* Add support for the OAUTHBEARER authentication method in Gmail. Thanks to

[alpine.git] / imap / src / c-client / smtp.c

/* ========================================================================
 * Copyright 2015-2020 Eduardo Chappa
 * Copyright 2008 Mark Crispin
 * ========================================================================
 */

/*
 * Program:     Simple Mail Transfer Protocol (SMTP) routines
 *
 * Author:      Mark Crispin
 *
 * Date:        27 July 1988
 * Last Edited: 19 November 2008 (Crispin)
 * Last Edited: 8 December 2018 (Chappa)
 *
 * Previous versions of this file were
 *
 * Copyright 1988-2008 University of Washington
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * This original version of this file is
 * Copyright 1988 Stanford University
 * and was developed in the Symbolic Systems Resources Group of the Knowledge
 * Systems Laboratory at Stanford University in 1987-88, and was funded by the
 * Biomedical Research Technology Program of the National Institutes of Health
 * under grant number RR-00785.
 */


#include <ctype.h>
#include <stdio.h>
#include "c-client.h"
\f
/* Constants */

#define SMTPSSLPORT (long) 465  /* former assigned SSL TCP contact port */
#define SMTPGREET (long) 220    /* SMTP successful greeting */
#define SMTPAUTHED (long) 235   /* SMTP successful authentication */
#define SMTPOK (long) 250       /* SMTP OK code */
#define SMTPAUTHREADY (long) 334/* SMTP ready for authentication */
#define SMTPREADY (long) 354    /* SMTP ready for data */
#define SMTPSOFTFATAL (long) 421/* SMTP soft fatal code */
#define SMTPWANTAUTH (long) 505 /* SMTP authentication needed */
#define SMTPWANTAUTH2 (long) 530/* SMTP authentication needed */
#define SMTPUNAVAIL (long) 550  /* SMTP mailbox unavailable */
#define SMTPHARDERROR (long) 554/* SMTP miscellaneous hard failure */


/* Convenient access to protocol-specific data */

#define ESMTP stream->protocol.esmtp


/* Function prototypes */

void *smtp_challenge (void *s,unsigned long *len);
long smtp_response (void *s,char *response,unsigned long size);
long smtp_auth (SENDSTREAM *stream,NETMBX *mb,char *tmp);
long smtp_rcpt (SENDSTREAM *stream,ADDRESS *adr,long *error);
long smtp_send (SENDSTREAM *stream,char *command,char *args);
long smtp_reply (SENDSTREAM *stream);
long smtp_ehlo (SENDSTREAM *stream,char *host,NETMBX *mb);
long smtp_fake (SENDSTREAM *stream,char *text);
static long smtp_seterror (SENDSTREAM *stream,long code,char *text);
long smtp_soutr (void *stream,char *s);
\f
/* Mailer parameters */

static unsigned long smtp_maxlogintrials = MAXLOGINTRIALS;
static long smtp_port = 0;      /* default port override */
static long smtp_sslport = 0;


#ifndef RFC2821
#define RFC2821                 /* RFC 2821 compliance */
#endif

/* SMTP limits, current as of RFC 2821 */

#define SMTPMAXLOCALPART 64
#define SMTPMAXDOMAIN 255
#define SMTPMAXPATH 256


/* I have seen local parts of more than 64 octets, in spite of the SMTP
 * limits.  So, we'll have a more generous limit that's still guaranteed
 * not to pop the buffer, and let the server worry about it.  As of this
 * writing, it comes out to 240.  Anyone with a mailbox name larger than
 * that is in serious need of a life or at least a new ISP!  23 June 1998
 */

#define MAXLOCALPART ((MAILTMPLEN - (SMTPMAXDOMAIN + SMTPMAXPATH + 32)) / 2)
\f
/* Mail Transfer Protocol manipulate driver parameters
 * Accepts: function code
 *          function-dependent value
 * Returns: function-dependent return value
 */

void *smtp_parameters (long function,void *value)
{
  switch ((int) function) {
  case SET_MAXLOGINTRIALS:
    smtp_maxlogintrials = (unsigned long) value;
    break;
  case GET_MAXLOGINTRIALS:
    value = (void *) smtp_maxlogintrials;
    break;
  case SET_SMTPPORT:
    smtp_port = (long) value;
    break;
  case GET_SMTPPORT:
    value = (void *) smtp_port;
    break;
  case SET_SSLSMTPPORT:
    smtp_sslport = (long) value;
    break;
  case GET_SSLSMTPPORT:
    value = (void *) smtp_sslport;
    break;
  default:
    value = NIL;                /* error case */
    break;
  }
  return value;
}
\f
/* Mail Transfer Protocol open connection
 * Accepts: network driver
 *          service host list
 *          port number
 *          service name
 *          SMTP open options
 * Returns: SEND stream on success, NIL on failure
 */

