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Tomcat 8 CookieProcessor 实现变化

问题

Tomcat 从7升级到8的时候出现了 java.lang.IllegalArgumentException: An invalid domain [.xxx.com] was specified for this cookie 异常。

配置中有这么段配置：

<Context useHttpOnly="true" sessionCookiePath="/" sessionCookieDomain=".jobmd.cn" />

解决

在tomcat context.xml中配置 <CookieProcessor className="org.apache.tomcat.util.http.LegacyCookieProcessor" /> 即可，或者你也可以把域名前面的 . 去掉。

分析

Tomcat 8更换了默认的 CookieProcessor 实现为 Rfc6265CookieProcessor ，之前的实现为 LegacyCookieProcessor 。前者是基于 RFC6265 ，而后者基于 RFC6265 、 RFC2109 、 RFC2616 。

RFC6265 中关于domain有这么一段描述：

Domain=domain  Optional. The Domain attribute specifies the domain for which the  cookie is valid. An explicitly specified domain must always start  with a dot.

而在 RFC6265 中：

If the attribute-name case-insensitively matches the string “Domain”,  the user agent MUST process the cookie-av as follows.
If the attribute-value is empty, the behavior is undefined. However,  the user agent SHOULD ignore the cookie-av entirely.
If the first character of the attribute-value string is %x2E (“.”):
Let cookie-domain be the attribute-value without the leading %x2E  (“.”) character.
Otherwise:
Let cookie-domain be the entire attribute-value.
Convert the cookie-domain to lower case.

一个说要 . 一个说不要，那再来看看具体代码实现（generateHeader方法）。

LegacyCookieProcessor （省略了部分代码）

@Override
public String generateHeader(Cookie cookie) {
        ......
        String domain = cookie.getDomain();
        ......
        // Add domain information, if present
        if (domain != null) {
                buf.append("; Domain=");
                maybeQuote(buf, domain, version);
        }
        ......
}

再看看maybeQuote方法实现：

private void maybeQuote(StringBuffer buf, String value, int version) {
        if (value == null || value.length() == 0) {
            buf.append("/"/"");
        } else if (alreadyQuoted(value)) {
            buf.append('"');
            escapeDoubleQuotes(buf, value,1,value.length()-1);
            buf.append('"');
        } else if (needsQuotes(value, version)) {
            buf.append('"');
            escapeDoubleQuotes(buf, value,0,value.length());
            buf.append('"');
        } else {
            buf.append(value);
        }
}

可以看到并没有做任何domain校验的操作；

Rfc6265CookieProcessor ：

@Override
public String generateHeader(Cookie cookie) {
        ......
        String domain = cookie.getDomain();
        if (domain != null && domain.length() > 0) {
            validateDomain(domain);
            header.append("; Domain=");
            header.append(domain);
        }
        ......
}

private void validateDomain(String domain) {
        int i = 0;
        int prev = -1;
        int cur = -1;
        char[] chars = domain.toCharArray();
        while (i < chars.length) {
            prev = cur;
            cur = chars[i];
            if (!domainValid.get(cur)) {
                throw new IllegalArgumentException(sm.getString(
                        "rfc6265CookieProcessor.invalidDomain", domain));
            }
            // labels must start with a letter or number
            // RFC6265实现
            if ((prev == '.' || prev == -1) && (cur == '.' || cur == '-')) {
                throw new IllegalArgumentException(sm.getString(
                        "rfc6265CookieProcessor.invalidDomain", domain));
            }
            // labels must end with a letter or number
            // RFC6265实现
            if (prev == '-' && cur == '.') {
                throw new IllegalArgumentException(sm.getString(
                        "rfc6265CookieProcessor.invalidDomain", domain));
            }
            i++;
        }
        // domain must end with a label
        if (cur == '.' || cur == '-') {
            throw new IllegalArgumentException(sm.getString(
                    "rfc6265CookieProcessor.invalidDomain", domain));
        }
}

validateDomain方法中实现了 RFC6265 ，这蛋疼的标准改动还真是随意。

参考文档：

https://tomcat.apache.org/tomcat-8.5-doc/config/cookie-processor.html

https://tools.ietf.org/html/rfc2109

https://tools.ietf.org/html/rfc6265#section-5.2.3

LegacyCookieProcessor源码

Rfc6265CookieProcessor源码

原文 https://minei.me/archives/407.html

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