c/apache_multipart_buffer.c

/* Copyright 2000-2004 The Apache Software Foundation

   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

   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.
*/

#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)
{
    int 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 - (ptr - (char *)haystack);

	/* done if matches up to capacity of buffer */
	if(memcmp(needle, ptr, needlen < len ? needlen : len) == 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 = self->r->remaining - 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;
	ap_hard_timeout("[libapreq] multipart_buffer.c:fill_buffer", self->r);
	actual_read = ap_get_client_block(self->r, buf, bytes_to_read);
	ap_kill_timeout(self->r);

	/* 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 -= (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, long length, request_rec *r)
{
    multipart_buffer *self = (multipart_buffer *)
	ap_pcalloc(r->pool, sizeof(multipart_buffer));

    int minsize = strlen(boundary)+6;
    if(minsize < FILLUNIT) minsize = FILLUNIT;

    self->r = r;
    self->buffer = (char *) ap_pcalloc(r->pool, minsize+1);
    self->bufsize = minsize;
    self->request_length = length;
    self->boundary = ap_pstrcat(r->pool, "--", boundary, NULL);
    self->boundary_next = ap_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)
{
    table *tab;
    char *line;

    /* didn't find boundary, abort */
    if(!find_boundary(self, self->boundary)) return NULL;

    /* get lines of text, or CRLF_CRLF */
    tab = ap_make_table(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(ap_isspace(*value));

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

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

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

    return tab;
}

/* read until a boundary condition */
int multipart_buffer_read(multipart_buffer *self, char *buf, int bytes)
{
    int len, max;
    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 -= 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 = ap_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;
}