nghttp2/lib/spdylay_frame.c

/*
 * Spdylay - SPDY Library
 *
 * Copyright (c) 2012 Tatsuhiro Tsujikawa
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#include "spdylay_frame.h"

#include <arpa/inet.h>
#include <string.h>
#include <assert.h>
#include <stdio.h>

#include "spdylay_helper.h"

static uint8_t spdylay_unpack_pri(const uint8_t *data)
{
  return (data[0] >> 6) & 0x3;
}

static uint8_t* spdylay_pack_str(uint8_t *buf, const char *str, size_t len)
{
  spdylay_put_uint16be(buf, len);
  buf += 2;
  memcpy(buf, str, len);
  return buf+len;
}

static void spdylay_frame_pack_ctrl_hd(uint8_t* buf, const spdylay_ctrl_hd *hd)
{
  spdylay_put_uint16be(&buf[0], hd->version);
  buf[0] |= 1 << 7;
  spdylay_put_uint16be(&buf[2], hd->type);
  spdylay_put_uint32be(&buf[4], hd->length);
  buf[4] = hd->flags;
}

static void spdylay_frame_unpack_ctrl_hd(spdylay_ctrl_hd *hd,
                                         const uint8_t* buf)
{
  hd->version = spdylay_get_uint16(buf) & SPDYLAY_VERSION_MASK;
  hd->type = spdylay_get_uint16(&buf[2]);
  hd->flags = buf[4];
  hd->length = spdylay_get_uint32(&buf[4]) & SPDYLAY_LENGTH_MASK;
}

static ssize_t spdylay_frame_alloc_pack_nv(uint8_t **buf_ptr,
                                           size_t *buflen_ptr,
                                           uint8_t **nvbuf_ptr,
                                           size_t *nvbuflen_ptr,
                                           char **nv, size_t nv_offset,
                                           spdylay_zlib *deflater)
{
  size_t nvspace;
  size_t maxframelen;
  ssize_t framelen;
  int r;
  nvspace = spdylay_frame_count_nv_space(nv);
  r = spdylay_reserve_buffer(nvbuf_ptr, nvbuflen_ptr, nvspace);
  if(r != 0) {
    return SPDYLAY_ERR_NOMEM;
  }
  maxframelen = nv_offset+spdylay_zlib_deflate_hd_bound(deflater, nvspace);
  r = spdylay_reserve_buffer(buf_ptr, buflen_ptr, maxframelen);
  if(r != 0) {
    return SPDYLAY_ERR_NOMEM;
  }
  spdylay_frame_pack_nv(*nvbuf_ptr, nv);
  framelen = spdylay_zlib_deflate_hd(deflater,
                                     (*buf_ptr)+nv_offset,
                                     maxframelen-nv_offset,
                                     *nvbuf_ptr, nvspace);
  if(framelen < 0) {
    return framelen;
  }
  framelen += nv_offset;
  return framelen;
}

int spdylay_frame_count_unpack_nv_space
(size_t *nvlen_ptr, size_t *buflen_ptr, const uint8_t *in, size_t inlen)
{
  uint16_t n;
  size_t buflen = 0;
  size_t nvlen = 0;
  size_t off = 0;
  const size_t len_size = sizeof(uint16_t);
  int i;
  if(inlen < len_size) {
    return SPDYLAY_ERR_INVALID_ARGUMENT;
  }
  n = spdylay_get_uint16(in);
  off += len_size;
  for(i = 0; i < n; ++i) {
    uint16_t len;
    int j;
    for(j = 0; j < 2; ++j) {
      if(inlen-off < len_size) {
        return SPDYLAY_ERR_INVALID_ARGUMENT;
      }
      len = spdylay_get_uint16(in+off);
      off += 2;
      if(inlen-off < len) {
        return SPDYLAY_ERR_INVALID_ARGUMENT;
      }
      buflen += len+1;
      off += len;
    }
    for(off -= len, j = off+len; off != j; ++off) {
      if(in[off] == '\0') {
        ++nvlen;
      }
    }
    ++nvlen;
  }
  *nvlen_ptr = nvlen;
  *buflen_ptr = buflen+(nvlen*2+1)*sizeof(char*);
  return 0;
}

