text: /* Based on src/http/ngx_http_parse.c from NGINX copyright Igor Sysoev
   *
   * Additional changes are licensed under the same terms as NGINX and
   * copyright Joyent, Inc. and other Node contributors. All rights reserved.
   *
   * 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 "http_parser.h"
  #include <assert.h>
  #include <stddef.h>
  #include <ctype.h>
  #include <stdlib.h>
  #include <string.h>
  #include <limits.h>
  
  #if defined(ULLONG_MAX) && __STDC_VERSION__ >= 199901L
  # define HTTP_PARSER_ULLONG_MAX ULLONG_MAX
  #else
  # define HTTP_PARSER_ULLONG_MAX ((uint64_t) -1) /* 2^64-1 */
  #endif
  
  #ifndef MIN
  # define MIN(a,b) ((a) < (b) ? (a) : (b))
  #endif
  
  
  #if HTTP_PARSER_DEBUG
  #define SET_ERRNO(e)                                                 \
  do {                                                                 \
    parser->http_errno = (e);                                          \
    parser->error_lineno = __LINE__;                                   \
  } while (0)
  #else
  #define SET_ERRNO(e)                                                 \
  do {                                                                 \
    parser->http_errno = (e);                                          \
  } while(0)
  #endif
  
  
  /* Run the notify callback FOR, returning ER if it fails */
  #define CALLBACK_NOTIFY_(FOR, ER)                                    \
  do {                                                                 \
    assert(HTTP_PARSER_ERRNO(parser) == HPE_OK);                       \
                                                                       \
    if (settings->on_##FOR) {                                          \
      if (0 != settings->on_##FOR(parser)) {                           \
        SET_ERRNO(HPE_CB_##FOR);                                       \
      }                                                                \
                                                                       \
      /* We either errored above or got paused; get out */             \
      if (HTTP_PARSER_ERRNO(parser) != HPE_OK) {                       \
        return (ER);                                                   \
      }                                                                \
    }                                                                  \
  } while (0)
  
  /* Run the notify callback FOR and consume the current byte */
  #define CALLBACK_NOTIFY(FOR)            CALLBACK_NOTIFY_(FOR, p - data + 1)
  
  /* Run the notify callback FOR and don't consume the current byte */
  #define CALLBACK_NOTIFY_NOADVANCE(FOR)  CALLBACK_NOTIFY_(FOR, p - data)
  
  /* Run data callback FOR with LEN bytes, returning ER if it fails */
  #define CALLBACK_DATA_(FOR, LEN, ER)                                 \
  do {                                                                 \
    assert(HTTP_PARSER_ERRNO(parser) == HPE_OK);                       \
                                                                       \
    if (FOR##_mark) {                                                  \
      if (settings->on_##FOR) {                                        \
        if (0 != settings->on_##FOR(parser, FOR##_mark, (LEN))) {      \
          SET_ERRNO(HPE_CB_##FOR);                                     \
        }                                                              \
                                                                       \
        /* We either errored above or got paused; get out */           \
        if (HTTP_PARSER_ERRNO(parser) != HPE_OK) {                     \
          return (ER);                                                 \
        }                                                              \
      }                                                                \
      FOR##_mark = NULL;                                               \
    }                                                                  \
  } while (0)
  
  /* Run the data callback FOR and consume the current byte */
  #define CALLBACK_DATA(FOR)                                           \
      CALLBACK_DATA_(FOR, p - FOR##_mark, p - data + 1)
  
  /* Run the data callback FOR and don't consume the current byte */
  #define CALLBACK_DATA_NOADVANCE(FOR)                                 \
      CALLBACK_DATA_(FOR, p - FOR##_mark, p - data)
  
  /* Set the mark FOR; non-destructive if mark is already set */
  #define MARK(FOR)                                                    \
  do {                                                                 \
    if (!FOR##_mark) {                                                 \
      FOR##_mark = p;                                                  \
    }                                                                  \
  } while (0)
  
  
  #define PROXY_CONNECTION "proxy-connection"
  #define CONNECTION "connection"
  #define CONTENT_LENGTH "content-length"
  #define TRANSFER_ENCODING "transfer-encoding"
  #define UPGRADE "upgrade"
  #define CHUNKED "chunked"
  #define KEEP_ALIVE "keep-alive"
  #define CLOSE "close"
  
  
  static const char *method_strings[] =
    { "DELETE"
    , "GET"
    , "HEAD"
    , "POST"
    , "PUT"
    , "CONNECT"
    , "OPTIONS"
    , "TRACE"
    , "COPY"
    , "LOCK"
    , "MKCOL"
    , "MOVE"
    , "PROPFIND"
    , "PROPPATCH"
    , "UNLOCK"
    , "REPORT"
    , "MKACTIVITY"
    , "CHECKOUT"
    , "MERGE"
    , "M-SEARCH"
    , "NOTIFY"
    , "SUBSCRIBE"
    , "UNSUBSCRIBE"
    , "PATCH"
    , "PURGE"
    };
  
  
  /* Tokens as defined by rfc 2616. Also lowercases them.
   *        token       = 1*<any CHAR except CTLs or separators>
   *     separators     = "(" | ")" | "<" | ">" | "@"
   *                    | "," | ";" | ":" | "\" | <">
   *                    | "/" | "[" | "]" | "?" | "="
   *                    | "{" | "}" | SP | HT
   */
  static const char tokens[256] = {
  /*   0 nul    1 soh    2 stx    3 etx    4 eot    5 enq    6 ack    7 bel  */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*   8 bs     9 ht    10 nl    11 vt    12 np    13 cr    14 so    15 si   */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*  16 dle   17 dc1   18 dc2   19 dc3   20 dc4   21 nak   22 syn   23 etb */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*  24 can   25 em    26 sub   27 esc   28 fs    29 gs    30 rs    31 us  */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*  32 sp    33  !    34  "    35  #    36  $    37  %    38  &    39  '  */
          0,      '!',      0,      '#',     '$',     '%',     '&',    '\'',
  /*  40  (    41  )    42  *    43  +    44  ,    45  -    46  .    47  /  */
          0,       0,      '*',     '+',      0,      '-',     '.',      0,
  /*  48  0    49  1    50  2    51  3    52  4    53  5    54  6    55  7  */
         '0',     '1',     '2',     '3',     '4',     '5',     '6',     '7',
  /*  56  8    57  9    58  :    59  ;    60  <    61  =    62  >    63  ?  */
         '8',     '9',      0,       0,       0,       0,       0,       0,
  /*  64  @    65  A    66  B    67  C    68  D    69  E    70  F    71  G  */
          0,      'a',     'b',     'c',     'd',     'e',     'f',     'g',
  /*  72  H    73  I    74  J    75  K    76  L    77  M    78  N    79  O  */
         'h',     'i',     'j',     'k',     'l',     'm',     'n',     'o',
  /*  80  P    81  Q    82  R    83  S    84  T    85  U    86  V    87  W  */
         'p',     'q',     'r',     's',     't',     'u',     'v',     'w',
  /*  88  X    89  Y    90  Z    91  [    92  \    93  ]    94  ^    95  _  */
         'x',     'y',     'z',      0,       0,       0,      '^',     '_',
  /*  96  `    97  a    98  b    99  c   100  d   101  e   102  f   103  g  */
         '`',     'a',     'b',     'c',     'd',     'e',     'f',     'g',
  /* 104  h   105  i   106  j   107  k   108  l   109  m   110  n   111  o  */
         'h',     'i',     'j',     'k',     'l',     'm',     'n',     'o',
  /* 112  p   113  q   114  r   115  s   116  t   117  u   118  v   119  w  */
         'p',     'q',     'r',     's',     't',     'u',     'v',     'w',
  /* 120  x   121  y   122  z   123  {   124  |   125  }   126  ~   127 del */
         'x',     'y',     'z',      0,      '|',      0,      '~',       0 };
  
