size_t http_parser_execute()

in gpcontrib/gpcloud/lib/http_parser.cpp [630:2123]


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;
    enum state p_state = (enum state) parser->state;

    /* We're in an error state. Don't bother doing anything. */
    if (HTTP_PARSER_ERRNO(parser) != HPE_OK) {
        return 0;
    }

    if (len == 0) {
        switch (CURRENT_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 (CURRENT_STATE() == s_header_field)
        header_field_mark = data;
    if (CURRENT_STATE() == s_header_value)
        header_value_mark = data;
    switch (CURRENT_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;
    default:
        break;
    }

    for (p=data; p != data + len; p++) {
        ch = *p;

        if (PARSING_HEADER(CURRENT_STATE()))
            COUNT_HEADER_SIZE(1);

reexecute:
        switch (CURRENT_STATE()) {

        case s_dead:
            /* this state is used after a 'Connection: close' message
             * the parser will error out if it reads another message
             */
            if (LIKELY(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') {
                UPDATE_STATE(s_res_or_resp_H);

                CALLBACK_NOTIFY(message_begin);
            } else {
                parser->type = HTTP_REQUEST;
                UPDATE_STATE(s_start_req);
                REEXECUTE();
            }

            break;
        }

        case s_res_or_resp_H:
            if (ch == 'T') {
                parser->type = HTTP_RESPONSE;
                UPDATE_STATE(s_res_HT);
            } else {
                if (UNLIKELY(ch != 'E')) {
                    SET_ERRNO(HPE_INVALID_CONSTANT);
                    goto error;
                }

                parser->type = HTTP_REQUEST;
                parser->method = HTTP_HEAD;
                parser->index = 2;
                UPDATE_STATE(s_req_method);
            }
            break;

        case s_start_res:
        {
            parser->flags = 0;
            parser->content_length = ULLONG_MAX;

            switch (ch) {
            case 'H':
                UPDATE_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');
            UPDATE_STATE(s_res_HT);
            break;

        case s_res_HT:
            STRICT_CHECK(ch != 'T');
            UPDATE_STATE(s_res_HTT);
            break;

        case s_res_HTT:
            STRICT_CHECK(ch != 'P');
            UPDATE_STATE(s_res_HTTP);
            break;

        case s_res_HTTP:
            STRICT_CHECK(ch != '/');
            UPDATE_STATE(s_res_first_http_major);
            break;

        case s_res_first_http_major:
            if (UNLIKELY(ch < '0' || ch > '9')) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            parser->http_major = ch - '0';
            UPDATE_STATE(s_res_http_major);
            break;

            /* major HTTP version or dot */
        case s_res_http_major:
        {
            if (ch == '.') {
                UPDATE_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 (UNLIKELY(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 (UNLIKELY(!IS_NUM(ch))) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            parser->http_minor = ch - '0';
            UPDATE_STATE(s_res_http_minor);
            break;

            /* minor HTTP version or end of request line */
        case s_res_http_minor:
        {
            if (ch == ' ') {
                UPDATE_STATE(s_res_first_status_code);
                break;
            }

            if (UNLIKELY(!IS_NUM(ch))) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            parser->http_minor *= 10;
            parser->http_minor += ch - '0';

            if (UNLIKELY(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';
            UPDATE_STATE(s_res_status_code);
            break;
        }

        case s_res_status_code:
        {
            if (!IS_NUM(ch)) {
                switch (ch) {
                case ' ':
                    UPDATE_STATE(s_res_status_start);
                    break;
                case CR:
                    UPDATE_STATE(s_res_line_almost_done);
                    break;
                case LF:
                    UPDATE_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 (UNLIKELY(parser->status_code > 999)) {
                SET_ERRNO(HPE_INVALID_STATUS);
                goto error;
            }

            break;
        }

        case s_res_status_start:
        {
            if (ch == CR) {
                UPDATE_STATE(s_res_line_almost_done);
                break;
            }

            if (ch == LF) {
                UPDATE_STATE(s_header_field_start);
                break;
            }

