path: root/src/mime-parsefull.cc

/**
 *  @file mime-parsefull.cc
 *  @brief Implementation of main mime parser components
 *  @author Andreas Aardal Hanssen
 *  @date 2002-2005
 */

#include "convert.h"
#include "mime-inputsource.h"
#include "mime-utils.h"
#include "mime.h"

#include <exception>
#include <iostream>
#include <map>
#include <string>
#include <vector>

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>

Binc::MimeInputSource *mimeSource = nullptr;

using std::string;
using std::vector;

void Binc::MimeDocument::parseFull(int fd) const
{
  if (allIsParsed) return;

  allIsParsed = true;

  if (!mimeSource || mimeSource->getFileDescriptor() != fd) {
    delete mimeSource;
    mimeSource = new MimeInputSource(fd);
  } else {
    mimeSource->reset();
  }

  headerstartoffsetcrlf = 0;
  headerlength = 0;
  bodystartoffsetcrlf = 0;
  bodylength = 0;
  size = 0;
  messagerfc822 = false;
  multipart = false;

  int bsize = 0;
  string bound;
  MimePart::parseFull(bound, bsize);

  // eat any trailing junk to get the correct size
  char c;
  while (mimeSource->getChar(&c))
    ;

  size = mimeSource->getOffset();
}

static bool parseOneHeaderLine(Binc::Header *header, unsigned int *nlines)
{
  using namespace ::Binc;
  char c;
  bool eof = false;
  char cqueue[4];
  string name;
  string content;

  while (mimeSource->getChar(&c)) {
    // If we encounter a \r before we got to the first ':', then
    // rewind back to the start of the line and assume we're at the
    // start of the body.
    if (c == '\r') {
      for (int i = 0; i < (int)name.length() + 1; ++i)
        mimeSource->ungetChar();
      return false;
    }

    // A colon marks the end of the header name
    if (c == ':') break;

    // Otherwise add to the header name
    name += c;
  }

  cqueue[0] = '\0';
  cqueue[1] = '\0';
  cqueue[2] = '\0';
  cqueue[3] = '\0';

  // Read until the end of the header.
  bool endOfHeaders = false;
  while (!endOfHeaders) {
    if (!mimeSource->getChar(&c)) {
      eof = true;
      break;
    }

    if (c == '\n') ++*nlines;

    for (int i = 0; i < 3; ++i)
      cqueue[i] = cqueue[i + 1];
    cqueue[3] = c;

    if (strncmp(cqueue, "\r\n\r\n", 4) == 0) {
      endOfHeaders = true;
      break;
    }

    // If the last character was a newline, and the first now is not
    // whitespace, then rewind one character and store the current
    // key,value pair.
    if (cqueue[2] == '\n' && c != ' ' && c != '\t') {
      if (content.length() > 2) content.resize(content.length() - 2);

      trim(content);
      header->add(name, content);

      if (c != '\r') {
        mimeSource->ungetChar();
        if (c == '\n') --*nlines;
        return true;
      }

      mimeSource->getChar(&c);
      return false;
    }

    content += c;
  }

  if (name != "") {
    if (content.length() > 2) content.resize(content.length() - 2);
    header->add(name, content);
  }

  return !(eof || endOfHeaders);
}

static void parseHeader(Binc::Header *header, unsigned int *nlines)
{
  while (parseOneHeaderLine(header, nlines)) {
  }
}

static void analyzeHeader(Binc::Header *header,
                          bool *multipart,
                          bool *messagerfc822,
                          string *subtype,
                          string *boundary)
{
  using namespace ::Binc;

  // Do simple parsing of headers to determine the
  // type of message (multipart,messagerfc822 etc)
  HeaderItem ctype;
  if (header->getFirstHeader("content-type", ctype)) {
    vector<string> types;
    split(ctype.getValue(), ";", types);

    if (types.size() > 0) {
      // first element should describe content type
      string tmp = types[0];
      trim(tmp);
      vector<string> v;
      split(tmp, "/", v);
      string key, value;

      key = (v.size() > 0) ? v[0] : "text";
      value = (v.size() > 1) ? v[1] : "plain";
      lowercase(key);

