nghttp2/lib/nghttp2_hd.c

/*
 * nghttp2 - HTTP/2 C Library
 *
 * Copyright (c) 2013 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 "nghttp2_hd.h"

#include <string.h>
#include <assert.h>
#include <stdio.h>

#include "nghttp2_helper.h"
#include "nghttp2_int.h"

/* Make scalar initialization form of nghttp2_hd_entry */
#define MAKE_STATIC_ENT(N, V, T, H)                                            \
  {                                                                            \
    { (uint8_t *)(N), (uint8_t *)(V), sizeof((N)) - 1, sizeof((V)) - 1, 0 }    \
    , NULL, 0, (H), (T), 1, NGHTTP2_HD_FLAG_NONE                               \
  }

/* Generated by mkstatictbl.py */
/* 3rd parameter is nghttp2_token value for header field name.  We use
   first enum value if same header names are repeated (e.g.,
   :status). */
static nghttp2_hd_entry static_table[] = {
    MAKE_STATIC_ENT(":authority", "", 0, 3153725150u),
    MAKE_STATIC_ENT(":method", "GET", 1, 695666056u),
    MAKE_STATIC_ENT(":method", "POST", 1, 695666056u),
    MAKE_STATIC_ENT(":path", "/", 3, 3292848686u),
    MAKE_STATIC_ENT(":path", "/index.html", 3, 3292848686u),
    MAKE_STATIC_ENT(":scheme", "http", 5, 2510477674u),
    MAKE_STATIC_ENT(":scheme", "https", 5, 2510477674u),
    MAKE_STATIC_ENT(":status", "200", 7, 4000288983u),
    MAKE_STATIC_ENT(":status", "204", 7, 4000288983u),
    MAKE_STATIC_ENT(":status", "206", 7, 4000288983u),
    MAKE_STATIC_ENT(":status", "304", 7, 4000288983u),
    MAKE_STATIC_ENT(":status", "400", 7, 4000288983u),
    MAKE_STATIC_ENT(":status", "404", 7, 4000288983u),
    MAKE_STATIC_ENT(":status", "500", 7, 4000288983u),
    MAKE_STATIC_ENT("accept-charset", "", 14, 3664010344u),
    MAKE_STATIC_ENT("accept-encoding", "gzip, deflate", 15, 3379649177u),
    MAKE_STATIC_ENT("accept-language", "", 16, 1979086614u),
    MAKE_STATIC_ENT("accept-ranges", "", 17, 1713753958u),
    MAKE_STATIC_ENT("accept", "", 18, 136609321u),
    MAKE_STATIC_ENT("access-control-allow-origin", "", 19, 2710797292u),
    MAKE_STATIC_ENT("age", "", 20, 742476188u),
    MAKE_STATIC_ENT("allow", "", 21, 2930878514u),
    MAKE_STATIC_ENT("authorization", "", 22, 2436257726u),
    MAKE_STATIC_ENT("cache-control", "", 23, 1355326669u),
    MAKE_STATIC_ENT("content-disposition", "", 24, 3889184348u),
    MAKE_STATIC_ENT("content-encoding", "", 25, 65203592u),
    MAKE_STATIC_ENT("content-language", "", 26, 24973587u),
    MAKE_STATIC_ENT("content-length", "", 27, 1308181789u),
    MAKE_STATIC_ENT("content-location", "", 28, 2302364718u),
    MAKE_STATIC_ENT("content-range", "", 29, 3555523146u),
    MAKE_STATIC_ENT("content-type", "", 30, 4244048277u),
    MAKE_STATIC_ENT("cookie", "", 31, 2007449791u),
    MAKE_STATIC_ENT("date", "", 32, 3564297305u),
    MAKE_STATIC_ENT("etag", "", 33, 113792960u),
    MAKE_STATIC_ENT("expect", "", 34, 2530896728u),
    MAKE_STATIC_ENT("expires", "", 35, 1049544579u),
    MAKE_STATIC_ENT("from", "", 36, 2513272949u),
    MAKE_STATIC_ENT("host", "", 37, 2952701295u),
    MAKE_STATIC_ENT("if-match", "", 38, 3597694698u),
    MAKE_STATIC_ENT("if-modified-since", "", 39, 2213050793u),
    MAKE_STATIC_ENT("if-none-match", "", 40, 2536202615u),
    MAKE_STATIC_ENT("if-range", "", 41, 2340978238u),
    MAKE_STATIC_ENT("if-unmodified-since", "", 42, 3794814858u),
    MAKE_STATIC_ENT("last-modified", "", 43, 3226950251u),
    MAKE_STATIC_ENT("link", "", 44, 232457833u),
    MAKE_STATIC_ENT("location", "", 45, 200649126u),
    MAKE_STATIC_ENT("max-forwards", "", 46, 1826162134u),
    MAKE_STATIC_ENT("proxy-authenticate", "", 47, 2709445359u),
    MAKE_STATIC_ENT("proxy-authorization", "", 48, 2686392507u),
    MAKE_STATIC_ENT("range", "", 49, 4208725202u),
    MAKE_STATIC_ENT("referer", "", 50, 3969579366u),
    MAKE_STATIC_ENT("refresh", "", 51, 3572655668u),
    MAKE_STATIC_ENT("retry-after", "", 52, 3336180598u),
    MAKE_STATIC_ENT("server", "", 53, 1085029842u),
    MAKE_STATIC_ENT("set-cookie", "", 54, 1848371000u),
    MAKE_STATIC_ENT("strict-transport-security", "", 55, 4138147361u),
    MAKE_STATIC_ENT("transfer-encoding", "", 56, 3719590988u),
    MAKE_STATIC_ENT("user-agent", "", 57, 606444526u),
    MAKE_STATIC_ENT("vary", "", 58, 1085005381u),
    MAKE_STATIC_ENT("via", "", 59, 1762798611u),
    MAKE_STATIC_ENT("www-authenticate", "", 60, 779865858u),
};

static int memeq(const void *s1, const void *s2, size_t n) {
  return memcmp(s1, s2, n) == 0;
}

