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namespace System.Web.Routing {
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Linq;
internal static class RouteParser {
private static string GetLiteral(string segmentLiteral) {
// Scan for errant single { and } and convert double {{ to { and double }} to }
// First we eliminate all escaped braces and then check if any other braces are remaining
string newLiteral = segmentLiteral.Replace("{{", "").Replace("}}", "");
if (newLiteral.Contains("{") || newLiteral.Contains("}")) {
return null;
}
// If it's a valid format, we unescape the braces
return segmentLiteral.Replace("{{", "{").Replace("}}", "}");
}
private static int IndexOfFirstOpenParameter(string segment, int startIndex) {
// Find the first unescaped open brace
while (true) {
startIndex = segment.IndexOf('{', startIndex);
if (startIndex == -1) {
// If there are no more open braces, stop
return -1;
}
if ((startIndex + 1 == segment.Length) ||
((startIndex + 1 < segment.Length) && (segment[startIndex + 1] != '{'))) {
// If we found an open brace that is followed by a non-open brace, it's
// a parameter delimiter.
// It's also a delimiter if the open brace is the last character - though
// it ends up being being called out as invalid later on.
return startIndex;
}
// Increment by two since we want to skip both the open brace that
// we're on as well as the subsequent character since we know for
// sure that it is part of an escape sequence.
startIndex += 2;
}
}
internal static bool IsSeparator(string s) {
return String.Equals(s, "/", StringComparison.Ordinal);
}
private static bool IsValidParameterName(string parameterName) {
if (parameterName.Length == 0) {
return false;
}
for (int i = 0; i < parameterName.Length; i++) {
char c = parameterName[i];
if (c == '/' || c == '{' || c == '}') {
return false;
}
}
return true;
}
internal static bool IsInvalidRouteUrl(string routeUrl) {
return (routeUrl.StartsWith("~", StringComparison.Ordinal) ||
routeUrl.StartsWith("/", StringComparison.Ordinal) ||
(routeUrl.IndexOf('?') != -1));
}
public static ParsedRoute Parse(string routeUrl) {
if (routeUrl == null) {
routeUrl = String.Empty;
}
if (IsInvalidRouteUrl(routeUrl)) {
throw new ArgumentException(SR.GetString(SR.Route_InvalidRouteUrl), "routeUrl");
}
IList<string> urlParts = SplitUrlToPathSegmentStrings(routeUrl);
Exception ex = ValidateUrlParts(urlParts);
if (ex != null) {
throw ex;
}
IList<PathSegment> pathSegments = SplitUrlToPathSegments(urlParts);
Debug.Assert(urlParts.Count == pathSegments.Count, "The number of string segments should be the same as the number of path segments");
return new ParsedRoute(pathSegments);
}
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2208:InstantiateArgumentExceptionsCorrectly",
Justification = "The exceptions are just constructed here, but they are thrown from a method that does have those parameter names.")]
private static IList<PathSubsegment> ParseUrlSegment(string segment, out Exception exception) {
int startIndex = 0;
List<PathSubsegment> pathSubsegments = new List<PathSubsegment>();
while (startIndex < segment.Length) {
int nextParameterStart = IndexOfFirstOpenParameter(segment, startIndex);
if (nextParameterStart == -1) {
// If there are no more parameters in the segment, capture the remainder as a literal and stop
string lastLiteralPart = GetLiteral(segment.Substring(startIndex));
if (lastLiteralPart == null) {
exception = new ArgumentException(
String.Format(
CultureInfo.CurrentUICulture,
SR.GetString(SR.Route_MismatchedParameter),
segment
),
"routeUrl");
return null;
}
if (lastLiteralPart.Length > 0) {
pathSubsegments.Add(new LiteralSubsegment(lastLiteralPart));
}
break;
}
int nextParameterEnd = segment.IndexOf('}', nextParameterStart + 1);
if (nextParameterEnd == -1) {
exception = new ArgumentException(
String.Format(
CultureInfo.CurrentUICulture,
SR.GetString(SR.Route_MismatchedParameter),
segment
),
"routeUrl");
return null;
}
string literalPart = GetLiteral(segment.Substring(startIndex, nextParameterStart - startIndex));
if (literalPart == null) {
exception = new ArgumentException(
String.Format(
CultureInfo.CurrentUICulture,
SR.GetString(SR.Route_MismatchedParameter),
segment
),
"routeUrl");
return null;
}
if (literalPart.Length > 0) {
pathSubsegments.Add(new LiteralSubsegment(literalPart));
}
string parameterName = segment.Substring(nextParameterStart + 1, nextParameterEnd - nextParameterStart - 1);
pathSubsegments.Add(new ParameterSubsegment(parameterName));
startIndex = nextParameterEnd + 1;
}
exception = null;
return pathSubsegments;
}
private static IList<PathSegment> SplitUrlToPathSegments(IList<string> urlParts) {
List<PathSegment> pathSegments = new List<PathSegment>();
foreach (string pathSegment in urlParts) {
bool isCurrentPartSeparator = IsSeparator(pathSegment);
if (isCurrentPartSeparator) {
pathSegments.Add(new SeparatorPathSegment());
}
else {
Exception exception;
IList<PathSubsegment> subsegments = ParseUrlSegment(pathSegment, out exception);
Debug.Assert(exception == null, "This only gets called after the path has been validated, so there should never be an exception here");
pathSegments.Add(new ContentPathSegment(subsegments));
}
}
return pathSegments;
}
internal static IList<string> SplitUrlToPathSegmentStrings(string url) {
List<string> parts = new List<string>();
if (String.IsNullOrEmpty(url)) {
return parts;
}
int currentIndex = 0;
// Split the incoming URL into individual parts
while (currentIndex < url.Length) {
int indexOfNextSeparator = url.IndexOf('/', currentIndex);
if (indexOfNextSeparator == -1) {
// If there are no more separators, the rest of the string is the last part
string finalPart = url.Substring(currentIndex);
if (finalPart.Length > 0) {
parts.Add(finalPart);
}
break;
}
string nextPart = url.Substring(currentIndex, indexOfNextSeparator - currentIndex);
if (nextPart.Length > 0) {
parts.Add(nextPart);
}
Debug.Assert(url[indexOfNextSeparator] == '/', "The separator char itself should always be a '/'.");
parts.Add("/");
currentIndex = indexOfNextSeparator + 1;
}
return parts;
}
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2208:InstantiateArgumentExceptionsCorrectly",
Justification = "The exceptions are just constructed here, but they are thrown from a method that does have those parameter names.")]
