internal static unsafe void UnescapeString(char *pStr, int start, int end, ref ValueStringBuilder dest,
char rsvd1, char rsvd2, char rsvd3, UnescapeMode unescapeMode, UriParser?syntax, bool isQuery)
{
if ((unescapeMode & UnescapeMode.EscapeUnescape) == UnescapeMode.CopyOnly)
{
dest.Append(pStr + start, end - start);
return;
}
bool escapeReserved = false;
bool iriParsing = Uri.IriParsingStatic(syntax) &&
((unescapeMode & UnescapeMode.EscapeUnescape) == UnescapeMode.EscapeUnescape);
for (int next = start; next < end;)
{
char ch = (char)0;
for (; next < end; ++next)
{
if ((ch = pStr[next]) == '%')
{
if ((unescapeMode & UnescapeMode.Unescape) == 0)
{
// re-escape, don't check anything else
escapeReserved = true;
}
else if (next + 2 < end)
{
ch = DecodeHexChars(pStr[next + 1], pStr[next + 2]);
// Unescape a good sequence if full unescape is requested
if (unescapeMode >= UnescapeMode.UnescapeAll)
{
if (ch == Uri.c_DummyChar)
{
if (unescapeMode >= UnescapeMode.UnescapeAllOrThrow)
{
// Should be a rare case where the app tries to feed an invalid escaped sequence
throw new UriFormatException(SR.net_uri_BadString);
}
continue;
}
}
// re-escape % from an invalid sequence
else if (ch == Uri.c_DummyChar)
{
if ((unescapeMode & UnescapeMode.Escape) != 0)
{
escapeReserved = true;
}
else
{
continue; // we should throw instead but since v1.0 would just print '%'
}
}
// Do not unescape '%' itself unless full unescape is requested
else if (ch == '%')
{
next += 2;
continue;
}
// Do not unescape a reserved char unless full unescape is requested
else if (ch == rsvd1 || ch == rsvd2 || ch == rsvd3)
{
next += 2;
continue;
}
// Do not unescape a dangerous char unless it's V1ToStringFlags mode
else if ((unescapeMode & UnescapeMode.V1ToStringFlag) == 0 && IsNotSafeForUnescape(ch))
{
next += 2;
continue;
}
else if (iriParsing && ((ch <= '\x9F' && IsNotSafeForUnescape(ch)) ||
(ch > '\x9F' && !IriHelper.CheckIriUnicodeRange(ch, isQuery))))
{
// check if unenscaping gives a char outside iri range
// if it does then keep it escaped
next += 2;
continue;
}
// unescape escaped char or escape %
break;
}
else if (unescapeMode >= UnescapeMode.UnescapeAll)
{
if (unescapeMode >= UnescapeMode.UnescapeAllOrThrow)
{
// Should be a rare case where the app tries to feed an invalid escaped sequence
throw new UriFormatException(SR.net_uri_BadString);
}
// keep a '%' as part of a bogus sequence
continue;
}
else
{
escapeReserved = true;
}
// escape (escapeReserved==true) or otherwise unescape the sequence
break;
}
else if ((unescapeMode & (UnescapeMode.Unescape | UnescapeMode.UnescapeAll))
== (UnescapeMode.Unescape | UnescapeMode.UnescapeAll))
{
continue;
}
else if ((unescapeMode & UnescapeMode.Escape) != 0)
{
// Could actually escape some of the characters
if (ch == rsvd1 || ch == rsvd2 || ch == rsvd3)
{
// found an unescaped reserved character -> escape it
escapeReserved = true;
break;
}
else if ((unescapeMode & UnescapeMode.V1ToStringFlag) == 0 &&
(ch <= '\x1F' || (ch >= '\x7F' && ch <= '\x9F')))
{
// found an unescaped reserved character -> escape it
escapeReserved = true;
break;
}
}
}
//copy off previous characters from input
while (start < next)
{
dest.Append(pStr[start++]);
}
if (next != end)
{
if (escapeReserved)
{
EscapeAsciiChar((byte)pStr[next], ref dest);
escapeReserved = false;
next++;
}
else if (ch <= 127)
{
dest.Append(ch);
next += 3;
}
else
{
// Unicode
int charactersRead = PercentEncodingHelper.UnescapePercentEncodedUTF8Sequence(
pStr + next,
end - next,
ref dest,
isQuery,
iriParsing);
Debug.Assert(charactersRead > 0);
next += charactersRead;
}
start = next;
}
}
}
//
// IRI normalization for strings containing characters that are not allowed or
// escaped characters that should be unescaped in the context of the specified Uri component.
//
internal static unsafe string EscapeUnescapeIri(char *pInput, int start, int end, UriComponents component)
{
int size = end - start;
ValueStringBuilder dest = size <= 256
? new ValueStringBuilder(stackalloc char[256])
: new ValueStringBuilder(size);
Span <byte> maxUtf8EncodedSpan = stackalloc byte[4];
for (int i = start; i < end; ++i)
{
char ch = pInput[i];
if (ch == '%')
{
if (end - i > 2)
{
ch = UriHelper.DecodeHexChars(pInput[i + 1], pInput[i + 2]);
// Do not unescape a reserved char
if (ch == Uri.c_DummyChar || ch == '%' || CheckIsReserved(ch, component) || UriHelper.IsNotSafeForUnescape(ch))
{
// keep as is
dest.Append(pInput[i++]);
dest.Append(pInput[i++]);
dest.Append(pInput[i]);
continue;
}
else if (ch <= '\x7F')
{
Debug.Assert(ch < 0xFF, "Expecting ASCII character.");
//ASCII
dest.Append(ch);
i += 2;
continue;
}
else
{
// possibly utf8 encoded sequence of unicode
int charactersRead = PercentEncodingHelper.UnescapePercentEncodedUTF8Sequence(
pInput + i,
end - i,
ref dest,
component == UriComponents.Query,
iriParsing: true);
Debug.Assert(charactersRead > 0);
i += charactersRead - 1; // -1 as i will be incremented in the loop
}
}
else
{
dest.Append(pInput[i]);
}
}
else if (ch > '\x7f')
{
// unicode
bool isInIriUnicodeRange;
bool surrogatePair = false;
char ch2 = '\0';
if ((char.IsHighSurrogate(ch)) && (i + 1 < end))
{
ch2 = pInput[i + 1];
isInIriUnicodeRange = CheckIriUnicodeRange(ch, ch2, out surrogatePair, component == UriComponents.Query);
}
else
{
isInIriUnicodeRange = CheckIriUnicodeRange(ch, component == UriComponents.Query);
}
if (isInIriUnicodeRange)
{
dest.Append(ch);
if (surrogatePair)
{
dest.Append(ch2);
}
}
else
{
Rune rune;
if (surrogatePair)
{
rune = new Rune(ch, ch2);
}
else if (!Rune.TryCreate(ch, out rune))
{
rune = Rune.ReplacementChar;
}
int bytesWritten = rune.EncodeToUtf8(maxUtf8EncodedSpan);
Span <byte> encodedBytes = maxUtf8EncodedSpan.Slice(0, bytesWritten);
foreach (byte b in encodedBytes)
{
UriHelper.EscapeAsciiChar(b, ref dest);
}
}
if (surrogatePair)
{
i++;
}
}
else
{
// just copy the character
dest.Append(pInput[i]);
}
}
return(dest.ToString());
}