/*
 * This function was generated by genlibtokenlookup.py.  Inspired by
 * h2o header lookup.  https://github.com/h2o/h2o
 */
static int lookup_token(const uint8_t *name, size_t namelen) {
  switch (namelen) {
  case 2:
    switch (name[1]) {
    case 'e':
      if (lstreq("t", name, 1)) {
        return NGHTTP2_TOKEN_TE;
      }
      break;
    }
    break;
  case 3:
    switch (name[2]) {
    case 'a':
      if (lstreq("vi", name, 2)) {
        return NGHTTP2_TOKEN_VIA;
      }
      break;
    case 'e':
      if (lstreq("ag", name, 2)) {
        return NGHTTP2_TOKEN_AGE;
      }
      break;
    }
    break;
  case 4:
    switch (name[3]) {
    case 'e':
      if (lstreq("dat", name, 3)) {
        return NGHTTP2_TOKEN_DATE;
      }
      break;
    case 'g':
      if (lstreq("eta", name, 3)) {
        return NGHTTP2_TOKEN_ETAG;
      }
      break;
    case 'k':
      if (lstreq("lin", name, 3)) {
        return NGHTTP2_TOKEN_LINK;
      }
      break;
    case 'm':
      if (lstreq("fro", name, 3)) {
        return NGHTTP2_TOKEN_FROM;
      }
      break;
    case 't':
      if (lstreq("hos", name, 3)) {
        return NGHTTP2_TOKEN_HOST;
      }
      break;
    case 'y':
      if (lstreq("var", name, 3)) {
        return NGHTTP2_TOKEN_VARY;
      }
      break;
    }
    break;
  case 5:
    switch (name[4]) {
    case 'e':
      if (lstreq("rang", name, 4)) {
        return NGHTTP2_TOKEN_RANGE;
      }
      break;
    case 'h':
      if (lstreq(":pat", name, 4)) {
        return NGHTTP2_TOKEN__PATH;
      }
      if (lstreq(":pat", name, 4)) {
        return NGHTTP2_TOKEN__PATH;
      }
      break;
    case 'w':
      if (lstreq("allo", name, 4)) {
        return NGHTTP2_TOKEN_ALLOW;
      }
      break;
    }
    break;
  case 6:
    switch (name[5]) {
    case 'e':
      if (lstreq("cooki", name, 5)) {
        return NGHTTP2_TOKEN_COOKIE;
      }
      break;
    case 'r':
      if (lstreq("serve", name, 5)) {
        return NGHTTP2_TOKEN_SERVER;
      }
      break;
    case 't':
      if (lstreq("accep", name, 5)) {
        return NGHTTP2_TOKEN_ACCEPT;
      }
      if (lstreq("expec", name, 5)) {
        return NGHTTP2_TOKEN_EXPECT;
      }
      break;
    }
    break;
  case 7:
    switch (name[6]) {
    case 'd':
      if (lstreq(":metho", name, 6)) {
        return NGHTTP2_TOKEN__METHOD;
      }
      if (lstreq(":metho", name, 6)) {
        return NGHTTP2_TOKEN__METHOD;
      }
      break;
    case 'e':
      if (lstreq(":schem", name, 6)) {
        return NGHTTP2_TOKEN__SCHEME;
      }
      if (lstreq(":schem", name, 6)) {
        return NGHTTP2_TOKEN__SCHEME;
      }
      if (lstreq("upgrad", name, 6)) {
        return NGHTTP2_TOKEN_UPGRADE;
      }
      break;
    case 'h':
      if (lstreq("refres", name, 6)) {
        return NGHTTP2_TOKEN_REFRESH;
      }
      break;
    case 'r':
      if (lstreq("refere", name, 6)) {
        return NGHTTP2_TOKEN_REFERER;
      }
      break;
    case 's':
      if (lstreq(":statu", name, 6)) {
        return NGHTTP2_TOKEN__STATUS;
      }
      if (lstreq(":statu", name, 6)) {
        return NGHTTP2_TOKEN__STATUS;
      }
      if (lstreq(":statu", name, 6)) {
        return NGHTTP2_TOKEN__STATUS;
      }
      if (lstreq(":statu", name, 6)) {
        return NGHTTP2_TOKEN__STATUS;
      }
      if (lstreq(":statu", name, 6)) {
        return NGHTTP2_TOKEN__STATUS;
      }
      if (lstreq(":statu", name, 6)) {
        return NGHTTP2_TOKEN__STATUS;
      }
      if (lstreq(":statu", name, 6)) {
        return NGHTTP2_TOKEN__STATUS;
      }
      if (lstreq("expire", name, 6)) {
        return NGHTTP2_TOKEN_EXPIRES;
      }
      break;
    }
    break;
  case 8:
    switch (name[7]) {
    case 'e':
      if (lstreq("if-rang", name, 7)) {
        return NGHTTP2_TOKEN_IF_RANGE;
      }
      break;
    case 'h':
      if (lstreq("if-matc", name, 7)) {
        return NGHTTP2_TOKEN_IF_MATCH;
      }
      break;
    case 'n':
      if (lstreq("locatio", name, 7)) {
        return NGHTTP2_TOKEN_LOCATION;
      }
      break;
    }
    break;
  case 10:
    switch (name[9]) {
    case 'e':
      if (lstreq("keep-aliv", name, 9)) {
        return NGHTTP2_TOKEN_KEEP_ALIVE;
      }
      if (lstreq("set-cooki", name, 9)) {
        return NGHTTP2_TOKEN_SET_COOKIE;
      }
      break;
    case 'n':
      if (lstreq("connectio", name, 9)) {
        return NGHTTP2_TOKEN_CONNECTION;
      }
      break;
    case 't':
      if (lstreq("user-agen", name, 9)) {
        return NGHTTP2_TOKEN_USER_AGENT;
      }
      break;
    case 'y':
      if (lstreq(":authorit", name, 9)) {
        return NGHTTP2_TOKEN__AUTHORITY;
      }
      break;
    }
    break;
  case 11:
    switch (name[10]) {
    case 'r':
      if (lstreq("retry-afte", name, 10)) {
        return NGHTTP2_TOKEN_RETRY_AFTER;
      }
      break;
    }
    break;
  case 12:
    switch (name[11]) {
    case 'e':
      if (lstreq("content-typ", name, 11)) {
        return NGHTTP2_TOKEN_CONTENT_TYPE;
      }
      break;
    case 's':
      if (lstreq("max-forward", name, 11)) {
        return NGHTTP2_TOKEN_MAX_FORWARDS;
      }
      break;
    }
    break;
  case 13:
    switch (name[12]) {
    case 'd':
      if (lstreq("last-modifie", name, 12)) {
        return NGHTTP2_TOKEN_LAST_MODIFIED;
      }
      break;
    case 'e':
      if (lstreq("content-rang", name, 12)) {
        return NGHTTP2_TOKEN_CONTENT_RANGE;
      }
      break;
    case 'h':
      if (lstreq("if-none-matc", name, 12)) {
        return NGHTTP2_TOKEN_IF_NONE_MATCH;
      }
      break;
    case 'l':
      if (lstreq("cache-contro", name, 12)) {
        return NGHTTP2_TOKEN_CACHE_CONTROL;
      }
      break;
    case 'n':
      if (lstreq("authorizatio", name, 12)) {
        return NGHTTP2_TOKEN_AUTHORIZATION;
      }
      break;
    case 's':
      if (lstreq("accept-range", name, 12)) {
        return NGHTTP2_TOKEN_ACCEPT_RANGES;
      }
      break;
    }
    break;
  case 14:
    switch (name[13]) {
    case 'h':
      if (lstreq("content-lengt", name, 13)) {
        return NGHTTP2_TOKEN_CONTENT_LENGTH;
      }
      break;
    case 't':
      if (lstreq("accept-charse", name, 13)) {
        return NGHTTP2_TOKEN_ACCEPT_CHARSET;
      }
      break;
    }
    break;
  case 15:
    switch (name[14]) {
    case 'e':
      if (lstreq("accept-languag", name, 14)) {
        return NGHTTP2_TOKEN_ACCEPT_LANGUAGE;
      }
      break;
    case 'g':
      if (lstreq("accept-encodin", name, 14)) {
        return NGHTTP2_TOKEN_ACCEPT_ENCODING;
      }
      break;
    }
    break;
  case 16:
    switch (name[15]) {
    case 'e':
      if (lstreq("content-languag", name, 15)) {
        return NGHTTP2_TOKEN_CONTENT_LANGUAGE;
      }
      if (lstreq("www-authenticat", name, 15)) {
        return NGHTTP2_TOKEN_WWW_AUTHENTICATE;
      }
      break;
    case 'g':
      if (lstreq("content-encodin", name, 15)) {
        return NGHTTP2_TOKEN_CONTENT_ENCODING;
      }
      break;
    case 'n':
      if (lstreq("content-locatio", name, 15)) {
        return NGHTTP2_TOKEN_CONTENT_LOCATION;
      }
      if (lstreq("proxy-connectio", name, 15)) {
        return NGHTTP2_TOKEN_PROXY_CONNECTION;
      }
      break;
    }
    break;
  case 17:
    switch (name[16]) {
    case 'e':
      if (lstreq("if-modified-sinc", name, 16)) {
        return NGHTTP2_TOKEN_IF_MODIFIED_SINCE;
      }
      break;
    case 'g':
      if (lstreq("transfer-encodin", name, 16)) {
        return NGHTTP2_TOKEN_TRANSFER_ENCODING;
      }
      break;
    }
    break;
  case 18:
    switch (name[17]) {
    case 'e':
      if (lstreq("proxy-authenticat", name, 17)) {
        return NGHTTP2_TOKEN_PROXY_AUTHENTICATE;
      }
      break;
    }
    break;
  case 19:
    switch (name[18]) {
    case 'e':
      if (lstreq("if-unmodified-sinc", name, 18)) {
        return NGHTTP2_TOKEN_IF_UNMODIFIED_SINCE;
      }
      break;
    case 'n':
      if (lstreq("content-dispositio", name, 18)) {
        return NGHTTP2_TOKEN_CONTENT_DISPOSITION;
      }
      if (lstreq("proxy-authorizatio", name, 18)) {
        return NGHTTP2_TOKEN_PROXY_AUTHORIZATION;
      }
      break;
    }
    break;
  case 25:
    switch (name[24]) {
    case 'y':
      if (lstreq("strict-transport-securit", name, 24)) {
        return NGHTTP2_TOKEN_STRICT_TRANSPORT_SECURITY;
      }
      break;
    }
    break;
  case 27:
    switch (name[26]) {
    case 'n':
      if (lstreq("access-control-allow-origi", name, 26)) {
        return NGHTTP2_TOKEN_ACCESS_CONTROL_ALLOW_ORIGIN;
      }
      break;
    }
    break;
  }
  return -1;
}

int nghttp2_hd_entry_init(nghttp2_hd_entry *ent, uint8_t flags, uint8_t *name,
                          size_t namelen, uint8_t *value, size_t valuelen,
                          int token, nghttp2_mem *mem) {
  int rv = 0;

  /* Since nghttp2_hd_entry is used for indexing, ent->nv.flags always
     NGHTTP2_NV_FLAG_NONE */
  ent->nv.flags = NGHTTP2_NV_FLAG_NONE;

  if ((flags & NGHTTP2_HD_FLAG_NAME_ALLOC) &&
      (flags & NGHTTP2_HD_FLAG_NAME_GIFT) == 0) {
    if (namelen == 0) {
      flags = (uint8_t)(flags & ~NGHTTP2_HD_FLAG_NAME_ALLOC);
      ent->nv.name = (uint8_t *)"";
    } else {
      /* copy including terminating NULL byte */
      ent->nv.name = nghttp2_memdup(name, namelen + 1, mem);
      if (ent->nv.name == NULL) {
        rv = NGHTTP2_ERR_NOMEM;
        goto fail;
      }
    }
  } else {
    ent->nv.name = name;
  }
  if ((flags & NGHTTP2_HD_FLAG_VALUE_ALLOC) &&
      (flags & NGHTTP2_HD_FLAG_VALUE_GIFT) == 0) {
    if (valuelen == 0) {
      flags = (uint8_t)(flags & ~NGHTTP2_HD_FLAG_VALUE_ALLOC);
      ent->nv.value = (uint8_t *)"";
    } else {
      /* copy including terminating NULL byte */
      ent->nv.value = nghttp2_memdup(value, valuelen + 1, mem);
      if (ent->nv.value == NULL) {
        rv = NGHTTP2_ERR_NOMEM;
        goto fail2;
      }
    }
  } else {
    ent->nv.value = value;
  }
  ent->nv.namelen = namelen;
  ent->nv.valuelen = valuelen;
  ent->token = token;
  ent->ref = 1;
  ent->flags = flags;
  ent->next = NULL;
  ent->hash = 0;

  return 0;

fail2:
  if ((flags & NGHTTP2_HD_FLAG_NAME_ALLOC) &&
      (flags & NGHTTP2_HD_FLAG_NAME_GIFT) == 0) {
    nghttp2_mem_free(mem, ent->nv.name);
  }
fail:
  return rv;
}

void nghttp2_hd_entry_free(nghttp2_hd_entry *ent, nghttp2_mem *mem) {
  assert(ent->ref == 0);
  if (ent->flags & NGHTTP2_HD_FLAG_NAME_ALLOC) {
    nghttp2_mem_free(mem, ent->nv.name);
  }
  if (ent->flags & NGHTTP2_HD_FLAG_VALUE_ALLOC) {
    nghttp2_mem_free(mem, ent->nv.value);
  }
}

static int name_eq(const nghttp2_nv *a, const nghttp2_nv *b) {
  return a->namelen == b->namelen && memeq(a->name, b->name, a->namelen);
}

static int value_eq(const nghttp2_nv *a, const nghttp2_nv *b) {
  return a->valuelen == b->valuelen && memeq(a->value, b->value, a->valuelen);
}

static uint32_t name_hash(const nghttp2_nv *nv) {
  /* 32 bit FNV-1a: http://isthe.com/chongo/tech/comp/fnv/ */
  uint32_t h = 2166136261u;
  size_t i;

  for (i = 0; i < nv->namelen; ++i) {
    h ^= nv->name[i];
    h += (h << 1) + (h << 4) + (h << 7) + (h << 8) + (h << 24);
  }

  return h;
}

static void hd_map_init(nghttp2_hd_map *map) {
  memset(map, 0, sizeof(nghttp2_hd_map));
}

static void hd_map_insert(nghttp2_hd_map *map, nghttp2_hd_entry *ent) {
  nghttp2_hd_entry **bucket;

  bucket = &map->table[ent->hash & (HD_MAP_SIZE - 1)];

  if (*bucket == NULL) {
    *bucket = ent;
    return;
  }

  /* lower index is linked near the root */
  ent->next = *bucket;
  *bucket = ent;
}

static nghttp2_hd_entry *hd_map_find(nghttp2_hd_map *map, int *exact_match,
                                     const nghttp2_nv *nv, int token,
                                     uint32_t hash) {
  nghttp2_hd_entry *p;
  nghttp2_hd_entry *res = NULL;

