external/ibm-public/postfix/dist/src/smtpd/smtpd_chat.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      smtpd_chat 3
   6 /* SUMMARY
   7 /*      SMTP server request/response support
   8 /* SYNOPSIS
   9 /*      #include <smtpd.h>
  10 /*      #include <smtpd_chat.h>
  11 /*
  12 /*      void    smtpd_chat_query(state)
  13 /*      SMTPD_STATE *state;
  14 /*
  15 /*      void    smtpd_chat_reply(state, format, ...)
  16 /*      SMTPD_STATE *state;
  17 /*      char    *format;
  18 /*
  19 /*      void    smtpd_chat_notify(state)
  20 /*      SMTPD_STATE *state;
  21 /*
  22 /*      void    smtpd_chat_reset(state)
  23 /*      SMTPD_STATE *state;
  24 /* DESCRIPTION
  25 /*      This module implements SMTP server support for request/reply
  26 /*      conversations, and maintains a limited SMTP transaction log.
  27 /*
  28 /*      smtpd_chat_query() receives a client request and appends a copy
  29 /*      to the SMTP transaction log.
  30 /*
  31 /*      smtpd_chat_reply() formats a server reply, sends it to the
  32 /*      client, and appends a copy to the SMTP transaction log.
  33 /*      When soft_bounce is enabled, all 5xx (reject) reponses are
  34 /*      replaced by 4xx (try again). In case of a 421 reply the
  35 /*      SMTPD_FLAG_HANGUP flag is set for orderly disconnect.
  36 /*
  37 /*      smtpd_chat_notify() sends a copy of the SMTP transaction log
  38 /*      to the postmaster for review. The postmaster notice is sent only
  39 /*      when delivery is possible immediately. It is an error to call
  40 /*      smtpd_chat_notify() when no SMTP transaction log exists.
  41 /*
  42 /*      smtpd_chat_reset() resets the transaction log. This is
  43 /*      typically done at the beginning of an SMTP session, or
  44 /*      within a session to discard non-error information.
  45 /* DIAGNOSTICS
  46 /*      Panic: interface violations. Fatal errors: out of memory.
  47 /*      internal protocol errors.
  48 /* LICENSE
  49 /* .ad
  50 /* .fi
  51 /*      The Secure Mailer license must be distributed with this software.
  52 /* AUTHOR(S)
  53 /*      Wietse Venema
  54 /*      IBM T.J. Watson Research
  55 /*      P.O. Box 704
  56 /*      Yorktown Heights, NY 10598, USA
  57 /*--*/
  58
  59 /* System library. */
  60
  61 #include <sys_defs.h>
  62 #include <setjmp.h>
  63 #include <unistd.h>
  64 #include <time.h>
  65 #include <stdlib.h>                     /* 44BSD stdarg.h uses abort() */
  66 #include <stdarg.h>
  67
  68 /* Utility library. */
  69
  70 #include <msg.h>
  71 #include <argv.h>
  72 #include <vstring.h>
  73 #include <vstream.h>
  74 #include <stringops.h>
  75 #include <line_wrap.h>
  76 #include <mymalloc.h>
  77
  78 /* Global library. */
  79
  80 #include <smtp_stream.h>
  81 #include <record.h>
  82 #include <rec_type.h>
  83 #include <mail_proto.h>
  84 #include <mail_params.h>
  85 #include <mail_addr.h>
  86 #include <post_mail.h>
  87 #include <mail_error.h>
  88
  89 /* Application-specific. */
  90
  91 #include "smtpd.h"
  92 #include "smtpd_chat.h"
  93
  94 #define STR     vstring_str
  95 #define LEN     VSTRING_LEN
  96
  97 /* smtp_chat_reset - reset SMTP transaction log */
  98
  99 void    smtpd_chat_reset(SMTPD_STATE *state)
 100 {
 101     if (state->history) {
 102         argv_free(state->history);
 103         state->history = 0;
 104     }
 105 }
 106
 107 /* smtp_chat_append - append record to SMTP transaction log */
 108
 109 static void smtp_chat_append(SMTPD_STATE *state, char *direction,
 110                                      const char *text)
 111 {
 112     char   *line;
 113
 114     if (state->notify_mask == 0)
 115         return;
 116
 117     if (state->history == 0)
 118         state->history = argv_alloc(10);
 119     line = concatenate(direction, text, (char *) 0);
 120     argv_add(state->history, line, (char *) 0);
 121     myfree(line);
 122 }
 123
 124 /* smtpd_chat_query - receive and record an SMTP request */
 125
 126 void    smtpd_chat_query(SMTPD_STATE *state)
 127 {
 128     int     last_char;
 129
 130     last_char = smtp_get(state->buffer, state->client, var_line_limit);
 131     smtp_chat_append(state, "In:  ", STR(state->buffer));
 132     if (last_char != '\n')
 133         msg_warn("%s: request longer than %d: %.30s...",
 134                  state->namaddr, var_line_limit,
 135                  printable(STR(state->buffer), '?'));
 136
 137     if (msg_verbose)
 138         msg_info("< %s: %s", state->namaddr, STR(state->buffer));
 139 }
 140
 141 /* smtpd_chat_reply - format, send and record an SMTP response */
 142
 143 void    smtpd_chat_reply(SMTPD_STATE *state, const char *format,...)