      if (key == "multipart") {
        *multipart = true;
        lowercase(value);
        *subtype = value;
      } else if (key == "message") {
        lowercase(value);
        if (value == "rfc822") *messagerfc822 = true;
      }
    }

    for (vector<string>::const_iterator i = types.begin(); i != types.end(); ++i) {
      string element = *i;
      trim(element);

      if (element.find("=") != string::npos) {
        string::size_type pos = element.find('=');
        string key = element.substr(0, pos);
        string value = element.substr(pos + 1);

        lowercase(key);
        trim(key);

        if (key == "boundary") {
          trim(value, " \"");
          *boundary = value;
        }
      }
    }
  }
}

static void parseMessageRFC822(vector<Binc::MimePart> *members,
                               bool *foundendofpart,
                               unsigned int *bodylength,
                               unsigned int *nbodylines,
                               const string &toboundary)
{
  using namespace Binc;

  // message rfc822 means a completely enclosed mime document. we
  // call the parser recursively, and pass on the boundary string
  // that we got. when parse() finds this boundary, it returns 0. if
  // it finds the end boundary (boundary + "--"), it returns != 0.
  MimePart m;

  unsigned int bodystartoffsetcrlf = mimeSource->getOffset();

  // parsefull returns the number of bytes that need to be removed
  // from the body because of the terminating boundary string.
  int bsize = 0;
  if (m.parseFull(toboundary, bsize)) *foundendofpart = true;

  // make sure bodylength doesn't overflow
  *bodylength = mimeSource->getOffset();
  if (*bodylength >= bodystartoffsetcrlf) {
    *bodylength -= bodystartoffsetcrlf;
    if (*bodylength >= (unsigned int)bsize)
      *bodylength -= (unsigned int)bsize;
    else
      *bodylength = 0;
  } else {
    *bodylength = 0;
  }

  *nbodylines += m.getNofLines();

  members->push_back(m);
}

static bool skipUntilBoundary(const string &delimiter, unsigned int *nlines, bool *eof)
{
  int endpos = delimiter.length();
  char *delimiterqueue = nullptr;
  int delimiterpos = 0;
  const char *delimiterStr = delimiter.c_str();
  if (delimiter != "") {
    delimiterqueue = new char[endpos];
    memset(delimiterqueue, 0, endpos);
  }

  // first, skip to the first delimiter string. Anything between the
  // header and the first delimiter string is simply ignored (it's
  // usually a text message intended for non-mime clients)
  char c;

  bool foundBoundary = false;
  for (;;) {
    if (!mimeSource->getChar(&c)) {
      *eof = true;
      break;
    }

    if (c == '\n') ++*nlines;

    // if there is no delimiter, we just read until the end of the
    // file.
    if (!delimiterqueue) continue;

    delimiterqueue[delimiterpos++ % endpos] = c;

    if (compareStringToQueue(delimiterStr, delimiterqueue, delimiterpos, endpos)) {
      foundBoundary = true;
      break;
    }
  }

  delete[] delimiterqueue;
  delimiterqueue = nullptr;

  return foundBoundary;
}

static void parseMultipart(const string &boundary,
                           const string &toboundary,
                           bool *eof,
                           unsigned int *nlines,
                           int *boundarysize,
                           bool *foundendofpart,
                           unsigned int *bodylength,
                           vector<Binc::MimePart> *members)
{
  using namespace ::Binc;
  unsigned int bodystartoffsetcrlf = mimeSource->getOffset();

  // multipart parsing starts with skipping to the first
  // boundary. then we call parse() for all parts. the last parse()
  // command will return a code indicating that it found the last
  // boundary of this multipart. Note that the first boundary does
  // not have to start with CRLF.
  string delimiter = "--" + boundary;

  skipUntilBoundary(delimiter, nlines, eof);

  if (!eof) *boundarysize = delimiter.size();

  // Read two more characters. This may be CRLF, it may be "--" and
  // it may be any other two characters.

  char a;
  if (!mimeSource->getChar(&a)) *eof = true;
  if (a == '\n') ++*nlines;

  char b;
  if (!mimeSource->getChar(&b)) *eof = true;
  if (b == '\n') ++*nlines;

