Import http parser code.

1 files changed, 2230 insertions, 0 deletions

diff --git a/contrib/http-parser/http_parser.c b/contrib/http-parser/http_parser.c
new file mode 100644
index 000000000..298eb28ea
--- /dev/null
+++ b/contrib/http-parser/http_parser.c
@@ -0,0 +1,2230 @@
+/* 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 "config.h"
+#include "http_parser.h"
+#include <assert.h>
+
+#ifndef ULLONG_MAX
+# define ULLONG_MAX ((uint64_t) -1) /* 2^64-1 */
+#endif
+
+#ifndef MIN
+# define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+#ifndef ARRAY_SIZE
+# define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
+#endif
+
+#ifndef BIT_AT
+# define BIT_AT(a, i)                                                \
+  (!!((unsigned int) (a)[(unsigned int) (i) >> 3] &                  \
+   (1 << ((unsigned int) (i) & 7))))
+#endif
+
+#ifndef ELEM_AT
+# define ELEM_AT(a, i, v) ((unsigned int) (i) < ARRAY_SIZE(a) ? (a)[(i)] : (v))
+#endif
+
+#define SET_ERRNO(e)                                                 \
+do {                                                                 \
+  parser->http_errno = (e);                                          \
+} while(0)
+
+
+/* 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[] =
+  {
+#define XX(num, name, string) #string,
+  HTTP_METHOD_MAP(XX)
+#undef XX
+  };
+
+
+/* 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
+  };
+
+
+#if HTTP_PARSER_STRICT
+# define T(v) 0
+#else
+# define T(v) v
+#endif
+
+
+static const uint8_t normal_url_char[32] = {
+/*   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    | T(2)   |   0    |   0    | T(16)  |   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    |   2    |   4    |   0    |   16   |   32   |   64   |  128,
+/*  40  (    41  )    42  *    43  +    44  ,    45  -    46  .    47  /  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  48  0    49  1    50  2    51  3    52  4    53  5    54  6    55  7  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  56  8    57  9    58  :    59  ;    60  <    61  =    62  >    63  ?  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |   0,
+/*  64  @    65  A    66  B    67  C    68  D    69  E    70  F    71  G  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  72  H    73  I    74  J    75  K    76  L    77  M    78  N    79  O  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  80  P    81  Q    82  R    83  S    84  T    85  U    86  V    87  W  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  88  X    89  Y    90  Z    91  [    92  \    93  ]    94  ^    95  _  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  96  `    97  a    98  b    99  c   100  d   101  e   102  f   103  g  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/* 104  h   105  i   106  j   107  k   108  l   109  m   110  n   111  o  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/* 112  p   113  q   114  r   115  s   116  t   117  u   118  v   119  w  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/* 120  x   121  y   122  z   123  {   124  |   125  }   126  ~   127 del */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |   0, };
+
+#undef T
+
+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_start
+  , 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_server_start
+  , s_req_server
+  , s_req_server_with_at
+  , 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
+  };
+
+enum http_host_state
+  {
+    s_http_host_dead = 1
+  , s_http_userinfo_start
+  , s_http_userinfo
+  , s_http_host_start
+  , s_http_host_v6_start
+  , s_http_host
+  , s_http_host_v6
+  , s_http_host_v6_end
+  , s_http_host_port_start
+  , s_http_host_port
+};
+
+/* 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'))
+#define IS_MARK(c)          ((c) == '-' || (c) == '_' || (c) == '.' || \
+  (c) == '!' || (c) == '~' || (c) == '*' || (c) == '\'' || (c) == '(' || \
+  (c) == ')')
+#define IS_USERINFO_CHAR(c) (IS_ALPHANUM(c) || IS_MARK(c) || (c) == '%' || \
+  (c) == ';' || (c) == ':' || (c) == '&' || (c) == '=' || (c) == '+' || \
+  (c) == '$' || (c) == ',')
+
+#if HTTP_PARSER_STRICT
+#define TOKEN(c)            (tokens[(unsigned char)c])
+#define IS_URL_CHAR(c)      (BIT_AT(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)                                                         \
+  (BIT_AT(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() (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 http_message_needs_eof(const 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)
+{
+  if (ch == ' ' || ch == '\r' || ch == '\n') {
+    return s_dead;
+  }
+
+#if HTTP_PARSER_STRICT
+  if (ch == '\t' || ch == '\f') {
+    return s_dead;
+  }
+#endif
+
+  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_server_start;
+      }
+
+      break;
+
+    case s_req_server_with_at:
+      if (ch == '@') {
+        return s_dead;
+      }
+
+    /* FALLTHROUGH */
+    case s_req_server_start:
+    case s_req_server:
+      if (ch == '/') {
+        return s_req_path;
+      }
+
+      if (ch == '?') {
+        return s_req_query_string_start;
+      }
+
+      if (ch == '@') {
+        return s_req_server_with_at;
+      }
+
+      if (IS_USERINFO_CHAR(ch) || ch == '[' || ch == ']') {
+        return s_req_server;
+      }
+
+      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 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;
+  const char *status_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_server_start:
+  case s_req_server:
+  case s_req_server_with_at:
+  case s_req_query_string_start:
+  case s_req_query_string:
+  case s_req_fragment_start:
+  case s_req_fragment:
+    url_mark = data;
+    break;
+  case s_res_status:
+    status_mark = data;
+    break;
+  }
+
+  for (p=data; p != data + len; p++) {
+    ch = *p;
+
+    if (PARSING_HEADER(parser->state)) {
+      ++parser->nread;
+      /* Don't allow the total size of the HTTP headers (including the status
+       * line) to exceed HTTP_MAX_HEADER_SIZE.  This check is here to protect
+       * embedders against denial-of-service attacks where the attacker feeds
+       * us a never-ending header that the embedder keeps buffering.
