diplodocus.org Git - nmh/blob - test/fakesmtp.c

   1 /*
   2  * fakesmtp - A fake SMTP server used by the nmh test suite
   3  *
   4  * This code is Copyright (c) 2012, by the authors of nmh.  See the
   5  * COPYRIGHT file in the root directory of the nmh distribution for
   6  * complete copyright information.
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13 #include <netdb.h>
  14 #include <errno.h>
  15 #include <sys/socket.h>
  16 #include <sys/types.h>
  17 #include <sys/select.h>
  18 #include <sys/stat.h>
  19 #include <sys/uio.h>
  20 #include <signal.h>
  21
  22 #define PIDFILE "/tmp/fakesmtp.pid"
  23
  24 #define LINESIZE 1024
  25
  26 static void killpidfile(void);
  27 static void handleterm(int);
  28 static void putsmtp(int, char *);
  29 static int getsmtp(int, char *);
  30
  31 int
  32 main(int argc, char *argv[])
  33 {
  34         struct addrinfo hints, *res;
  35         int rc, l, conn, on, datamode;
  36         FILE *f, *pid;
  37         fd_set readfd;
  38         struct stat st;
  39         struct timeval tv;
  40
  41         if (argc != 3) {
  42                 fprintf(stderr, "Usage: %s output-filename port\n", argv[0]);
  43                 exit(1);
  44         }
  45
  46         if (!(f = fopen(argv[1], "w"))) {
  47                 fprintf(stderr, "Unable to open output file \"%s\": %s\n",
  48                         argv[1], strerror(errno));
  49                 exit(1);
  50         }
  51
  52         memset(&hints, 0, sizeof(hints));
  53
  54         hints.ai_family = PF_INET;
  55         hints.ai_socktype = SOCK_STREAM;
  56         hints.ai_protocol = IPPROTO_TCP;
  57         hints.ai_flags = AI_PASSIVE;
  58
  59         rc = getaddrinfo("127.0.0.1", argv[2], &hints, &res);
  60
  61         if (rc) {
  62                 fprintf(stderr, "Unable to resolve localhost/%s: %s\n",
  63                         argv[2], gai_strerror(rc));
  64                 exit(1);
  65         }
  66
  67         l = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
  68
  69         if (l == -1) {
  70                 fprintf(stderr, "Unable to create listening socket: %s\n",
  71                         strerror(errno));
  72                 exit(1);
  73         }
  74
  75         on = 1;
  76
  77         if (setsockopt(l, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) {
  78                 fprintf(stderr, "Unable to set SO_REUSEADDR: %s\n",
  79                         strerror(errno));
  80                 exit(1);
  81         }
  82
  83         if (bind(l, res->ai_addr, res->ai_addrlen) == -1) {
  84                 fprintf(stderr, "Unable to bind socket: %s\n", strerror(errno));
  85                 exit(1);
  86         }
  87
  88         if (listen(l, 1) == -1) {
  89                 fprintf(stderr, "Unable to listen on socket: %s\n",
  90                         strerror(errno));
  91                 exit(1);
  92         }
  93
  94         /*
  95          * Now that our socket & files are set up, do the following things:
  96          *
  97          * - Check for a PID file.  If there is one, kill the old version.
  98          * - Wait 30 seconds for a connection.  If there isn't one, then
  99          *   exit.
 100          */
 101
 102         if (stat(PIDFILE, &st) == 0) {
 103                 long oldpid;
 104
 105                 if (!(pid = fopen(PIDFILE, "r"))) {
 106                         fprintf(stderr, "Cannot open " PIDFILE
 107                                 " (%s), continuing ...\n", strerror(errno));
 108                 } else {
 109                         rc = fscanf(pid, "%ld", &oldpid);
 110                         fclose(pid);
 111
 112                         if (rc != 1) {
 113                                 fprintf(stderr, "Unable to parse pid in "
 114                                         PIDFILE ", continuing ...\n");
 115                         } else {
 116                                 kill((pid_t) oldpid, SIGTERM);
 117                         }
 118                 }
 119
 120                 unlink(PIDFILE);
 121         }
 122
 123         if (!(pid = fopen(PIDFILE, "w"))) {
 124                 fprintf(stderr, "Cannot open " PIDFILE ": %s\n",
 125                         strerror(errno));
 126                 exit(1);
 127         }
 128
 129         fprintf(pid, "%ld\n", (long) getpid());
 130         fclose(pid);
 131
 132         signal(SIGTERM, handleterm);
 133         atexit(killpidfile);
 134
 135         FD_ZERO(&readfd);
 136         FD_SET(l, &readfd);
 137         tv.tv_sec = 30;
 138         tv.tv_usec = 0;
 139
 140         rc = select(l + 1, &readfd, NULL, NULL, &tv);
 141
 142         if (rc < 0) {
 143                 fprintf(stderr, "select() failed: %s\n", strerror(errno));
 144                 exit(1);
 145         }
 146
 147         /*
 148          * I think if we get a timeout, we should just exit quietly.