            MARK(status);
            UPDATE_STATE(s_res_status);
            parser->index = 0;
            break;
        }

        case s_res_status:
            if (ch == CR) {
                UPDATE_STATE(s_res_line_almost_done);
                CALLBACK_DATA(status);
                break;
            }

            if (ch == LF) {
                UPDATE_STATE(s_header_field_start);
                CALLBACK_DATA(status);
                break;
            }

            break;

        case s_res_line_almost_done:
            STRICT_CHECK(ch != LF);
            UPDATE_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 (UNLIKELY(!IS_ALPHA(ch))) {
                SET_ERRNO(HPE_INVALID_METHOD);
                goto error;
            }

            parser->method = (enum http_method) 0;
            parser->index = 1;
            switch (ch) {
            case 'A':
                parser->method = HTTP_ACL;
                break;
            case 'B':
                parser->method = HTTP_BIND;
                break;
            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, MKCALENDAR */ 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; /* or REBIND */ 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, UNBIND */ break;
            default:
                SET_ERRNO(HPE_INVALID_METHOD);
                goto error;
            }
            UPDATE_STATE(s_req_method);

            CALLBACK_NOTIFY(message_begin);

            break;
        }

        case s_req_method:
        {
            const char *matcher;
            if (UNLIKELY(ch == '\0')) {
                SET_ERRNO(HPE_INVALID_METHOD);
                goto error;
            }

            matcher = method_strings[parser->method];
            if (ch == ' ' && matcher[parser->index] == '\0') {
                UPDATE_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 if (parser->index == 3 && ch == 'A') {
                    parser->method = HTTP_MKCALENDAR;
                } 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->method == HTTP_REPORT) {
                if (parser->index == 2 && ch == 'B') {
                    parser->method = HTTP_REBIND;
                } 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 if(ch == 'B') {
                        parser->method = HTTP_UNBIND;
                    } 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) {
                UPDATE_STATE(s_req_server_start);
            }

            UPDATE_STATE(parse_url_char(CURRENT_STATE(), ch));
            if (UNLIKELY(CURRENT_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:
                UPDATE_STATE(parse_url_char(CURRENT_STATE(), ch));
                if (UNLIKELY(CURRENT_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 ' ':
                UPDATE_STATE(s_req_http_start);
                CALLBACK_DATA(url);
                break;
            case CR:
            case LF:
                parser->http_major = 0;
                parser->http_minor = 9;
                UPDATE_STATE((ch == CR) ?
                             s_req_line_almost_done :
                             s_header_field_start);
                CALLBACK_DATA(url);
                break;
            default:
                UPDATE_STATE(parse_url_char(CURRENT_STATE(), ch));
                if (UNLIKELY(CURRENT_STATE() == s_dead)) {
                    SET_ERRNO(HPE_INVALID_URL);
                    goto error;
                }
            }
            break;
        }

        case s_req_http_start:
            switch (ch) {
            case 'H':
                UPDATE_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');
            UPDATE_STATE(s_req_http_HT);
            break;

        case s_req_http_HT:
            STRICT_CHECK(ch != 'T');
            UPDATE_STATE(s_req_http_HTT);
            break;

        case s_req_http_HTT:
            STRICT_CHECK(ch != 'P');
            UPDATE_STATE(s_req_http_HTTP);
            break;

        case s_req_http_HTTP:
            STRICT_CHECK(ch != '/');
            UPDATE_STATE(s_req_first_http_major);
            break;

            /* first digit of major HTTP version */
        case s_req_first_http_major:
            if (UNLIKELY(ch < '1' || ch > '9')) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            parser->http_major = ch - '0';
            UPDATE_STATE(s_req_http_major);
            break;

            /* major HTTP version or dot */
        case s_req_http_major:
        {
            if (ch == '.') {
                UPDATE_STATE(s_req_first_http_minor);
                break;
            }

            if (UNLIKELY(!IS_NUM(ch))) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            parser->http_major *= 10;
            parser->http_major += ch - '0';

            if (UNLIKELY(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 (UNLIKELY(!IS_NUM(ch))) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            parser->http_minor = ch - '0';
            UPDATE_STATE(s_req_http_minor);
            break;

            /* minor HTTP version or end of request line */
        case s_req_http_minor:
        {
            if (ch == CR) {
                UPDATE_STATE(s_req_line_almost_done);
                break;
            }

            if (ch == LF) {
                UPDATE_STATE(s_header_field_start);
                break;
            }