+       *
+       * This check is arguably the responsibility of embedders but we're doing
+       * it on the embedder's behalf because most won't bother and this way we
+       * make the web a little safer.  HTTP_MAX_HEADER_SIZE is still far bigger
+       * than any reasonable request or response so this should never affect
+       * day-to-day operation.
+       */
+      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 = 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 = 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_start;
+              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_start:
+      {
+        if (ch == CR) {
+          parser->state = s_res_line_almost_done;
+          break;
+        }
+
+        if (ch == LF) {
+          parser->state = s_header_field_start;
+          break;
+        }
+
+        MARK(status);
+        parser->state = s_res_status;
+        parser->index = 0;
+        break;
+      }
+
+      case s_res_status:
+        if (ch == CR) {
+          parser->state = s_res_line_almost_done;
+          CALLBACK_DATA(status);
+          break;
+        }
+
+        if (ch == LF) {
+          parser->state = s_header_field_start;
+          CALLBACK_DATA(status);
+          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 = 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; /* or SEARCH */ 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 {
+            SET_ERRNO(HPE_INVALID_METHOD);
+            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 {
+            SET_ERRNO(HPE_INVALID_METHOD);
+            goto error;
+          }
+        } else if (parser->method == HTTP_SUBSCRIBE) {
+          if (parser->index == 1 && ch == 'E') {
+            parser->method = HTTP_SEARCH;
+          } else {
+            SET_ERRNO(HPE_INVALID_METHOD);
+            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 {
+            SET_ERRNO(HPE_INVALID_METHOD);
+            goto error;
+          }
+        } else if (parser->index == 2) {
+          if (parser->method == HTTP_PUT) {
+            if (ch == 'R') {
+              parser->method = HTTP_PURGE;
+            } else {
+              SET_ERRNO(HPE_INVALID_METHOD);
+              goto error;
+            }
+          } else if (parser->method == HTTP_UNLOCK) {
+            if (ch == 'S') {
+              parser->method = HTTP_UNSUBSCRIBE;
+            } else {
+              SET_ERRNO(HPE_INVALID_METHOD);
+              goto error;
+            }
+          } else {
+            SET_ERRNO(HPE_INVALID_METHOD);
+            goto error;
+          }
+        } 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_server_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_server_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_server:
+      case s_req_server_with_at:
+      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 == 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 != ULLONG_MAX) {
+            /* Content-Length header given and non-zero */
+            parser->state = s_body_identity;
+          } else {
+            if (parser->type == HTTP_REQUEST ||
+                !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 != 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 == 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 != 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) +
+          (status_mark ? 1 : 0)) <= 1);
+
+  CALLBACK_DATA_NOADVANCE(header_field);
+  CALLBACK_DATA_NOADVANCE(header_value);
+  CALLBACK_DATA_NOADVANCE(url);
+  CALLBACK_DATA_NOADVANCE(body);
+  CALLBACK_DATA_NOADVANCE(status);
+
+  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
+http_message_needs_eof (const 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 != ULLONG_MAX) {
+    return 0;
+  }
+
+  return 1;
+}
+
+
+int
+http_should_keep_alive (const 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 !http_message_needs_eof(parser);
+}
+
+
+const char *
+http_method_str (enum http_method m)
+{
+  return ELEM_AT(method_strings, m, "<unknown>");
+}
+
+
+void
+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 *
+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 *
+http_errno_description(enum http_errno err) {
+  assert(err < (sizeof(http_strerror_tab)/sizeof(http_strerror_tab[0])));
+  return http_strerror_tab[err].description;
+}
+
+static enum http_host_state
+http_parse_host_char(enum http_host_state s, const char ch) {
