HttpCapabilitiesSectionHandler.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / Configuration / HttpCapabilitiesSectionHandler.cs / 2 / HttpCapabilitiesSectionHandler.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.Configuration { 
 
    using System.Collections;
    using System.Configuration; 
    using System.IO;
    using System.Security;
    using System.Security.Permissions;
    using System.Text.RegularExpressions; 
    using System.Web.Configuration;
    using System.Web.Util; 
    using System.Xml; 

    using Pair = System.Web.UI.Pair; 

    //
    // ConfigureCapabilities is used to configure the CapabilitiesEvaluator object
    // 
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    public class HttpCapabilitiesSectionHandler : IConfigurationSectionHandler { 

        private const int _defaultUserAgentCacheKeyLength = 64; 

        public HttpCapabilitiesSectionHandler() {
        }
 

        class ParseState { 
            internal string SectionName; 
            internal HttpCapabilitiesEvaluator Evaluator;
            internal ArrayList RuleList = new ArrayList(); 
            internal ArrayList FileList = new ArrayList();
            internal bool IsExternalFile = false;

            internal ParseState() {} 
        }
 
        // 
        // As required by IConfigurationSectionHandler
        // 
        public object Create(object parent, object configurationContext, XmlNode section) {
            // if called through client config don't even load HttpRuntime
            if (!HandlerBase.IsServerConfiguration(configurationContext)) {
                return null; 
            }
 
            ParseState parseState = new ParseState(); 
            parseState.SectionName = section.Name;
 
            // the rule is going to be the previous rule followed by a list containing the new rules
            parseState.Evaluator = new HttpCapabilitiesEvaluator((HttpCapabilitiesEvaluator)parent);

            int userAgentCacheKeyLength = 0; 
            // Get the useragent string cachekey length
            if (parent != null) { 
                userAgentCacheKeyLength = ((HttpCapabilitiesEvaluator)parent).UserAgentCacheKeyLength; 
            }
            HandlerBase.GetAndRemovePositiveIntegerAttribute(section, "userAgentCacheKeyLength", ref userAgentCacheKeyLength); 

            if (userAgentCacheKeyLength == 0) {
                userAgentCacheKeyLength = _defaultUserAgentCacheKeyLength;
            } 
            parseState.Evaluator.UserAgentCacheKeyLength = userAgentCacheKeyLength;
 
            // check for random attributes 

            HandlerBase.CheckForUnrecognizedAttributes(section); 


            // iterate through XML section in order and apply the directives
 
            ArrayList sublist;
 
            sublist = RuleListFromElement(parseState, section, true); 

            if (sublist.Count > 0) { 
                parseState.RuleList.Add(new CapabilitiesSection(CapabilitiesRule.Filter, null, null, sublist));
            }

            if (parseState.FileList.Count > 0) { 
                parseState.IsExternalFile = true;
                ResolveFiles(parseState, configurationContext); 
            } 

            // Add the new rules 

            parseState.Evaluator.AddRuleList(parseState.RuleList);

            return parseState.Evaluator; 
        }
 
        // 
        // Create a rule from an element
        // 
        static CapabilitiesRule RuleFromElement(ParseState parseState, XmlNode element) {
            int ruletype;
            DelayedRegex regex;
            CapabilitiesPattern pat; 

            // grab tag name 
 
            if (element.Name == "filter") {
                ruletype = CapabilitiesRule.Filter; 
            }
            else if (element.Name=="case") {
                ruletype = CapabilitiesRule.Case;
            } 
            else if (element.Name == "use") {
                HandlerBase.CheckForNonCommentChildNodes(element); 
 
                string var = HandlerBase.RemoveRequiredAttribute(element, "var");
                string strAs = HandlerBase.RemoveAttribute(element, "as"); 
                HandlerBase.CheckForUnrecognizedAttributes(element);

                if (strAs == null)
                    strAs = String.Empty; 

                parseState.Evaluator.AddDependency(var); 
 
                return new CapabilitiesUse(var, strAs);
            } 
            else {
                throw new ConfigurationErrorsException(
                                                SR.GetString(SR.Unknown_tag_in_caps_config, element.Name),
                                                element); 
            }
 
            // grab attributes 
            String matchpat = HandlerBase.RemoveAttribute(element, "match");
            String testpat = HandlerBase.RemoveAttribute(element, "with"); 
            HandlerBase.CheckForUnrecognizedAttributes(element);

            if (matchpat == null) {
                if (testpat != null) 
                    throw new ConfigurationErrorsException(SR.GetString(SR.Cannot_specify_test_without_match), element);
                regex = null; 
                pat = null; 
            }
            else { 
                try {
                    regex = new DelayedRegex(matchpat);
                }
                catch (Exception e) { 
                    throw new ConfigurationErrorsException(e.Message, e, element);
                } 
 
                if (testpat == null)
                    pat = CapabilitiesPattern.Default; 
                else
                    pat = new CapabilitiesPattern(testpat);
            }
 