 149          */
 150
 151         if (rc == 0) {
 152                 exit(1);
 153         }
 154
 155         /*
 156          * Alright, got a connection!  Accept it.
 157          */
 158
 159         if ((conn = accept(l, NULL, NULL)) == -1) {
 160                 fprintf(stderr, "Unable to accept connection: %s\n",
 161                         strerror(errno));
 162                 exit(1);
 163         }
 164
 165         close(l);
 166
 167         /*
 168          * Pretend to be an SMTP server.
 169          */
 170
 171         putsmtp(conn, "220 Not really an ESMTP server");
 172         datamode = 0;
 173
 174         for (;;) {
 175                 char line[LINESIZE];
 176
 177                 rc = getsmtp(conn, line);
 178
 179                 if (rc == -1)
 180                         break;  /* EOF */
 181
 182                 fprintf(f, "%s\n", line);
 183
 184                 /*
 185                  * If we're in DATA mode, then check to see if we've got
 186                  * a "."; otherwise, continue
 187                  */
 188
 189                 if (datamode) {
 190                         if (strcmp(line, ".") == 0) {
 191                                 datamode = 0;
 192                                 putsmtp(conn, "250 Thanks for the info!");
 193                         }
 194                         continue;
 195                 }
 196
 197                 /*
 198                  * Most commands we ignore and send the same response to.
 199                  */
 200
 201                 if (strcmp(line, "QUIT") == 0) {
 202                         putsmtp(conn, "221 Later alligator!");
 203                         close(conn);
 204                         break;
 205                 } else if (strcmp(line, "DATA") == 0) {
 206                         putsmtp(conn, "354 Go ahead");
 207                         datamode = 1;
 208                 } else {
 209                         putsmtp(conn, "250 I'll buy that for a dollar!");
 210                 }
 211         }
 212
 213         fclose(f);
 214
 215         exit(0);
 216 }
 217
 218 /*
 219  * Write a line to the SMTP client on the other end
 220  */
 221
 222 static void
 223 putsmtp(int socket, char *data)
 224 {
 225         struct iovec iov[2];
 226
 227         iov[0].iov_base = data;
 228         iov[0].iov_len = strlen(data);
 229         iov[1].iov_base = "\r\n";
 230         iov[1].iov_len = 2;
 231
 232         writev(socket, iov, 2);
 233 }
 234
 235 /*
 236  * Read a line (up to the \r\n)
 237  */
 238
 239 static int
 240 getsmtp(int socket, char *data)
 241 {
 242         int cc;
 243         static unsigned int bytesinbuf = 0;
 244         static char buffer[LINESIZE * 2], *p;
 245
 246         for (;;) {
 247                 /*
 248                  * Find our \r\n
 249                  */
 250
 251                 if (bytesinbuf > 0 && (p = strchr(buffer, '\r')) &&
 252                                                         *(p + 1) == '\n') {
 253                         *p = '\0';
 254                         strncpy(data, buffer, LINESIZE);
 255                         data[LINESIZE - 1] = '\0';
 256                         cc = strlen(buffer);
 257
 258                         /*
 259                          * Shuffle leftover bytes back to the beginning
 260                          */
 261
 262                         bytesinbuf -= cc + 2;   /* Don't forget \r\n */
 263                         if (bytesinbuf > 0) {
 264                                 memmove(buffer, buffer + cc + 2, bytesinbuf);
 265                         }
 266                         return cc;
 267                 }
 268
 269                 if (bytesinbuf >= sizeof(buffer)) {
 270                         fprintf(stderr, "Buffer overflow in getsmtp()!\n");
 271                         exit(1);
 272                 }
 273
 274                 memset(buffer + bytesinbuf, 0, sizeof(buffer) - bytesinbuf);
 275                 cc = read(socket, buffer + bytesinbuf,
 276                           sizeof(buffer) - bytesinbuf);
 277
 278                 if (cc < 0) {
 279                         fprintf(stderr, "Read failed: %s\n", strerror(errno));
 280                         exit(1);
 281                 }
 282
 283                 if (cc == 0)
 284                         return -1;
 285
 286                 bytesinbuf += cc;
 287         }
 288 }
 289
 290 /*
 291  * Handle a SIGTERM
 292  */
 293
 294 static void
 295 handleterm(int signal)
 296 {
 297         (void) signal;
 298
 299         killpidfile();
 300         fflush(NULL);
 301         _exit(1);
 302 }
 303
 304 /*
 305  * Get rid of our pid file
 306  */
 307
 308 static void
 309 killpidfile(void)
 310 {
 311         unlink(PIDFILE);
 312 }