  
  static const int8_t unhex[256] =
    {-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
    ,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
    ,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
    , 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1
    ,-1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1
    ,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
    ,-1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1
    ,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
    };
  
  
  static const uint8_t normal_url_char[256] = {
  /*   0 nul    1 soh    2 stx    3 etx    4 eot    5 enq    6 ack    7 bel  */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*   8 bs     9 ht    10 nl    11 vt    12 np    13 cr    14 so    15 si   */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*  16 dle   17 dc1   18 dc2   19 dc3   20 dc4   21 nak   22 syn   23 etb */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*  24 can   25 em    26 sub   27 esc   28 fs    29 gs    30 rs    31 us  */
          0,       0,       0,       0,       0,       0,       0,       0,
  /*  32 sp    33  !    34  "    35  #    36  $    37  %    38  &    39  '  */
          0,       1,       1,       0,       1,       1,       1,       1,
  /*  40  (    41  )    42  *    43  +    44  ,    45  -    46  .    47  /  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /*  48  0    49  1    50  2    51  3    52  4    53  5    54  6    55  7  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /*  56  8    57  9    58  :    59  ;    60  <    61  =    62  >    63  ?  */
          1,       1,       1,       1,       1,       1,       1,       0,
  /*  64  @    65  A    66  B    67  C    68  D    69  E    70  F    71  G  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /*  72  H    73  I    74  J    75  K    76  L    77  M    78  N    79  O  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /*  80  P    81  Q    82  R    83  S    84  T    85  U    86  V    87  W  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /*  88  X    89  Y    90  Z    91  [    92  \    93  ]    94  ^    95  _  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /*  96  `    97  a    98  b    99  c   100  d   101  e   102  f   103  g  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /* 104  h   105  i   106  j   107  k   108  l   109  m   110  n   111  o  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /* 112  p   113  q   114  r   115  s   116  t   117  u   118  v   119  w  */
          1,       1,       1,       1,       1,       1,       1,       1,
  /* 120  x   121  y   122  z   123  {   124  |   125  }   126  ~   127 del */
          1,       1,       1,       1,       1,       1,       1,       0, };
  
  
  enum state
    { s_dead = 1 /* important that this is > 0 */
  
    , s_start_req_or_res
    , s_res_or_resp_H
    , s_start_res
    , s_res_H
    , s_res_HT
    , s_res_HTT
    , s_res_HTTP
    , s_res_first_http_major
    , s_res_http_major
    , s_res_first_http_minor
    , s_res_http_minor
    , s_res_first_status_code
    , s_res_status_code
    , s_res_status
    , s_res_line_almost_done
  
    , s_start_req
  
    , s_req_method
    , s_req_spaces_before_url
    , s_req_schema
    , s_req_schema_slash
    , s_req_schema_slash_slash
    , s_req_host_start
    , s_req_host_v6_start
    , s_req_host_v6
    , s_req_host_v6_end
    , s_req_host
    , s_req_port_start
    , s_req_port
    , s_req_path
    , s_req_query_string_start
    , s_req_query_string
    , s_req_fragment_start
    , s_req_fragment
    , s_req_http_start
    , s_req_http_H
    , s_req_http_HT
    , s_req_http_HTT
    , s_req_http_HTTP
    , s_req_first_http_major
    , s_req_http_major
    , s_req_first_http_minor
    , s_req_http_minor
    , s_req_line_almost_done
  
    , s_header_field_start
    , s_header_field
    , s_header_value_start
    , s_header_value
    , s_header_value_lws
  
    , s_header_almost_done
  
    , s_chunk_size_start
    , s_chunk_size
    , s_chunk_parameters
    , s_chunk_size_almost_done
  
    , s_headers_almost_done
    , s_headers_done
  
    /* Important: 's_headers_done' must be the last 'header' state. All
     * states beyond this must be 'body' states. It is used for overflow
     * checking. See the PARSING_HEADER() macro.
     */
  
    , s_chunk_data
    , s_chunk_data_almost_done
    , s_chunk_data_done
  
    , s_body_identity
    , s_body_identity_eof
  
    , s_message_done
    };
  
  
  #define PARSING_HEADER(state) (state <= s_headers_done)
  
  
  enum header_states
    { h_general = 0
    , h_C
    , h_CO
    , h_CON
  
    , h_matching_connection
    , h_matching_proxy_connection
    , h_matching_content_length
    , h_matching_transfer_encoding
    , h_matching_upgrade
  
    , h_connection
    , h_content_length
    , h_transfer_encoding
    , h_upgrade
  
    , h_matching_transfer_encoding_chunked
    , h_matching_connection_keep_alive
    , h_matching_connection_close
  
    , h_transfer_encoding_chunked
    , h_connection_keep_alive
    , h_connection_close
    };
  
  
  /* Macros for character classes; depends on strict-mode  */
  #define CR                  '\r'
  #define LF                  '\n'
  #define LOWER(c)            (unsigned char)(c | 0x20)
  #define IS_ALPHA(c)         (LOWER(c) >= 'a' && LOWER(c) <= 'z')
  #define IS_NUM(c)           ((c) >= '0' && (c) <= '9')
  #define IS_ALPHANUM(c)      (IS_ALPHA(c) || IS_NUM(c))
  #define IS_HEX(c)           (IS_NUM(c) || (LOWER(c) >= 'a' && LOWER(c) <= 'f'))
  
  #if HTTP_PARSER_STRICT
  #define TOKEN(c)            (tokens[(unsigned char)c])
  #define IS_URL_CHAR(c)      (normal_url_char[(unsigned char) (c)])
  #define IS_HOST_CHAR(c)     (IS_ALPHANUM(c) || (c) == '.' || (c) == '-')
  #else
  #define TOKEN(c)            ((c == ' ') ? ' ' : tokens[(unsigned char)c])
  #define IS_URL_CHAR(c)                                                         \
    (normal_url_char[(unsigned char) (c)] || ((c) & 0x80))
  #define IS_HOST_CHAR(c)                                                        \
    (IS_ALPHANUM(c) || (c) == '.' || (c) == '-' || (c) == '_')
  #endif
  
  
  #define start_state (parser->type == HTTP_REQUEST ? s_start_req : s_start_res)
  