            // grab contents
            ArrayList subrules = RuleListFromElement(parseState, element, false); 
 
            return new CapabilitiesSection(ruletype, regex, pat, subrules);
        } 

        //
        // Create a rulelist from an element's children
        // 
        static ArrayList RuleListFromElement(ParseState parseState, XmlNode node, bool top) {
            ArrayList result = new ArrayList(); 
 
            foreach (XmlNode child in node.ChildNodes) {
                switch (child.NodeType) { 
                    case XmlNodeType.Text:
                    case XmlNodeType.CDATA:
                        top = false;
                        AppendLines(result, child.Value, node); 
                        break;
 
                    case XmlNodeType.Element: 
                        switch (child.Name) {
                            case "result": 
                                if (top) {
                                    ProcessResult(parseState.Evaluator, child);
                                }
                                else { 
                                    throw new ConfigurationErrorsException(
                                                    SR.GetString(SR.Result_must_be_at_the_top_browser_section), 
                                                    child); 
                                }
                                break; 

                            case "file":
                                if (parseState.IsExternalFile) {
                                    throw new ConfigurationErrorsException( 
                                                    SR.GetString(SR.File_element_only_valid_in_config),
                                                    child); 
                                } 
                                ProcessFile(parseState.FileList, child);
                                break; 

                            default:
                                result.Add(RuleFromElement(parseState, child));
                                break; 
                        }
                        top = false; 
                        break; 

                    case XmlNodeType.Comment: 
                    case XmlNodeType.Whitespace:
                        break;

                    default: 
                        HandlerBase.ThrowUnrecognizedElement(child);
                        break; 
                } 
            }
 
            return result;
        }

 
        //
        // Handle  elements 
        // 
        static void ProcessFile(ArrayList fileList, XmlNode node) {
 
            string filename = null;
            XmlNode attr = HandlerBase.GetAndRemoveRequiredStringAttribute(node, "src", ref filename);

            HandlerBase.CheckForUnrecognizedAttributes(node); 
            HandlerBase.CheckForNonCommentChildNodes(node);
 
            fileList.Add(new Pair(filename, attr)); 
        }
 

        //
        // Handle the  tag
        // 
        static void ProcessResult(HttpCapabilitiesEvaluator capabilitiesEvaluator, XmlNode node) {
 
            bool inherit = true; 
            HandlerBase.GetAndRemoveBooleanAttribute(node, "inherit", ref inherit);
            if (inherit == false) { 
                capabilitiesEvaluator.ClearParent();
            }

            Type resultType = null; 
            XmlNode attribute = HandlerBase.GetAndRemoveTypeAttribute(node, "type", ref resultType);
            if (attribute != null) { 
                if (resultType.Equals(capabilitiesEvaluator._resultType) == false) { 
                    // be sure the new type is assignable to the parent type
                    HandlerBase.CheckAssignableType(attribute, capabilitiesEvaluator._resultType, resultType); 
                    capabilitiesEvaluator._resultType = resultType;
                }
            }
 
            int cacheTime = 0;
            attribute = HandlerBase.GetAndRemovePositiveIntegerAttribute(node, "cacheTime", ref cacheTime); 
            //NOTE: we continue to parse the cacheTime for backwards compat 
            // it has never been used.  Customer scenarios don't require this support.
            if (attribute != null) { 
                capabilitiesEvaluator.SetCacheTime(cacheTime);
            }

            HandlerBase.CheckForUnrecognizedAttributes(node); 
            HandlerBase.CheckForNonCommentChildNodes(node);
 
        } 

 
        //
        // ResolveFiles - parse files referenced with 
        //
        static void ResolveFiles(ParseState parseState, object configurationContext) { 

            // 
            // 1) get the directory of the configuration file currently being parsed 
            //
 
            HttpConfigurationContext httpConfigurationContext = (HttpConfigurationContext) configurationContext;
            string configurationDirectory = null;
            bool useAssert = false;
 
            //
            // Only assert to read cap files when parsing machine.config 
            // (allow device updates to work in restricted trust levels). 
            //
            // Machine.config can be securely identified by the context being 
            // an HttpConfigurationContext with null path.
            //
            try {
                if (httpConfigurationContext.VirtualPath == null) { 
                    useAssert = true;
                    // we need to assert here to get the file path from ConfigurationException 
                    FileIOPermission fiop = new FileIOPermission(PermissionState.None); 
                    fiop.AllFiles = FileIOPermissionAccess.PathDiscovery;
                    fiop.Assert(); 
                }