+  switch(s) {
+    case s_http_userinfo:
+    case s_http_userinfo_start:
+      if (ch == '@') {
+        return s_http_host_start;
+      }
+
+      if (IS_USERINFO_CHAR(ch)) {
+        return s_http_userinfo;
+      }
+      break;
+
+    case s_http_host_start:
+      if (ch == '[') {
+        return s_http_host_v6_start;
+      }
+
+      if (IS_HOST_CHAR(ch)) {
+        return s_http_host;
+      }
+
+      break;
+
+    case s_http_host:
+      if (IS_HOST_CHAR(ch)) {
+        return s_http_host;
+      }
+
+    /* FALLTHROUGH */
+    case s_http_host_v6_end:
+      if (ch == ':') {
+        return s_http_host_port_start;
+      }
+
+      break;
+
+    case s_http_host_v6:
+      if (ch == ']') {
+        return s_http_host_v6_end;
+      }
+
+    /* FALLTHROUGH */
+    case s_http_host_v6_start:
+      if (IS_HEX(ch) || ch == ':' || ch == '.') {
+        return s_http_host_v6;
+      }
+
+      break;
+
+    case s_http_host_port:
+    case s_http_host_port_start:
+      if (IS_NUM(ch)) {
+        return s_http_host_port;
+      }
+
+      break;
+
+    default:
+      break;
+  }
+  return s_http_host_dead;
+}
+
+static int
+http_parse_host(const char * buf, struct http_parser_url *u, int found_at) {
+  enum http_host_state s;
+
+  const char *p;
+  size_t buflen = u->field_data[UF_HOST].off + u->field_data[UF_HOST].len;
+
+  u->field_data[UF_HOST].len = 0;
+
+  s = found_at ? s_http_userinfo_start : s_http_host_start;
+
+  for (p = buf + u->field_data[UF_HOST].off; p < buf + buflen; p++) {
+    enum http_host_state new_s = http_parse_host_char(s, *p);
+
+    if (new_s == s_http_host_dead) {
+      return 1;
+    }
+
+    switch(new_s) {
+      case s_http_host:
+        if (s != s_http_host) {
+          u->field_data[UF_HOST].off = p - buf;
+        }
+        u->field_data[UF_HOST].len++;
+        break;
+
+      case s_http_host_v6:
+        if (s != s_http_host_v6) {
+          u->field_data[UF_HOST].off = p - buf;
+        }
+        u->field_data[UF_HOST].len++;
+        break;
+
+      case s_http_host_port:
+        if (s != s_http_host_port) {
+          u->field_data[UF_PORT].off = p - buf;
+          u->field_data[UF_PORT].len = 0;
+          u->field_set |= (1 << UF_PORT);
+        }
+        u->field_data[UF_PORT].len++;
+        break;
+
+      case s_http_userinfo:
+        if (s != s_http_userinfo) {
+          u->field_data[UF_USERINFO].off = p - buf ;
+          u->field_data[UF_USERINFO].len = 0;
+          u->field_set |= (1 << UF_USERINFO);
+        }
+        u->field_data[UF_USERINFO].len++;
+        break;
+
+      default:
+        break;
+    }
+    s = new_s;
+  }
+
+  /* Make sure we don't end somewhere unexpected */
+  switch (s) {
+    case s_http_host_start:
+    case s_http_host_v6_start:
+    case s_http_host_v6:
+    case s_http_host_port_start:
+    case s_http_userinfo:
+    case s_http_userinfo_start:
+      return 1;
+    default:
+      break;
+  }
+
+  return 0;
+}
+
+int
+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;
+  int found_at = 0;
+
+  u->port = u->field_set = 0;
+  s = is_connect ? s_req_server_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_server_start:
+      case s_req_query_string_start:
+      case s_req_fragment_start:
+        continue;
+
+      case s_req_schema:
+        uf = UF_SCHEMA;
+        break;
+
+      case s_req_server_with_at:
+        found_at = 1;
+
+      /* FALLTROUGH */
+      case s_req_server:
+        uf = UF_HOST;
+        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 = p - buf;
+    u->field_data[uf].len = 1;
+
+    u->field_set |= (1 << uf);
+    old_uf = uf;
+  }
+
+  /* host must be present if there is a schema */
+  /* parsing http:///toto will fail */
+  if ((u->field_set & ((1 << UF_SCHEMA) | (1 << UF_HOST))) != 0) {
+    if (http_parse_host(buf, u, found_at) != 0) {
+      return 1;
+    }
+  }
+
+  /* CONNECT requests can only contain "hostname:port" */
+  if (is_connect && u->field_set != ((1 << UF_HOST)|(1 << UF_PORT))) {
+    return 1;
+  }
+
+  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
+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");
+  }
+}
+
+int
+http_body_is_final(const struct http_parser *parser) {
+    return parser->state == s_message_done;
+}
+
+unsigned long
+http_parser_version(void) {
+  return HTTP_PARSER_VERSION_MAJOR * 0x10000 |
+         HTTP_PARSER_VERSION_MINOR * 0x00100 |
+         HTTP_PARSER_VERSION_PATCH * 0x00001;
+}