_END);
 186
 187         /* New mails start with \nFrom ...., unless we're at the beginning of the mbox */
 188         if (mboxlen == 0)
 189                 newline = "";
 190
 191         /* If we're bouncing a message, claim it comes from MAILER-DAEMON */
 192         sender = it->sender;
 193         if (strcmp(sender, "") == 0)
 194                 sender = "MAILER-DAEMON";
 195
 196         if (fseek(it->mailf, 0, SEEK_SET) != 0) {
 197                 syslog(LOG_NOTICE, "local delivery deferred: can not seek: %m");
 198                 goto out;
 199         }
 200
 201         error = snprintf(line, sizeof(line), "%sFrom %s %s", newline, sender, ctime(&now));
 202         if (error < 0 || (size_t)error >= sizeof(line)) {
 203                 syslog(LOG_NOTICE, "local delivery deferred: can not write header: %m");
 204                 goto out;
 205         }
 206         if (write(mbox, line, error) != error)
 207                 goto wrerror;
 208
 209         while (!feof(it->mailf)) {
 210                 if (fgets(line, sizeof(line), it->mailf) == NULL)
 211                         break;
 212                 linelen = strlen(line);
 213                 if (linelen == 0 || line[linelen - 1] != '\n') {
 214                         syslog(LOG_CRIT, "local delivery failed: corrupted queue file");
 215                         snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
 216                         error = -1;
 217                         goto chop;
 218                 }
 219
 220                 /*
 221                  * mboxro processing:
 222                  * - escape lines that start with "From " with a > sign.
 223                  * - be reversible by escaping lines that contain an arbitrary
 224                  *   number of > signs, followed by "From ", i.e. />*From / in regexp.
 225                  * - strict mbox processing only requires escaping after empty lines,
 226                  *   yet most MUAs seem to relax this requirement and will treat any
 227                  *   line starting with "From " as the beginning of a new mail.
 228                  */
 229                 if ((!MBOX_STRICT || hadnl) &&
 230                     strncmp(&line[strspn(line, ">")], "From ", 5) == 0) {
 231                         const char *gt = ">";
 232
 233                         if (write(mbox, gt, 1) != 1)
 234                                 goto wrerror;
 235                         hadnl = 0;
 236                 } else if (strcmp(line, "\n") == 0) {
 237                         hadnl = 1;
 238                 } else {
 239                         hadnl = 0;
 240                 }
 241                 if ((size_t)write(mbox, line, linelen) != linelen)
 242                         goto wrerror;
 243         }
 244         close(mbox);
 245         return (0);
 246
 247 wrerror:
 248         syslog(LOG_ERR, "local delivery failed: write error: %m");
 249         error = 1;
 250 chop:
 251         if (ftruncate(mbox, mboxlen) != 0)
 252                 syslog(LOG_WARNING, "error recovering mbox `%s': %m", fn);
 253 out:
 254         close(mbox);
 255         return (error);
 256 }