SENDSTREAM *smtp_open_full (NETDRIVER *dv,char **hostlist,char *service,
                            unsigned long port,long options)
{
  SENDSTREAM *stream = NIL;
  long reply;
  char *s,tmp[MAILTMPLEN];
  NETSTREAM *netstream;
  NETMBX mb;
  if (!(hostlist && *hostlist)) mm_log ("Missing SMTP service host",ERROR);
                                /* maximum domain name is 64 characters */
  else do if (strlen (*hostlist) < SMTPMAXDOMAIN) {
    sprintf (tmp,"{%.1000s}",*hostlist);
    if (!mail_valid_net_parse_work (tmp,&mb,service ? service : "smtp") ||
        mb.anoflag || mb.readonlyflag) {
      sprintf (tmp,"Invalid host specifier: %.80s",*hostlist);
      mm_log (tmp,ERROR);
    }
    else {                      /* light tryssl flag if requested */
      mb.trysslflag = (options & SOP_TRYSSL) ? T : NIL;
                                /* explicit port overrides all */
      if (mb.port) port = mb.port;
                                /* else /submit overrides port argument */
      else if (!compare_cstring (mb.service,"submit")) {
        port = SUBMITTCPPORT;   /* override port, use IANA name */
        strcpy (mb.service,"submission");
      }
                                /* else port argument overrides SMTP port */
      else if (!port) port = smtp_port ? smtp_port : SMTPTCPPORT;
      if ((netstream =          /* try to open ordinary connection */
          net_open (&mb,dv,port,
                    (NETDRIVER *) mail_parameters (NIL,GET_SSLDRIVER,NIL),
                    "*smtps",smtp_sslport ? smtp_sslport : SMTPSSLPORT)) != NULL) {
        stream = (SENDSTREAM *) memset (fs_get (sizeof (SENDSTREAM)),0,
                                        sizeof (SENDSTREAM));
        stream->netstream = netstream;
        stream->host = cpystr ((long) mail_parameters (NIL,GET_TRUSTDNS,NIL) ?
                               net_host (netstream) : mb.host);
        stream->debug = (mb.dbgflag || (options & OP_DEBUG)) ? T : NIL;
        if (options & SOP_SECURE) mb.secflag = T;
                                /* get name of local host to use */
        s = compare_cstring ("localhost",mb.host) ?
          net_localhost (netstream) : "localhost";
\f
        do reply = smtp_reply (stream);
        while ((reply < 100) || (stream->reply[3] == '-'));
        if (reply != SMTPGREET){/* get SMTP greeting */
          sprintf (tmp,"SMTP greeting failure: %.80s",stream->reply);
          mm_log (tmp,ERROR);
          stream = smtp_close (stream);
        }
                                /* try EHLO first, then HELO */
        else if (((reply = smtp_ehlo (stream,s,&mb)) != SMTPOK) &&
                 ((reply = smtp_send (stream,"HELO",s)) != SMTPOK)) {
          sprintf (tmp,"SMTP hello failure: %.80s",stream->reply);
          mm_log (tmp,ERROR);
          stream = smtp_close (stream);
        }
        else {
          NETDRIVER *ssld =(NETDRIVER *)mail_parameters(NIL,GET_SSLDRIVER,NIL);
          sslstart_t stls = (sslstart_t) mail_parameters(NIL,GET_SSLSTART,NIL);
          ESMTP.ok = T;         /* ESMTP server, start TLS if present */
          if (!dv && stls && ESMTP.service.starttls &&
              !mb.sslflag && !mb.notlsflag &&
              (smtp_send (stream,"STARTTLS",NIL) == SMTPGREET)) {
            mb.tlsflag = T;     /* TLS OK, get into TLS at this end */
            stream->netstream->dtb = ssld;
                                /* TLS started, negotiate it */
            if (!(stream->netstream->stream = (*stls)
                  (stream->netstream->stream,mb.host,
                   SSL_MTHD(mb) | (mb.novalidate ? NET_NOVALIDATECERT:NIL)))){
                                /* TLS negotiation failed after STARTTLS */
              sprintf (tmp,"Unable to negotiate TLS with this server: %.80s",
                       mb.host);
              mm_log (tmp,ERROR);
                                /* close without doing QUIT */
              if (stream->netstream) net_close (stream->netstream);
              stream->netstream = NIL;
              stream = smtp_close (stream);
            }
                                /* TLS OK, re-negotiate EHLO */
            else if ((reply = smtp_ehlo (stream,s,&mb)) != SMTPOK) {
              sprintf (tmp,"SMTP EHLO failure after STARTTLS: %.80s",
                       stream->reply);
              mm_log (tmp,ERROR);
              stream = smtp_close (stream);
            }
            else ESMTP.ok = T;  /* TLS OK and EHLO successful */
          }
          else if (mb.tlsflag) {/* user specified /tls but can't do it */
            sprintf (tmp,"TLS unavailable with this server: %.80s",mb.host);
            mm_log (tmp,ERROR);
            stream = smtp_close (stream);
          }
\f
                                /* remote name for authentication */
          if (stream && ((mb.secflag || mb.user[0]))) {
            if (ESMTP.auth) {   /* use authenticator? */
              if ((long) mail_parameters (NIL,GET_TRUSTDNS,NIL)) {
                                /* remote name for authentication */
                strncpy (mb.host,
                         (long) mail_parameters (NIL,GET_SASLUSESPTRNAME,NIL) ?
                         net_remotehost (netstream) : net_host (netstream),
                         NETMAXHOST-1);
                mb.host[NETMAXHOST-1] = '\0';
              }
              if (!smtp_auth (stream,&mb,tmp)) stream = smtp_close (stream);
            }
            else {              /* no available authenticators? */
              sprintf (tmp,"%sSMTP authentication not available: %.80s",
                       mb.secflag ? "Secure " : "",mb.host);
              mm_log (tmp,ERROR);
              stream = smtp_close (stream);
            }
          }
        }
      }
    }
  } while (!stream && *++hostlist);
  if (stream) {                 /* set stream options if have a stream */
    if (options &(SOP_DSN | SOP_DSN_NOTIFY_FAILURE | SOP_DSN_NOTIFY_DELAY |
                  SOP_DSN_NOTIFY_SUCCESS | SOP_DSN_RETURN_FULL)) {
      ESMTP.dsn.want = T;
      if (options & SOP_DSN_NOTIFY_FAILURE) ESMTP.dsn.notify.failure = T;
      if (options & SOP_DSN_NOTIFY_DELAY) ESMTP.dsn.notify.delay = T;
      if (options & SOP_DSN_NOTIFY_SUCCESS) ESMTP.dsn.notify.success = T;
      if (options & SOP_DSN_RETURN_FULL) ESMTP.dsn.full = T;
    }
    if (options & SOP_8BITMIME) ESMTP.eightbit.want = T;
  }
  return stream;
}
\f
/* SMTP authenticate
 * Accepts: stream to login
 *          parsed network mailbox structure
 *          scratch buffer
 *          place to return user name
 * Returns: T on success, NIL on failure
 */