int spdylay_frame_unpack_nv(char ***nv_ptr, const uint8_t *in, size_t inlen)
{
  size_t nvlen, buflen;
  int r, i;
  char *buf, **index, *data;
  uint16_t n;
  r = spdylay_frame_count_unpack_nv_space(&nvlen, &buflen, in, inlen);
  if(r != 0) {
    return r;
  }
  buf = malloc(buflen);
  if(buf == NULL) {
    return SPDYLAY_ERR_NOMEM;
  }
  index = (char**)buf;
  data = buf+(nvlen*2+1)*sizeof(char*);
  n = spdylay_get_uint16(in);
  in += 2;
  for(i = 0; i < n; ++i) {
    uint16_t len;
    char *name, *val;
    char *stop;
    len = spdylay_get_uint16(in);
    in += 2;
    name = data;
    memcpy(data, in, len);
    data += len;
    *data = '\0';
    ++data;
    in += len;

    len = spdylay_get_uint16(in);
    in += 2;
    val = data;
    memcpy(data, in, len);

    for(stop = data+len; data != stop; ++data) {
      if(*data == '\0') {
        *index++ = name;
        *index++ = val;
        val = data+1;
      }
    }
    *data = '\0';
    ++data;
    in += len;

    *index++ = name;
    *index++ = val;
  }
  *index = NULL;
  assert((char*)index-buf == (nvlen*2)*sizeof(char*));
  *nv_ptr = (char**)buf;
  return 0;
}

static int spdylay_frame_alloc_unpack_nv(char ***nv_ptr,
                                         const uint8_t *in, size_t inlen,
                                         spdylay_zlib *inflater)
{
  ssize_t r;
  spdylay_buffer outbuffer;
  spdylay_buffer_init(&outbuffer, 4096);
  r = spdylay_zlib_inflate_hd(inflater, &outbuffer, in, inlen);
  if(r < 0) {
    spdylay_buffer_free(&outbuffer);
    return r;
  } else {
    uint8_t *buf = malloc(r);
    if(buf == NULL) {
      spdylay_buffer_free(&outbuffer);
      return SPDYLAY_ERR_NOMEM;
    }
    spdylay_buffer_serialize(&outbuffer, buf);
    spdylay_buffer_free(&outbuffer);
    r = spdylay_frame_unpack_nv(nv_ptr, buf, r);
    free(buf);
    return r;
  }
}

size_t spdylay_frame_count_nv_space(char **nv)
{
  size_t sum = 2;
  int i;
  const char *prev = "";
  size_t prevlen = 0;
  for(i = 0; nv[i]; i += 2) {
    const char *key = nv[i];
    const char *val = nv[i+1];
    size_t keylen = strlen(key);
    size_t vallen = strlen(val);
    if(prevlen == keylen && memcmp(prev, key, keylen) == 0) {
      /* Join previous value, with NULL character */
      sum += vallen+1;
    } else {
      prev = key;
      /* SPDY NV header does not include terminating NULL byte */
      sum += keylen+vallen+4;
    }
  }
  return sum;
}

ssize_t spdylay_frame_pack_nv(uint8_t *buf, char **nv)
{
  int i;
  uint8_t *bufp = buf+2;
  uint16_t num_nv = 0;
  /* TODO Join values with same keys, using '\0' as a delimiter */
  const char *prev = "";
  uint8_t *prev_vallen_buf = NULL;
  uint16_t prev_vallen = 0;
  for(i = 0; nv[i]; i += 2) {
    const char *key = nv[i];
    const char *val = nv[i+1];
    size_t keylen = strlen(key);
    size_t vallen = strlen(val);
    if(strcmp(prev, key) == 0) {
      prev_vallen += vallen+1;
      spdylay_put_uint16be(prev_vallen_buf, prev_vallen);
      *bufp = '\0';
      ++bufp;
      memcpy(bufp, val, vallen);
      bufp += vallen;
    } else {
      ++num_nv;
      bufp = spdylay_pack_str(bufp, key, keylen);
      prev = key;
      prev_vallen_buf = bufp;
      prev_vallen = vallen;
      bufp = spdylay_pack_str(bufp, val, vallen);
    }
  }
  spdylay_put_uint16be(buf, num_nv);
  return bufp-buf;
}

int spdylay_frame_is_ctrl_frame(uint8_t first_byte)
{
  return first_byte & 0x80;
}

void spdylay_frame_nv_del(char **nv)
{
  free(nv);
}

char** spdylay_frame_nv_copy(const char **nv)
{
  int i;
  char *buf;
  char **index, *data;
  size_t buflen = 0;
  for(i = 0; nv[i]; ++i) {
    buflen += strlen(nv[i])+1;
  }
  buflen += (i+1)*sizeof(char*);
  buf = malloc(buflen);
  if(buf == NULL) {
    return NULL;
  }
  index = (char**)buf;
  data = buf+(i+1)*sizeof(char*);