  *exact_match = 0;

  for (p = map->table[hash & (HD_MAP_SIZE - 1)]; p; p = p->next) {
    if (hash != p->hash || token != p->token ||
        (token == -1 && !name_eq(&p->nv, nv))) {
      continue;
    }
    if (!res) {
      res = p;
    }
    if (value_eq(&p->nv, nv)) {
      res = p;
      *exact_match = 1;
      break;
    }
  }

  return res;
}

static void hd_map_remove(nghttp2_hd_map *map, nghttp2_hd_entry *ent) {
  nghttp2_hd_entry **bucket;
  nghttp2_hd_entry *p;

  bucket = &map->table[ent->hash & (HD_MAP_SIZE - 1)];

  if (*bucket == NULL) {
    return;
  }

  if (*bucket == ent) {
    *bucket = ent->next;
    ent->next = NULL;
    return;
  }

  for (p = *bucket; p; p = p->next) {
    if (p->next == ent) {
      p->next = ent->next;
      ent->next = NULL;
      return;
    }
  }
}

static int hd_ringbuf_init(nghttp2_hd_ringbuf *ringbuf, size_t bufsize,
                           nghttp2_mem *mem) {
  size_t size;
  for (size = 1; size < bufsize; size <<= 1)
    ;
  ringbuf->buffer = nghttp2_mem_malloc(mem, sizeof(nghttp2_hd_entry *) * size);
  if (ringbuf->buffer == NULL) {
    return NGHTTP2_ERR_NOMEM;
  }
  ringbuf->mask = size - 1;
  ringbuf->first = 0;
  ringbuf->len = 0;
  return 0;
}

static nghttp2_hd_entry *hd_ringbuf_get(nghttp2_hd_ringbuf *ringbuf,
                                        size_t idx) {
  assert(idx < ringbuf->len);
  return ringbuf->buffer[(ringbuf->first + idx) & ringbuf->mask];
}

static int hd_ringbuf_reserve(nghttp2_hd_ringbuf *ringbuf, size_t bufsize,
                              nghttp2_mem *mem) {
  size_t i;
  size_t size;
  nghttp2_hd_entry **buffer;

  if (ringbuf->mask + 1 >= bufsize) {
    return 0;
  }
  for (size = 1; size < bufsize; size <<= 1)
    ;
  buffer = nghttp2_mem_malloc(mem, sizeof(nghttp2_hd_entry *) * size);
  if (buffer == NULL) {
    return NGHTTP2_ERR_NOMEM;
  }
  for (i = 0; i < ringbuf->len; ++i) {
    buffer[i] = hd_ringbuf_get(ringbuf, i);
  }
  nghttp2_mem_free(mem, ringbuf->buffer);
  ringbuf->buffer = buffer;
  ringbuf->mask = size - 1;
  ringbuf->first = 0;
  return 0;
}

static void hd_ringbuf_free(nghttp2_hd_ringbuf *ringbuf, nghttp2_mem *mem) {
  size_t i;
  if (ringbuf == NULL) {
    return;
  }
  for (i = 0; i < ringbuf->len; ++i) {
    nghttp2_hd_entry *ent = hd_ringbuf_get(ringbuf, i);
    --ent->ref;
    nghttp2_hd_entry_free(ent, mem);
    nghttp2_mem_free(mem, ent);
  }
  nghttp2_mem_free(mem, ringbuf->buffer);
}

static int hd_ringbuf_push_front(nghttp2_hd_ringbuf *ringbuf,
                                 nghttp2_hd_entry *ent, nghttp2_mem *mem) {
  int rv;

  rv = hd_ringbuf_reserve(ringbuf, ringbuf->len + 1, mem);

  if (rv != 0) {
    return rv;
  }

  ringbuf->buffer[--ringbuf->first & ringbuf->mask] = ent;
  ++ringbuf->len;

  return 0;
}

static void hd_ringbuf_pop_back(nghttp2_hd_ringbuf *ringbuf) {
  assert(ringbuf->len > 0);
  --ringbuf->len;
}

static int hd_context_init(nghttp2_hd_context *context, nghttp2_mem *mem) {
  int rv;
  context->mem = mem;
  context->bad = 0;
  context->hd_table_bufsize_max = NGHTTP2_HD_DEFAULT_MAX_BUFFER_SIZE;
  rv = hd_ringbuf_init(&context->hd_table, context->hd_table_bufsize_max /
                                               NGHTTP2_HD_ENTRY_OVERHEAD,
                       mem);
  if (rv != 0) {
    return rv;
  }

  context->hd_table_bufsize = 0;
  context->next_seq = 0;

  return 0;
}

static void hd_context_free(nghttp2_hd_context *context) {
  hd_ringbuf_free(&context->hd_table, context->mem);
}

int nghttp2_hd_deflate_init(nghttp2_hd_deflater *deflater, nghttp2_mem *mem) {
  return nghttp2_hd_deflate_init2(
      deflater, NGHTTP2_HD_DEFAULT_MAX_DEFLATE_BUFFER_SIZE, mem);
}

int nghttp2_hd_deflate_init2(nghttp2_hd_deflater *deflater,
                             size_t deflate_hd_table_bufsize_max,
                             nghttp2_mem *mem) {
  int rv;
  rv = hd_context_init(&deflater->ctx, mem);
  if (rv != 0) {
    return rv;
  }

  hd_map_init(&deflater->map);

  if (deflate_hd_table_bufsize_max < NGHTTP2_HD_DEFAULT_MAX_BUFFER_SIZE) {
    deflater->notify_table_size_change = 1;
    deflater->ctx.hd_table_bufsize_max = deflate_hd_table_bufsize_max;
  } else {
    deflater->notify_table_size_change = 0;
  }

  deflater->deflate_hd_table_bufsize_max = deflate_hd_table_bufsize_max;
  deflater->min_hd_table_bufsize_max = UINT32_MAX;

  return 0;
}

int nghttp2_hd_inflate_init(nghttp2_hd_inflater *inflater, nghttp2_mem *mem) {
  int rv;

  rv = hd_context_init(&inflater->ctx, mem);
  if (rv != 0) {
    goto fail;
  }

  inflater->settings_hd_table_bufsize_max = NGHTTP2_HD_DEFAULT_MAX_BUFFER_SIZE;

  inflater->ent_keep = NULL;
  inflater->nv_keep = NULL;

  inflater->opcode = NGHTTP2_HD_OPCODE_NONE;
  inflater->state = NGHTTP2_HD_STATE_INFLATE_START;

  rv = nghttp2_bufs_init3(&inflater->nvbufs, NGHTTP2_HD_MAX_NV / 8, 8, 1, 0,
                          mem);

  if (rv != 0) {
    goto nvbufs_fail;
  }

  inflater->huffman_encoded = 0;
  inflater->index = 0;
  inflater->left = 0;
  inflater->shift = 0;
  inflater->newnamelen = 0;
  inflater->index_required = 0;
  inflater->no_index = 0;

  return 0;

nvbufs_fail:
  hd_context_free(&inflater->ctx);
fail:
  return rv;
}

static void hd_inflate_keep_free(nghttp2_hd_inflater *inflater) {
  nghttp2_mem *mem;

  mem = inflater->ctx.mem;
  if (inflater->ent_keep) {
    if (inflater->ent_keep->ref == 0) {
      nghttp2_hd_entry_free(inflater->ent_keep, mem);
      nghttp2_mem_free(mem, inflater->ent_keep);
    }
    inflater->ent_keep = NULL;
  }

  nghttp2_mem_free(mem, inflater->nv_keep);
  inflater->nv_keep = NULL;
}

void nghttp2_hd_deflate_free(nghttp2_hd_deflater *deflater) {
  hd_context_free(&deflater->ctx);
}

void nghttp2_hd_inflate_free(nghttp2_hd_inflater *inflater) {
  hd_inflate_keep_free(inflater);
  nghttp2_bufs_free(&inflater->nvbufs);
  hd_context_free(&inflater->ctx);
}

static size_t entry_room(size_t namelen, size_t valuelen) {
  return NGHTTP2_HD_ENTRY_OVERHEAD + namelen + valuelen;
}

static int emit_indexed_header(nghttp2_nv *nv_out, int *token_out,
                               nghttp2_hd_entry *ent) {
  DEBUGF(fprintf(stderr, "inflatehd: header emission: %s: %s\n", ent->nv.name,
                 ent->nv.value));
  /* ent->ref may be 0. This happens if the encoder emits literal
     block larger than header table capacity with indexing. */
  *nv_out = ent->nv;
  *token_out = ent->token;
  return 0;
}

static int emit_literal_header(nghttp2_nv *nv_out, int *token_out,
                               nghttp2_nv *nv) {
  DEBUGF(fprintf(stderr, "inflatehd: header emission: %s: %s\n", nv->name,
                 nv->value));
  *nv_out = *nv;
  *token_out = lookup_token(nv->name, nv->namelen);
  return 0;
}

static size_t count_encoded_length(size_t n, size_t prefix) {
  size_t k = (size_t)((1 << prefix) - 1);
  size_t len = 0;

  if (n < k) {
    return 1;
  }

  n -= k;
  ++len;

  for (; n >= 128; n >>= 7, ++len)
    ;

  return len + 1;
}

static size_t encode_length(uint8_t *buf, size_t n, size_t prefix) {
  size_t k = (size_t)((1 << prefix) - 1);
  uint8_t *begin = buf;

