rfcparse.c

/*
 * Copyright (c) 1995-2019 Peter Simons <simons@cryp.to>
 * Copyright (c) 2000-2001 Cable & Wireless GmbH
 * Copyright (c) 1999-2000 CyberSolutions GmbH
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "librfc822/rfc822.h"
#include "libtext/text.h"
#include "petidomo.h"

void
RemoveCarrigeReturns(char * buffer)
{
    char *   src = buffer;
    char *   dst = buffer;

    while(*src != '\0') {
        switch(*src) {
          case '\n':
              *dst++ = ' ';
              while(isspace((int)*src))
                src++;
              break;
          default:
              *dst++ = *src++;
        }
    }
    *dst++ = '\0';
}

bool
isRFC822Address(const char * buffer)
{
    char *   address;
    int      rc;

    rc = rfc822_parse_address(buffer, &address, NULL, NULL);
    if (rc == RFC822_OK) {
        free(address);
        return TRUE;
    }
    else
        return FALSE;
}

int
ParseAddressLine(char * buffer)
{
    struct rfc822_address_sep_state   sep_state;
    char *   p,
         *   address;
    int      rc;

    /* Handle continuation lines. */

    RemoveCarrigeReturns(buffer);

    /* Initialize the structure needed for address_sep(). */

    sep_state.address_line = buffer;
    sep_state.group_nest   = 0;

    /* We want only the first address, if multiple are there. */

    while ((p = rfc822_address_sep(&sep_state)) != NULL) {
        if (*p == '\0')
          continue;
        else
          break;
    }

    if (p == NULL) {
        /* line is empty */
        return -1;
    }

    rc = rfc822_parse_address(p, &address, NULL, NULL);
    if (rc == RFC822_OK && address != NULL) {
        strcpy(buffer, address);
        free(address);
        return 0;
    }
    else
      return -1;
}

int
ParseReplyToLine(char * buffer)
{
    return ParseAddressLine(buffer);
}

int
ParseFromLine(char * buffer)
{
    return ParseAddressLine(buffer);
}

int
ParseMessageIdLine(char * buffer)
{
    int   rc;

    rc = ParseAddressLine(buffer);
    if (rc != 0)
      return rc;                /* Error! */

    memmove(buffer+1, buffer, strlen(buffer)+1);
    buffer[0] = '<';
    strcat(buffer, ">");

    return rc;
}

int
ParseApproveLine(char * buffer)
{
    char *       src;
    char *       dst;

    RemoveCarrigeReturns(buffer);

    src = buffer;
    dst = buffer;

    /* Skip leading whitespace. */

    while(isspace((int)*src))
      src++;

    /* Skip a quote if there is one. */

    if (*src == '\"')
      src++;

    /* Copy String. */

    while((*dst++ = *src++) != '\0')
      ;
    dst--;

    /* Kill trailing whitespace. */

    while(isspace((int)dst[-1]))
      *(--dst) = '\0';

    /* Kill a quote if there is one. */

    if (dst[-1] == '\"')
      *(--dst) = '\0';

    return 0;
}

void
CanonizeAddress(char ** buffer, const char * fqdn)
{
    const struct PD_Config *     MasterConfig;
    char *                       newbuf;
    char *   local,
         *   host;
    int      rc;

    assert(buffer != NULL);
    assert(*buffer != NULL);

    if (buffer == NULL || *buffer == NULL)
      return;

    rc = rfc822_parse_address(*buffer, NULL, &local, &host);
    if (rc == RFC822_OK) {
        if (local != NULL && host == NULL) {
            if (fqdn == NULL) {
                MasterConfig = getMasterConfig();
                fqdn = MasterConfig->fqdn;
            }
            newbuf = xmalloc(strlen(*buffer) + strlen(fqdn) + 3);
            sprintf(newbuf, "%s@%s", local, fqdn);
            free(local);
            *buffer = newbuf;
        }
    }
}

int
ParseMail(struct Mail **result, char * incoming_mail, const char * fqdn)
{
    struct Mail *   MailStruct;
    char *          currLine;
    char *          nextLine;
    int             rc;

    /* Allocate structure. */

    MailStruct = calloc(sizeof(struct Mail), 1);
    if (MailStruct == NULL) {
        syslog(LOG_ERR, "Failed to allocate memory for Mail data structure.");
        return -1;
    }

    /* Rescue the mail in its original state, before the parsing
       routines have havoc in the buffer. */

    MailStruct->Header = strdup(incoming_mail);
    if (MailStruct->Header == NULL) {
        syslog(LOG_ERR, "Failed to allocate memory for the incoming mail.");
        return -1;
    }
    for (MailStruct->Body = MailStruct->Header;
         *MailStruct->Body != '\n' && *MailStruct->Body != '\0';
         MailStruct->Body = text_find_next_line(MailStruct->Body))
      ;
    if (*MailStruct->Body == '\n') {
        *MailStruct->Body = '\0';
        MailStruct->Body++;
    }