long smtp_auth (SENDSTREAM *stream,NETMBX *mb,char *tmp)
{
  unsigned long trial,auths, authsaved;
  char *lsterr = NIL;
  char usr[MAILTMPLEN];
  AUTHENTICATOR *at, *atsaved;
  long ret = NIL;
  for (auths = ESMTP.auth, stream->saslcancel = NIL;
       !ret && stream->netstream && auths &&
       (at = mail_lookup_auth (find_rightmost_bit (&auths) + 1)); ) {
    if(mb && *mb->auth){
       if(!compare_cstring(at->name, mb->auth))
          atsaved = at;
       else{
          authsaved = auths;
          continue;
       }
    }
    if (lsterr) {               /* previous authenticator failed? */
      sprintf (tmp,"Retrying using %s authentication after %.80s",
               at->name,lsterr);
      mm_log (tmp,NIL);
      fs_give ((void **) &lsterr);
    }
    trial = 0;                  /* initial trial count */
    tmp[0] = '\0';              /* empty buffer */
    if (stream->netstream) do {
      if (lsterr) {
        sprintf (tmp,"Retrying %s authentication after %.80s",at->name,lsterr);
        mm_log (tmp,WARN);
        fs_give ((void **) &lsterr);
      }
      stream->saslcancel = NIL;
      if (smtp_send (stream,"AUTH",at->name) == SMTPAUTHREADY) {
                                /* hide client authentication responses */
        if (!(at->flags & AU_SECURE)) stream->sensitive = T;
        if ((*at->client) (smtp_challenge,smtp_response,"smtp",mb,stream,
                           net_port(stream->netstream),&trial,usr)) {
          if (stream->replycode == SMTPAUTHED) {
            ESMTP.auth = NIL;   /* disable authenticators */
            ret = LONGT;
          }
                                /* if main program requested cancellation */
          else if (!trial) mm_log ("SMTP Authentication cancelled",ERROR);
        }
        stream->sensitive = NIL;/* unhide */
      }
                                /* remember response if error and no cancel */
      if (!ret && trial) lsterr = cpystr (stream->reply);
    } while (!ret && stream->netstream && trial &&
             (trial < smtp_maxlogintrials));
  }
  if (lsterr) {                 /* previous authenticator failed? */
    if (!stream->saslcancel) {  /* don't do this if a cancel */
      sprintf (tmp,"Can not authenticate to SMTP server: %.80s",lsterr);
      mm_log (tmp,ERROR);
    }
    fs_give ((void **) &lsterr);
  }
  if(mb && *mb->auth){
      if(!authsaved) sprintf (tmp, "Client does not support AUTH=%.80s authenticator",mb->auth);
      else if (!atsaved) sprintf (tmp,"SMTP server does not support AUTH=%.80s authenticator",mb->auth);
      if (!authsaved || !atsaved) mm_log (tmp,ERROR);
  }
  return ret;                   /* authentication failed */
}
\f
/* Get challenge to authenticator in binary
 * Accepts: stream
 *          pointer to returned size
 * Returns: challenge or NIL if not challenge
 */