  *buf = (uint8_t)(*buf & ~k);

  if (n < k) {
    *buf = (uint8_t)(*buf | n);
    return 1;
  }

  *buf = (uint8_t)(*buf | k);
  ++buf;

  n -= k;

  for (; n >= 128; n >>= 7) {
    *buf++ = (uint8_t)((1 << 7) | (n & 0x7f));
  }

  *buf++ = (uint8_t)n;

  return (size_t)(buf - begin);
}

/*
 * Decodes |prefix| prefixed integer stored from |in|.  The |last|
 * represents the 1 beyond the last of the valid contiguous memory
 * region from |in|.  The decoded integer must be less than or equal
 * to UINT32_MAX.
 *
 * If the |initial| is nonzero, it is used as a initial value, this
 * function assumes the |in| starts with intermediate data.
 *
 * An entire integer is decoded successfully, decoded, the |*final| is
 * set to nonzero.
 *
 * This function stores the decoded integer in |*res| if it succeed,
 * including partial decoding (in this case, number of shift to make
 * in the next call will be stored in |*shift_ptr|) and returns number
 * of bytes processed, or returns -1, indicating decoding error.
 */
static ssize_t decode_length(uint32_t *res, size_t *shift_ptr, int *final,
                             uint32_t initial, size_t shift, uint8_t *in,
                             uint8_t *last, size_t prefix) {
  uint32_t k = (uint8_t)((1 << prefix) - 1);
  uint32_t n = initial;
  uint8_t *start = in;

  *shift_ptr = 0;
  *final = 0;

  if (n == 0) {
    if ((*in & k) != k) {
      *res = (*in) & k;
      *final = 1;
      return 1;
    }

    n = k;

    if (++in == last) {
      *res = n;
      return (ssize_t)(in - start);
    }
  }

  for (; in != last; ++in, shift += 7) {
    uint32_t add = *in & 0x7f;

    if ((UINT32_MAX >> shift) < add) {
      DEBUGF(fprintf(stderr, "inflate: integer overflow on shift\n"));
      return -1;
    }

    add <<= shift;

    if (UINT32_MAX - add < n) {
      DEBUGF(fprintf(stderr, "inflate: integer overflow on addition\n"));
      return -1;
    }

    n += add;

    if ((*in & (1 << 7)) == 0) {
      break;
    }
  }

  *shift_ptr = shift;

  if (in == last) {
    *res = n;
    return (ssize_t)(in - start);
  }

  *res = n;
  *final = 1;
  return (ssize_t)(in + 1 - start);
}

static int emit_table_size(nghttp2_bufs *bufs, size_t table_size) {
  int rv;
  uint8_t *bufp;
  size_t blocklen;
  uint8_t sb[16];

  DEBUGF(fprintf(stderr, "deflatehd: emit table_size=%zu\n", table_size));

  blocklen = count_encoded_length(table_size, 5);

  if (sizeof(sb) < blocklen) {
    return NGHTTP2_ERR_HEADER_COMP;
  }

  bufp = sb;

  *bufp = 0x20u;

  encode_length(bufp, table_size, 5);

  rv = nghttp2_bufs_add(bufs, sb, blocklen);
  if (rv != 0) {
    return rv;
  }

  return 0;
}

static int emit_indexed_block(nghttp2_bufs *bufs, size_t idx) {
  int rv;
  size_t blocklen;
  uint8_t sb[16];
  uint8_t *bufp;

  blocklen = count_encoded_length(idx + 1, 7);

  DEBUGF(fprintf(stderr, "deflatehd: emit indexed index=%zu, %zu bytes\n", idx,
                 blocklen));

  if (sizeof(sb) < blocklen) {
    return NGHTTP2_ERR_HEADER_COMP;
  }

  bufp = sb;
  *bufp = 0x80u;
  encode_length(bufp, idx + 1, 7);

  rv = nghttp2_bufs_add(bufs, sb, blocklen);
  if (rv != 0) {
    return rv;
  }

  return 0;
}

static int emit_string(nghttp2_bufs *bufs, const uint8_t *str, size_t len) {
  int rv;
  uint8_t sb[16];
  uint8_t *bufp;
  size_t blocklen;
  size_t enclen;
  int huffman = 0;

  enclen = nghttp2_hd_huff_encode_count(str, len);

  if (enclen < len) {
    huffman = 1;
  } else {
    enclen = len;
  }

  blocklen = count_encoded_length(enclen, 7);

  DEBUGF(fprintf(stderr, "deflatehd: emit string str="));
  DEBUGF(fwrite(str, len, 1, stderr));
  DEBUGF(fprintf(stderr, ", length=%zu, huffman=%d, encoded_length=%zu\n", len,
                 huffman, enclen));

  if (sizeof(sb) < blocklen) {
    return NGHTTP2_ERR_HEADER_COMP;
  }

  bufp = sb;
  *bufp = huffman ? 1 << 7 : 0;
  encode_length(bufp, enclen, 7);

  rv = nghttp2_bufs_add(bufs, sb, blocklen);
  if (rv != 0) {
    return rv;
  }

  if (huffman) {
    rv = nghttp2_hd_huff_encode(bufs, str, len);
  } else {
    assert(enclen == len);
    rv = nghttp2_bufs_add(bufs, str, len);
  }

  return rv;
}

static uint8_t pack_first_byte(int indexing_mode) {
  switch (indexing_mode) {
  case NGHTTP2_HD_WITH_INDEXING:
    return 0x40u;
  case NGHTTP2_HD_WITHOUT_INDEXING:
    return 0;
  case NGHTTP2_HD_NEVER_INDEXING:
    return 0x10u;
  default:
    assert(0);
  }
  /* This is required to compile with android NDK r10d +
     --enable-werror */
  return 0;
}

static int emit_indname_block(nghttp2_bufs *bufs, size_t idx,
                              const nghttp2_nv *nv, int indexing_mode) {
  int rv;
  uint8_t *bufp;
  size_t blocklen;
  uint8_t sb[16];
  size_t prefixlen;

  if (indexing_mode == NGHTTP2_HD_WITH_INDEXING) {
    prefixlen = 6;
  } else {
    prefixlen = 4;
  }

  DEBUGF(fprintf(stderr, "deflatehd: emit indname index=%zu, valuelen=%zu, "
                         "indexing_mode=%d\n",
                 idx, nv->valuelen, indexing_mode));

  blocklen = count_encoded_length(idx + 1, prefixlen);

  if (sizeof(sb) < blocklen) {
    return NGHTTP2_ERR_HEADER_COMP;
  }

  bufp = sb;

  *bufp = pack_first_byte(indexing_mode);

  encode_length(bufp, idx + 1, prefixlen);

  rv = nghttp2_bufs_add(bufs, sb, blocklen);
  if (rv != 0) {
    return rv;
  }

  rv = emit_string(bufs, nv->value, nv->valuelen);
  if (rv != 0) {
    return rv;
  }

  return 0;
}

static int emit_newname_block(nghttp2_bufs *bufs, const nghttp2_nv *nv,
                              int indexing_mode) {
  int rv;

  DEBUGF(fprintf(stderr, "deflatehd: emit newname namelen=%zu, valuelen=%zu, "
                         "indexing_mode=%d\n",
                 nv->namelen, nv->valuelen, indexing_mode));

  rv = nghttp2_bufs_addb(bufs, pack_first_byte(indexing_mode));
  if (rv != 0) {
    return rv;
  }

  rv = emit_string(bufs, nv->name, nv->namelen);
  if (rv != 0) {
    return rv;
  }

  rv = emit_string(bufs, nv->value, nv->valuelen);
  if (rv != 0) {
    return rv;
  }

  return 0;
}

static nghttp2_hd_entry *
add_hd_table_incremental(nghttp2_hd_context *context, const nghttp2_nv *nv,
                         int token, uint8_t entry_flags, nghttp2_hd_map *map,
                         uint32_t hash) {
  int rv;
  nghttp2_hd_entry *new_ent;
  size_t room;
  nghttp2_mem *mem;

  mem = context->mem;
  room = entry_room(nv->namelen, nv->valuelen);

  while (context->hd_table_bufsize + room > context->hd_table_bufsize_max &&
         context->hd_table.len > 0) {

    size_t idx = context->hd_table.len - 1;
    nghttp2_hd_entry *ent = hd_ringbuf_get(&context->hd_table, idx);

    context->hd_table_bufsize -= entry_room(ent->nv.namelen, ent->nv.valuelen);

    DEBUGF(fprintf(stderr, "hpack: remove item from header table: %s: %s\n",
                   ent->nv.name, ent->nv.value));

    hd_ringbuf_pop_back(&context->hd_table);
    if (map) {
      hd_map_remove(map, ent);
    }
    if (--ent->ref == 0) {
      nghttp2_hd_entry_free(ent, mem);
      nghttp2_mem_free(mem, ent);
    }
  }

  new_ent = nghttp2_mem_malloc(mem, sizeof(nghttp2_hd_entry));
  if (new_ent == NULL) {
    return NULL;
  }

  rv = nghttp2_hd_entry_init(new_ent, entry_flags, nv->name, nv->namelen,
                             nv->value, nv->valuelen, token, mem);
  if (rv != 0) {
    nghttp2_mem_free(mem, new_ent);
    return NULL;
  }

  if (room > context->hd_table_bufsize_max) {
    /* The entry taking more than NGHTTP2_HD_MAX_BUFFER_SIZE is
       immediately evicted. */
    --new_ent->ref;
  } else {
    rv = hd_ringbuf_push_front(&context->hd_table, new_ent, mem);

    if (rv != 0) {
      --new_ent->ref;

      if ((entry_flags & NGHTTP2_HD_FLAG_NAME_ALLOC) &&
          (entry_flags & NGHTTP2_HD_FLAG_NAME_GIFT)) {
        /* nv->name are managed by caller. */
        new_ent->nv.name = NULL;
        new_ent->nv.namelen = 0;
      }
      if ((entry_flags & NGHTTP2_HD_FLAG_VALUE_ALLOC) &&
          (entry_flags & NGHTTP2_HD_FLAG_VALUE_GIFT)) {
        /* nv->value are managed by caller. */
        new_ent->nv.value = NULL;
        new_ent->nv.valuelen = 0;
      }

      nghttp2_hd_entry_free(new_ent, mem);
      nghttp2_mem_free(mem, new_ent);

      return NULL;
    }

    new_ent->seq = context->next_seq++;
    new_ent->hash = hash;