  // If we find two dashes after the boundary, then this is the end
  // of boundary marker.
  if (!*eof) {
    if (a == '-' && b == '-') {
      *foundendofpart = true;
      *boundarysize += 2;

      if (!mimeSource->getChar(&a)) *eof = true;
      if (a == '\n') ++*nlines;
      if (!mimeSource->getChar(&b)) *eof = true;
      if (b == '\n') ++*nlines;
    }

    if (a == '\r' && b == '\n') {
      // This exception is to handle a special case where the
      // delimiter of one part is not followed by CRLF, but
      // immediately followed by a CRLF prefixed delimiter.
      if (!mimeSource->getChar(&a) || !mimeSource->getChar(&b)) {
        *eof = true;
      } else if (a == '-' && b == '-') {
        mimeSource->ungetChar();
        mimeSource->ungetChar();
        mimeSource->ungetChar();
        mimeSource->ungetChar();
      } else {
        mimeSource->ungetChar();
        mimeSource->ungetChar();
      }

      *boundarysize += 2;
    } else {
      mimeSource->ungetChar();
      mimeSource->ungetChar();
    }
  }

  // read all mime parts.
  if (!*foundendofpart && !*eof) {
    bool quit = false;
    do {
      MimePart m;

      // If parseFull returns != 0, then it encountered the multipart's
      // final boundary.
      int bsize = 0;
      if (m.parseFull(boundary, bsize)) {
        quit = true;
        *boundarysize = bsize;
      }

      members->push_back(m);

    } while (!quit);
  }

  if (!*foundendofpart && !*eof) {
    // multipart parsing starts with skipping to the first
    // boundary. then we call parse() for all parts. the last parse()
    // command will return a code indicating that it found the last
    // boundary of this multipart. Note that the first boundary does
    // not have to start with CRLF.
    string delimiter = "\r\n--" + toboundary;

    skipUntilBoundary(delimiter, nlines, eof);

    if (!*eof) *boundarysize = delimiter.size();

    // Read two more characters. This may be CRLF, it may be "--" and
    // it may be any other two characters.

    char a = '\0';
    if (!mimeSource->getChar(&a)) *eof = true;
    if (a == '\n') ++*nlines;

    char b = '\0';
    if (!mimeSource->getChar(&b)) *eof = true;
    if (b == '\n') ++*nlines;

    // If we find two dashes after the boundary, then this is the end
    // of boundary marker.
    if (!*eof) {
      if (a == '-' && b == '-') {
        *foundendofpart = true;
        *boundarysize += 2;
        if (!mimeSource->getChar(&a)) *eof = true;
        if (a == '\n') ++*nlines;
        if (!mimeSource->getChar(&b)) *eof = true;
        if (b == '\n') ++*nlines;
      }

      if (a == '\r' && b == '\n') {
        // This exception is to handle a special case where the
        // delimiter of one part is not followed by CRLF, but
        // immediately followed by a CRLF prefixed delimiter.
        if (!mimeSource->getChar(&a) || !mimeSource->getChar(&b)) {
          *eof = true;
        } else if (a == '-' && b == '-') {
          mimeSource->ungetChar();
          mimeSource->ungetChar();
          mimeSource->ungetChar();
          mimeSource->ungetChar();
        } else {
          mimeSource->ungetChar();
          mimeSource->ungetChar();
        }

        *boundarysize += 2;
      } else {
        mimeSource->ungetChar();
        mimeSource->ungetChar();
      }
    }
  }

  // make sure bodylength doesn't overflow
  *bodylength = mimeSource->getOffset();
  if (*bodylength >= bodystartoffsetcrlf) {
    *bodylength -= bodystartoffsetcrlf;
    if (*bodylength >= (unsigned int)*boundarysize)
      *bodylength -= (unsigned int)*boundarysize;
    else
      *bodylength = 0;
  } else {
    *bodylength = 0;
  }
}

static void parseSinglePart(const string &toboundary,
                            int *boundarysize,
                            unsigned int *nbodylines,
                            unsigned int *nlines,
                            bool *eof,
                            bool *foundendofpart,
                            unsigned int *bodylength)
{
  using namespace ::Binc;
  unsigned int bodystartoffsetcrlf = mimeSource->getOffset();