            /* XXX allow spaces after digit? */

            if (UNLIKELY(!IS_NUM(ch))) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            parser->http_minor *= 10;
            parser->http_minor += ch - '0';

            if (UNLIKELY(parser->http_minor > 999)) {
                SET_ERRNO(HPE_INVALID_VERSION);
                goto error;
            }

            break;
        }

        /* end of request line */
        case s_req_line_almost_done:
        {
            if (UNLIKELY(ch != LF)) {
                SET_ERRNO(HPE_LF_EXPECTED);
                goto error;
            }

            UPDATE_STATE(s_header_field_start);
            break;
        }

        case s_header_field_start:
        {
            if (ch == CR) {
                UPDATE_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*/
                UPDATE_STATE(s_headers_almost_done);
                REEXECUTE();
            }

            c = TOKEN(ch);

            if (UNLIKELY(!c)) {
                SET_ERRNO(HPE_INVALID_HEADER_TOKEN);
                goto error;
            }

            MARK(header_field);

            parser->index = 0;
            UPDATE_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:
        {
            const char* start = p;
            for (; p != data + len; p++) {
                ch = *p;
                c = TOKEN(ch);

                if (!c)
                    break;

                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;
                }
            }

            COUNT_HEADER_SIZE(p - start);

            if (p == data + len) {
                --p;
                break;
            }

            if (ch == ':') {
                UPDATE_STATE(s_header_value_discard_ws);
                CALLBACK_DATA(header_field);
                break;
            }

            SET_ERRNO(HPE_INVALID_HEADER_TOKEN);
            goto error;
        }

        case s_header_value_discard_ws:
            if (ch == ' ' || ch == '\t') break;

            if (ch == CR) {
                UPDATE_STATE(s_header_value_discard_ws_almost_done);
                break;
            }

            if (ch == LF) {
                UPDATE_STATE(s_header_value_discard_lws);
                break;
            }

            /* FALLTHROUGH */

        case s_header_value_start:
        {
            MARK(header_value);

            UPDATE_STATE(s_header_value);
            parser->index = 0;

            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 (UNLIKELY(!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 if (c == 'u') {
                    parser->header_state = h_matching_connection_upgrade;
                } else {
                    parser->header_state = h_matching_connection_token;
                }
                break;

                /* Multi-value `Connection` header */
            case h_matching_connection_token_start:
                break;

            default:
                parser->header_state = h_general;
                break;
            }
            break;
        }

        case s_header_value:
        {
            const char* start = p;
            enum header_states h_state = (enum header_states) parser->header_state;
            for (; p != data + len; p++) {
                ch = *p;
                if (ch == CR) {
                    UPDATE_STATE(s_header_almost_done);
                    parser->header_state = h_state;
                    CALLBACK_DATA(header_value);
                    break;
                }

                if (ch == LF) {
                    UPDATE_STATE(s_header_almost_done);
                    COUNT_HEADER_SIZE(p - start);
                    parser->header_state = h_state;
                    CALLBACK_DATA_NOADVANCE(header_value);
                    REEXECUTE();
                }

                c = LOWER(ch);

                switch (h_state) {
                case h_general:
                {
                    const char* p_cr;
                    const char* p_lf;
                    size_t limit = data + len - p;

                    limit = MIN(limit, HTTP_MAX_HEADER_SIZE);

                    p_cr = (const char*) memchr(p, CR, limit);
                    p_lf = (const char*) memchr(p, LF, limit);
                    if (p_cr != NULL) {
                        if (p_lf != NULL && p_cr >= p_lf)
                            p = p_lf;
                        else
                            p = p_cr;
                    } else if (UNLIKELY(p_lf != NULL)) {
                        p = p_lf;
                    } else {
                        p = data + len;
                    }
                    --p;

                    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 (UNLIKELY(!IS_NUM(ch))) {
                        SET_ERRNO(HPE_INVALID_CONTENT_LENGTH);
                        parser->header_state = h_state;
                        goto error;
                    }

                    t = parser->content_length;
                    t *= 10;
                    t += ch - '0';