    DEBUGF(fprintf(stderr, "deflatehd: indexed at %zu\n",
                   context->hd_table.len + NGHTTP2_STATIC_TABLE_LENGTH));

    if (map) {
      hd_map_insert(map, new_ent);
    }

    context->hd_table_bufsize += room;
  }
  return new_ent;
}

typedef struct {
  ssize_t index;
  /* Nonzero if both name and value are matched. */
  uint8_t name_value_match;
} search_result;

static search_result search_static_table(const nghttp2_nv *nv, int token,
                                         int indexing_mode) {
  search_result res = {token, 0};
  int i;

  if (indexing_mode == NGHTTP2_HD_NEVER_INDEXING) {
    return res;
  }

  for (i = token;
       i <= NGHTTP2_TOKEN_WWW_AUTHENTICATE && static_table[i].token == token;
       ++i) {
    if (value_eq(&static_table[i].nv, nv)) {
      res.index = i;
      res.name_value_match = 1;
      return res;
    }
  }
  return res;
}

static search_result search_hd_table(nghttp2_hd_context *context,
                                     const nghttp2_nv *nv, int token,
                                     int indexing_mode, nghttp2_hd_map *map,
                                     uint32_t hash) {
  search_result res = {-1, 0};
  nghttp2_hd_entry *ent;
  int exact_match;

  if (token >= 0 && token <= NGHTTP2_TOKEN_WWW_AUTHENTICATE) {
    res = search_static_table(nv, token, indexing_mode);
    if (res.name_value_match) {
      return res;
    }
  }

  exact_match = 0;
  ent = hd_map_find(map, &exact_match, nv, token, hash);
  if (ent == NULL) {
    return res;
  }

  if (res.index != -1 && !exact_match) {
    return res;
  }

  res.index =
      (ssize_t)(context->next_seq - 1 - ent->seq + NGHTTP2_STATIC_TABLE_LENGTH);

  if (exact_match) {
    res.name_value_match = 1;
  }

  return res;
}

static void hd_context_shrink_table_size(nghttp2_hd_context *context,
                                         nghttp2_hd_map *map) {
  nghttp2_mem *mem;

  mem = context->mem;

  while (context->hd_table_bufsize > context->hd_table_bufsize_max &&
         context->hd_table.len > 0) {
    size_t idx = context->hd_table.len - 1;
    nghttp2_hd_entry *ent = hd_ringbuf_get(&context->hd_table, idx);
    context->hd_table_bufsize -= entry_room(ent->nv.namelen, ent->nv.valuelen);
    hd_ringbuf_pop_back(&context->hd_table);
    if (map) {
      hd_map_remove(map, ent);
    }
    if (--ent->ref == 0) {
      nghttp2_hd_entry_free(ent, mem);
      nghttp2_mem_free(mem, ent);
    }
  }
}

int nghttp2_hd_deflate_change_table_size(nghttp2_hd_deflater *deflater,
                                         size_t settings_hd_table_bufsize_max) {
  size_t next_bufsize = nghttp2_min(settings_hd_table_bufsize_max,
                                    deflater->deflate_hd_table_bufsize_max);

  deflater->ctx.hd_table_bufsize_max = next_bufsize;

  deflater->min_hd_table_bufsize_max =
      nghttp2_min(deflater->min_hd_table_bufsize_max, next_bufsize);

  deflater->notify_table_size_change = 1;

  hd_context_shrink_table_size(&deflater->ctx, &deflater->map);
  return 0;
}

int nghttp2_hd_inflate_change_table_size(nghttp2_hd_inflater *inflater,
                                         size_t settings_hd_table_bufsize_max) {
  switch (inflater->state) {
  case NGHTTP2_HD_STATE_EXPECT_TABLE_SIZE:
  case NGHTTP2_HD_STATE_INFLATE_START:
    break;
  default:
    return NGHTTP2_ERR_INVALID_STATE;
  }

  inflater->state = NGHTTP2_HD_STATE_EXPECT_TABLE_SIZE;
  inflater->settings_hd_table_bufsize_max = settings_hd_table_bufsize_max;
  inflater->ctx.hd_table_bufsize_max = settings_hd_table_bufsize_max;
  hd_context_shrink_table_size(&inflater->ctx, NULL);
  return 0;
}

#define INDEX_RANGE_VALID(context, idx)                                        \
  ((idx) < (context)->hd_table.len + NGHTTP2_STATIC_TABLE_LENGTH)

static size_t get_max_index(nghttp2_hd_context *context) {
  return context->hd_table.len + NGHTTP2_STATIC_TABLE_LENGTH - 1;
}

nghttp2_hd_entry *nghttp2_hd_table_get(nghttp2_hd_context *context,
                                       size_t idx) {
  assert(INDEX_RANGE_VALID(context, idx));
  if (idx >= NGHTTP2_STATIC_TABLE_LENGTH) {
    return hd_ringbuf_get(&context->hd_table,
                          idx - NGHTTP2_STATIC_TABLE_LENGTH);
  } else {
    return &static_table[idx];
  }
}

static int hd_deflate_decide_indexing(nghttp2_hd_deflater *deflater,
                                      const nghttp2_nv *nv, int token) {
  if (token == NGHTTP2_TOKEN__PATH || token == NGHTTP2_TOKEN_AGE ||
      token == NGHTTP2_TOKEN_CONTENT_LENGTH || token == NGHTTP2_TOKEN_ETAG ||
      token == NGHTTP2_TOKEN_IF_MODIFIED_SINCE ||
      token == NGHTTP2_TOKEN_IF_NONE_MATCH || token == NGHTTP2_TOKEN_LOCATION ||
      token == NGHTTP2_TOKEN_SET_COOKIE ||
      entry_room(nv->namelen, nv->valuelen) >
          deflater->ctx.hd_table_bufsize_max * 3 / 4) {
    return NGHTTP2_HD_WITHOUT_INDEXING;
  }

  return NGHTTP2_HD_WITH_INDEXING;
}

static int deflate_nv(nghttp2_hd_deflater *deflater, nghttp2_bufs *bufs,
                      const nghttp2_nv *nv) {
  int rv;
  search_result res;
  ssize_t idx;
  int indexing_mode;
  int token;
  nghttp2_mem *mem;
  uint32_t hash;

  DEBUGF(fprintf(stderr, "deflatehd: deflating %s: %s\n", nv->name, nv->value));

  mem = deflater->ctx.mem;

  token = lookup_token(nv->name, nv->namelen);
  if (token == -1 || token > NGHTTP2_TOKEN_WWW_AUTHENTICATE) {
    hash = name_hash(nv);
  } else {
    hash = static_table[token].hash;
  }

  /* Don't index authorization header field since it may contain low
     entropy secret data (e.g., id/password).  Also cookie header
     field with less than 20 bytes value is also never indexed.  This
     is the same criteria used in Firefox codebase. */
  indexing_mode =
      token == NGHTTP2_TOKEN_AUTHORIZATION ||
              (token == NGHTTP2_TOKEN_COOKIE && nv->valuelen < 20) ||
              (nv->flags & NGHTTP2_NV_FLAG_NO_INDEX)
          ? NGHTTP2_HD_NEVER_INDEXING
          : hd_deflate_decide_indexing(deflater, nv, token);

  res = search_hd_table(&deflater->ctx, nv, token, indexing_mode,
                        &deflater->map, hash);

  idx = res.index;

  if (res.name_value_match) {

    DEBUGF(fprintf(stderr, "deflatehd: name/value match index=%zd\n", idx));

    rv = emit_indexed_block(bufs, (size_t)idx);
    if (rv != 0) {
      return rv;
    }

    return 0;
  }

  if (res.index != -1) {
    DEBUGF(fprintf(stderr, "deflatehd: name match index=%zd\n", res.index));
  }

  if (indexing_mode == NGHTTP2_HD_WITH_INDEXING) {
    nghttp2_hd_entry *new_ent;
    if (idx != -1 && idx < (ssize_t)NGHTTP2_STATIC_TABLE_LENGTH) {
      nghttp2_nv nv_indname;
      nv_indname = *nv;
      nv_indname.name =
          nghttp2_hd_table_get(&deflater->ctx, (size_t)idx)->nv.name;
      new_ent = add_hd_table_incremental(&deflater->ctx, &nv_indname, token,
                                         NGHTTP2_HD_FLAG_VALUE_ALLOC,
                                         &deflater->map, hash);
    } else {
      new_ent = add_hd_table_incremental(&deflater->ctx, nv, token,
                                         NGHTTP2_HD_FLAG_NAME_ALLOC |
                                             NGHTTP2_HD_FLAG_VALUE_ALLOC,
                                         &deflater->map, hash);
    }
    if (!new_ent) {
      return NGHTTP2_ERR_HEADER_COMP;
    }
    if (new_ent->ref == 0) {
      nghttp2_hd_entry_free(new_ent, mem);
      nghttp2_mem_free(mem, new_ent);
    }
  }
  if (idx == -1) {
    rv = emit_newname_block(bufs, nv, indexing_mode);
  } else {
    rv = emit_indname_block(bufs, (size_t)idx, nv, indexing_mode);
  }
  if (rv != 0) {
    return rv;
  }

  return 0;
}

int nghttp2_hd_deflate_hd_bufs(nghttp2_hd_deflater *deflater,
                               nghttp2_bufs *bufs, const nghttp2_nv *nv,
                               size_t nvlen) {
  size_t i;
  int rv = 0;

  if (deflater->ctx.bad) {
    return NGHTTP2_ERR_HEADER_COMP;
  }

  if (deflater->notify_table_size_change) {
    size_t min_hd_table_bufsize_max;

    min_hd_table_bufsize_max = deflater->min_hd_table_bufsize_max;

    deflater->notify_table_size_change = 0;
    deflater->min_hd_table_bufsize_max = UINT32_MAX;

    if (deflater->ctx.hd_table_bufsize_max > min_hd_table_bufsize_max) {

      rv = emit_table_size(bufs, min_hd_table_bufsize_max);

      if (rv != 0) {
        goto fail;
      }
    }

    rv = emit_table_size(bufs, deflater->ctx.hd_table_bufsize_max);

    if (rv != 0) {
      goto fail;
    }
  }

  for (i = 0; i < nvlen; ++i) {
    rv = deflate_nv(deflater, bufs, &nv[i]);
    if (rv != 0) {
      goto fail;
    }
  }

  DEBUGF(
      fprintf(stderr, "deflatehd: all input name/value pairs were deflated\n"));

  return 0;
fail:
  DEBUGF(fprintf(stderr, "deflatehd: error return %d\n", rv));

  deflater->ctx.bad = 1;
  return rv;
}

ssize_t nghttp2_hd_deflate_hd(nghttp2_hd_deflater *deflater, uint8_t *buf,
                              size_t buflen, const nghttp2_nv *nv,
                              size_t nvlen) {
  nghttp2_bufs bufs;
  int rv;
  nghttp2_mem *mem;

  mem = deflater->ctx.mem;

  rv = nghttp2_bufs_wrap_init(&bufs, buf, buflen, mem);

  if (rv != 0) {
    return rv;
  }

  rv = nghttp2_hd_deflate_hd_bufs(deflater, &bufs, nv, nvlen);

  buflen = nghttp2_bufs_len(&bufs);

  nghttp2_bufs_wrap_free(&bufs);

  if (rv == NGHTTP2_ERR_BUFFER_ERROR) {
    return NGHTTP2_ERR_INSUFF_BUFSIZE;
  }

  if (rv != 0) {
    return rv;
  }

  return (ssize_t)buflen;
}

size_t nghttp2_hd_deflate_bound(nghttp2_hd_deflater *deflater _U_,
                                const nghttp2_nv *nva, size_t nvlen) {
  size_t n = 0;
  size_t i;

  /* Possible Maximum Header Table Size Change.  Encoding (1u << 31) -
     1 using 4 bit prefix requires 6 bytes.  We may emit this at most
     twice. */
  n += 12;

  /* Use Literal Header Field without indexing - New Name, since it is
     most space consuming format.  Also we choose the less one between
     non-huffman and huffman, so using literal byte count is
     sufficient for upper bound.