  // If toboundary is empty, then we read until the end of the
  // file. Otherwise we will read until we encounter toboundary.
  string _toboundary;
  if (toboundary != "") {
    _toboundary = "\r\n--";
    _toboundary += toboundary;
  }

  //  if (skipUntilBoundary(_toboundary, nlines, eof))
  //    *boundarysize = _toboundary.length();

  char *boundaryqueue = nullptr;
  int endpos = _toboundary.length();
  if (toboundary != "") {
    boundaryqueue = new char[endpos];
    memset(boundaryqueue, 0, endpos);
  }
  int boundarypos = 0;

  *boundarysize = 0;

  const char *_toboundaryStr = _toboundary.c_str();
  string line;
  bool toboundaryIsEmpty = (toboundary == "");
  char c;
  while (mimeSource->getChar(&c)) {
    if (c == '\n') {
      ++*nbodylines;
      ++*nlines;
    }
    if (toboundaryIsEmpty) continue;

    // find boundary
    boundaryqueue[boundarypos++ % endpos] = c;

    if (compareStringToQueue(_toboundaryStr, boundaryqueue, boundarypos, endpos)) {
      *boundarysize = _toboundary.length();
      break;
    }
  }

  delete[] boundaryqueue;

  if (toboundary != "") {
    char a;
    if (!mimeSource->getChar(&a)) *eof = true;
    if (a == '\n') ++*nlines;

    char b;
    if (!mimeSource->getChar(&b)) *eof = true;
    if (b == '\n') ++*nlines;

    if (a == '-' && b == '-') {
      *boundarysize += 2;
      *foundendofpart = true;
      if (!mimeSource->getChar(&a)) *eof = true;
      if (a == '\n') ++*nlines;
      if (!mimeSource->getChar(&b)) *eof = true;
      if (b == '\n') ++*nlines;
    }

    if (a == '\r' && b == '\n') {
      // This exception is to handle a special case where the
      // delimiter of one part is not followed by CRLF, but
      // immediately followed by a CRLF prefixed delimiter.
      if (!mimeSource->getChar(&a) || !mimeSource->getChar(&b)) {
        *eof = true;
      } else if (a == '-' && b == '-') {
        mimeSource->ungetChar();
        mimeSource->ungetChar();
        mimeSource->ungetChar();
        mimeSource->ungetChar();
      } else {
        mimeSource->ungetChar();
        mimeSource->ungetChar();
      }

      *boundarysize += 2;
    } else {
      mimeSource->ungetChar();
      mimeSource->ungetChar();
    }
  }

  // make sure bodylength doesn't overflow
  *bodylength = mimeSource->getOffset();
  if (*bodylength >= bodystartoffsetcrlf) {
    *bodylength -= bodystartoffsetcrlf;
    if (*bodylength >= (unsigned int)*boundarysize)
      *bodylength -= (unsigned int)*boundarysize;
    else
      *bodylength = 0;
  } else {
    *bodylength = 0;
  }
}

int Binc::MimePart::parseFull(const string &toboundary, int &boundarysize) const
{
  headerstartoffsetcrlf = mimeSource->getOffset();

  // Parse the header of this mime part.
  parseHeader(&h, &nlines);

  // Headerlength includes the seperating CRLF. Body starts after the
  // CRLF.
  headerlength = mimeSource->getOffset() - headerstartoffsetcrlf;
  bodystartoffsetcrlf = mimeSource->getOffset();
  bodylength = 0;

  // Determine the type of mime part by looking at fields in the
  // header.
  analyzeHeader(&h, &multipart, &messagerfc822, &subtype, &boundary);

  bool eof = false;
  bool foundendofpart = false;

  if (messagerfc822) {
    parseMessageRFC822(&members, &foundendofpart, &bodylength, &nbodylines, toboundary);

  } else if (multipart) {
    parseMultipart(boundary,
                   toboundary,
                   &eof,
                   &nlines,
                   &boundarysize,
                   &foundendofpart,
                   &bodylength,
                   &members);
  } else {
    parseSinglePart(toboundary,
                    &boundarysize,
                    &nbodylines,
                    &nlines,
                    &eof,
                    &foundendofpart,
                    &bodylength);
  }

  return (eof || foundendofpart) ? 1 : 0;
}