  
  #if HTTP_PARSER_STRICT
  # define STRICT_CHECK(cond)                                          \
  do {                                                                 \
    if (cond) {                                                        \
      SET_ERRNO(HPE_STRICT);                                           \
      goto error;                                                      \
    }                                                                  \
  } while (0)
  # define NEW_MESSAGE() (_lcb_http_should_keep_alive(parser) ? start_state : s_dead)
  #else
  # define STRICT_CHECK(cond)
  # define NEW_MESSAGE() start_state
  #endif
  
  
  /* Map errno values to strings for human-readable output */
  #define HTTP_STRERROR_GEN(n, s) { "HPE_" #n, s },
  static struct {
    const char *name;
    const char *description;
  } http_strerror_tab[] = {
    HTTP_ERRNO_MAP(HTTP_STRERROR_GEN)
  };
  #undef HTTP_STRERROR_GEN
  
  int _lcb_http_message_needs_eof(http_parser *parser);
  
  /* Our URL parser.
   *
   * This is designed to be shared by http_parser_execute() for URL validation,
   * hence it has a state transition + byte-for-byte interface. In addition, it
   * is meant to be embedded in http_parser_parse_url(), which does the dirty
   * work of turning state transitions URL components for its API.
   *
   * This function should only be invoked with non-space characters. It is
   * assumed that the caller cares about (and can detect) the transition between
   * URL and non-URL states by looking for these.
   */
  static enum state
  parse_url_char(enum state s, const char ch)
  {
    assert(!isspace(ch));
  
    switch (s) {
      case s_req_spaces_before_url:
        /* Proxied requests are followed by scheme of an absolute URI (alpha).
         * All methods except CONNECT are followed by '/' or '*'.
         */
  
        if (ch == '/' || ch == '*') {
          return s_req_path;
        }
  
        if (IS_ALPHA(ch)) {
          return s_req_schema;
        }
  
        break;
  
      case s_req_schema:
        if (IS_ALPHA(ch)) {
          return s;
        }
  
        if (ch == ':') {
          return s_req_schema_slash;
        }
  
        break;
  
      case s_req_schema_slash:
        if (ch == '/') {
          return s_req_schema_slash_slash;
        }
  
        break;
  
      case s_req_schema_slash_slash:
        if (ch == '/') {
          return s_req_host_start;
        }
  
        break;
  
      case s_req_host_start:
        if (ch == '[') {
          return s_req_host_v6_start;
        }
  
        if (IS_HOST_CHAR(ch)) {
          return s_req_host;
        }
  
        break;
  
      case s_req_host:
        if (IS_HOST_CHAR(ch)) {
          return s_req_host;
        }
  
        /* FALLTHROUGH */
      case s_req_host_v6_end:
        switch (ch) {
          case ':':
            return s_req_port_start;
  
          case '/':
            return s_req_path;
  
          case '?':
            return s_req_query_string_start;
        }
  
        break;
  
      case s_req_host_v6:
        if (ch == ']') {
          return s_req_host_v6_end;
        }
  
        /* FALLTHROUGH */
      case s_req_host_v6_start:
        if (IS_HEX(ch) || ch == ':') {
          return s_req_host_v6;
        }
        break;
  
      case s_req_port:
        switch (ch) {
          case '/':
            return s_req_path;
  
          case '?':
            return s_req_query_string_start;
        }
  
        /* FALLTHROUGH */
      case s_req_port_start:
        if (IS_NUM(ch)) {
          return s_req_port;
        }
  
        break;
  
      case s_req_path:
        if (IS_URL_CHAR(ch)) {
          return s;
        }
  
        switch (ch) {
          case '?':
            return s_req_query_string_start;
  
          case '#':
            return s_req_fragment_start;
        }
  
        break;
  
      case s_req_query_string_start:
      case s_req_query_string:
        if (IS_URL_CHAR(ch)) {
          return s_req_query_string;
        }
  
        switch (ch) {
          case '?':
            /* allow extra '?' in query string */
            return s_req_query_string;
  
          case '#':
            return s_req_fragment_start;
        }
  
        break;
  
      case s_req_fragment_start:
        if (IS_URL_CHAR(ch)) {
          return s_req_fragment;
        }
  
        switch (ch) {
          case '?':
            return s_req_fragment;
  
          case '#':
            return s;
        }
  
        break;
  
      case s_req_fragment:
        if (IS_URL_CHAR(ch)) {
          return s;
        }
  
        switch (ch) {
          case '?':
          case '#':
            return s;
        }
  
        break;
  
      default:
        break;
    }
  
    /* We should never fall out of the switch above unless there's an error */
    return s_dead;
  }
  
  size_t _lcb_http_parser_execute (http_parser *parser,
                              const http_parser_settings *settings,
                              const char *data,
                              size_t len)
  {
    char c, ch;
    int8_t unhex_val;
    const char *p = data;
    const char *header_field_mark = 0;
    const char *header_value_mark = 0;
    const char *url_mark = 0;
    const char *body_mark = 0;
  
    /* We're in an error state. Don't bother doing anything. */
    if (HTTP_PARSER_ERRNO(parser) != HPE_OK) {
      return 0;
    }
  
    if (len == 0) {
      switch (parser->state) {
        case s_body_identity_eof:
          /* Use of CALLBACK_NOTIFY() here would erroneously return 1 byte read if
           * we got paused.
           */
          CALLBACK_NOTIFY_NOADVANCE(message_complete);
          return 0;
  
        case s_dead:
        case s_start_req_or_res:
        case s_start_res:
        case s_start_req:
          return 0;
  
        default:
          SET_ERRNO(HPE_INVALID_EOF_STATE);
          return 1;
      }
    }
  
  
    if (parser->state == s_header_field)
      header_field_mark = data;
    if (parser->state == s_header_value)
      header_value_mark = data;
    switch (parser->state) {
    case s_req_path:
    case s_req_schema:
    case s_req_schema_slash:
    case s_req_schema_slash_slash:
    case s_req_host_start:
    case s_req_host_v6_start:
    case s_req_host_v6:
    case s_req_host_v6_end:
    case s_req_host:
    case s_req_port_start:
    case s_req_port:
    case s_req_query_string_start:
    case s_req_query_string:
    case s_req_fragment_start:
    case s_req_fragment:
      url_mark = data;
      break;
    }
  
    for (p=data; p != data + len; p++) {
      ch = *p;
  
      if (PARSING_HEADER(parser->state)) {
        ++parser->nread;
        /* Buffer overflow attack */
        if (parser->nread > HTTP_MAX_HEADER_SIZE) {
          SET_ERRNO(HPE_HEADER_OVERFLOW);
          goto error;
        }
      }
  
      reexecute_byte:
      switch (parser->state) {
  
        case s_dead:
          /* this state is used after a 'Connection: close' message
           * the parser will error out if it reads another message
           */
          if (ch == CR || ch == LF)
            break;
  
          SET_ERRNO(HPE_CLOSED_CONNECTION);
          goto error;
  
        case s_start_req_or_res:
        {
          if (ch == CR || ch == LF)
            break;
          parser->flags = 0;
          parser->content_length = HTTP_PARSER_ULLONG_MAX;
  
          if (ch == 'H') {
            parser->state = s_res_or_resp_H;
  
