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//  Copyright (c) 1995-2019 Mort Bay Consulting Pty. Ltd.
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package org.eclipse.jetty.http;

import java.util.Arrays;
import java.util.EnumSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;

import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;

import static java.util.Arrays.asList;
import static java.util.Collections.unmodifiableSet;
import static java.util.EnumSet.allOf;
import static java.util.EnumSet.complementOf;
import static java.util.EnumSet.noneOf;
import static java.util.EnumSet.of;

HTTP compliance modes for Jetty HTTP parsing and handling. A Compliance mode consists of a set of Violations which are applied when the mode is enabled. /**
 * HTTP compliance modes for Jetty HTTP parsing and handling.
 * A Compliance mode consists of a set of {@link Violation}s which are applied
 * when the mode is enabled.
 */
public final class HttpCompliance implements ComplianceViolation.Mode
{

    // These are compliance violations, which may optionally be allowed by the compliance mode, which mean that
    // the relevant section of the RFC is not strictly adhered to.
    public enum Violation implements ComplianceViolation
    {
        CASE_SENSITIVE_FIELD_NAME("https://tools.ietf.org/html/rfc7230#section-3.2", "Field name is case-insensitive"),
        CASE_INSENSITIVE_METHOD("https://tools.ietf.org/html/rfc7230#section-3.1.1", "Method is case-sensitive"),
        HTTP_0_9("https://tools.ietf.org/html/rfc7230#appendix-A.2", "HTTP/0.9 not supported"),
        MULTILINE_FIELD_VALUE("https://tools.ietf.org/html/rfc7230#section-3.2.4", "Line Folding not supported"),
        MULTIPLE_CONTENT_LENGTHS("https://tools.ietf.org/html/rfc7230#section-3.3.1", "Multiple Content-Lengths"),
        TRANSFER_ENCODING_WITH_CONTENT_LENGTH("https://tools.ietf.org/html/rfc7230#section-3.3.1", "Transfer-Encoding and Content-Length"),
        WHITESPACE_AFTER_FIELD_NAME("https://tools.ietf.org/html/rfc7230#section-3.2.4", "Whitespace not allowed after field name"),
        NO_COLON_AFTER_FIELD_NAME("https://tools.ietf.org/html/rfc7230#section-3.2", "Fields must have a Colon");

        private final String url;
        private final String description;

        Violation(String url, String description)
        {
            this.url = url;
            this.description = description;
        }

        @Override
        public String getName()
        {
            return name();
        }

        @Override
        public String getURL()
        {
            return url;
        }

        @Override
        public String getDescription()
        {
            return description;
        }
    }

    private static final Logger LOG = Log.getLogger(HttpParser.class);
    public static final String VIOLATIONS_ATTR = "org.eclipse.jetty.http.compliance.violations";

    public static final HttpCompliance RFC7230 = new HttpCompliance("RFC7230", noneOf(Violation.class));
    public static final HttpCompliance RFC2616 = new HttpCompliance("RFC2616", of(Violation.HTTP_0_9, Violation.MULTILINE_FIELD_VALUE));
    public static final HttpCompliance LEGACY = new HttpCompliance("LEGACY", complementOf(of(Violation.CASE_INSENSITIVE_METHOD)));
    public static final HttpCompliance RFC2616_LEGACY = RFC2616.with("RFC2616_LEGACY",
        Violation.CASE_INSENSITIVE_METHOD,
        Violation.NO_COLON_AFTER_FIELD_NAME,
        Violation.TRANSFER_ENCODING_WITH_CONTENT_LENGTH,
        Violation.MULTIPLE_CONTENT_LENGTHS);
    public static final HttpCompliance RFC7230_LEGACY = RFC7230.with("RFC7230_LEGACY", Violation.CASE_INSENSITIVE_METHOD);

    private static final List<HttpCompliance> KNOWN_MODES = Arrays.asList(RFC7230, RFC2616, LEGACY, RFC2616_LEGACY, RFC7230_LEGACY);
    private static final AtomicInteger __custom = new AtomicInteger();

    public static HttpCompliance valueOf(String name)
    {
        for (HttpCompliance compliance : KNOWN_MODES)
        {
            if (compliance.getName().equals(name))
                return compliance;
        }
        return null;
    }

    
Create compliance set from string.

