parse.c

C语言实现的一个简易的POP3服务器代码

/*
 *  Embedded POP3 Parser
 *
 *  ./software/ch6/empop3c/parse.c
 *
 *  [e-mail]
 *
 */

#include <stdio.h>
#include <string.h>
#include "empop3c.h"


/*
 *  parseEntry()
 *
 *  Given a retrieved mail object and a search string, load into 'dest'
 *  the value that follows the searchstring.  For example "To: me" would
 *  load "me" into the dest argument for a searchstring of "To:".
 *
 *  Returns 0 on success, -1 on failure.
 *
 */

int parseEntry( mail_t *mail, char *searchString, char *dest )
{
  int i, index, len;

  len = strlen(searchString);

  /* Grab the subject */
  for (i = 0 ; i < mail->email_len ; i++) {
    if (mail->email[i] == searchString[0]) {
      if (!strncmp(&mail->email[i], searchString, len )) {
        i += (len + 1);
        index = 0;
        while (!((mail->email[i] == 0x0d) && (mail->email[i+1] == 0x0a))) {
          if (mail->email[i] == 0) i++;
          else dest[index++] = mail->email[i++];
        }
        dest[index] = 0;
        break;
      }
    }
  }

  if (i == mail->email_len) {
    return -1;
  }

  return 0;
}


/*
 *  findBody()
 *
 *  Given a retrieved mail object, find the body portion of the email
 *  (identified by the CR LF CR LF -- blank line).  A blank line separates
 *  the header from the body of the email.
 *
 *  Returns 0 on success, -1 on failure.
 *
 */

int findBody( mail_t *mail )
{
  int i, result=-1;

  for (i = 0 ; i < mail->email_len ; i++) {
    if ((mail->email[i] == 0x0d) && (mail->email[i+1] == 0x0a) &&
        (mail->email[i+2] == 0x0d) && (mail->email[i+3] == 0x0a)) {
      i+=4;
      break;
    }
  }

  if (i < mail->email_len) {
    mail->bodyStart = &mail->email[i];
    result = 0;
  }

  return result;
}


/*
 *  fixAddress()
 *
 *  Given a passed email address, extract the real address from the possible
 *  SMTP <> definition.  For example, an address passed as "me <[e-mail]>"
 *  will result in the filtered "[e-mail]" address.  Addresses that are
 *  already in the proper form will not be altered.
 *
 *  Returns 0 on success, -1 on failure.
 *
 */

int fixAddress ( char *address )
{
  int i, j, len;
  char string[MAX_STRING+1];

  len = strlen(address);
  for (i = 0 ; i < len ; i++) {
    if (address[i] == '<') break;
  }

  if (i++ == len) return 0;

  j = 0;
  for ( ; i < len ; i++) {
    if (address[i] == '>') break;
    string[j++] = address[i];
  }
  string[j] = 0;

  strcpy(address, string);

  return 0;
}


/*
 *  pop3cParse()
 *
 *  This function performs some preliminary parsing on the retrieved email
 *  object.  The following actions are performed:
 *
 *    The Subject of the email is parsed into the subject element of mail.
 *
 *    The From of the email is parsed into the sender element of mail.
 *
 *    The To of the email is parsed into the recipient element of mail.
 *
 *    The start of the body of the email is loaded into the bodyStart
 *    element of the mail object.
 *
 *  Returns 0 on success, -1 on failure.
 *
 */

int pop3cParse ( mail_t *mail )
{
  int result;

  result = parseEntry( mail, "Subject:", mail->subject );
  if (result < 0) return result;

  result = parseEntry( mail, "From:", mail->sender );
  if (result < 0) return result;
  fixAddress( mail->sender );

  result = parseEntry( mail, "To:", mail->recipient );
  if (result < 0) return result;
  fixAddress( mail->recipient );

  result = findBody( mail );

  printf("body is \n%s\n", mail->bodyStart);

  return result;
}

/*
 *  Copyright (c) 2002 Charles River Media.  All rights reserved.
 * 
 *  Redistribution and use in source and binary forms, with or 
 *  without modification, is hereby granted without fee provided 
 *  that the following conditions are met:
 * 
 *    1.  Redistributions of source code must retain the above 
 *        copyright notice, this list of conditions and the 
 *        following disclaimer.
 *    2.  Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the 
 *        following disclaimer in the documentation and/or other 
 *        materials provided with the distribution.
 *    3.  Neither the name of Charles River Media nor the names of 
 *        its contributors may be used to endorse or promote products 
 *        derived from this software without specific prior 
 *        written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY CHARLES RIVER MEDIA AND CONTRIBUTERS 
 * 'AS IS' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS 
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL CHARLES
 * RIVER MEDIA OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 * INCIDENTAL, SPECIAL, EXEMPLARAY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 */