            CALLBACK_NOTIFY(message_begin);
          } else {
            parser->type = HTTP_REQUEST;
            parser->state = s_start_req;
            goto reexecute_byte;
          }
  
          break;
        }
  
        case s_res_or_resp_H:
          if (ch == 'T') {
            parser->type = HTTP_RESPONSE;
            parser->state = s_res_HT;
          } else {
            if (ch != 'E') {
              SET_ERRNO(HPE_INVALID_CONSTANT);
              goto error;
            }
  
            parser->type = HTTP_REQUEST;
            parser->method = HTTP_HEAD;
            parser->index = 2;
            parser->state = s_req_method;
          }
          break;
  
        case s_start_res:
        {
          parser->flags = 0;
          parser->content_length = HTTP_PARSER_ULLONG_MAX;
  
          switch (ch) {
            case 'H':
              parser->state = s_res_H;
              break;
  
            case CR:
            case LF:
              break;
  
            default:
              SET_ERRNO(HPE_INVALID_CONSTANT);
              goto error;
          }
  
          CALLBACK_NOTIFY(message_begin);
          break;
        }
  
        case s_res_H:
          STRICT_CHECK(ch != 'T');
          parser->state = s_res_HT;
          break;
  
        case s_res_HT:
          STRICT_CHECK(ch != 'T');
          parser->state = s_res_HTT;
          break;
  
        case s_res_HTT:
          STRICT_CHECK(ch != 'P');
          parser->state = s_res_HTTP;
          break;
  
        case s_res_HTTP:
          STRICT_CHECK(ch != '/');
          parser->state = s_res_first_http_major;
          break;
  
        case s_res_first_http_major:
          if (ch < '0' || ch > '9') {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_major = ch - '0';
          parser->state = s_res_http_major;
          break;
  
        /* major HTTP version or dot */
        case s_res_http_major:
        {
          if (ch == '.') {
            parser->state = s_res_first_http_minor;
            break;
          }
  
          if (!IS_NUM(ch)) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_major *= 10;
          parser->http_major += ch - '0';
  
          if (parser->http_major > 999) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          break;
        }
  
        /* first digit of minor HTTP version */
        case s_res_first_http_minor:
          if (!IS_NUM(ch)) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_minor = ch - '0';
          parser->state = s_res_http_minor;
          break;
  
        /* minor HTTP version or end of request line */
        case s_res_http_minor:
        {
          if (ch == ' ') {
            parser->state = s_res_first_status_code;
            break;
          }
  
          if (!IS_NUM(ch)) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_minor *= 10;
          parser->http_minor += ch - '0';
  
          if (parser->http_minor > 999) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          break;
        }
  
        case s_res_first_status_code:
        {
          if (!IS_NUM(ch)) {
            if (ch == ' ') {
              break;
            }
  
            SET_ERRNO(HPE_INVALID_STATUS);
            goto error;
          }
          parser->status_code = ch - '0';
          parser->state = s_res_status_code;
          break;
        }
  
        case s_res_status_code:
        {
          if (!IS_NUM(ch)) {
            switch (ch) {
              case ' ':
                parser->state = s_res_status;
                break;
              case CR:
                parser->state = s_res_line_almost_done;
                break;
              case LF:
                parser->state = s_header_field_start;
                break;
              default:
                SET_ERRNO(HPE_INVALID_STATUS);
                goto error;
            }
            break;
          }
  
          parser->status_code *= 10;
          parser->status_code += ch - '0';
  
          if (parser->status_code > 999) {
            SET_ERRNO(HPE_INVALID_STATUS);
            goto error;
          }
  
          break;
        }
  
        case s_res_status:
          /* the human readable status. e.g. "NOT FOUND"
           * we are not humans so just ignore this */
          if (ch == CR) {
            parser->state = s_res_line_almost_done;
            break;
          }
  
          if (ch == LF) {
            parser->state = s_header_field_start;
            break;
          }
          break;
  
        case s_res_line_almost_done:
          STRICT_CHECK(ch != LF);
          parser->state = s_header_field_start;
          break;
  
        case s_start_req:
        {
          if (ch == CR || ch == LF)
            break;
          parser->flags = 0;
          parser->content_length = HTTP_PARSER_ULLONG_MAX;
  
          if (!IS_ALPHA(ch)) {
            SET_ERRNO(HPE_INVALID_METHOD);
            goto error;
          }
  
          parser->method = (enum http_method) 0;
          parser->index = 1;
          switch (ch) {
            case 'C': parser->method = HTTP_CONNECT; /* or COPY, CHECKOUT */ break;
            case 'D': parser->method = HTTP_DELETE; break;
            case 'G': parser->method = HTTP_GET; break;
            case 'H': parser->method = HTTP_HEAD; break;
            case 'L': parser->method = HTTP_LOCK; break;
            case 'M': parser->method = HTTP_MKCOL; /* or MOVE, MKACTIVITY, MERGE, M-SEARCH */ break;
            case 'N': parser->method = HTTP_NOTIFY; break;
            case 'O': parser->method = HTTP_OPTIONS; break;
            case 'P': parser->method = HTTP_POST;
              /* or PROPFIND|PROPPATCH|PUT|PATCH|PURGE */
              break;
            case 'R': parser->method = HTTP_REPORT; break;
            case 'S': parser->method = HTTP_SUBSCRIBE; break;
            case 'T': parser->method = HTTP_TRACE; break;
            case 'U': parser->method = HTTP_UNLOCK; /* or UNSUBSCRIBE */ break;
            default:
              SET_ERRNO(HPE_INVALID_METHOD);
              goto error;
          }
          parser->state = s_req_method;
  
          CALLBACK_NOTIFY(message_begin);
  
          break;
        }
  
        case s_req_method:
        {
          const char *matcher;
          if (ch == '\0') {
            SET_ERRNO(HPE_INVALID_METHOD);
            goto error;
          }
  
          matcher = method_strings[parser->method];
          if (ch == ' ' && matcher[parser->index] == '\0') {
            parser->state = s_req_spaces_before_url;
          } else if (ch == matcher[parser->index]) {
            ; /* nada */
          } else if (parser->method == HTTP_CONNECT) {
            if (parser->index == 1 && ch == 'H') {
              parser->method = HTTP_CHECKOUT;
            } else if (parser->index == 2  && ch == 'P') {
              parser->method = HTTP_COPY;
            } else {
              goto error;
            }
          } else if (parser->method == HTTP_MKCOL) {
            if (parser->index == 1 && ch == 'O') {
              parser->method = HTTP_MOVE;
            } else if (parser->index == 1 && ch == 'E') {
              parser->method = HTTP_MERGE;
            } else if (parser->index == 1 && ch == '-') {
              parser->method = HTTP_MSEARCH;
            } else if (parser->index == 2 && ch == 'A') {
              parser->method = HTTP_MKACTIVITY;
            } else {
              goto error;
            }
          } else if (parser->index == 1 && parser->method == HTTP_POST) {
            if (ch == 'R') {
              parser->method = HTTP_PROPFIND; /* or HTTP_PROPPATCH */
            } else if (ch == 'U') {
              parser->method = HTTP_PUT; /* or HTTP_PURGE */
            } else if (ch == 'A') {
              parser->method = HTTP_PATCH;
            } else {
              goto error;
            }
          } else if (parser->index == 2) {
            if (parser->method == HTTP_PUT) {
              if (ch == 'R') parser->method = HTTP_PURGE;
            } else if (parser->method == HTTP_UNLOCK) {
              if (ch == 'S') parser->method = HTTP_UNSUBSCRIBE;
            }
          } else if (parser->index == 4 && parser->method == HTTP_PROPFIND && ch == 'P') {
            parser->method = HTTP_PROPPATCH;
          } else {
            SET_ERRNO(HPE_INVALID_METHOD);
            goto error;
          }
  