 144 {
 145     va_list ap;
 146     int     delay = 0;
 147     char   *cp;
 148     char   *next;
 149     char   *end;
 150
 151     /*
 152      * Slow down clients that make errors. Sleep-on-anything slows down
 153      * clients that make an excessive number of errors within a session.
 154      */
 155     if (state->error_count >= var_smtpd_soft_erlim)
 156         sleep(delay = var_smtpd_err_sleep);
 157
 158     va_start(ap, format);
 159     vstring_vsprintf(state->buffer, format, ap);
 160     va_end(ap);
 161     /* All 5xx replies must have a 5.xx.xx detail code. */
 162     for (cp = STR(state->buffer), end = cp + strlen(STR(state->buffer));;) {
 163         if (var_soft_bounce) {
 164             if (cp[0] == '5') {
 165                 cp[0] = '4';
 166                 if (cp[4] == '5')
 167                     cp[4] = '4';
 168             }
 169         }
 170         /* This is why we use strlen() above instead of VSTRING_LEN(). */
 171         if ((next = strstr(cp, "\r\n")) != 0) {
 172             *next = 0;
 173         } else {
 174             next = end;
 175         }
 176         smtp_chat_append(state, "Out: ", cp);
 177
 178         if (msg_verbose)
 179             msg_info("> %s: %s", state->namaddr, cp);
 180
 181         smtp_fputs(cp, next - cp, state->client);
 182         if (next < end)
 183             cp = next + 2;
 184         else
 185             break;
 186     }
 187
 188     /*
 189      * Flush unsent output if no I/O happened for a while. This avoids
 190      * timeouts with pipelined SMTP sessions that have lots of server-side
 191      * delays (tarpit delays or DNS lookups for UCE restrictions).
 192      */
 193     if (delay || time((time_t *) 0) - vstream_ftime(state->client) > 10)
 194         vstream_fflush(state->client);
 195
 196     /*
 197      * Abort immediately if the connection is broken.
 198      */
 199     if (vstream_ftimeout(state->client))
 200         vstream_longjmp(state->client, SMTP_ERR_TIME);
 201     if (vstream_ferror(state->client))
 202         vstream_longjmp(state->client, SMTP_ERR_EOF);
 203
 204     /*
 205      * Orderly disconnect in case of 421 or 521 reply.
 206      */
 207     if (strncmp(STR(state->buffer), "421", 3) == 0
 208         || strncmp(STR(state->buffer), "521", 3) == 0)
 209         state->flags |= SMTPD_FLAG_HANGUP;
 210 }
 211
 212 /* print_line - line_wrap callback */
 213
 214 static void print_line(const char *str, int len, int indent, char *context)
 215 {
 216     VSTREAM *notice = (VSTREAM *) context;
 217
 218     post_mail_fprintf(notice, " %*s%.*s", indent, "", len, str);
 219 }
 220
 221 /* smtpd_chat_notify - notify postmaster */
 222
 223 void    smtpd_chat_notify(SMTPD_STATE *state)
 224 {
 225     const char *myname = "smtpd_chat_notify";
 226     VSTREAM *notice;
 227     char  **cpp;
 228
 229     /*
 230      * Sanity checks.
 231      */
 232     if (state->history == 0)
 233         msg_panic("%s: no conversation history", myname);
 234     if (msg_verbose)
 235         msg_info("%s: notify postmaster", myname);
 236
 237     /*
 238      * Construct a message for the postmaster, explaining what this is all
 239      * about. This is junk mail: don't send it when the mail posting service
 240      * is unavailable, and use the double bounce sender address to prevent
 241      * mail bounce wars. Always prepend one space to message content that we
 242      * generate from untrusted data.
 243      */
 244 #define NULL_TRACE_FLAGS        0
 245 #define NO_QUEUE_ID             ((VSTRING *) 0)
 246 #define LENGTH  78
 247 #define INDENT  4
 248
 249     notice = post_mail_fopen_nowait(mail_addr_double_bounce(),
 250                                     var_error_rcpt,
 251                                     INT_FILT_MASK_NOTIFY,
 252                                     NULL_TRACE_FLAGS, NO_QUEUE_ID);
 253     if (notice == 0) {
 254         msg_warn("postmaster notify: %m");
 255         return;
 256     }
 257     post_mail_fprintf(notice, "From: %s (Mail Delivery System)",
 258                       mail_addr_mail_daemon());
 259     post_mail_fprintf(notice, "To: %s (Postmaster)", var_error_rcpt);
 260     post_mail_fprintf(notice, "Subject: %s SMTP server: errors from %s",
 261                       var_mail_name, state->namaddr);
 262     post_mail_fputs(notice, "");
 263     post_mail_fputs(notice, "Transcript of session follows.");
 264     post_mail_fputs(notice, "");
 265     argv_terminate(state->history);
 266     for (cpp = state->history->argv; *cpp; cpp++)
 267         line_wrap(printable(*cpp, '?'), LENGTH, INDENT, print_line,
 268                   (char *) notice);
 269     post_mail_fputs(notice, "");
 270     if (state->reason)
 271         post_mail_fprintf(notice, "Session aborted, reason: %s", state->reason);
 272     post_mail_fputs(notice, "");
 273     post_mail_fprintf(notice, "For other details, see the local mail logfile");
 274     (void) post_mail_fclose(notice);
 275 }