                    /* Overflow? Test against a conservative limit for simplicity. */
                    if (UNLIKELY((ULLONG_MAX - 10) / 10 < parser->content_length)) {
                        SET_ERRNO(HPE_INVALID_CONTENT_LENGTH);
                        parser->header_state = h_state;
                        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]) {
                        h_state = h_general;
                    } else if (parser->index == sizeof(CHUNKED)-2) {
                        h_state = h_transfer_encoding_chunked;
                    }
                    break;

                case h_matching_connection_token_start:
                    /* looking for 'Connection: keep-alive' */
                    if (c == 'k') {
                        h_state = h_matching_connection_keep_alive;
                        /* looking for 'Connection: close' */
                    } else if (c == 'c') {
                        h_state = h_matching_connection_close;
                    } else if (c == 'u') {
                        h_state = h_matching_connection_upgrade;
                    } else if (STRICT_TOKEN(c)) {
                        h_state = h_matching_connection_token;
                    } else if (c == ' ' || c == '\t') {
                        /* Skip lws */
                    } else {
                        h_state = h_general;
                    }
                    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]) {
                        h_state = h_matching_connection_token;
                    } else if (parser->index == sizeof(KEEP_ALIVE)-2) {
                        h_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]) {
                        h_state = h_matching_connection_token;
                    } else if (parser->index == sizeof(CLOSE)-2) {
                        h_state = h_connection_close;
                    }
                    break;

                    /* looking for 'Connection: upgrade' */
                case h_matching_connection_upgrade:
                    parser->index++;
                    if (parser->index > sizeof(UPGRADE) - 1 ||
                            c != UPGRADE[parser->index]) {
                        h_state = h_matching_connection_token;
                    } else if (parser->index == sizeof(UPGRADE)-2) {
                        h_state = h_connection_upgrade;
                    }
                    break;

                case h_matching_connection_token:
                    if (ch == ',') {
                        h_state = h_matching_connection_token_start;
                        parser->index = 0;
                    }
                    break;

                case h_transfer_encoding_chunked:
                    if (ch != ' ') h_state = h_general;
                    break;

                case h_connection_keep_alive:
                case h_connection_close:
                case h_connection_upgrade:
                    if (ch == ',') {
                        if (h_state == h_connection_keep_alive) {
                            parser->flags |= F_CONNECTION_KEEP_ALIVE;
                        } else if (h_state == h_connection_close) {
                            parser->flags |= F_CONNECTION_CLOSE;
                        } else if (h_state == h_connection_upgrade) {
                            parser->flags |= F_CONNECTION_UPGRADE;
                        }
                        h_state = h_matching_connection_token_start;
                        parser->index = 0;
                    } else if (ch != ' ') {
                        h_state = h_matching_connection_token;
                    }
                    break;

                default:
                    UPDATE_STATE(s_header_value);
                    h_state = h_general;
                    break;
                }
            }
            parser->header_state = h_state;

            COUNT_HEADER_SIZE(p - start);

            if (p == data + len)
                --p;
            break;
        }

        case s_header_almost_done:
        {
            STRICT_CHECK(ch != LF);

            UPDATE_STATE(s_header_value_lws);
            break;
        }

        case s_header_value_lws:
        {
            if (ch == ' ' || ch == '\t') {
                UPDATE_STATE(s_header_value_start);
                REEXECUTE();
            }

            /* finished the header */
            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;
            case h_connection_upgrade:
                parser->flags |= F_CONNECTION_UPGRADE;
                break;
            default:
                break;
            }

            UPDATE_STATE(s_header_field_start);
            REEXECUTE();
        }

        case s_header_value_discard_ws_almost_done:
        {
            STRICT_CHECK(ch != LF);
            UPDATE_STATE(s_header_value_discard_lws);
            break;
        }

        case s_header_value_discard_lws:
        {
            if (ch == ' ' || ch == '\t') {
                UPDATE_STATE(s_header_value_discard_ws);
                break;
            } else {
                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_connection_upgrade:
                    parser->flags |= F_CONNECTION_UPGRADE;
                    break;
                case h_transfer_encoding_chunked:
                    parser->flags |= F_CHUNKED;
                    break;
                default:
                    break;
                }

                /* header value was empty */
                MARK(header_value);
                UPDATE_STATE(s_header_field_start);
                CALLBACK_DATA_NOADVANCE(header_value);
                REEXECUTE();
            }
        }

        case s_headers_almost_done:
        {
            STRICT_CHECK(ch != LF);

            if (parser->flags & F_TRAILING) {
                /* End of a chunked request */
                UPDATE_STATE(s_message_done);
                CALLBACK_NOTIFY_NOADVANCE(chunk_complete);
                REEXECUTE();
            }