          ++parser->index;
          break;
        }
  
        case s_req_spaces_before_url:
        {
          if (ch == ' ') break;
  
          MARK(url);
          if (parser->method == HTTP_CONNECT) {
            parser->state = s_req_host_start;
          }
  
          parser->state = parse_url_char((enum state)parser->state, ch);
          if (parser->state == s_dead) {
            SET_ERRNO(HPE_INVALID_URL);
            goto error;
          }
  
          break;
        }
  
        case s_req_schema:
        case s_req_schema_slash:
        case s_req_schema_slash_slash:
        case s_req_host_start:
        case s_req_host_v6_start:
        case s_req_host_v6:
        case s_req_port_start:
        {
          switch (ch) {
            /* No whitespace allowed here */
            case ' ':
            case CR:
            case LF:
              SET_ERRNO(HPE_INVALID_URL);
              goto error;
            default:
              parser->state = parse_url_char((enum state)parser->state, ch);
              if (parser->state == s_dead) {
                SET_ERRNO(HPE_INVALID_URL);
                goto error;
              }
          }
  
          break;
        }
  
        case s_req_host:
        case s_req_host_v6_end:
        case s_req_port:
        case s_req_path:
        case s_req_query_string_start:
        case s_req_query_string:
        case s_req_fragment_start:
        case s_req_fragment:
        {
          switch (ch) {
            case ' ':
              parser->state = s_req_http_start;
              CALLBACK_DATA(url);
              break;
            case CR:
            case LF:
              parser->http_major = 0;
              parser->http_minor = 9;
              parser->state = (ch == CR) ?
                s_req_line_almost_done :
                s_header_field_start;
              CALLBACK_DATA(url);
              break;
            default:
              parser->state = parse_url_char((enum state)parser->state, ch);
              if (parser->state == s_dead) {
                SET_ERRNO(HPE_INVALID_URL);
                goto error;
              }
          }
          break;
        }
  
        case s_req_http_start:
          switch (ch) {
            case 'H':
              parser->state = s_req_http_H;
              break;
            case ' ':
              break;
            default:
              SET_ERRNO(HPE_INVALID_CONSTANT);
              goto error;
          }
          break;
  
        case s_req_http_H:
          STRICT_CHECK(ch != 'T');
          parser->state = s_req_http_HT;
          break;
  
        case s_req_http_HT:
          STRICT_CHECK(ch != 'T');
          parser->state = s_req_http_HTT;
          break;
  
        case s_req_http_HTT:
          STRICT_CHECK(ch != 'P');
          parser->state = s_req_http_HTTP;
          break;
  
        case s_req_http_HTTP:
          STRICT_CHECK(ch != '/');
          parser->state = s_req_first_http_major;
          break;
  
        /* first digit of major HTTP version */
        case s_req_first_http_major:
          if (ch < '1' || ch > '9') {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_major = ch - '0';
          parser->state = s_req_http_major;
          break;
  
        /* major HTTP version or dot */
        case s_req_http_major:
        {
          if (ch == '.') {
            parser->state = s_req_first_http_minor;
            break;
          }
  
          if (!IS_NUM(ch)) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_major *= 10;
          parser->http_major += ch - '0';
  
          if (parser->http_major > 999) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          break;
        }
  
        /* first digit of minor HTTP version */
        case s_req_first_http_minor:
          if (!IS_NUM(ch)) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_minor = ch - '0';
          parser->state = s_req_http_minor;
          break;
  
        /* minor HTTP version or end of request line */
        case s_req_http_minor:
        {
          if (ch == CR) {
            parser->state = s_req_line_almost_done;
            break;
          }
  
          if (ch == LF) {
            parser->state = s_header_field_start;
            break;
          }
  
          /* XXX allow spaces after digit? */
  
          if (!IS_NUM(ch)) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          parser->http_minor *= 10;
          parser->http_minor += ch - '0';
  
          if (parser->http_minor > 999) {
            SET_ERRNO(HPE_INVALID_VERSION);
            goto error;
          }
  
          break;
        }
  
        /* end of request line */
        case s_req_line_almost_done:
        {
          if (ch != LF) {
            SET_ERRNO(HPE_LF_EXPECTED);
            goto error;
          }
  
          parser->state = s_header_field_start;
          break;
        }
  
        case s_header_field_start:
        {
          if (ch == CR) {
            parser->state = s_headers_almost_done;
            break;
          }
  
          if (ch == LF) {
            /* they might be just sending \n instead of \r\n so this would be
             * the second \n to denote the end of headers*/
            parser->state = s_headers_almost_done;
            goto reexecute_byte;
          }
  
          c = TOKEN(ch);
  
          if (!c) {
            SET_ERRNO(HPE_INVALID_HEADER_TOKEN);
            goto error;
          }
  
          MARK(header_field);
  
          parser->index = 0;
          parser->state = s_header_field;
  
          switch (c) {
            case 'c':
              parser->header_state = h_C;
              break;
  
            case 'p':
              parser->header_state = h_matching_proxy_connection;
              break;
  
            case 't':
              parser->header_state = h_matching_transfer_encoding;
              break;
  
            case 'u':
              parser->header_state = h_matching_upgrade;
              break;
  
            default:
              parser->header_state = h_general;
              break;
          }
          break;
        }
  
        case s_header_field:
        {
          c = TOKEN(ch);
  
          if (c) {
            switch (parser->header_state) {
              case h_general:
                break;
  
              case h_C:
                parser->index++;
                parser->header_state = (c == 'o' ? h_CO : h_general);
                break;
  
              case h_CO:
                parser->index++;
                parser->header_state = (c == 'n' ? h_CON : h_general);
                break;
  
              case h_CON:
                parser->index++;
                switch (c) {
                  case 'n':
                    parser->header_state = h_matching_connection;
                    break;
                  case 't':
                    parser->header_state = h_matching_content_length;
                    break;
                  default:
                    parser->header_state = h_general;
                    break;
                }
                break;
  
              /* connection */
  
              case h_matching_connection:
                parser->index++;
                if (parser->index > sizeof(CONNECTION)-1
                    || c != CONNECTION[parser->index]) {
                  parser->header_state = h_general;
                } else if (parser->index == sizeof(CONNECTION)-2) {
                  parser->header_state = h_connection;
                }
                break;
  