  for(i = 0; nv[i]; ++i) {
    size_t len = strlen(nv[i])+1;
    memcpy(data, nv[i], len);
    *index++ = data;
    data += len;
  }
  *index = NULL;
  return (char**)buf;
}

static int spdylay_string_compar(const void *lhs, const void *rhs)
{
  return strcmp(*(char **)lhs, *(char **)rhs);
}

void spdylay_frame_nv_sort(char **nv)
{
  int n;
  for(n = 0; nv[n]; ++n);
  qsort(nv, n/2, 2*sizeof(char*), spdylay_string_compar);
}

void spdylay_frame_nv_downcase(char **nv)
{
  int i, j;
  for(i = 0; nv[i]; i += 2) {
    for(j = 0; nv[i][j] != '\0'; ++j) {
      if('A' <= nv[i][j] && nv[i][j] <= 'Z') {
        nv[i][j] += 'a'-'A';
      }
    }
  }
}

void spdylay_frame_syn_stream_init(spdylay_syn_stream *frame, uint8_t flags,
                                   int32_t stream_id, int32_t assoc_stream_id,
                                   uint8_t pri, char **nv)
{
  memset(frame, 0, sizeof(spdylay_syn_stream));
  frame->hd.version = SPDYLAY_PROTO_VERSION;
  frame->hd.type = SPDYLAY_SYN_STREAM;
  frame->hd.flags = flags;
  frame->stream_id = stream_id;
  frame->assoc_stream_id = assoc_stream_id;
  frame->pri = pri;
  frame->nv = nv;
}

void spdylay_frame_syn_stream_free(spdylay_syn_stream *frame)
{
  spdylay_frame_nv_del(frame->nv);
}

void spdylay_frame_syn_reply_init(spdylay_syn_reply *frame, uint8_t flags,
                                  int32_t stream_id, char **nv)
{
  memset(frame, 0, sizeof(spdylay_syn_reply));
  frame->hd.version = SPDYLAY_PROTO_VERSION;
  frame->hd.type = SPDYLAY_SYN_REPLY;
  frame->hd.flags = flags;
  frame->stream_id = stream_id;
  frame->nv = nv;
}

void spdylay_frame_syn_reply_free(spdylay_syn_reply *frame)
{
  spdylay_frame_nv_del(frame->nv);
}

void spdylay_frame_ping_init(spdylay_ping *frame, uint32_t unique_id)
{
  memset(frame, 0, sizeof(spdylay_ping));
  frame->hd.version = SPDYLAY_PROTO_VERSION;
  frame->hd.type = SPDYLAY_PING;
  frame->hd.flags = SPDYLAY_FLAG_NONE;
  frame->hd.length = 4;
  frame->unique_id = unique_id;
}

void spdylay_frame_ping_free(spdylay_ping *frame)
{}

void spdylay_frame_goaway_init(spdylay_goaway *frame,
                               int32_t last_good_stream_id)
{
  memset(frame, 0, sizeof(spdylay_goaway));
  frame->hd.version = SPDYLAY_PROTO_VERSION;
  frame->hd.type = SPDYLAY_GOAWAY;
  frame->hd.length = 4;
  frame->last_good_stream_id = last_good_stream_id;
}

void spdylay_frame_goaway_free(spdylay_goaway *frame)
{}

void spdylay_frame_headers_init(spdylay_headers *frame, uint8_t flags,
                                int32_t stream_id, char **nv)
{
  memset(frame, 0, sizeof(spdylay_headers));
  frame->hd.version = SPDYLAY_PROTO_VERSION;
  frame->hd.type = SPDYLAY_HEADERS;
  frame->hd.flags = flags;
  frame->stream_id = stream_id;
  frame->nv = nv;
}

void spdylay_frame_headers_free(spdylay_headers *frame)
{
  spdylay_frame_nv_del(frame->nv);
}

void spdylay_frame_rst_stream_init(spdylay_rst_stream *frame,
                                   int32_t stream_id, uint32_t status_code)
{
  memset(frame, 0, sizeof(spdylay_rst_stream));
  frame->hd.version = SPDYLAY_PROTO_VERSION;
  frame->hd.type = SPDYLAY_RST_STREAM;
  frame->hd.flags = 0;
  frame->hd.length = 8;
  frame->stream_id = stream_id;
  frame->status_code = status_code;
}