     Encoding (1u << 31) - 1 using 7 bit prefix requires 6 bytes.  We
     need 2 of this for |nvlen| header fields. */
  n += 6 * 2 * nvlen;

  for (i = 0; i < nvlen; ++i) {
    n += nva[i].namelen + nva[i].valuelen;
  }

  return n;
}

int nghttp2_hd_deflate_new(nghttp2_hd_deflater **deflater_ptr,
                           size_t deflate_hd_table_bufsize_max) {
  return nghttp2_hd_deflate_new2(deflater_ptr, deflate_hd_table_bufsize_max,
                                 NULL);
}

int nghttp2_hd_deflate_new2(nghttp2_hd_deflater **deflater_ptr,
                            size_t deflate_hd_table_bufsize_max,
                            nghttp2_mem *mem) {
  int rv;
  nghttp2_hd_deflater *deflater;

  if (mem == NULL) {
    mem = nghttp2_mem_default();
  }

  deflater = nghttp2_mem_malloc(mem, sizeof(nghttp2_hd_deflater));

  if (deflater == NULL) {
    return NGHTTP2_ERR_NOMEM;
  }

  rv = nghttp2_hd_deflate_init2(deflater, deflate_hd_table_bufsize_max, mem);

  if (rv != 0) {
    nghttp2_mem_free(mem, deflater);

    return rv;
  }

  *deflater_ptr = deflater;

  return 0;
}

void nghttp2_hd_deflate_del(nghttp2_hd_deflater *deflater) {
  nghttp2_mem *mem;

  mem = deflater->ctx.mem;

  nghttp2_hd_deflate_free(deflater);

  nghttp2_mem_free(mem, deflater);
}

static void hd_inflate_set_huffman_encoded(nghttp2_hd_inflater *inflater,
                                           const uint8_t *in) {
  inflater->huffman_encoded = (*in & (1 << 7)) != 0;
}

/*
 * Decodes the integer from the range [in, last).  The result is
 * assigned to |inflater->left|.  If the |inflater->left| is 0, then
 * it performs variable integer decoding from scratch. Otherwise, it
 * uses the |inflater->left| as the initial value and continues to
 * decode assuming that [in, last) begins with intermediary sequence.
 *
 * This function returns the number of bytes read if it succeeds, or
 * one of the following negative error codes:
 *
 * NGHTTP2_ERR_HEADER_COMP
 *   Integer decoding failed
 */
static ssize_t hd_inflate_read_len(nghttp2_hd_inflater *inflater, int *rfin,
                                   uint8_t *in, uint8_t *last, size_t prefix,
                                   size_t maxlen) {
  ssize_t rv;
  uint32_t out;

  *rfin = 0;

  rv = decode_length(&out, &inflater->shift, rfin, (uint32_t)inflater->left,
                     inflater->shift, in, last, prefix);

  if (rv == -1) {
    DEBUGF(fprintf(stderr, "inflatehd: integer decoding failed\n"));
    return NGHTTP2_ERR_HEADER_COMP;
  }

  if (out > maxlen) {
    DEBUGF(fprintf(
        stderr, "inflatehd: integer exceeded the maximum value %zu\n", maxlen));
    return NGHTTP2_ERR_HEADER_COMP;
  }

  inflater->left = out;

  DEBUGF(fprintf(stderr, "inflatehd: decoded integer is %u\n", out));

  return rv;
}

/*
 * Reads |inflater->left| bytes from the range [in, last) and performs
 * huffman decoding against them and pushes the result into the
 * |buffer|.
 *
 * This function returns the number of bytes read if it succeeds, or
 * one of the following negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *   Out of memory
 * NGHTTP2_ERR_HEADER_COMP
 *   Huffman decoding failed
 * NGHTTP2_ERR_BUFFER_ERROR
 *     Out of buffer space.
 */
static ssize_t hd_inflate_read_huff(nghttp2_hd_inflater *inflater,
                                    nghttp2_bufs *bufs, uint8_t *in,
                                    uint8_t *last) {
  ssize_t readlen;
  int final = 0;
  if ((size_t)(last - in) >= inflater->left) {
    last = in + inflater->left;
    final = 1;
  }
  readlen = nghttp2_hd_huff_decode(&inflater->huff_decode_ctx, bufs, in,
                                   (size_t)(last - in), final);

  if (readlen < 0) {
    DEBUGF(fprintf(stderr, "inflatehd: huffman decoding failed\n"));
    return readlen;
  }
  inflater->left -= (size_t)readlen;
  return readlen;
}

/*
 * Reads |inflater->left| bytes from the range [in, last) and copies
 * them into the |buffer|.
 *
 * This function returns the number of bytes read if it succeeds, or
 * one of the following negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *   Out of memory
 * NGHTTP2_ERR_HEADER_COMP
 *   Header decompression failed
 * NGHTTP2_ERR_BUFFER_ERROR
 *     Out of buffer space.
 */
static ssize_t hd_inflate_read(nghttp2_hd_inflater *inflater,
                               nghttp2_bufs *bufs, uint8_t *in, uint8_t *last) {
  int rv;
  size_t len = nghttp2_min((size_t)(last - in), inflater->left);
  rv = nghttp2_bufs_add(bufs, in, len);
  if (rv != 0) {
    return rv;
  }
  inflater->left -= len;
  return (ssize_t)len;
}

/*
 * Finalize indexed header representation reception. If header is
 * emitted, |*nv_out| is filled with that value and 0 is returned. If
 * no header is emitted, 1 is returned.
 *
 * This function returns either 0 or 1 if it succeeds, or one of the
 * following negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *   Out of memory
 */
static int hd_inflate_commit_indexed(nghttp2_hd_inflater *inflater,
                                     nghttp2_nv *nv_out, int *token_out) {
  nghttp2_hd_entry *ent = nghttp2_hd_table_get(&inflater->ctx, inflater->index);

  emit_indexed_header(nv_out, token_out, ent);

  return 0;
}

static int hd_inflate_remove_bufs(nghttp2_hd_inflater *inflater, nghttp2_nv *nv,
                                  int value_only) {
  ssize_t rv;
  size_t buflen;
  uint8_t *buf;
  nghttp2_buf *pbuf;

  if (inflater->index_required ||
      inflater->nvbufs.head != inflater->nvbufs.cur) {

    rv = nghttp2_bufs_remove(&inflater->nvbufs, &buf);

    if (rv < 0) {
      return NGHTTP2_ERR_NOMEM;
    }

    nghttp2_bufs_reset(&inflater->nvbufs);

    buflen = (size_t)rv;

    if (value_only) {
      /* we don't use this value, so no need to NULL-terminate */
      nv->name = NULL;
      nv->namelen = 0;

      nv->value = buf;
      nv->valuelen = buflen - 1;
    } else {
      nv->name = buf;
      nv->namelen = inflater->newnamelen;

      nv->value = buf + nv->namelen + 1;
      nv->valuelen = buflen - nv->namelen - 2;
    }

    return 0;
  }

  /* If we are not going to store header in header table and
     name/value are in first chunk, we just refer them from nv,
     instead of mallocing another memory. */

  pbuf = &inflater->nvbufs.head->buf;

  if (value_only) {
    /* we don't use this value, so no need to NULL-terminate */
    nv->name = NULL;
    nv->namelen = 0;

    nv->value = pbuf->pos;
    nv->valuelen = nghttp2_buf_len(pbuf) - 1;
  } else {
    nv->name = pbuf->pos;
    nv->namelen = inflater->newnamelen;

    nv->value = pbuf->pos + nv->namelen + 1;
    nv->valuelen = nghttp2_buf_len(pbuf) - nv->namelen - 2;
  }

  /* Resetting does not change the content of first buffer */
  nghttp2_bufs_reset(&inflater->nvbufs);

  return 0;
}

static int hd_inflate_remove_bufs_with_name(nghttp2_hd_inflater *inflater,
                                            nghttp2_nv *nv,
                                            nghttp2_hd_entry *ent_name) {
#ifndef NDEBUG
  size_t rv;
#endif
  size_t buflen;
  uint8_t *buf;
  nghttp2_mem *mem;

  mem = inflater->ctx.mem;

  /* Allocate buffer including name in ent_name, plus terminating
     NULL. */
  buflen = ent_name->nv.namelen + 1 + nghttp2_bufs_len(&inflater->nvbufs);

  buf = nghttp2_mem_malloc(mem, buflen);
  if (buf == NULL) {
    return NGHTTP2_ERR_NOMEM;
  }