              /* proxy-connection */
  
              case h_matching_proxy_connection:
                parser->index++;
                if (parser->index > sizeof(PROXY_CONNECTION)-1
                    || c != PROXY_CONNECTION[parser->index]) {
                  parser->header_state = h_general;
                } else if (parser->index == sizeof(PROXY_CONNECTION)-2) {
                  parser->header_state = h_connection;
                }
                break;
  
              /* content-length */
  
              case h_matching_content_length:
                parser->index++;
                if (parser->index > sizeof(CONTENT_LENGTH)-1
                    || c != CONTENT_LENGTH[parser->index]) {
                  parser->header_state = h_general;
                } else if (parser->index == sizeof(CONTENT_LENGTH)-2) {
                  parser->header_state = h_content_length;
                }
                break;
  
              /* transfer-encoding */
  
              case h_matching_transfer_encoding:
                parser->index++;
                if (parser->index > sizeof(TRANSFER_ENCODING)-1
                    || c != TRANSFER_ENCODING[parser->index]) {
                  parser->header_state = h_general;
                } else if (parser->index == sizeof(TRANSFER_ENCODING)-2) {
                  parser->header_state = h_transfer_encoding;
                }
                break;
  
              /* upgrade */
  
              case h_matching_upgrade:
                parser->index++;
                if (parser->index > sizeof(UPGRADE)-1
                    || c != UPGRADE[parser->index]) {
                  parser->header_state = h_general;
                } else if (parser->index == sizeof(UPGRADE)-2) {
                  parser->header_state = h_upgrade;
                }
                break;
  
              case h_connection:
              case h_content_length:
              case h_transfer_encoding:
              case h_upgrade:
                if (ch != ' ') parser->header_state = h_general;
                break;
  
              default:
                assert(0 && "Unknown header_state");
                break;
            }
            break;
          }
  
          if (ch == ':') {
            parser->state = s_header_value_start;
            CALLBACK_DATA(header_field);
            break;
          }
  
          if (ch == CR) {
            parser->state = s_header_almost_done;
            CALLBACK_DATA(header_field);
            break;
          }
  
          if (ch == LF) {
            parser->state = s_header_field_start;
            CALLBACK_DATA(header_field);
            break;
          }
  
          SET_ERRNO(HPE_INVALID_HEADER_TOKEN);
          goto error;
        }
  
        case s_header_value_start:
        {
          if (ch == ' ' || ch == '\t') break;
  
          MARK(header_value);
  
          parser->state = s_header_value;
          parser->index = 0;
  
          if (ch == CR) {
            parser->header_state = h_general;
            parser->state = s_header_almost_done;
            CALLBACK_DATA(header_value);
            break;
          }
  
          if (ch == LF) {
            parser->state = s_header_field_start;
            CALLBACK_DATA(header_value);
            break;
          }
  
          c = LOWER(ch);
  
          switch (parser->header_state) {
            case h_upgrade:
              parser->flags |= F_UPGRADE;
              parser->header_state = h_general;
              break;
  
            case h_transfer_encoding:
              /* looking for 'Transfer-Encoding: chunked' */
              if ('c' == c) {
                parser->header_state = h_matching_transfer_encoding_chunked;
              } else {
                parser->header_state = h_general;
              }
              break;
  
            case h_content_length:
              if (!IS_NUM(ch)) {
                SET_ERRNO(HPE_INVALID_CONTENT_LENGTH);
                goto error;
              }
  
              parser->content_length = ch - '0';
              break;
  
            case h_connection:
              /* looking for 'Connection: keep-alive' */
              if (c == 'k') {
                parser->header_state = h_matching_connection_keep_alive;
              /* looking for 'Connection: close' */
              } else if (c == 'c') {
                parser->header_state = h_matching_connection_close;
              } else {
                parser->header_state = h_general;
              }
              break;
  
            default:
              parser->header_state = h_general;
              break;
          }
          break;
        }
  
        case s_header_value:
        {
  
          if (ch == CR) {
            parser->state = s_header_almost_done;
            CALLBACK_DATA(header_value);
            break;
          }
  
          if (ch == LF) {
            parser->state = s_header_almost_done;
            CALLBACK_DATA_NOADVANCE(header_value);
            goto reexecute_byte;
          }
  
          c = LOWER(ch);
  
          switch (parser->header_state) {
            case h_general:
              break;
  
            case h_connection:
            case h_transfer_encoding:
              assert(0 && "Shouldn't get here.");
              break;
  
            case h_content_length:
            {
              uint64_t t;
  
              if (ch == ' ') break;
  
              if (!IS_NUM(ch)) {
                SET_ERRNO(HPE_INVALID_CONTENT_LENGTH);
                goto error;
              }
  
              t = parser->content_length;
              t *= 10;
              t += ch - '0';
  
              /* Overflow? */
              if (t < parser->content_length || t == HTTP_PARSER_ULLONG_MAX) {
                SET_ERRNO(HPE_INVALID_CONTENT_LENGTH);
                goto error;
              }
  
              parser->content_length = t;
              break;
            }
  
            /* Transfer-Encoding: chunked */
            case h_matching_transfer_encoding_chunked:
              parser->index++;
              if (parser->index > sizeof(CHUNKED)-1
                  || c != CHUNKED[parser->index]) {
                parser->header_state = h_general;
              } else if (parser->index == sizeof(CHUNKED)-2) {
                parser->header_state = h_transfer_encoding_chunked;
              }
              break;
  
            /* looking for 'Connection: keep-alive' */
            case h_matching_connection_keep_alive:
              parser->index++;
              if (parser->index > sizeof(KEEP_ALIVE)-1
                  || c != KEEP_ALIVE[parser->index]) {
                parser->header_state = h_general;
              } else if (parser->index == sizeof(KEEP_ALIVE)-2) {
                parser->header_state = h_connection_keep_alive;
              }
              break;
  
            /* looking for 'Connection: close' */
            case h_matching_connection_close:
              parser->index++;
              if (parser->index > sizeof(CLOSE)-1 || c != CLOSE[parser->index]) {
                parser->header_state = h_general;
              } else if (parser->index == sizeof(CLOSE)-2) {
                parser->header_state = h_connection_close;
              }
              break;
  
            case h_transfer_encoding_chunked:
            case h_connection_keep_alive:
            case h_connection_close:
              if (ch != ' ') parser->header_state = h_general;
              break;
  
            default:
              parser->state = s_header_value;
              parser->header_state = h_general;
              break;
          }
          break;
        }
  
        case s_header_almost_done:
        {
          STRICT_CHECK(ch != LF);
  
          parser->state = s_header_value_lws;
  
          switch (parser->header_state) {
            case h_connection_keep_alive:
              parser->flags |= F_CONNECTION_KEEP_ALIVE;
              break;
            case h_connection_close:
              parser->flags |= F_CONNECTION_CLOSE;
              break;
            case h_transfer_encoding_chunked:
              parser->flags |= F_CHUNKED;
              break;
            default:
              break;
          }
  
          break;
        }
  
        case s_header_value_lws:
        {
          if (ch == ' ' || ch == '\t')
            parser->state = s_header_value_start;
          else
          {
            parser->state = s_header_field_start;
            goto reexecute_byte;
          }
          break;
        }
  
        case s_headers_almost_done:
        {
          STRICT_CHECK(ch != LF);
  
          if (parser->flags & F_TRAILING) {
            /* End of a chunked request */
            parser->state = NEW_MESSAGE();
            CALLBACK_NOTIFY(message_complete);
            break;
          }
  
          parser->state = s_headers_done;
  