void spdylay_frame_rst_stream_free(spdylay_rst_stream *frame)
{}

void spdylay_frame_settings_init(spdylay_settings *frame, uint8_t flags,
                                 spdylay_settings_entry *iv, size_t niv)
{
  memset(frame, 0, sizeof(spdylay_settings));
  frame->hd.version = SPDYLAY_PROTO_VERSION;
  frame->hd.type = SPDYLAY_SETTINGS;
  frame->hd.flags = flags;
  frame->hd.length = 4+niv*8;
  frame->niv = niv;
  frame->iv = iv;
}

void spdylay_frame_settings_free(spdylay_settings *frame)
{
  free(frame->iv);
}

void spdylay_frame_data_init(spdylay_data *frame, int32_t stream_id,
                             uint8_t flags, spdylay_data_provider *data_prd)
{
  memset(frame, 0, sizeof(spdylay_data));
  frame->stream_id = stream_id;
  frame->flags = flags;
  frame->data_prd = *data_prd;
}

void spdylay_frame_data_free(spdylay_data *frame)
{}

#define SPDYLAY_SYN_STREAM_NV_OFFSET 18

ssize_t spdylay_frame_pack_syn_stream(uint8_t **buf_ptr,
                                      size_t *buflen_ptr,
                                      uint8_t **nvbuf_ptr,
                                      size_t *nvbuflen_ptr,
                                      spdylay_syn_stream *frame,
                                      spdylay_zlib *deflater)
{
  ssize_t framelen;
  framelen = spdylay_frame_alloc_pack_nv(buf_ptr, buflen_ptr,
                                         nvbuf_ptr, nvbuflen_ptr,
                                         frame->nv,
                                         SPDYLAY_SYN_STREAM_NV_OFFSET,
                                         deflater);
  if(framelen < 0) {
    return framelen;
  }
  frame->hd.length = framelen-SPDYLAY_FRAME_HEAD_LENGTH;
  memset(*buf_ptr, 0, SPDYLAY_SYN_STREAM_NV_OFFSET);
  /* pack ctrl header after length is determined */
  spdylay_frame_pack_ctrl_hd(*buf_ptr, &frame->hd);
  spdylay_put_uint32be(&(*buf_ptr)[8], frame->stream_id);
  spdylay_put_uint32be(&(*buf_ptr)[12], frame->assoc_stream_id);
  (*buf_ptr)[16] = (frame->pri << 6);
  return framelen;
}

int spdylay_frame_unpack_syn_stream(spdylay_syn_stream *frame,
                                    const uint8_t *head, size_t headlen,
                                    const uint8_t *payload, size_t payloadlen,
                                    spdylay_zlib *inflater)
{
  int r;
  if(payloadlen < 12) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  spdylay_frame_unpack_ctrl_hd(&frame->hd, head);
  frame->stream_id = spdylay_get_uint32(payload) & SPDYLAY_STREAM_ID_MASK;
  frame->assoc_stream_id =
    spdylay_get_uint32(payload+4) & SPDYLAY_STREAM_ID_MASK;
  frame->pri = spdylay_unpack_pri(payload+8);
  r = spdylay_frame_alloc_unpack_nv(&frame->nv, payload+10, payloadlen-10,
                                    inflater);
  return r;
}

#define SPDYLAY_SYN_REPLY_NV_OFFSET 14

ssize_t spdylay_frame_pack_syn_reply(uint8_t **buf_ptr,
                                     size_t *buflen_ptr,
                                     uint8_t **nvbuf_ptr,
                                     size_t *nvbuflen_ptr,
                                     spdylay_syn_reply *frame,
                                     spdylay_zlib *deflater)
{
  ssize_t framelen;
  framelen = spdylay_frame_alloc_pack_nv(buf_ptr, buflen_ptr,
                                         nvbuf_ptr, nvbuflen_ptr,
                                         frame->nv,
                                         SPDYLAY_SYN_REPLY_NV_OFFSET, deflater);
  if(framelen < 0) {
    return framelen;
  }
  frame->hd.length = framelen-SPDYLAY_FRAME_HEAD_LENGTH;
  memset(*buf_ptr, 0, SPDYLAY_SYN_REPLY_NV_OFFSET);
  spdylay_frame_pack_ctrl_hd(*buf_ptr, &frame->hd);
  spdylay_put_uint32be(&(*buf_ptr)[8], frame->stream_id);
  return framelen;
}