                Pair pair0 = (Pair)parseState.FileList[0];
                XmlNode srcAttribute = (XmlNode)pair0.Second; 
                configurationDirectory = Path.GetDirectoryName(ConfigurationErrorsException.GetFilename(srcAttribute));
            } 
            finally { 
                if (useAssert) {
                    CodeAccessPermission.RevertAssert(); 
                }
            }

            // 
            // 2) iterate through list of referenced files, builing rule lists for each
            // 
            foreach (Pair pair in parseState.FileList) { 
                string srcFilename = (string)pair.First;
                string fullFilename = Path.Combine(configurationDirectory, srcFilename); 

                XmlNode section;
                try {
                    if (useAssert) { 
                        InternalSecurityPermissions.FileReadAccess(fullFilename).Assert();
                    } 
 
                    Exception fcmException = null;
 
                    try {
                        HttpConfigurationSystem.AddFileDependency(fullFilename);
                    }
                    catch (Exception e) { 
                        fcmException = e;
                    } 
 
                    ConfigXmlDocument configDoc = new ConfigXmlDocument();
 
                    try {
                        configDoc.Load(fullFilename);
                        section = configDoc.DocumentElement;
                    } 
                    catch (Exception e) {
                        throw new ConfigurationErrorsException(SR.GetString(SR.Error_loading_XML_file, fullFilename, e.Message), 
                                        e, (XmlNode)pair.Second); 
                    }
 
                    if (fcmException != null) {
                        throw fcmException;
                    }
                } 
                finally {
                    if (useAssert) { 
                        // Cannot apply next FileReadAccess PermissionSet unless 
                        // current set is explicitly reverted.  Also minimizes
                        // granted permissions. 
                        CodeAccessPermission.RevertAssert();
                    }
                }
 
                if (section.Name != parseState.SectionName) {
                    throw new ConfigurationErrorsException(SR.GetString(SR.Capability_file_root_element, parseState.SectionName), 
                                    section); 
                }
 
                HandlerBase.CheckForUnrecognizedAttributes(section);

                ArrayList sublist = RuleListFromElement(parseState, section, true);
 
                if (sublist.Count > 0) {
                    parseState.RuleList.Add(new CapabilitiesSection(CapabilitiesRule.Filter, null, null, sublist)); 
                } 
            }
        } 

        //
        // Regex dealing with a=b lines
        // 
        static Regex lineRegex = new Regex
                                          ( 
                                          "\\G" +                                 // anchored 
                                          "(?\\w+)" +                        // variable name
                                          "\\s*=\\s*" +                           // equals sign 
                                          "(?:" +
                                          "\"(?[^\"\r\n\\\\]*" +         // quoted pattern
                                          "(?:\\\\.[^\"\r\n\\\\]*)*)\"" +
                                          "|(?!\")(?\\S+)" +             // unquoted pattern 
                                          ")" +
                                          "\\s*"                                  // trailing whitespace 
                                          ); 

        static Regex wsRegex = new Regex("\\G\\s*"); 
        static Regex errRegex = new Regex("\\G\\S {0,8}");

        static void AppendLines(ArrayList setlist, String text, XmlNode node) {
            int lineNumber = ConfigurationErrorsException.GetLineNumber(node); 
            int textpos;
 
            textpos = 0; 

            for (;;) { 
                Match match;

                if ((match = wsRegex.Match(text, textpos)).Success) {
                    lineNumber += System.Web.UI.Util.LineCount(text, textpos, match.Index + match.Length); 
                    textpos = match.Index + match.Length;
                } 
 
                if (textpos == text.Length)
                    break; 

                if ((match = lineRegex.Match(text, textpos)).Success) {
                    setlist.Add(new CapabilitiesAssignment(match.Groups["var"].Value,
                                                           new CapabilitiesPattern(match.Groups["pat"].Value))); 

                    lineNumber += System.Web.UI.Util.LineCount(text, textpos, match.Index + match.Length); 
                    textpos = match.Index + match.Length; 
                }
                else { 
                    match = errRegex.Match(text, textpos);

                    throw new ConfigurationErrorsException(
                                    SR.GetString(SR.Problem_reading_caps_config, match.ToString()), 
                                    ConfigurationErrorsException.GetFilename(node),
                                    lineNumber); 
                } 
            }
        } 

    }
}

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