          /* Set this here so that on_headers_complete() callbacks can see it */
          parser->upgrade =
            (parser->flags & F_UPGRADE || parser->method == HTTP_CONNECT);
  
          /* Here we call the headers_complete callback. This is somewhat
           * different than other callbacks because if the user returns 1, we
           * will interpret that as saying that this message has no body. This
           * is needed for the annoying case of recieving a response to a HEAD
           * request.
           *
           * We'd like to use CALLBACK_NOTIFY_NOADVANCE() here but we cannot, so
           * we have to simulate it by handling a change in errno below.
           */
          if (settings->on_headers_complete) {
            switch (settings->on_headers_complete(parser)) {
              case 0:
                break;
  
              case 1:
                parser->flags |= F_SKIPBODY;
                break;
  
              default:
                SET_ERRNO(HPE_CB_headers_complete);
                return p - data; /* Error */
            }
          }
  
          if (HTTP_PARSER_ERRNO(parser) != HPE_OK) {
            return p - data;
          }
  
          goto reexecute_byte;
        }
  
        case s_headers_done:
        {
          STRICT_CHECK(ch != LF);
  
          parser->nread = 0;
  
          /* Exit, the rest of the connect is in a different protocol. */
          if (parser->upgrade) {
            parser->state = NEW_MESSAGE();
            CALLBACK_NOTIFY(message_complete);
            return (p - data) + 1;
          }
  
          if (parser->flags & F_SKIPBODY) {
            parser->state = NEW_MESSAGE();
            CALLBACK_NOTIFY(message_complete);
          } else if (parser->flags & F_CHUNKED) {
            /* chunked encoding - ignore Content-Length header */
            parser->state = s_chunk_size_start;
          } else {
            if (parser->content_length == 0) {
              /* Content-Length header given but zero: Content-Length: 0\r\n */
              parser->state = NEW_MESSAGE();
              CALLBACK_NOTIFY(message_complete);
            } else if (parser->content_length != HTTP_PARSER_ULLONG_MAX) {
              /* Content-Length header given and non-zero */
              parser->state = s_body_identity;
            } else {
              if (parser->type == HTTP_REQUEST ||
                  !_lcb_http_message_needs_eof(parser)) {
                /* Assume content-length 0 - read the next */
                parser->state = NEW_MESSAGE();
                CALLBACK_NOTIFY(message_complete);
              } else {
                /* Read body until EOF */
                parser->state = s_body_identity_eof;
              }
            }
          }
  
          break;
        }
  
        case s_body_identity:
        {
          uint64_t to_read = MIN(parser->content_length,
                                 (uint64_t) ((data + len) - p));
  
          assert(parser->content_length != 0
              && parser->content_length != HTTP_PARSER_ULLONG_MAX);
  
          /* The difference between advancing content_length and p is because
           * the latter will automaticaly advance on the next loop iteration.
           * Further, if content_length ends up at 0, we want to see the last
           * byte again for our message complete callback.
           */
          MARK(body);
          parser->content_length -= to_read;
          p += to_read - 1;
  
          if (parser->content_length == 0) {
            parser->state = s_message_done;
  
            /* Mimic CALLBACK_DATA_NOADVANCE() but with one extra byte.
             *
             * The alternative to doing this is to wait for the next byte to
             * trigger the data callback, just as in every other case. The
             * problem with this is that this makes it difficult for the test
             * harness to distinguish between complete-on-EOF and
             * complete-on-length. It's not clear that this distinction is
             * important for applications, but let's keep it for now.
             */
            CALLBACK_DATA_(body, p - body_mark + 1, p - data);
            goto reexecute_byte;
          }
  
          break;
        }
  
        /* read until EOF */
        case s_body_identity_eof:
          MARK(body);
          p = data + len - 1;
  
          break;
  
        case s_message_done:
          parser->state = NEW_MESSAGE();
          CALLBACK_NOTIFY(message_complete);
          break;
  
        case s_chunk_size_start:
        {
          assert(parser->nread == 1);
          assert(parser->flags & F_CHUNKED);
  
          unhex_val = unhex[(unsigned char)ch];
          if (unhex_val == -1) {
            SET_ERRNO(HPE_INVALID_CHUNK_SIZE);
            goto error;
          }
  
          parser->content_length = unhex_val;
          parser->state = s_chunk_size;
          break;
        }
  
        case s_chunk_size:
        {
          uint64_t t;
  
          assert(parser->flags & F_CHUNKED);
  
          if (ch == CR) {
            parser->state = s_chunk_size_almost_done;
            break;
          }
  
          unhex_val = unhex[(unsigned char)ch];
  
          if (unhex_val == -1) {
            if (ch == ';' || ch == ' ') {
              parser->state = s_chunk_parameters;
              break;
            }
  
            SET_ERRNO(HPE_INVALID_CHUNK_SIZE);
            goto error;
          }
  
          t = parser->content_length;
          t *= 16;
          t += unhex_val;
  
          /* Overflow? */
          if (t < parser->content_length || t == HTTP_PARSER_ULLONG_MAX) {
            SET_ERRNO(HPE_INVALID_CONTENT_LENGTH);
            goto error;
          }
  
          parser->content_length = t;
          break;
        }
  
        case s_chunk_parameters:
        {
          assert(parser->flags & F_CHUNKED);
          /* just ignore this shit. TODO check for overflow */
          if (ch == CR) {
            parser->state = s_chunk_size_almost_done;
            break;
          }
          break;
        }
  
        case s_chunk_size_almost_done:
        {
          assert(parser->flags & F_CHUNKED);
          STRICT_CHECK(ch != LF);
  
          parser->nread = 0;
  
          if (parser->content_length == 0) {
            parser->flags |= F_TRAILING;
            parser->state = s_header_field_start;
          } else {
            parser->state = s_chunk_data;
          }
          break;
        }
  
        case s_chunk_data:
        {
          uint64_t to_read = MIN(parser->content_length,
                                 (uint64_t) ((data + len) - p));
  
          assert(parser->flags & F_CHUNKED);
          assert(parser->content_length != 0
              && parser->content_length != HTTP_PARSER_ULLONG_MAX);
  