void *smtp_challenge (void *s,unsigned long *len)
{
  char tmp[MAILTMPLEN];
  void *ret = NIL;
  SENDSTREAM *stream = (SENDSTREAM *) s;
  if ((stream->replycode == SMTPAUTHREADY) &&
      !(ret = rfc822_base64 ((unsigned char *) stream->reply + 4,
                             strlen (stream->reply + 4),len))) {
    sprintf (tmp,"SMTP SERVER BUG (invalid challenge, continuing): %.80s",stream->reply+4);
    mm_log (tmp,ERROR);
    ret = cpystr("");   /* This is silly: fake a reply, it will be ignored */
  }
  return ret;
}


/* Send authenticator response in BASE64
 * Accepts: MAIL stream
 *          string to send
 *          length of string
 * Returns: T, always
 */

long smtp_response (void *s,char *response,unsigned long size)
{
  SENDSTREAM *stream = (SENDSTREAM *) s;
  unsigned long i,j;
  char *t,*u;
  if (response) {               /* make CRLFless BASE64 string */
    if (size) {
      for (t = (char *) rfc822_binary ((void *) response,size,&i),u = t,j = 0;
           j < i; j++) if (t[j] > ' ') *u++ = t[j];
      *u = '\0';                /* tie off string */
      i = smtp_send (stream,t,NIL);
      fs_give ((void **) &t);
    }
    else i = smtp_send (stream,"",NIL);
  }
  else {                        /* abort requested */
    i = smtp_send (stream,"*",NIL);
    stream->saslcancel = T;     /* mark protocol-requested SASL cancel */
  }
  return LONGT;
}
\f
/* Mail Transfer Protocol close connection
 * Accepts: SEND stream
 * Returns: NIL always
 */

SENDSTREAM *smtp_close (SENDSTREAM *stream)
{
  if (stream) {                 /* send "QUIT" */
    if (stream->netstream) {    /* do close actions if have netstream */
      smtp_send (stream,"QUIT",NIL);
      if (stream->netstream) net_close (stream->netstream);
    }
                                /* clean up */
    if (stream->host) fs_give ((void **) &stream->host);
    if (stream->reply) fs_give ((void **) &stream->reply);
    if (ESMTP.dsn.envid) fs_give ((void **) &ESMTP.dsn.envid);
    if (ESMTP.atrn.domains) fs_give ((void **) &ESMTP.atrn.domains);
    fs_give ((void **) &stream);/* flush the stream */
  }
  return NIL;
}
\f
/* Mail Transfer Protocol deliver mail
 * Accepts: SEND stream
 *          delivery option (MAIL, SEND, SAML, SOML)
 *          message envelope
 *          message body
 * Returns: T on success, NIL on failure
 */