            UPDATE_STATE(s_headers_done);

            /* Set this here so that on_headers_complete() callbacks can see it */
            parser->upgrade =
                ((parser->flags & (F_UPGRADE | F_CONNECTION_UPGRADE)) ==
                 (F_UPGRADE | F_CONNECTION_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);
            }

            REEXECUTE();
        }

        case s_headers_done:
        {
            int hasBody;
            STRICT_CHECK(ch != LF);

            parser->nread = 0;

            hasBody = parser->flags & F_CHUNKED ||
                      (parser->content_length > 0 && parser->content_length != ULLONG_MAX);
            if (parser->upgrade && (parser->method == HTTP_CONNECT ||
                                    (parser->flags & F_SKIPBODY) || !hasBody)) {
                /* Exit, the rest of the message is in a different protocol. */
                UPDATE_STATE(NEW_MESSAGE());
                CALLBACK_NOTIFY(message_complete);
                RETURN((p - data) + 1);
            }

            if (parser->flags & F_SKIPBODY) {
                UPDATE_STATE(NEW_MESSAGE());
                CALLBACK_NOTIFY(message_complete);
            } else if (parser->flags & F_CHUNKED) {
                /* chunked encoding - ignore Content-Length header */
                UPDATE_STATE(s_chunk_size_start);
            } else {
                if (parser->content_length == 0) {
                    /* Content-Length header given but zero: Content-Length: 0\r\n */
                    UPDATE_STATE(NEW_MESSAGE());
                    CALLBACK_NOTIFY(message_complete);
                } else if (parser->content_length != ULLONG_MAX) {
                    /* Content-Length header given and non-zero */
                    UPDATE_STATE(s_body_identity);
                } else {
                    if (!http_message_needs_eof(parser)) {
                        /* Assume content-length 0 - read the next */
                        UPDATE_STATE(NEW_MESSAGE());
                        CALLBACK_NOTIFY(message_complete);
                    } else {
                        /* Read body until EOF */
                        UPDATE_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) {
                UPDATE_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);
                REEXECUTE();
            }

            break;
        }

        /* read until EOF */
        case s_body_identity_eof:
            MARK(body);
            p = data + len - 1;

            break;

        case s_message_done:
            UPDATE_STATE(NEW_MESSAGE());
            CALLBACK_NOTIFY(message_complete);
            if (parser->upgrade) {
                /* Exit, the rest of the message is in a different protocol. */
                RETURN((p - data) + 1);
            }
            break;

        case s_chunk_size_start:
        {
            assert(parser->nread == 1);
            assert(parser->flags & F_CHUNKED);

            unhex_val = unhex[(unsigned char)ch];
            if (UNLIKELY(unhex_val == -1)) {
                SET_ERRNO(HPE_INVALID_CHUNK_SIZE);
                goto error;
            }

            parser->content_length = unhex_val;
            UPDATE_STATE(s_chunk_size);
            break;
        }

        case s_chunk_size:
        {
            uint64_t t;

            assert(parser->flags & F_CHUNKED);

            if (ch == CR) {
                UPDATE_STATE(s_chunk_size_almost_done);
                break;
            }

            unhex_val = unhex[(unsigned char)ch];

            if (unhex_val == -1) {
                if (ch == ';' || ch == ' ') {
                    UPDATE_STATE(s_chunk_parameters);
                    break;
                }

                SET_ERRNO(HPE_INVALID_CHUNK_SIZE);
                goto error;
            }

            t = parser->content_length;
            t *= 16;
            t += unhex_val;

            /* Overflow? Test against a conservative limit for simplicity. */
            if (UNLIKELY((ULLONG_MAX - 16) / 16 < parser->content_length)) {
                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) {
                UPDATE_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;
                UPDATE_STATE(s_header_field_start);
            } else {
                UPDATE_STATE(s_chunk_data);
            }
            CALLBACK_NOTIFY(chunk_header);
            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) {
                UPDATE_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);
            UPDATE_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;
            UPDATE_STATE(s_chunk_size_start);
            CALLBACK_NOTIFY(chunk_complete);
            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);
}