int spdylay_frame_unpack_syn_reply(spdylay_syn_reply *frame,
                                   const uint8_t *head, size_t headlen,
                                   const uint8_t *payload, size_t payloadlen,
                                   spdylay_zlib *inflater)
{
  int r;
  if(payloadlen < 8) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  spdylay_frame_unpack_ctrl_hd(&frame->hd, head);
  frame->stream_id = spdylay_get_uint32(payload) & SPDYLAY_STREAM_ID_MASK;
  r = spdylay_frame_alloc_unpack_nv(&frame->nv, payload+6, payloadlen-6,
                                    inflater);
  return r;
}

ssize_t spdylay_frame_pack_ping(uint8_t **buf_ptr, size_t *buflen_ptr,
                                spdylay_ping *frame)
{
  ssize_t framelen = 12;
  int r;
  r = spdylay_reserve_buffer(buf_ptr, buflen_ptr, framelen);
  if(r != 0) {
    return r;
  }
  memset(*buf_ptr, 0, framelen);
  spdylay_frame_pack_ctrl_hd(*buf_ptr, &frame->hd);
  spdylay_put_uint32be(&(*buf_ptr)[8], frame->unique_id);
  return framelen;
}

int spdylay_frame_unpack_ping(spdylay_ping *frame,
                              const uint8_t *head, size_t headlen,
                              const uint8_t *payload, size_t payloadlen)
{
  if(payloadlen < 4) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  spdylay_frame_unpack_ctrl_hd(&frame->hd, head);
  frame->unique_id = spdylay_get_uint32(payload);
  return 0;
}

ssize_t spdylay_frame_pack_goaway(uint8_t **buf_ptr, size_t *buflen_ptr,
                                  spdylay_goaway *frame)
{
  ssize_t framelen = 12;
  int r;
  r = spdylay_reserve_buffer(buf_ptr, buflen_ptr, framelen);
  if(r != 0) {
    return r;
  }
  memset(*buf_ptr, 0, framelen);
  spdylay_frame_pack_ctrl_hd(*buf_ptr, &frame->hd);
  spdylay_put_uint32be(&(*buf_ptr)[8], frame->last_good_stream_id);
  return framelen;
}

int spdylay_frame_unpack_goaway(spdylay_goaway *frame,
                                const uint8_t *head, size_t headlen,
                                const uint8_t *payload, size_t payloadlen)
{
  if(payloadlen < 4) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  spdylay_frame_unpack_ctrl_hd(&frame->hd, head);
  frame->last_good_stream_id = spdylay_get_uint32(payload) &
    SPDYLAY_STREAM_ID_MASK;
  return 0;
}

#define SPDYLAY_HEADERS_NV_OFFSET 14

ssize_t spdylay_frame_pack_headers(uint8_t **buf_ptr, size_t *buflen_ptr,
                                   uint8_t **nvbuf_ptr, size_t *nvbuflen_ptr,
                                   spdylay_headers *frame,
                                   spdylay_zlib *deflater)
{
  ssize_t framelen;
  framelen = spdylay_frame_alloc_pack_nv(buf_ptr, buflen_ptr,
                                         nvbuf_ptr, nvbuflen_ptr,
                                         frame->nv,
                                         SPDYLAY_HEADERS_NV_OFFSET, deflater);
  if(framelen < 0) {
    return framelen;
  }
  frame->hd.length = framelen-SPDYLAY_FRAME_HEAD_LENGTH;
  memset(*buf_ptr, 0, SPDYLAY_HEADERS_NV_OFFSET);
  spdylay_frame_pack_ctrl_hd(*buf_ptr, &frame->hd);
  spdylay_put_uint32be(&(*buf_ptr)[8], frame->stream_id);
  return framelen;
}

int spdylay_frame_unpack_headers(spdylay_headers *frame,
                                 const uint8_t *head, size_t headlen,
                                 const uint8_t *payload, size_t payloadlen,
                                 spdylay_zlib *inflater)
{
  int r;
  if(payloadlen < 8) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  spdylay_frame_unpack_ctrl_hd(&frame->hd, head);
  frame->stream_id = spdylay_get_uint32(payload) & SPDYLAY_STREAM_ID_MASK;
  r = spdylay_frame_alloc_unpack_nv(&frame->nv, payload+6, payloadlen-6,
                                    inflater);
  return r;
}