long smtp_mail (SENDSTREAM *stream,char *type,ENVELOPE *env,BODY *body)
{
  RFC822BUFFER buf;
  char tmp[SENDBUFLEN+1], smtpserver[SENDBUFLEN+1], *error_string;
  long error = NIL, i;
  long retry = NIL;
  buf.f = smtp_soutr;           /* initialize buffer */
  buf.s = stream->netstream;
  buf.end = (buf.beg = buf.cur = tmp) + SENDBUFLEN;
  tmp[SENDBUFLEN] = '\0';       /* must have additional null guard byte */
  smtpserver[SENDBUFLEN] = '\0';
  if (!(env->to || env->cc || env->bcc)) {
                                /* no recipients in request */
    smtp_seterror (stream,SMTPHARDERROR,"No recipients specified");
    return NIL;
  }
  /* get this now in case the rug is pulled from under us */
  sprintf (smtpserver,"{%.200s/smtp%s}<none>",
    (long) mail_parameters (NIL,GET_TRUSTDNS,NIL) ?
    ((long) mail_parameters (NIL,GET_SASLUSESPTRNAME,NIL) ?
      net_remotehost (stream->netstream) :
      net_host (stream->netstream)) :
         stream->host,
         (stream->netstream->dtb ==
      (NETDRIVER *) mail_parameters (NIL,GET_SSLDRIVER,NIL)) ?
         "/ssl" : "");
  do {
    if (retry) {                /* need to retry with authentication? */
      NETMBX mb;
                                /* make sure stream is in good shape */
      smtp_send (stream,"RSET",NIL);
                                /* yes, build remote name for authentication */
      mail_valid_net_parse (smtpserver,&mb);
      if (!smtp_auth (stream,&mb,smtpserver)) return NIL;
      retry = NIL;              /* no retry at this point */
    }
\f
    strcpy (tmp,"FROM:<");      /* compose "MAIL FROM:<return-path>" */
#ifdef RFC2821
    if (env->return_path && env->return_path->host &&
        !((strlen (env->return_path->mailbox) > SMTPMAXLOCALPART) ||
          (strlen (env->return_path->host) > SMTPMAXDOMAIN))) {
      rfc822_cat (tmp,env->return_path->mailbox,NIL);
      sprintf (tmp + strlen (tmp),"@%s",env->return_path->host);
    }
#else                           /* old code with A-D-L support */
    if (env->return_path && env->return_path->host &&
        !((env->return_path->adl &&
           (strlen (env->return_path->adl) > SMTPMAXPATH)) ||
          (strlen (env->return_path->mailbox) > SMTPMAXLOCALPART) ||
          (strlen (env->return_path->host) > SMTPMAXDOMAIN)))
      rfc822_address (tmp,env->return_path);
#endif
    strcat (tmp,">");
    if (ESMTP.ok) {
      if (ESMTP.eightbit.ok && ESMTP.eightbit.want)
        strcat (tmp," BODY=8BITMIME");
      if (ESMTP.dsn.ok && ESMTP.dsn.want) {
        strcat (tmp,ESMTP.dsn.full ? " RET=FULL" : " RET=HDRS");
        if (ESMTP.dsn.envid)
          sprintf (tmp + strlen (tmp)," ENVID=%.100s",ESMTP.dsn.envid);
      }
    }
                                /* send "MAIL FROM" command */
    switch (i = smtp_send (stream,type,tmp)) {
    case SMTPUNAVAIL:           /* mailbox unavailable? */
    case SMTPWANTAUTH:          /* wants authentication? */
    case SMTPWANTAUTH2:
      if (ESMTP.auth) retry = T;/* yes, retry with authentication */
    case SMTPOK:                /* looks good */
      break;
    default:                    /* other failure */
      error_string = stream && stream->reply ? cpystr(stream->reply) : NIL;
      smtp_send (stream,"RSET",NIL);
      if(error_string){         /* report it */
        smtp_seterror(stream, i, error_string);
        fs_give((void **) &error_string);
      }
      return NIL;
    }
                                /* negotiate the recipients */
    if (!retry && env->to) retry = smtp_rcpt (stream,env->to,&error);
    if (!retry && env->cc) retry = smtp_rcpt (stream,env->cc,&error);
    if (!retry && env->bcc) retry = smtp_rcpt (stream,env->bcc,&error);
    if (!retry && error) {      /* any recipients failed? */
      smtp_send (stream,"RSET",NIL);
      smtp_seterror (stream,SMTPHARDERROR,"One or more recipients failed");
      return NIL;
    }
  } while (retry);
                                /* negotiate data command */
  if (!(smtp_send (stream,"DATA",NIL) == SMTPREADY)) {
    smtp_send (stream,"RSET",NIL);
    return NIL;
  }
                                /* send message data */
  if (!rfc822_output_full (&buf,env,body,
                           ESMTP.eightbit.ok && ESMTP.eightbit.want)) {
    smtp_fake (stream,"SMTP connection broken (message data)");
    return NIL;                 /* can't do much else here */
  }
                                /* send trailing dot */
  if (smtp_send (stream,".",NIL) != SMTPOK) {
    smtp_send (stream,"RSET",NIL);
    return NIL;
  }
  return LONGT;
}
\f
/* Simple Mail Transfer Protocol send VERBose
 * Accepts: SMTP stream
 * Returns: T if successful, else NIL
 *
 * Descriptive text formerly in [al]pine sources:
 * At worst, this command may cause the SMTP connection to get nuked.  Modern
 * sendmail's recognize it, and possibly other SMTP implementations (the "ON"
 * arg is for PMDF).  What's more, if it works, the reply code and accompanying
 * text may vary from server to server.
 */

