/* apache_multipart_buffer.c -- form multipart data handling */

/*
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you 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

    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.
*/

/* Rivet config */
#ifdef HAVE_CONFIG_H
#include <rivet_config.h>
#endif

#include <apr_strings.h>
#include <apr_lib.h>
#include <apr_strings.h>

#include "apache_multipart_buffer.h"

/*********************** internal functions *********************/

/*
  search for a string in a fixed-length byte string.
  if partial is true, partial matches are allowed at the end of the buffer.
  returns NULL if not found, or a pointer to the start of the first match.
*/
void* my_memstr(char* haystack,int haystacklen,const char* needle,int partial)
{
    size_t needlen = strlen(needle);
    int len = haystacklen;
    char *ptr = haystack;

    /* iterate through first character matches */
    while( (ptr = memchr(ptr, needle[0], len)) ) {
		/* calculate length after match */
		len = haystacklen - (int)(ptr - (char *)haystack);

		/* done if matches up to capacity of buffer */
		if(memcmp(needle, ptr, needlen) == 0 && (partial || len >= needlen))
		{
			break;
		}
		
		/* next character */
		ptr++; len--;
    }

    return ptr;
}

/*
  fill up the buffer with client data.
  returns number of bytes added to buffer.
*/
int fill_buffer(multipart_buffer *self)
{
    int bytes_to_read, actual_read = 0;

    /* shift the existing data if necessary */
    if(self->bytes_in_buffer > 0 && self->buf_begin != self->buffer)
	memmove(self->buffer, self->buf_begin, self->bytes_in_buffer);

    self->buf_begin = self->buffer;

    /* calculate the free space in the buffer */
    bytes_to_read = self->bufsize - self->bytes_in_buffer;

    if (bytes_to_read >= self->r->remaining) {
        bytes_to_read = (int)(self->r->remaining - (apr_off_t)strlen(self->boundary));
#ifdef DEBUG
        ap_log_rerror(MPB_ERROR, "mozilla 0.97 hack: '%ld'", self->r->remaining);
#endif
    }

    /* read the required number of bytes */
    if(bytes_to_read > 0) {
	char *buf = self->buffer + self->bytes_in_buffer;

	actual_read = ap_get_client_block(self->r, buf, bytes_to_read);

	/* update the buffer length */
	if(actual_read > 0)
	  self->bytes_in_buffer += actual_read;
    }

    return actual_read;
}

/*
  gets the next CRLF terminated line from the input buffer.
  if it doesn't find a CRLF, and the buffer isn't completely full, returns
  NULL; otherwise, returns the beginning of the null-terminated line,
  minus the CRLF.

  note that we really just look for LF terminated lines. this works
  around a bug in internet explorer for the macintosh which sends mime
  boundaries that are only LF terminated when you use an image submit
  button in a multipart/form-data form.
 */
char* next_line(multipart_buffer *self)
{
    /* look for LF in the data */
    char* line = self->buf_begin;
    char* ptr = memchr(self->buf_begin, '\n', self->bytes_in_buffer);

    /* LF found */
    if(ptr) {
	/* terminate the string, remove CRLF */
	if((ptr - line) > 0 && *(ptr-1) == '\r') *(ptr-1) = 0;
	else *ptr = 0;

	/* bump the pointer */
	self->buf_begin = ptr + 1;
	self->bytes_in_buffer -= (int)(self->buf_begin - line);
    }

    /* no LF found */
    else {
	/* buffer isn't completely full, fail */
	if(self->bytes_in_buffer < self->bufsize)
	  return NULL;

	/* return entire buffer as a partial line */
	line[self->bufsize] = 0;
	self->buf_begin = ptr;
	self->bytes_in_buffer = 0;
    }

    return line;
}

/* returns the next CRLF terminated line from the client */
char* get_line(multipart_buffer *self)
{
    char* ptr = next_line(self);

    if(!ptr) {
	fill_buffer(self);
	ptr = next_line(self);
    }

#ifdef DEBUG
    ap_log_rerror(MPB_ERROR, "get_line: '%s'", ptr);
#endif

    return ptr;
}

/* finds a boundary */
int find_boundary(multipart_buffer *self, char *boundary)
{
    char *line;