ssize_t spdylay_frame_pack_rst_stream(uint8_t **buf_ptr, size_t *buflen_ptr,
                                      spdylay_rst_stream *frame)
{
  ssize_t framelen = 16;
  int r;
  r = spdylay_reserve_buffer(buf_ptr, buflen_ptr, framelen);
  if(r != 0) {
    return r;
  }
  memset(*buf_ptr, 0, framelen);
  spdylay_frame_pack_ctrl_hd(*buf_ptr, &frame->hd);
  spdylay_put_uint32be(&(*buf_ptr)[8], frame->stream_id);
  spdylay_put_uint32be(&(*buf_ptr)[12], frame->status_code);
  return framelen;
}

int spdylay_frame_unpack_rst_stream(spdylay_rst_stream *frame,
                                    const uint8_t *head, size_t headlen,
                                    const uint8_t *payload, size_t payloadlen)
{
  if(payloadlen < 8) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  spdylay_frame_unpack_ctrl_hd(&frame->hd, head);
  frame->stream_id = spdylay_get_uint32(payload) & SPDYLAY_STREAM_ID_MASK;
  frame->status_code = spdylay_get_uint32(payload+4);
  return 0;
}

ssize_t spdylay_frame_pack_settings(uint8_t **buf_ptr, size_t *buflen_ptr,
                                    spdylay_settings *frame)
{
  ssize_t framelen = SPDYLAY_FRAME_HEAD_LENGTH+frame->hd.length;
  int i, r;
  r = spdylay_reserve_buffer(buf_ptr, buflen_ptr, framelen);
  if(r != 0) {
    return r;
  }
  memset(*buf_ptr, 0, framelen);
  spdylay_frame_pack_ctrl_hd(*buf_ptr, &frame->hd);
  spdylay_put_uint32be(&(*buf_ptr)[8], frame->niv);
  for(i = 0; i < frame->niv; ++i) {
    int off = i*8;
    /* spdy/2 spec says ID is network byte order, but publicly
       deployed server sends little endian host byte order. */
    char *id_ptr = (char*)(&frame->iv[i].settings_id);
#ifdef WORDS_BIGENDIAN
    (*buf_ptr)[12+off] = id_ptr[3];
    (*buf_ptr)[12+off+1] = id_ptr[2];
    (*buf_ptr)[12+off+2] = id_ptr[1];
#else /* !WORDS_BIGENDIAN */
    memcpy(&(*buf_ptr)[12+off], id_ptr, 3);
#endif /* !WORDS_BIGENDIAN */
    (*buf_ptr)[15+off] = frame->iv[i].flags;
    spdylay_put_uint32be(&(*buf_ptr)[16+off], frame->iv[i].value);
  }
  return framelen;
}

int spdylay_frame_unpack_settings(spdylay_settings *frame,
                                  const uint8_t *head, size_t headlen,
                                  const uint8_t *payload, size_t payloadlen)
{
  int i;
  if(payloadlen < 4) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  spdylay_frame_unpack_ctrl_hd(&frame->hd, head);
  frame->niv = spdylay_get_uint32(payload);
  if(payloadlen != 4+frame->niv*8) {
    return SPDYLAY_ERR_INVALID_FRAME;
  }
  frame->iv = malloc(frame->niv*sizeof(spdylay_settings_entry));
  if(frame->iv == NULL) {
    return SPDYLAY_ERR_NOMEM;
  }
  for(i = 0; i < frame->niv; ++i) {
    int off = i*8;
    /* ID is little endian. See comments in
       spdylay_frame_pack_settings(). */
    frame->iv[i].settings_id = 0;
#ifdef WORDS_BIGENDIAN
    *(char*)(&frame->iv[i].settings_id[1]) = &payload[4+off+2];
    *(char*)(&frame->iv[i].settings_id[2]) = &payload[4+off+1];
    *(char*)(&frame->iv[i].settings_id[3]) = &payload[4+off+0];
#else /* !WORDS_BIGENDIAN */
    memcpy(&frame->iv[i].settings_id, &payload[4+off], 3);
#endif /* !WORDS_BIGENDIAN */
    frame->iv[i].flags = payload[7+off];
    frame->iv[i].value = spdylay_get_uint32(&payload[8+off]);
  }
  return 0;
}

spdylay_settings_entry* spdylay_frame_iv_copy(const spdylay_settings_entry *iv,
                                              size_t niv)
{
  spdylay_settings_entry *iv_copy;
  size_t len = niv*sizeof(spdylay_settings_entry);
  iv_copy = malloc(len);
  if(iv_copy == NULL) {
    return NULL;
  }
  memcpy(iv_copy, iv, len);
  return iv_copy;
}