long smtp_verbose (SENDSTREAM *stream)
{
                                /* accept any 2xx reply code */
  return ((smtp_send (stream,"VERB","ON") / (long) 100) == 2) ? LONGT : NIL;
}
\f
/* Internal routines */


/* Simple Mail Transfer Protocol send recipient
 * Accepts: SMTP stream
 *          address list
 *          pointer to error flag
 * Returns: T if should retry, else NIL
 */

long smtp_rcpt (SENDSTREAM *stream,ADDRESS *adr,long *error)
{
 char *s,tmp[2*MAILTMPLEN],orcpt[MAILTMPLEN];
  while (adr) {                 /* for each address on the list */
                                /* clear any former error */
    if (adr->error) fs_give ((void **) &adr->error);
    if (adr->host) {            /* ignore group syntax */
                                /* enforce SMTP limits to protect the buffer */
      if (strlen (adr->mailbox) > MAXLOCALPART) {
        adr->error = cpystr ("501 Recipient name too long");
        *error = T;
      }
      else if ((strlen (adr->host) > SMTPMAXDOMAIN)) {
        adr->error = cpystr ("501 Recipient domain too long");
        *error = T;
      }
#ifndef RFC2821                 /* old code with A-D-L support */
      else if (adr->adl && (strlen (adr->adl) > SMTPMAXPATH)) {
        adr->error = cpystr ("501 Path too long");
        *error = T;
      }
#endif
\f
      else {
        strcpy (tmp,"TO:<");    /* compose "RCPT TO:<return-path>" */
#ifdef RFC2821
        rfc822_cat (tmp,adr->mailbox,NIL);
        sprintf (tmp + strlen (tmp),"@%s>",adr->host);
#else                           /* old code with A-D-L support */
        rfc822_address (tmp,adr);
        strcat (tmp,">");
#endif
                                /* want notifications */
        if (ESMTP.ok && ESMTP.dsn.ok && ESMTP.dsn.want) {
                                /* yes, start with prefix */
          strcat (tmp," NOTIFY=");
          s = tmp + strlen (tmp);
          if (ESMTP.dsn.notify.failure) strcat (s,"FAILURE,");
          if (ESMTP.dsn.notify.delay) strcat (s,"DELAY,");
          if (ESMTP.dsn.notify.success) strcat (s,"SUCCESS,");
                                /* tie off last comma */
          if (*s) s[strlen (s) - 1] = '\0';
          else strcat (tmp,"NEVER");
          if (adr->orcpt.addr) {
            sprintf (orcpt,"%.498s;%.498s",
                     adr->orcpt.type ? adr->orcpt.type : "rfc822",
                     adr->orcpt.addr);
            sprintf (tmp + strlen (tmp)," ORCPT=%.500s",orcpt);
          }
        }
        switch (smtp_send (stream,"RCPT",tmp)) {
        case SMTPOK:            /* looks good */
          break;
        case SMTPUNAVAIL:       /* mailbox unavailable? */
        case SMTPWANTAUTH:      /* wants authentication? */
        case SMTPWANTAUTH2:
          if (ESMTP.auth) return T;
        default:                /* other failure */
          *error = T;           /* note that an error occurred */
          adr->error = cpystr (stream->reply);
        }
      }
    }
    adr = adr->next;            /* do any subsequent recipients */
  }
  return NIL;                   /* no retry called for */
}
\f
/* Simple Mail Transfer Protocol send command
 * Accepts: SEND stream
 *          text
 * Returns: reply code
 */