          /* See the explanation in s_body_identity for why the content
           * length and data pointers are managed this way.
           */
          MARK(body);
          parser->content_length -= to_read;
          p += to_read - 1;
  
          if (parser->content_length == 0) {
            parser->state = s_chunk_data_almost_done;
          }
  
          break;
        }
  
        case s_chunk_data_almost_done:
          assert(parser->flags & F_CHUNKED);
          assert(parser->content_length == 0);
          STRICT_CHECK(ch != CR);
          parser->state = s_chunk_data_done;
          CALLBACK_DATA(body);
          break;
  
        case s_chunk_data_done:
          assert(parser->flags & F_CHUNKED);
          STRICT_CHECK(ch != LF);
          parser->nread = 0;
          parser->state = s_chunk_size_start;
          break;
  
        default:
          assert(0 && "unhandled state");
          SET_ERRNO(HPE_INVALID_INTERNAL_STATE);
          goto error;
      }
    }
  
    /* Run callbacks for any marks that we have leftover after we ran our of
     * bytes. There should be at most one of these set, so it's OK to invoke
     * them in series (unset marks will not result in callbacks).
     *
     * We use the NOADVANCE() variety of callbacks here because 'p' has already
     * overflowed 'data' and this allows us to correct for the off-by-one that
     * we'd otherwise have (since CALLBACK_DATA() is meant to be run with a 'p'
     * value that's in-bounds).
     */
  
    assert(((header_field_mark ? 1 : 0) +
            (header_value_mark ? 1 : 0) +
            (url_mark ? 1 : 0)  +
            (body_mark ? 1 : 0)) <= 1);
  
    CALLBACK_DATA_NOADVANCE(header_field);
    CALLBACK_DATA_NOADVANCE(header_value);
    CALLBACK_DATA_NOADVANCE(url);
    CALLBACK_DATA_NOADVANCE(body);
  
    return len;
  
  error:
    if (HTTP_PARSER_ERRNO(parser) == HPE_OK) {
      SET_ERRNO(HPE_UNKNOWN);
    }
  
    return (p - data);
  }
  
  
  /* Does the parser need to see an EOF to find the end of the message? */
  int
  _lcb_http_message_needs_eof (http_parser *parser)
  {
    if (parser->type == HTTP_REQUEST) {
      return 0;
    }
  
    /* See RFC 2616 section 4.4 */
    if (parser->status_code / 100 == 1 || /* 1xx e.g. Continue */
        parser->status_code == 204 ||     /* No Content */
        parser->status_code == 304 ||     /* Not Modified */
        parser->flags & F_SKIPBODY) {     /* response to a HEAD request */
      return 0;
    }
  
    if ((parser->flags & F_CHUNKED) || parser->content_length != HTTP_PARSER_ULLONG_MAX) {
      return 0;
    }
  
    return 1;
  }
  
  
  int
  _lcb_http_should_keep_alive (http_parser *parser)
  {
    if (parser->http_major > 0 && parser->http_minor > 0) {
      /* HTTP/1.1 */
      if (parser->flags & F_CONNECTION_CLOSE) {
        return 0;
      }
    } else {
      /* HTTP/1.0 or earlier */
      if (!(parser->flags & F_CONNECTION_KEEP_ALIVE)) {
        return 0;
      }
    }
  
    return !_lcb_http_message_needs_eof(parser);
  }
  
  
  const char * _lcb_http_method_str (enum http_method m)
  {
    return method_strings[m];
  }
  
  
  void
  _lcb_http_parser_init (http_parser *parser, enum http_parser_type t)
  {
    void *data = parser->data; /* preserve application data */
    memset(parser, 0, sizeof(*parser));
    parser->data = data;
    parser->type = t;
    parser->state = (t == HTTP_REQUEST ? s_start_req : (t == HTTP_RESPONSE ? s_start_res : s_start_req_or_res));
    parser->http_errno = HPE_OK;
  }
  
  const char *
  _lcb_http_errno_name(enum http_errno err) {
    assert(err < (sizeof(http_strerror_tab)/sizeof(http_strerror_tab[0])));
    return http_strerror_tab[err].name;
  }
  
  const char *
  _lcb_http_errno_description(enum http_errno err) {
    assert(err < (sizeof(http_strerror_tab)/sizeof(http_strerror_tab[0])));
    return http_strerror_tab[err].description;
  }
  
  int
  _lcb_http_parser_parse_url(const char *buf, size_t buflen, int is_connect,
                        struct http_parser_url *u)
  {
    enum state s;
    const char *p;
    enum http_parser_url_fields uf, old_uf;
  
    u->port = u->field_set = 0;
    s = is_connect ? s_req_host_start : s_req_spaces_before_url;
    uf = old_uf = UF_MAX;
  
    for (p = buf; p < buf + buflen; p++) {
      s = parse_url_char(s, *p);
  
      /* Figure out the next field that we're operating on */
      switch (s) {
        case s_dead:
          return 1;
  
        /* Skip delimeters */
        case s_req_schema_slash:
        case s_req_schema_slash_slash:
        case s_req_host_start:
        case s_req_host_v6_start:
        case s_req_host_v6_end:
        case s_req_port_start:
        case s_req_query_string_start:
        case s_req_fragment_start:
          continue;
  
        case s_req_schema:
          uf = UF_SCHEMA;
          break;
  
        case s_req_host:
        case s_req_host_v6:
          uf = UF_HOST;
          break;
  
        case s_req_port:
          uf = UF_PORT;
          break;
  
        case s_req_path:
          uf = UF_PATH;
          break;
  
        case s_req_query_string:
          uf = UF_QUERY;
          break;
  
        case s_req_fragment:
          uf = UF_FRAGMENT;
          break;
  
        default:
          assert(!"Unexpected state");
          return 1;
      }
  
      /* Nothing's changed; soldier on */
      if (uf == old_uf) {
        u->field_data[uf].len++;
        continue;
      }
  
      u->field_data[uf].off = (uint16_t)(p - buf);
      u->field_data[uf].len = 1;
  
      u->field_set |= (1 << uf);
      old_uf = uf;
    }
  
    /* CONNECT requests can only contain "hostname:port" */
    if (is_connect && u->field_set != ((1 << UF_HOST)|(1 << UF_PORT))) {
      return 1;
    }
  
    /* Make sure we don't end somewhere unexpected */
    switch (s) {
    case s_req_host_v6_start:
    case s_req_host_v6:
    case s_req_host_v6_end:
    case s_req_host:
    case s_req_port_start:
      return 1;
    default:
      break;
    }
  
    if (u->field_set & (1 << UF_PORT)) {
      /* Don't bother with endp; we've already validated the string */
      unsigned long v = strtoul(buf + u->field_data[UF_PORT].off, NULL, 10);
  
      /* Ports have a max value of 2^16 */
      if (v > 0xffff) {
        return 1;
      }
  
      u->port = (uint16_t) v;
    }
  
    return 0;
  }
  
  void
  _lcb_http_parser_pause(http_parser *parser, int paused) {
    /* Users should only be pausing/unpausing a parser that is not in an error
     * state. In non-debug builds, there's not much that we can do about this
     * other than ignore it.
     */
    if (HTTP_PARSER_ERRNO(parser) == HPE_OK ||
        HTTP_PARSER_ERRNO(parser) == HPE_PAUSED) {
      SET_ERRNO((paused) ? HPE_PAUSED : HPE_OK);
    } else {
      assert(0 && "Attempting to pause parser in error state");
    }
  }
  