private static Exception ValidateUrlParts(IList<string> pathSegments) {
Debug.Assert(pathSegments != null, "The value should always come from SplitUrl(), and that function should never return null.");
HashSet<string> usedParameterNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
bool? isPreviousPartSeparator = null;
bool foundCatchAllParameter = false;
foreach (string pathSegment in pathSegments) {
if (foundCatchAllParameter) {
// If we ever start an iteration of the loop and we've already found a
// catchall parameter then we have an invalid URL format.
return new ArgumentException(
String.Format(
CultureInfo.CurrentCulture,
SR.GetString(SR.Route_CatchAllMustBeLast)
),
"routeUrl");
}
bool isCurrentPartSeparator;
if (isPreviousPartSeparator == null) {
// Prime the loop with the first value
isPreviousPartSeparator = IsSeparator(pathSegment);
isCurrentPartSeparator = isPreviousPartSeparator.Value;
}
else {
isCurrentPartSeparator = IsSeparator(pathSegment);
// If both the previous part and the current part are separators, it's invalid
if (isCurrentPartSeparator && isPreviousPartSeparator.Value) {
return new ArgumentException(SR.GetString(SR.Route_CannotHaveConsecutiveSeparators), "routeUrl");
}
Debug.Assert(isCurrentPartSeparator != isPreviousPartSeparator.Value, "This assert should only happen if both the current and previous parts are non-separators. This should never happen because consecutive non-separators are always parsed as a single part.");
isPreviousPartSeparator = isCurrentPartSeparator;
}
// If it's not a separator, parse the segment for parameters and validate it
if (!isCurrentPartSeparator) {
Exception exception;
IList<PathSubsegment> subsegments = ParseUrlSegment(pathSegment, out exception);
if (exception != null) {
return exception;
}
exception = ValidateUrlSegment(subsegments, usedParameterNames, pathSegment);
if (exception != null) {
return exception;
}
foundCatchAllParameter = subsegments.Any<PathSubsegment>(seg => (seg is ParameterSubsegment) && (((ParameterSubsegment)seg).IsCatchAll));
}
}
return null;
}
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2208:InstantiateArgumentExceptionsCorrectly",
Justification = "The exceptions are just constructed here, but they are thrown from a method that does have those parameter names.")]
private static Exception ValidateUrlSegment(IList<PathSubsegment> pathSubsegments, HashSet<string> usedParameterNames, string pathSegment) {
bool segmentContainsCatchAll = false;
Type previousSegmentType = null;
foreach (PathSubsegment subsegment in pathSubsegments) {
if (previousSegmentType != null) {
if (previousSegmentType == subsegment.GetType()) {
return new ArgumentException(
String.Format(
CultureInfo.CurrentCulture,
SR.GetString(SR.Route_CannotHaveConsecutiveParameters)
),
"routeUrl");
}
}
previousSegmentType = subsegment.GetType();
LiteralSubsegment literalSubsegment = subsegment as LiteralSubsegment;
if (literalSubsegment != null) {
// Nothing to validate for literals - everything is valid
}
else {
ParameterSubsegment parameterSubsegment = subsegment as ParameterSubsegment;
if (parameterSubsegment != null) {
string parameterName = parameterSubsegment.ParameterName;
if (parameterSubsegment.IsCatchAll) {
segmentContainsCatchAll = true;
}
// Check for valid characters in the parameter name
if (!IsValidParameterName(parameterName)) {
return new ArgumentException(
String.Format(
CultureInfo.CurrentUICulture,
SR.GetString(SR.Route_InvalidParameterName),
parameterName
),
"routeUrl");
}
if (usedParameterNames.Contains(parameterName)) {
return new ArgumentException(
String.Format(
CultureInfo.CurrentUICulture,
SR.GetString(SR.Route_RepeatedParameter),
parameterName
),
"routeUrl");
}
else {
usedParameterNames.Add(parameterName);
}
}
else {
Debug.Fail("Invalid path subsegment type");
}
}
}
if (segmentContainsCatchAll && (pathSubsegments.Count != 1)) {
return new ArgumentException(
String.Format(
CultureInfo.CurrentCulture,
SR.GetString(SR.Route_CannotHaveCatchAllInMultiSegment)
),
"routeUrl");
}
return null;
}
}
}
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