long smtp_send (SENDSTREAM *stream,char *command,char *args)
{
  long ret;
  char *s = (char *) fs_get (strlen (command) + (args ? strlen (args) + 1 : 0)
                             + 3);
                                /* build the complete command */
  if (args) sprintf (s,"%s %s",command,args);
  else strcpy (s,command);
  if (stream->debug) mail_dlog (s,stream->sensitive);
  strcat (s,"\015\012");
                                /* send the command */
  if (stream->netstream && net_soutr (stream->netstream,s)) {
    do stream->replycode = smtp_reply (stream);
    while ((stream->replycode < 100) || (stream->reply[3] == '-'));
    ret = stream->replycode;
  }
  else ret = smtp_fake (stream,"SMTP connection broken (command)");
  fs_give ((void **) &s);
  return ret;
}


/* Simple Mail Transfer Protocol get reply
 * Accepts: SMTP stream
 * Returns: reply code
 */

long smtp_reply (SENDSTREAM *stream)
{
  smtpverbose_t pv = (smtpverbose_t) mail_parameters (NIL,GET_SMTPVERBOSE,NIL);
  long reply;
                                /* flush old reply */
  if (stream->reply) fs_give ((void **) &stream->reply);
                                /* get reply */
  if (stream->netstream && (stream->reply = net_getline (stream->netstream))) {
    if (stream->debug) mm_dlog (stream->reply);
                                /* return response code */
    reply = atol (stream->reply);
    if (pv && (reply < 100)) (*pv) (stream->reply);
  }
  else reply = smtp_fake (stream,"SMTP connection broken (reply)");
  return reply;
}
\f
/* Simple Mail Transfer Protocol send EHLO
 * Accepts: SMTP stream
 *          host name to use in EHLO
 *          NETMBX structure
 * Returns: reply code
 */