  /* Copy including terminal NULL */
  memcpy(buf, ent_name->nv.name, ent_name->nv.namelen + 1);
#ifndef NDEBUG
  rv =
#endif
      nghttp2_bufs_remove_copy(&inflater->nvbufs,
                               buf + ent_name->nv.namelen + 1);
  assert(ent_name->nv.namelen + 1 + rv == buflen);

  nghttp2_bufs_reset(&inflater->nvbufs);

  nv->name = buf;
  nv->namelen = ent_name->nv.namelen;

  nv->value = buf + nv->namelen + 1;
  nv->valuelen = buflen - nv->namelen - 2;

  return 0;
}

/*
 * Finalize literal header representation - new name- reception. If
 * header is emitted, |*nv_out| is filled with that value and 0 is
 * returned.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *   Out of memory
 */
static int hd_inflate_commit_newname(nghttp2_hd_inflater *inflater,
                                     nghttp2_nv *nv_out, int *token_out) {
  int rv;
  nghttp2_nv nv;
  nghttp2_mem *mem;

  mem = inflater->ctx.mem;

  rv = hd_inflate_remove_bufs(inflater, &nv, 0 /* name and value */);
  if (rv != 0) {
    return NGHTTP2_ERR_NOMEM;
  }

  if (inflater->no_index) {
    nv.flags = NGHTTP2_NV_FLAG_NO_INDEX;
  } else {
    nv.flags = NGHTTP2_NV_FLAG_NONE;
  }

  if (inflater->index_required) {
    nghttp2_hd_entry *new_ent;
    uint8_t ent_flags;

    /* nv->value points to the middle of the buffer pointed by
       nv->name.  So we just need to keep track of nv->name for memory
       management. */
    ent_flags = NGHTTP2_HD_FLAG_NAME_ALLOC | NGHTTP2_HD_FLAG_NAME_GIFT;

    new_ent = add_hd_table_incremental(&inflater->ctx, &nv,
                                       lookup_token(nv.name, nv.namelen),
                                       ent_flags, NULL, 0);

    if (new_ent) {
      emit_indexed_header(nv_out, token_out, new_ent);
      inflater->ent_keep = new_ent;

      return 0;
    }

    nghttp2_mem_free(mem, nv.name);

    return NGHTTP2_ERR_NOMEM;
  }

  emit_literal_header(nv_out, token_out, &nv);

  if (nv.name != inflater->nvbufs.head->buf.pos) {
    inflater->nv_keep = nv.name;
  }

  return 0;
}

/*
 * Finalize literal header representation - indexed name-
 * reception. If header is emitted, |*nv_out| is filled with that
 * value and 0 is returned.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * NGHTTP2_ERR_NOMEM
 *   Out of memory
 */
static int hd_inflate_commit_indname(nghttp2_hd_inflater *inflater,
                                     nghttp2_nv *nv_out, int *token_out) {
  int rv;
  nghttp2_nv nv;
  nghttp2_hd_entry *ent_name;
  nghttp2_mem *mem;

  mem = inflater->ctx.mem;

  if (inflater->no_index) {
    nv.flags = NGHTTP2_NV_FLAG_NO_INDEX;
  } else {
    nv.flags = NGHTTP2_NV_FLAG_NONE;
  }

  ent_name = nghttp2_hd_table_get(&inflater->ctx, inflater->index);

  if (inflater->index_required) {
    nghttp2_hd_entry *new_ent;
    uint8_t ent_flags;

    if (inflater->index < NGHTTP2_STATIC_TABLE_LENGTH) {
      /* We don't copy name in static table */
      rv = hd_inflate_remove_bufs(inflater, &nv, 1 /* value only */);
      if (rv != 0) {
        return NGHTTP2_ERR_NOMEM;
      }
      nv.name = ent_name->nv.name;
      nv.namelen = ent_name->nv.namelen;

      ent_flags = NGHTTP2_HD_FLAG_VALUE_ALLOC | NGHTTP2_HD_FLAG_VALUE_GIFT;
    } else {
      rv = hd_inflate_remove_bufs_with_name(inflater, &nv, ent_name);
      if (rv != 0) {
        return NGHTTP2_ERR_NOMEM;
      }
      /* nv->name and nv->value are in the same buffer. */
      ent_flags = NGHTTP2_HD_FLAG_NAME_ALLOC | NGHTTP2_HD_FLAG_NAME_GIFT;
    }

    new_ent = add_hd_table_incremental(&inflater->ctx, &nv, ent_name->token,
                                       ent_flags, NULL, 0);

    /* At this point, ent_name might be deleted. */

    if (new_ent) {
      emit_indexed_header(nv_out, token_out, new_ent);

      inflater->ent_keep = new_ent;

      return 0;
    }

    if (inflater->index < NGHTTP2_STATIC_TABLE_LENGTH) {
      nghttp2_mem_free(mem, nv.value);
    } else {
      nghttp2_mem_free(mem, nv.name);
    }

    return NGHTTP2_ERR_NOMEM;
  }

  rv = hd_inflate_remove_bufs(inflater, &nv, 1 /* value only */);
  if (rv != 0) {
    return NGHTTP2_ERR_NOMEM;
  }

  nv.name = ent_name->nv.name;
  nv.namelen = ent_name->nv.namelen;

  emit_literal_header(nv_out, token_out, &nv);

  if (nv.value != inflater->nvbufs.head->buf.pos) {
    inflater->nv_keep = nv.value;
  }

  return 0;
}

ssize_t nghttp2_hd_inflate_hd(nghttp2_hd_inflater *inflater, nghttp2_nv *nv_out,
                              int *inflate_flags, uint8_t *in, size_t inlen,
                              int in_final) {
  int token;

  return nghttp2_hd_inflate_hd2(inflater, nv_out, inflate_flags, &token, in,
                                inlen, in_final);
}

ssize_t nghttp2_hd_inflate_hd2(nghttp2_hd_inflater *inflater,
                               nghttp2_nv *nv_out, int *inflate_flags,
                               int *token_out, uint8_t *in, size_t inlen,
                               int in_final) {
  ssize_t rv = 0;
  uint8_t *first = in;
  uint8_t *last = in + inlen;
  int rfin = 0;
  int busy = 0;

  if (inflater->ctx.bad) {
    return NGHTTP2_ERR_HEADER_COMP;
  }

  DEBUGF(fprintf(stderr, "inflatehd: start state=%d\n", inflater->state));
  hd_inflate_keep_free(inflater);
  *token_out = -1;
  *inflate_flags = NGHTTP2_HD_INFLATE_NONE;
  for (; in != last || busy;) {
    busy = 0;
    switch (inflater->state) {
    case NGHTTP2_HD_STATE_EXPECT_TABLE_SIZE:
      if ((*in & 0xe0u) != 0x20u) {
        DEBUGF(fprintf(stderr, "inflatehd: header table size change was "
                               "expected, but saw 0x%02x as first byte",
                       *in));
        rv = NGHTTP2_ERR_HEADER_COMP;
        goto fail;
      }
    /* fall through */
    case NGHTTP2_HD_STATE_INFLATE_START:
    case NGHTTP2_HD_STATE_OPCODE:
      if ((*in & 0xe0u) == 0x20u) {
        DEBUGF(fprintf(stderr, "inflatehd: header table size change\n"));
        if (inflater->state == NGHTTP2_HD_STATE_OPCODE) {
          DEBUGF(fprintf(stderr, "inflatehd: header table size change must "
                                 "appear at the head of header block\n"));
          rv = NGHTTP2_ERR_HEADER_COMP;
          goto fail;
        }
        inflater->opcode = NGHTTP2_HD_OPCODE_INDEXED;
        inflater->state = NGHTTP2_HD_STATE_READ_TABLE_SIZE;
      } else if (*in & 0x80u) {
        DEBUGF(fprintf(stderr, "inflatehd: indexed repr\n"));
        inflater->opcode = NGHTTP2_HD_OPCODE_INDEXED;
        inflater->state = NGHTTP2_HD_STATE_READ_INDEX;
      } else {
        if (*in == 0x40u || *in == 0 || *in == 0x10u) {
          DEBUGF(
              fprintf(stderr, "inflatehd: literal header repr - new name\n"));
          inflater->opcode = NGHTTP2_HD_OPCODE_NEWNAME;
          inflater->state = NGHTTP2_HD_STATE_NEWNAME_CHECK_NAMELEN;
        } else {
          DEBUGF(fprintf(stderr,
                         "inflatehd: literal header repr - indexed name\n"));
          inflater->opcode = NGHTTP2_HD_OPCODE_INDNAME;
          inflater->state = NGHTTP2_HD_STATE_READ_INDEX;
        }
        inflater->index_required = (*in & 0x40) != 0;
        inflater->no_index = (*in & 0xf0u) == 0x10u;
        DEBUGF(fprintf(stderr, "inflatehd: indexing required=%d, no_index=%d\n",
                       inflater->index_required, inflater->no_index));
        if (inflater->opcode == NGHTTP2_HD_OPCODE_NEWNAME) {
          ++in;
        }
      }
      inflater->left = 0;
      inflater->shift = 0;
      break;
    case NGHTTP2_HD_STATE_READ_TABLE_SIZE:
      rfin = 0;
      rv = hd_inflate_read_len(inflater, &rfin, in, last, 5,
                               inflater->settings_hd_table_bufsize_max);
      if (rv < 0) {
        goto fail;
      }
      in += rv;
      if (!rfin) {
        goto almost_ok;
      }
      DEBUGF(fprintf(stderr, "inflatehd: table_size=%zu\n", inflater->left));
      inflater->ctx.hd_table_bufsize_max = inflater->left;
      hd_context_shrink_table_size(&inflater->ctx, NULL);
      inflater->state = NGHTTP2_HD_STATE_INFLATE_START;
      break;
    case NGHTTP2_HD_STATE_READ_INDEX: {
      size_t prefixlen;

      if (inflater->opcode == NGHTTP2_HD_OPCODE_INDEXED) {
        prefixlen = 7;
      } else if (inflater->index_required) {
        prefixlen = 6;
      } else {
        prefixlen = 4;
      }

      rfin = 0;
      rv = hd_inflate_read_len(inflater, &rfin, in, last, prefixlen,
                               get_max_index(&inflater->ctx) + 1);
      if (rv < 0) {
        goto fail;
      }

      in += rv;

      if (!rfin) {
        goto almost_ok;
      }

      if (inflater->left == 0) {
        rv = NGHTTP2_ERR_HEADER_COMP;
        goto fail;
      }