    /* Get the envelope. */

    currLine = incoming_mail;
    nextLine = text_find_next_line(incoming_mail);
    if (strncasecmp("From ", currLine, strlen("From ")) == 0) {
        if (nextLine[-1] == '\n')
          nextLine[-1] = '\0';
        currLine += strlen("From ");
        while (isspace((int)*currLine))
          currLine++;
        MailStruct->Envelope = currLine;
        while (!isspace((int)*currLine))
          currLine++;
        *currLine = '\0';
        CanonizeAddress(&(MailStruct->Envelope), fqdn);
        currLine = nextLine;
    }

    /* Parse the incoming mail's header. */

    for (nextLine = text_find_next_line(currLine);
         *currLine != '\n' && *currLine != '\0';
         currLine = nextLine, nextLine = text_find_next_line(currLine)) {

        /* Find continuation lines. */

        while (*nextLine == ' ' || *nextLine == '\t')
          nextLine = text_find_next_line(nextLine);

        /* remove trailing \n */

        if (nextLine[-1] == '\n')
          nextLine[-1] = '\0';

        /* Check whether it is a header we're interested in. */

        if (strncasecmp("From:", currLine, strlen("From:")) == 0) {
            if (MailStruct->From != NULL) {
                syslog(LOG_INFO, "Received mail with multiple From: lines.");
                continue;
            }
            MailStruct->From = &currLine[strlen("From:")];
            rc = ParseFromLine(MailStruct->From);
            if (rc != 0)
              return rc;
            CanonizeAddress(&(MailStruct->From), fqdn);
        } else if (strncasecmp("Reply-To:", currLine, strlen("Reply-To:")) == 0) {
            if (MailStruct->Reply_To != NULL) {
                syslog(LOG_INFO, "Received mail with multiple Reply-To: lines.");
                continue;
            }
            MailStruct->Reply_To = &currLine[strlen("Reply-To:")];
            rc = ParseReplyToLine(MailStruct->Reply_To);
            if (rc != 0)
              return rc;
            CanonizeAddress(&(MailStruct->Reply_To), fqdn);
        } else if (strncasecmp("Message-Id:", currLine, strlen("Message-Id:")) == 0) {
            if (MailStruct->Message_Id != NULL) {
                syslog(LOG_NOTICE, "Received mail with multiple Message-Id: lines.");
                continue;
            }
            MailStruct->Message_Id = &currLine[strlen("Message-Id:")];
            rc = ParseMessageIdLine(MailStruct->Message_Id);
            if (rc != 0)
              return rc;
        }
        else if (strncasecmp("Approve:", currLine, strlen("Approve:")) == 0) {
            if (MailStruct->Approve != NULL)
              syslog(LOG_INFO, "Received mail with multiple Approve: lines.");
            MailStruct->Approve = &currLine[strlen("Approve:")];
            rc = ParseApproveLine(MailStruct->Approve);
            if (rc != 0)
              return rc;
        }
        else if (strncasecmp("Approved:", currLine, strlen("Approved:")) == 0) {
            if (MailStruct->Approve != NULL)
              syslog(LOG_INFO, "Received mail with multiple Approve: lines.");
            MailStruct->Approve = &currLine[strlen("Approved:")];
            rc = ParseApproveLine(MailStruct->Approve);
            if (rc != 0)
              return rc;
        }
        else if (strncasecmp("Subject:", currLine, strlen("Subject:")) == 0) {
            if (MailStruct->Subject != NULL)
              syslog(LOG_INFO, "Received mail with multiple Subject: lines.");
            MailStruct->Subject = &currLine[strlen("Subject:")];
            if (*MailStruct->Subject == ' ')
              MailStruct->Subject += 1;
        }
        else if (strncasecmp("Sender:", currLine, strlen("Sender:")) == 0) {
            if (MailStruct->Envelope != NULL)
              syslog(LOG_NOTICE, "Received mail with multiple sender addresses.");
            MailStruct->Envelope = &currLine[strlen("Sender:")];
            if (*MailStruct->Envelope == ' ')
              MailStruct->Envelope += 1;
        }
        else if (strncasecmp("Return-Path:", currLine, strlen("Return-Path:")) == 0 &&
                 MailStruct->Envelope == NULL)
        {
            if (MailStruct->Envelope != NULL)
              syslog(LOG_NOTICE, "Received mail with multiple sender addresses.");
            MailStruct->Envelope = &currLine[strlen("Return-Path:")];
            if (*MailStruct->Envelope == ' ')
              MailStruct->Envelope += 1;
        }
    }

    *result = MailStruct;
    return 0;
}