    /* loop thru lines */
    while( (line = get_line(self)) ) {
#ifdef DEBUG
      ap_log_rerror(MPB_ERROR, "find_boundary: '%s' ?= '%s'",
		    line, boundary);
#endif

      /* finished if we found the boundary */
      if(strEQ(line, boundary))
	  return 1;
    }

    /* didn't find the boundary */
    return 0;
}

/*********************** external functions *********************/

/* create new multipart_buffer structure */
multipart_buffer *multipart_buffer_new(char *boundary, apr_off_t length, request_rec *r)
{
    multipart_buffer *self = (multipart_buffer *)
	apr_pcalloc (r->pool, sizeof(multipart_buffer));

    size_t minsize = strlen(boundary)+6;

    if(minsize < FILLUNIT) minsize = FILLUNIT;

    self->r = r;
    self->buffer = (char *) apr_pcalloc(r->pool, minsize+1);
    self->bufsize = (int)minsize;
    self->request_length = length;
    self->boundary = (char*) apr_pstrcat(r->pool, "--", boundary, NULL);
    self->boundary_next = (char*) apr_pstrcat(r->pool, "\n", self->boundary, NULL);
    self->buf_begin = self->buffer;
    self->bytes_in_buffer = 0;

    return self;
}

/* parse headers and return them in an apache table */
//table *multipart_buffer_headers(multipart_buffer *self)
apr_table_t *multipart_buffer_headers(multipart_buffer *self)
{
    apr_table_t *tab;
    char *line;

    /* didn't find boundary, abort */

    if(!find_boundary(self, self->boundary)) return NULL;

    /* get lines of text, or CRLF_CRLF */

    tab = apr_table_make(self->r->pool, 10);
    while( (line = get_line(self)) && strlen(line) > 0 ) {
	/* add header to table */
	char *key = line;
	char *value = strchr(line, ':');

	if(value) {
	    *value = 0;
	    do {
	    	value++;
	    } while (apr_isspace(*value));

#ifdef DEBUG
	    ap_log_rerror(MPB_ERROR,
			  "multipart_buffer_headers: '%s' = '%s'",
			  key, value);
#endif

	    apr_table_add(tab, key, value);
	} else {
#ifdef DEBUG
	    ap_log_rerror(MPB_ERROR,
			  "multipart_buffer_headers: '%s' = ''", key);
#endif

	    apr_table_add(tab, key, "");
	}
    }

    return tab;
}

/* read until a boundary condition */
size_t multipart_buffer_read(multipart_buffer *self, char *buf, size_t bytes)
{
	size_t 	max;
    size_t 	len;
    char*	bound;

    /* fill buffer if needed */
    if(bytes > self->bytes_in_buffer) fill_buffer(self);

    /* look for a potential boundary match, only read data up to that point */
    if( (bound = my_memstr(self->buf_begin, self->bytes_in_buffer, self->boundary_next, 1)) ) {
		max = bound - self->buf_begin;
    } else {
		max = self->bytes_in_buffer;
		}
    /* maximum number of bytes we are reading */
    len = max < bytes-1 ? max : bytes-1;


    /* if we read any data... */
    if (len > 0) {
		/* copy the data */
		memcpy(buf, self->buf_begin, len);
		buf[len] = 0;
		if(bound && len > 0 && buf[len-1] == '\r') buf[--len] = 0;

		/* update the buffer */
		self->bytes_in_buffer -= (int)len;
		self->buf_begin += len;
    }

#ifdef DEBUG
    ap_log_rerror(MPB_ERROR, "multipart_buffer_read: %d bytes", len);
#endif

    return len;
}

/*
  XXX: this is horrible memory-usage-wise, but we only expect
  to do this on small pieces of form data.
*/
char *multipart_buffer_read_body(multipart_buffer *self)
{
    char buf[FILLUNIT], *out = "";

    while(multipart_buffer_read(self, buf, sizeof(buf)))
	out = (char*) apr_pstrcat(self->r->pool, out, buf, NULL);

#ifdef DEBUG
    ap_log_rerror(MPB_ERROR, "multipart_buffer_read_body: '%s'", out);
#endif

    return out;
}

/* eof if we are out of bytes, or if we hit the final boundary */
int multipart_buffer_eof(multipart_buffer *self)
{
    if( (self->bytes_in_buffer == 0 && fill_buffer(self) < 1) )
	return 1;
    else
	return 0;
}