Format:


0
No Violations
*
All Violations
RFC2616
The set of Violations application to https://tools.ietf.org/html/rfc2616, but not https://tools.ietf.org/html/rfc7230
RFC7230
The set of Violations application to https://tools.ietf.org/html/rfc7230
name
Any of the known modes defined in KNOWN_MODES

 The remainder of the list can contain then names of Violations to include them in the mode, or prefixed with a '-' to exclude thm from the mode. 
Params:
spec – A string in the format of a comma separated list starting with one of the following strings:
Returns:
the compliance from the string spec/**
     * Create compliance set from string.
     * <p>
     * Format:
     * </p>
     * <dl>
     * <dt>0</dt><dd>No {@link Violation}s</dd>
     * <dt>*</dt><dd>All {@link Violation}s</dd>
     * <dt>RFC2616</dt><dd>The set of {@link Violation}s application to https://tools.ietf.org/html/rfc2616,
     * but not https://tools.ietf.org/html/rfc7230</dd>
     * <dt>RFC7230</dt><dd>The set of {@link Violation}s application to https://tools.ietf.org/html/rfc7230</dd>
     * <dt>name</dt><dd>Any of the known modes defined in {@link HttpCompliance#KNOWN_MODES}</dd>
     * </dl>
     * <p>
     * The remainder of the list can contain then names of {@link Violation}s to include them in the mode, or prefixed
     * with a '-' to exclude thm from the mode.
     * </p>
     *
     * @param spec A string in the format of a comma separated list starting with one of the following strings:
     * @return the compliance from the string spec
     */
    public static HttpCompliance from(String spec)
    {
        Set<Violation> sections;
        String[] elements = spec.split("\\s*,\\s*");
        switch (elements[0])
        {
            case "0":
                sections = noneOf(Violation.class);
                break;

            case "*":
                sections = allOf(Violation.class);
                break;

            default:
            {
                HttpCompliance mode = HttpCompliance.valueOf(elements[0]);
                if (mode == null)
                    sections = noneOf(Violation.class);
                else
                    sections = copyOf(mode.getAllowed());
            }
        }

        for (int i = 1; i < elements.length; i++)
        {
            String element = elements[i];
            boolean exclude = element.startsWith("-");
            if (exclude)
                element = element.substring(1);
            Violation section = Violation.valueOf(element);
            if (section == null)
            {
                LOG.warn("Unknown section '" + element + "' in HttpCompliance spec: " + spec);
                continue;
            }
            if (exclude)
                sections.remove(section);
            else
                sections.add(section);
        }

        return new HttpCompliance("CUSTOM" + __custom.getAndIncrement(), sections);
    }

    private final String _name;
    private final Set<Violation> _violations;

    private HttpCompliance(String name, Set<Violation> violations)
    {
        Objects.nonNull(violations);
        _name = name;
        _violations = unmodifiableSet(violations.isEmpty() ? noneOf(Violation.class) : copyOf(violations));
    }

    @Override
    public boolean allows(ComplianceViolation violation)
    {
        return _violations.contains(violation);
    }

    @Override
    public String getName()
    {
        return _name;
    }

    
Get the set of Violations allowed by this compliance mode. 
Returns:
The immutable set of Violations allowed by this compliance mode./**
     * Get the set of {@link Violation}s allowed by this compliance mode.
     *
     * @return The immutable set of {@link Violation}s allowed by this compliance mode.
     */
    @Override
    public Set<Violation> getAllowed()
    {
        return _violations;
    }

    @Override
    public Set<Violation> getKnown()
    {
        return EnumSet.allOf(Violation.class);
    }

    
Create a new HttpCompliance mode that includes the passed Violations. 
Params:
name – The name of the new mode
violations – The violations to include
Returns:
A new HttpCompliance mode./**
     * Create a new HttpCompliance mode that includes the passed {@link Violation}s.
     *
     * @param name The name of the new mode
     * @param violations The violations to include
     * @return A new {@link HttpCompliance} mode.
     */
    public HttpCompliance with(String name, Violation... violations)
    {
        Set<Violation> union = _violations.isEmpty() ? EnumSet.noneOf(Violation.class) : copyOf(_violations);
        union.addAll(copyOf(violations));
        return new HttpCompliance(name, union);
    }

    
Create a new HttpCompliance mode that excludes the passed Violations. 
Params:
name – The name of the new mode
violations – The violations to exclude
Returns:
A new HttpCompliance mode./**
     * Create a new HttpCompliance mode that excludes the passed {@link Violation}s.
     *
     * @param name The name of the new mode
     * @param violations The violations to exclude
     * @return A new {@link HttpCompliance} mode.
     */
    public HttpCompliance without(String name, Violation... violations)
    {
        Set<Violation> remainder = _violations.isEmpty() ? EnumSet.noneOf(Violation.class) : copyOf(_violations);
        remainder.removeAll(copyOf(violations));
        return new HttpCompliance(name, remainder);
    }

    @Override
    public String toString()
    {
        return String.format("%s%s", _name, _violations);
    }

    private static Set<Violation> copyOf(Violation[] violations)
    {
        if (violations == null || violations.length == 0)
            return EnumSet.noneOf(Violation.class);
        return EnumSet.copyOf(asList(violations));
    }

    private static Set<Violation> copyOf(Set<Violation> violations)
    {
        if (violations == null || violations.isEmpty())
            return EnumSet.noneOf(Violation.class);
        return EnumSet.copyOf(violations);
    }
}