      DEBUGF(fprintf(stderr, "inflatehd: index=%zu\n", inflater->left));
      if (inflater->opcode == NGHTTP2_HD_OPCODE_INDEXED) {
        inflater->index = inflater->left;
        --inflater->index;

        rv = hd_inflate_commit_indexed(inflater, nv_out, token_out);
        if (rv < 0) {
          goto fail;
        }
        inflater->state = NGHTTP2_HD_STATE_OPCODE;
        /* If rv == 1, no header was emitted */
        if (rv == 0) {
          *inflate_flags |= NGHTTP2_HD_INFLATE_EMIT;
          return (ssize_t)(in - first);
        }
      } else {
        inflater->index = inflater->left;
        --inflater->index;

        inflater->state = NGHTTP2_HD_STATE_CHECK_VALUELEN;
      }
      break;
    }
    case NGHTTP2_HD_STATE_NEWNAME_CHECK_NAMELEN:
      hd_inflate_set_huffman_encoded(inflater, in);
      inflater->state = NGHTTP2_HD_STATE_NEWNAME_READ_NAMELEN;
      inflater->left = 0;
      inflater->shift = 0;
      DEBUGF(fprintf(stderr, "inflatehd: huffman encoded=%d\n",
                     inflater->huffman_encoded != 0));
    /* Fall through */
    case NGHTTP2_HD_STATE_NEWNAME_READ_NAMELEN:
      rfin = 0;
      rv = hd_inflate_read_len(inflater, &rfin, in, last, 7, NGHTTP2_HD_MAX_NV);
      if (rv < 0) {
        goto fail;
      }
      in += rv;
      if (!rfin) {
        DEBUGF(fprintf(stderr,
                       "inflatehd: integer not fully decoded. current=%zu\n",
                       inflater->left));

        goto almost_ok;
      }

      if (inflater->huffman_encoded) {
        nghttp2_hd_huff_decode_context_init(&inflater->huff_decode_ctx);

        inflater->state = NGHTTP2_HD_STATE_NEWNAME_READ_NAMEHUFF;
      } else {
        inflater->state = NGHTTP2_HD_STATE_NEWNAME_READ_NAME;
      }
      break;
    case NGHTTP2_HD_STATE_NEWNAME_READ_NAMEHUFF:
      rv = hd_inflate_read_huff(inflater, &inflater->nvbufs, in, last);
      if (rv < 0) {
        goto fail;
      }

      in += rv;

      DEBUGF(fprintf(stderr, "inflatehd: %zd bytes read\n", rv));

      if (inflater->left) {
        DEBUGF(fprintf(stderr, "inflatehd: still %zu bytes to go\n",
                       inflater->left));

        goto almost_ok;
      }

      inflater->newnamelen = nghttp2_bufs_len(&inflater->nvbufs);

      rv = nghttp2_bufs_addb(&inflater->nvbufs, '\0');
      if (rv != 0) {
        goto fail;
      }

      inflater->state = NGHTTP2_HD_STATE_CHECK_VALUELEN;

      break;
    case NGHTTP2_HD_STATE_NEWNAME_READ_NAME:
      rv = hd_inflate_read(inflater, &inflater->nvbufs, in, last);
      if (rv < 0) {
        goto fail;
      }

      in += rv;

      DEBUGF(fprintf(stderr, "inflatehd: %zd bytes read\n", rv));
      if (inflater->left) {
        DEBUGF(fprintf(stderr, "inflatehd: still %zu bytes to go\n",
                       inflater->left));

        goto almost_ok;
      }

      inflater->newnamelen = nghttp2_bufs_len(&inflater->nvbufs);

      rv = nghttp2_bufs_addb(&inflater->nvbufs, '\0');
      if (rv != 0) {
        goto fail;
      }

      inflater->state = NGHTTP2_HD_STATE_CHECK_VALUELEN;

      break;
    case NGHTTP2_HD_STATE_CHECK_VALUELEN:
      hd_inflate_set_huffman_encoded(inflater, in);
      inflater->state = NGHTTP2_HD_STATE_READ_VALUELEN;
      inflater->left = 0;
      inflater->shift = 0;
      DEBUGF(fprintf(stderr, "inflatehd: huffman encoded=%d\n",
                     inflater->huffman_encoded != 0));
    /* Fall through */
    case NGHTTP2_HD_STATE_READ_VALUELEN:
      rfin = 0;
      rv = hd_inflate_read_len(inflater, &rfin, in, last, 7, NGHTTP2_HD_MAX_NV);
      if (rv < 0) {
        goto fail;
      }

      in += rv;

      if (!rfin) {
        goto almost_ok;
      }

      DEBUGF(fprintf(stderr, "inflatehd: valuelen=%zu\n", inflater->left));

      if (inflater->huffman_encoded) {
        nghttp2_hd_huff_decode_context_init(&inflater->huff_decode_ctx);

        inflater->state = NGHTTP2_HD_STATE_READ_VALUEHUFF;
      } else {
        inflater->state = NGHTTP2_HD_STATE_READ_VALUE;
      }

      busy = 1;

      break;
    case NGHTTP2_HD_STATE_READ_VALUEHUFF:
      rv = hd_inflate_read_huff(inflater, &inflater->nvbufs, in, last);
      if (rv < 0) {
        goto fail;
      }

      in += rv;

      DEBUGF(fprintf(stderr, "inflatehd: %zd bytes read\n", rv));

      if (inflater->left) {
        DEBUGF(fprintf(stderr, "inflatehd: still %zu bytes to go\n",
                       inflater->left));

        goto almost_ok;
      }

      rv = nghttp2_bufs_addb(&inflater->nvbufs, '\0');
      if (rv != 0) {
        goto fail;
      }

      if (inflater->opcode == NGHTTP2_HD_OPCODE_NEWNAME) {
        rv = hd_inflate_commit_newname(inflater, nv_out, token_out);
      } else {
        rv = hd_inflate_commit_indname(inflater, nv_out, token_out);
      }

      if (rv != 0) {
        goto fail;
      }

      inflater->state = NGHTTP2_HD_STATE_OPCODE;
      *inflate_flags |= NGHTTP2_HD_INFLATE_EMIT;

      return (ssize_t)(in - first);
    case NGHTTP2_HD_STATE_READ_VALUE:
      rv = hd_inflate_read(inflater, &inflater->nvbufs, in, last);
      if (rv < 0) {
        DEBUGF(fprintf(stderr, "inflatehd: value read failure %zd: %s\n", rv,
                       nghttp2_strerror((int)rv)));
        goto fail;
      }

      in += rv;

      DEBUGF(fprintf(stderr, "inflatehd: %zd bytes read\n", rv));

      if (inflater->left) {
        DEBUGF(fprintf(stderr, "inflatehd: still %zu bytes to go\n",
                       inflater->left));
        goto almost_ok;
      }

      rv = nghttp2_bufs_addb(&inflater->nvbufs, '\0');
      if (rv != 0) {
        goto fail;
      }

      if (inflater->opcode == NGHTTP2_HD_OPCODE_NEWNAME) {
        rv = hd_inflate_commit_newname(inflater, nv_out, token_out);
      } else {
        rv = hd_inflate_commit_indname(inflater, nv_out, token_out);
      }

      if (rv != 0) {
        goto fail;
      }

      inflater->state = NGHTTP2_HD_STATE_OPCODE;
      *inflate_flags |= NGHTTP2_HD_INFLATE_EMIT;

      return (ssize_t)(in - first);
    }
  }

  assert(in == last);

  DEBUGF(fprintf(stderr, "inflatehd: all input bytes were processed\n"));

  if (in_final) {
    DEBUGF(fprintf(stderr, "inflatehd: in_final set\n"));

    if (inflater->state != NGHTTP2_HD_STATE_OPCODE) {
      DEBUGF(fprintf(stderr, "inflatehd: unacceptable state=%d\n",
                     inflater->state));
      rv = NGHTTP2_ERR_HEADER_COMP;

      goto fail;
    }
    *inflate_flags |= NGHTTP2_HD_INFLATE_FINAL;
  }
  return (ssize_t)(in - first);

almost_ok:
  if (in_final && inflater->state != NGHTTP2_HD_STATE_OPCODE) {
    DEBUGF(fprintf(stderr, "inflatehd: input ended prematurely\n"));

    rv = NGHTTP2_ERR_HEADER_COMP;

    goto fail;
  }
  return (ssize_t)(in - first);

fail:
  DEBUGF(fprintf(stderr, "inflatehd: error return %zd\n", rv));

  inflater->ctx.bad = 1;
  return rv;
}

int nghttp2_hd_inflate_end_headers(nghttp2_hd_inflater *inflater) {
  hd_inflate_keep_free(inflater);
  inflater->state = NGHTTP2_HD_STATE_INFLATE_START;
  return 0;
}

int nghttp2_hd_inflate_new(nghttp2_hd_inflater **inflater_ptr) {
  return nghttp2_hd_inflate_new2(inflater_ptr, NULL);
}

int nghttp2_hd_inflate_new2(nghttp2_hd_inflater **inflater_ptr,
                            nghttp2_mem *mem) {
  int rv;
  nghttp2_hd_inflater *inflater;

  if (mem == NULL) {
    mem = nghttp2_mem_default();
  }

  inflater = nghttp2_mem_malloc(mem, sizeof(nghttp2_hd_inflater));

  if (inflater == NULL) {
    return NGHTTP2_ERR_NOMEM;
  }

  rv = nghttp2_hd_inflate_init(inflater, mem);

  if (rv != 0) {
    nghttp2_mem_free(mem, inflater);

    return rv;
  }

  *inflater_ptr = inflater;

  return 0;
}

void nghttp2_hd_inflate_del(nghttp2_hd_inflater *inflater) {
  nghttp2_mem *mem;

  mem = inflater->ctx.mem;
  nghttp2_hd_inflate_free(inflater);

  nghttp2_mem_free(mem, inflater);
}

int nghttp2_hd_emit_indname_block(nghttp2_bufs *bufs, size_t idx,
                                  nghttp2_nv *nv, int indexing_mode) {

  return emit_indname_block(bufs, idx, nv, indexing_mode);
}

int nghttp2_hd_emit_newname_block(nghttp2_bufs *bufs, nghttp2_nv *nv,
                                  int indexing_mode) {
  return emit_newname_block(bufs, nv, indexing_mode);
}

int nghttp2_hd_emit_table_size(nghttp2_bufs *bufs, size_t table_size) {
  return emit_table_size(bufs, table_size);
}

ssize_t nghttp2_hd_decode_length(uint32_t *res, size_t *shift_ptr, int *final,
                                 uint32_t initial, size_t shift, uint8_t *in,
                                 uint8_t *last, size_t prefix) {
  return decode_length(res, shift_ptr, final, initial, shift, in, last, prefix);
}