Commit 46a27c2f authored by Nick Mathewson's avatar Nick Mathewson 🥔
Browse files

r15750@tombo: nickm | 2007-12-29 19:12:51 -0500 

 Make HTTP-processing code in buffers.c faster: do not pull up 50K of text into the first chunk if the headers end earlier than that.


svn:r13006
parent cd85eac0

src/or/buffers.c

+36 −57
Original line number Diff line number Diff line
@@ -943,28 +943,32 @@ move_buf_to_buf(buf_t *buf_out, buf_t *buf_in, size_t *buf_flushlen) 
  return cp;

}



// #define BUFPOS

#ifdef BUFPOS

/** Internal structure: represents a position in a buffer. */

typedef struct buf_pos_t {

  chunk_t *chunk;

  int pos;

  int pos_absolute;

};

  const chunk_t *chunk; /**< Which chunk are we pointing to? */

  int pos; /**< Which character inside the chunk's data are we pointing to? */

  int pos_absolute; /**< Which character inside the buffer are we pointing to?

                     */

} buf_pos_t;



/** Initialize <b>out</b> to point to the first character of <b>buf</b>.*/

static void

buf_pos_init(buf_t *buf, buf_pos_t *out)

buf_pos_init(const buf_t *buf, buf_pos_t *out)

{

  out->chunk = buf->head;

  out->pos = 0;

  out->pos_absolute = 0;

}



/** Advance <b>out</b> to the first appearance of <b>ch</b> at the current

 * position of <b>out</b>, or later.  Return -1 if no instances are found;

 * otherwise returns the absolute position of the character. */

static int

buf_find_pos_of_char(const buf_t *buf, char ch, buf_pos_t *out)

buf_find_pos_of_char(char ch, buf_pos_t *out)

{

  chunk_t *chunk;

  const chunk_t *chunk;

  int offset = 0;

  int pos = chunk->pos;

  int pos = out->pos;

  for (chunk = out->chunk; chunk; chunk = chunk->next) {

    char *cp = memchr(chunk->data+pos, ch, chunk->datalen-pos);

    if (cp) {
@@ -980,10 +984,12 @@ buf_find_pos_of_char(const buf_t *buf, char ch, buf_pos_t *out) 
  return -1;

}



/** Advance <b>pos</b> by a single character, if there are any more characters

 * in the buffer.  Returns 0 on sucess, -1 on failure. */

static INLINE int

buf_pos_inc(buf_pos_t *pos)

{

  if (pos->pos == pos->chunk->datalen) {

  if ((size_t)pos->pos == pos->chunk->datalen) {

    if (!pos->chunk->next)

      return -1;

    pos->chunk = pos->chunk->next;
@@ -992,43 +998,46 @@ buf_pos_inc(buf_pos_t *pos) 
    ++pos->pos;

  }

  ++pos->pos_absolute;

  return 0;

}



/** Return true iff the <b>n</b>-character string in <b>s</b> appears

 * (verbatim) at <b>pos</b>. */

static int

buf_matches_at_pos(const buf_t *buf, const buf_pos_t *pos, const char *s,

                   int n)

buf_matches_at_pos(const buf_pos_t *pos, const char *s, int n)

{

  buf_pos_t p;

  memcpy(p, pos, sizeof(p));

  memcpy(&p, pos, sizeof(p));



  while (n) {

    char ch = p->chunk->data[p->pos];

    char ch = p.chunk->data[p.pos];

    if (ch != *s)

      return 0;

    ++s;

    --n;

    if (buf_pos_inc(p)<0)

    if (buf_pos_inc(&p)<0)

      return 0;

  }

  return 1;

}



/** Return the first position in <b>buf</b> at which the <b>n</b>-character

 * string <b>s</b> occurs, or -1 if it does not occur. */

static int

buf_find_string_offset(const char *buf, const char *s, int n)

buf_find_string_offset(const buf_t *buf, const char *s, int n)

{

  buf_pos_t pos;

  buf_pos_init(buf, &pos);

  while (buf_find_pos_of_char(buf, *s, &pos) >= 0) {

    if (buf_matches_at_pos(buf, pos, s, n)) {

      return pos->pos_absolute;

  while (buf_find_pos_of_char(*s, &pos) >= 0) {

    if (buf_matches_at_pos(&pos, s, n)) {

      return pos.pos_absolute;

    } else {

      if (buf_pos_inc(pos)<0)

      if (buf_pos_inc(&pos)<0)

        return -1;

    }

  }

  return -1;

}

#endif



/** There is a (possibly incomplete) http statement on <b>buf</b>, of the

 * form "\%s\\r\\n\\r\\n\%s", headers, body. (body may contain nuls.)
@@ -1055,21 +1064,17 @@ fetch_from_buf_http(buf_t *buf, 
                    char **body_out, size_t *body_used, size_t max_bodylen,

                    int force_complete)

{

  char *headers, *p, *body;

  char *headers, *p;

  size_t headerlen, bodylen, contentlen;

#ifdef BUFPOS

  int crlf_offset;

#endif



  check();

  if (!buf->head)

    return 0;



  headers = buf->head->data;



#ifdef BUFPOS

  crlf_offset = buf_find_string_offset(buf, "\r\n\r\n", 4);

  if (crlf_offset > max_headerlen ||

  if (crlf_offset > (int)max_headerlen ||

      (crlf_offset < 0 && buf->datalen > max_headerlen)) {

    log_debug(LD_HTTP,"headers too long.");

    return -1;
@@ -1077,37 +1082,11 @@ fetch_from_buf_http(buf_t *buf, 
    log_debug(LD_HTTP,"headers not all here yet.");

    return 0;

  }

  if (buf->head->datalen < crlf_offset + 4)

  /* Okay, we have a full header.  Make sure it all appears in the first

   * chunk. */

  if ((int)buf->head->datalen < crlf_offset + 4)

    buf_pullup(buf, crlf_offset+4, 0);

  headerlen = crlf_offset + 4;

  body = buf->data + headerlen; /*XXX020 unused. */

#else

  /* See if CRLFCRLF is already in the head chunk.  If it is, we don't need

   * to move or resize anything. */

  body = (char*) tor_memmem(buf->head->data, buf->head->datalen,

                            "\r\n\r\n", 4);

  if (!body && buf->datalen > buf->head->datalen) {

    size_t len_scanned = buf->head->datalen;

    buf_pullup(buf, max_headerlen, 0);

    headers = buf->head->data;

    /* avoid searching the original part of the head chunk twice. */

    len_scanned = (len_scanned > 4) ? len_scanned - 4 : 0;

    body = (char*) tor_memmem(buf->head->data + len_scanned,

                              buf->head->datalen - len_scanned,

                              "\r\n\r\n", 4);

  }



  if (!body) {

    if (buf->head->datalen >= max_headerlen) {

      log_debug(LD_HTTP,"headers too long.");

      return -1;

    }

    log_debug(LD_HTTP,"headers not all here yet.");

    return 0;

  }

  body += 4; /* Skip the the CRLFCRLF */

  headerlen = body-headers; /* includes the CRLFCRLF */

#endif



  bodylen = buf->datalen - headerlen;

  log_debug(LD_HTTP,"headerlen %d, bodylen %d.", (int)headerlen, (int)bodylen);