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feat(httpsys): support chunked transfer-encoding #35

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4f4fc9b
feat(httpsys): support chunked transfer-encoding
Aug 19, 2026
a4c506f
fix(httpsys): harden chunked body handling
Aug 19, 2026
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70 changes: 64 additions & 6 deletions Libraries/SimpleServer/dwsHTTPSysServer.pas
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Original file line number Diff line number Diff line change
Expand Up @@ -366,6 +366,8 @@ implementation

const
cDefaultMaxInputCountLength = 10*1024*1024; // 10 MB
// QuBES patch #1333: default cumulative cap for bodies of unknown length (chunked)
cDefaultMaxChunkedInputLength = 100*1024*1024; // 100 MB

var
vWsaDataOnce : TWSADATA;
Expand Down Expand Up @@ -627,6 +629,7 @@ constructor THttpApi2Server.CreateClone(From : THttpApi2Server);
end;
FServerEvents := From.FServerEvents;
FURLRewriter := From.URLRewriter;
FMaxInputCountLength := From.FMaxInputCountLength; // QuBES patch #1333
end;

// SendStaticFile
Expand Down Expand Up @@ -1250,17 +1253,67 @@ procedure THttpApi2Server.RegisterCompress(aFunction : THttpSocketCompress);
//
function THttpApi2Server.GetRequestContentBody(request : PHTTP_REQUEST_V2; response : PHTTP_RESPONSE_V2;
var inContent : RawByteString) : Boolean;
const
cChunkedReadBufferSize = 65536; // 64 KB per ReceiveRequestEntityBody call
var
inContentLength, inContentLengthRead, bytesRead : Cardinal;
inContentLength, inContentLengthRead, bytesRead, capacity : Cardinal;
bufRead : PAnsiChar;
flags, errCode : Integer;
i, n : Integer;
compressRec : PHttpSocketCompressRec;
contentEncoding : PHTTP_KNOWN_HEADER;
transferEncoding : RawByteString;
chunked : Boolean;
inputCap, maxBodyLength : Cardinal;
begin
if Win32MajorVersion>5 then // speed optimization for Vista+
flags := HTTP_RECEIVE_REQUEST_ENTITY_BODY_FLAG_FILL_BUFFER
else flags := 0;
with request^.Headers.KnownHeaders[reqContentLength] do
inContentLength := GetCardinal(pRawValue, pRawValue+RawValueLength);
if inContentLength<>0 then begin
// QuBES patch #1333: chunked transfer-encoding support
// http.sys de-chunks natively, the body just has to be read until ERROR_HANDLE_EOF
// without assuming a known Content-Length
with request^.Headers.KnownHeaders[reqTransferEncoding] do
SetString(transferEncoding, pRawValue, RawValueLength);
chunked := (transferEncoding<>'') and (Pos('chunked', LowerCase(String(transferEncoding)))>0);
if chunked or (inContentLength=0) then begin
// unknown body length: cumulative size cap enforced while reading
if MaxInputCountLength>0 then
inputCap := MaxInputCountLength
else inputCap := cDefaultMaxChunkedInputLength;
maxBodyLength := inputCap;
inContentLengthRead := 0;
capacity := cChunkedReadBufferSize;
SetLength(inContent, capacity);
repeat
// grow geometrically to avoid O(n^2) reallocations on large bodies
if capacity-inContentLengthRead < cChunkedReadBufferSize then begin
capacity := capacity*2;
SetLength(inContent, capacity);
end;
bufRead := PAnsiChar(Pointer(inContent))+inContentLengthRead;
bytesRead := 0;
errCode := HttpAPI.ReceiveRequestEntityBody(FReqQueue, request^.RequestId, flags,
bufRead, cChunkedReadBufferSize, bytesRead);
inc(inContentLengthRead, bytesRead); // ERROR_HANDLE_EOF may carry final bytes
if inContentLengthRead>inputCap then begin
// send the 413 first so the client gets a clean status, then cancel to stop
// the remaining (unread) body from flooding the connection
SendError(request, response, 413, 'Payload Too Large');
HttpAPI.CancelHttpRequest(FReqQueue, request^.RequestId, nil);
Exit(False);
end;
if (errCode=NO_ERROR) and (bytesRead=0) then
break; // no progress means end of body
until errCode<>NO_ERROR;
if (errCode<>ERROR_HANDLE_EOF) and (errCode<>NO_ERROR) then begin
SendError(request, response, 406, SysErrorMessage(errCode));
Exit(False);
end;
SetLength(inContent, inContentLengthRead);
end else begin
maxBodyLength := MaxInputCountLength; // 0 = historical unbounded behavior
if (MaxInputCountLength>0) and (inContentLength>MaxInputCountLength) then begin
// ideally SendError(412, 'Content-Length too large');
// but if we don't cancel the request, it'll eat all the
Expand All @@ -1273,9 +1326,6 @@ function THttpApi2Server.GetRequestContentBody(request : PHTTP_REQUEST_V2; respo
inContentLengthRead := 0;
repeat
bytesRead := 0;
if Win32MajorVersion>5 then // speed optimization for Vista+
flags := HTTP_RECEIVE_REQUEST_ENTITY_BODY_FLAG_FILL_BUFFER
else flags := 0;
errCode := HttpAPI.ReceiveRequestEntityBody(FReqQueue, request^.RequestId, flags,
bufRead, inContentLength-inContentLengthRead, bytesRead);
inc(inContentLengthRead, BytesRead);
Expand All @@ -1293,7 +1343,9 @@ function THttpApi2Server.GetRequestContentBody(request : PHTTP_REQUEST_V2; respo
SendError(request, response, 406, SysErrorMessage(errCode));
Exit(False);
end;
// attempt to decompress if necessary
end;
// attempt to decompress if necessary (QuBES patch #1333: common to both read paths)
if inContent<>'' then begin
contentEncoding:=@request^.Headers.KnownHeaders[reqContentEncoding];
n:=contentEncoding.RawValueLength;
if n>0 then begin
Expand All @@ -1302,6 +1354,12 @@ function THttpApi2Server.GetRequestContentBody(request : PHTTP_REQUEST_V2; respo
if (compressRec.NameLength=n)
and CompareMem(Pointer(compressRec.Name), contentEncoding.pRawValue, n) then begin
compressRec.Func(inContent, false); // uncompress
// QuBES patch #1333: guard against decompression bombs -- the cap above
// only bounds the compressed bytes read off the wire, not the output
if (maxBodyLength>0) and (Cardinal(Length(inContent))>maxBodyLength) then begin
SendError(request, response, 413, 'Payload Too Large');
Exit(False);
end;
break;
end;
end;
Expand Down