long smtp_ehlo (SENDSTREAM *stream,char *host,NETMBX *mb)
{
  unsigned long i,j;
  long flags = (mb->secflag ? AU_SECURE : NIL) |
    (mb->authuser[0] ? AU_AUTHUSER : NIL);
  char *s,*t,*r,tmp[MAILTMPLEN];
                                /* clear ESMTP data */
  memset (&ESMTP,0,sizeof (ESMTP));
  if (mb->loser) return 500;    /* never do EHLO if a loser */
  sprintf (tmp,"EHLO %s",host); /* build the complete command */
  if (stream->debug) mm_dlog (tmp);
  strcat (tmp,"\015\012");
                                /* send the command */
  if (!net_soutr (stream->netstream,tmp))
    return smtp_fake (stream,"SMTP connection broken (EHLO)");
                                /* got an OK reply? */
  do if ((i = smtp_reply (stream)) == SMTPOK) {
                                /* hack for AUTH= */
    if (stream->reply[4] && stream->reply[5] && stream->reply[6] &&
        stream->reply[7] && (stream->reply[8] == '=')) stream->reply[8] = ' ';
                                /* get option code */
    if (!(s = strtok_r (stream->reply+4," ",&r)));
                                /* have option, does it have a value */
    else if ((t = strtok_r (NIL," ",&r)) && *t) {
                                /* EHLO options which take arguments */
      if (!compare_cstring (s,"SIZE")) {
        if (isdigit (*t)) ESMTP.size.limit = strtoul (t,&t,10);
        ESMTP.size.ok = T;
      }
      else if (!compare_cstring (s,"DELIVERBY")) {
        if (isdigit (*t)) ESMTP.deliverby.minby = strtoul (t,&t,10);
        ESMTP.deliverby.ok = T;
      }
      else if (!compare_cstring (s,"ATRN")) {
        ESMTP.atrn.domains = cpystr (t);
        ESMTP.atrn.ok = T;
      }
      else if (!compare_cstring (s,"AUTH"))
        do if ((j = mail_lookup_auth_name (t,flags)) &&
               (--j < MAXAUTHENTICATORS)) ESMTP.auth |= (1 << j);
        while ((t = strtok_r (NIL," ",&r)) && *t);
    }
                                /* EHLO options which do not take arguments */
    else if (!compare_cstring (s,"SIZE")) ESMTP.size.ok = T;
    else if (!compare_cstring (s,"8BITMIME")) ESMTP.eightbit.ok = T;
    else if (!compare_cstring (s,"DSN")) ESMTP.dsn.ok = T;
    else if (!compare_cstring (s,"ATRN")) ESMTP.atrn.ok = T;
    else if (!compare_cstring (s,"SEND")) ESMTP.service.send = T;
    else if (!compare_cstring (s,"SOML")) ESMTP.service.soml = T;
    else if (!compare_cstring (s,"SAML")) ESMTP.service.saml = T;
    else if (!compare_cstring (s,"EXPN")) ESMTP.service.expn = T;
    else if (!compare_cstring (s,"HELP")) ESMTP.service.help = T;
    else if (!compare_cstring (s,"TURN")) ESMTP.service.turn = T;
    else if (!compare_cstring (s,"ETRN")) ESMTP.service.etrn = T;
    else if (!compare_cstring (s,"STARTTLS")) ESMTP.service.starttls = T;
    else if (!compare_cstring (s,"RELAY")) ESMTP.service.relay = T;
    else if (!compare_cstring (s,"PIPELINING")) ESMTP.service.pipe = T;
    else if (!compare_cstring (s,"ENHANCEDSTATUSCODES"))
      ESMTP.service.ensc = T;
    else if (!compare_cstring (s,"BINARYMIME")) ESMTP.service.bmime = T;
    else if (!compare_cstring (s,"CHUNKING")) ESMTP.service.chunk = T;
  }
  while ((i < 100) || (stream->reply[3] == '-'));
                                /* disable LOGIN if PLAIN also advertised */
  if ((j = mail_lookup_auth_name ("PLAIN",NIL)) && (--j < MAXAUTHENTICATORS) &&
      (ESMTP.auth & (1 << j)) &&
      (j = mail_lookup_auth_name ("LOGIN",NIL)) && (--j < MAXAUTHENTICATORS))
    ESMTP.auth &= ~(1 << j);
  return i;                     /* return the response code */
}
\f
/* Simple Mail Transfer Protocol set fake error and abort
 * Accepts: SMTP stream
 *          error text
 * Returns: SMTPSOFTFATAL, always
 */

long smtp_fake (SENDSTREAM *stream,char *text)
{
  if (stream->netstream) {      /* close net connection if still open */
    net_close (stream->netstream);
    stream->netstream = NIL;
  }
                                /* set last error */
  return smtp_seterror (stream,SMTPSOFTFATAL,text);
}


/* Simple Mail Transfer Protocol set error
 * Accepts: SMTP stream
 *          SMTP error code
 *          error text
 * Returns: error code
 */

static long smtp_seterror (SENDSTREAM *stream,long code,char *text)
{
                                /* flush any old reply */
  if (stream->reply ) fs_give ((void **) &stream->reply);
                                /* set up pseudo-reply string */
  stream->reply = (char *) fs_get (20+strlen (text));
  sprintf (stream->reply,"%ld %s",code,text);
  return code;                  /* return error code */
}


/* Simple Mail Transfer Protocol filter mail
 * Accepts: stream
 *          string
 * Returns: T on success, NIL on failure
 */

long smtp_soutr (void *stream,char *s)
{
  char c,*t;
                                /* "." on first line */
  if (s[0] == '.') net_sout (stream,".",1);
                                /* find lines beginning with a "." */
  while ((t = strstr (s,"\015\012.")) != NULL) {
    c = *(t += 3);              /* remember next character after "." */
    *t = '\0';                  /* tie off string */
                                /* output prefix */
    if (!net_sout (stream,s,t-s)) return NIL;
    *t = c;                     /* restore delimiter */
    s = t - 1;                  /* push pointer up to the "." */
  }
                                /* output remainder of text */
  return *s ? net_soutr (stream,s) : T;
}