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Rebuild CGIFormData on Parser/StreamReader, fix a 2-byte-lookahead bug

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CGIFormData now inherits Parser instead of MString and parses a CGI
request body (urlencoded or multipart/form-data) resumably against the
shared StreamReader, exposing the result via operator[] - matching every
other Parser in this redesign. multipart/form-data reuses IMFBoundary and
IMFHeader via checkParse() (chained through the same StreamReader) for
each part's boundary line and header block; urlencoded bodies wait for
the full Content-Length before delegating to the existing
CGIFormattedData parser. File-upload parts (Content-Disposition with a
filename= parameter) are recognized and skipped, matching this
codebase's convention that uploads get a separate mechanism.

Values are stored under an indexed "name:N" key (N = 0-based occurrence
count for that name), matching the :N-suffix convention JetCore's
Tag::getVariable already applies to its $[:name] CGI variable syntax
(defaulting to :0) - this also naturally supports repeated field names
(checkboxes, multi-select). operator[] applies the same :0 default so a
bare name still works when called directly, not just through that
convention layer.

Two real resumability bugs found and fixed via a byte-at-a-time test
(feeding one byte per StreamReader::feed() call, the harshest possible
fragmentation):
- CGIFormData's opening boundary marker ("--boundary", no leading CRLF
  per RFC 2046 for the first boundary) crammed "find+consume the marker"
  and "disambiguate -- vs CRLF" into one state; when the disambiguation
  needed more data, INCOMPLETE was returned without recording that the
  marker was already consumed, so retrying re-searched for it past where
  it had already been consumed, silently skipping content forever. Split
  into two states (INIT / OPENING_TAIL), the same fix already applied
  once to IMFBoundary's PREFIX/TAIL split.
- IMFHeader's FIELD state checked eod() (a 1-byte availability check)
  immediately before an ifNext("\r\n") call that needs 2 bytes - a lone
  trailing \r with no \n yet available was wrongly treated as malformed
  instead of "wait for more data". Fixed to check getLength() < 2.

Verified via a dedicated test (64 assertions total across this and the
earlier Parser/StreamReader test) covering urlencoded, multipart with a
skipped file upload, and the byte-at-a-time stress case - plus a real
end-to-end run through jet-2.0 with a simulated CGI multipart POST
request (see the matching JetCore commit).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
This commit is contained in:
Brad ArantandClaude Sonnet 5 committed 2026-08-23 15:07:09 -07:00
1 parent a033cc6718
commit bf6810b781
3 files changed
+218 -56
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CGIFormData.cpp
+153 -43
View File
@@ -1,58 +1,168 @@
#include "CGIFormData.h"
#include "malloc.h"
#include "CGIFormattedData.h"
#include "Exception.h"
namespace coreutils {
CGIFormData::CGIFormData(int fd, ZString contentType, int contentLength, ZString boundary)
: contentType(contentType) {
if(contentType.startsWith("application/x-www-form-urlencoded")) {
read(fd, contentLength);
formdata = new CGIFormattedData(*this);
} else if(contentType.startsWith("multipart/form-data")) {
read(fd, contentLength);
formdata = new CGIFormattedData();
MString delimiter;
delimiter << "--" << boundary;
ZString body(*this);
body.split(delimiter);
CGIFormData::CGIFormData(StreamReader &reader, ZString contentType, int contentLength, ZString boundary)
: Parser(reader), contentType(contentType), contentLength(contentLength), boundary(boundary) {
if (contentType.startsWith("application/x-www-form-urlencoded"))
mode = URLENCODED;
else if (contentType.startsWith("multipart/form-data"))
mode = MULTIPART;
else
mode = UNKNOWN;
}
for(int ix = 0; ix < body.getList().size(); ++ix) {
ZString part = body[ix];
if(part.getLength() == 0 || part.startsWith("--"))
continue;
CGIFormData::~CGIFormData() {
delete headerParser;
delete boundaryParser;
}
int headerEnd = part.find("\r\n\r\n");
if(headerEnd == -1)
continue;
void CGIFormData::extractPartName(IMFHeader &header) {
auto &fields = header.getHeaders();
MString disposition = fields[MString("Content-Disposition")];
ZString dz(disposition.getData(), disposition.getLength());
ZString headers = part.substring(0, headerEnd);
if(headers.find("filename=\"") != -1)
// file uploads are out of scope here; handled via a separate upload mechanism.
continue;
currentSkip = (dz.find(ZString("filename=\"")) != -1);
int namePos = headers.find("name=\"");
if(namePos == -1)
continue;
ZString afterName = headers.substring(namePos + 6);
int nameEnd = afterName.find("\"");
if(nameEnd == -1)
continue;
ZString name = afterName.substring(0, nameEnd);
ZString value = part.substring(headerEnd + 4);
value.trimCRLF();
formdata->data[name] = value;
}
int namePos = dz.find(ZString("name=\""));
if (namePos != -1) {
ZString afterName = dz.substring(namePos + 6);
int nameEnd = afterName.find(ZString("\""));
if (nameEnd != -1)
currentName = MString(afterName.substring(0, nameEnd));
}
}
Parser::Status CGIFormData::parse() {
MString &buffer = reader.getBuffer();
if (mode == UNKNOWN) {
state = DONE;
return Status::COMPLETE;
}
switch (state) {
case INIT:
if (mode == URLENCODED) {
state = URLENCODED_BODY;
return Status::DATA_AVAIL;
}
// MULTIPART: the very first boundary line has no leading CRLF
// (RFC 2046) - handled here directly rather than via IMFBoundary,
// which always expects the CRLF that terminates a PRECEDING part.
// Split into two states (find+consume the marker, then separately
// disambiguate -- vs CRLF) so that if the marker is consumed but
// there isn't yet enough data to tell -- from CRLF, retrying does
// not re-search for (and skip past) a marker that is already
// behind the cursor - the exact bug class already fixed once in
// IMFBoundary's PREFIX/TAIL split.
{
MString marker;
marker << "--";
marker << boundary;
int pos = buffer.find(marker);
if (pos < 0)
return Status::INCOMPLETE;
if (!buffer.ifNext(marker))
throw coreutils::Exception("CGIFormData: opening boundary vanished between find and ifNext.");
state = OPENING_TAIL;
return Status::DATA_AVAIL;
}
case OPENING_TAIL:
if (buffer.getLength() < 2)
return Status::INCOMPLETE;
if (buffer.ifNext(ZString("--"))) {
state = DONE;
return Status::COMPLETE;
}
if (!buffer.ifNext(ZString("\r\n")))
throw coreutils::Exception("CGIFormData: malformed opening boundary line.");
state = PART_HEADERS;
return Status::DATA_AVAIL;
case URLENCODED_BODY:
if ((int)buffer.getLength() < contentLength)
return Status::INCOMPLETE;
{
ZString body(buffer.getCursor(), contentLength);
buffer.setCursor(buffer.getCursor() + contentLength);
CGIFormattedData parsed(body);
for (auto &pair : parsed.data)
storeValue(pair.first, pair.second);
}
state = DONE;
return Status::COMPLETE;
case PART_HEADERS:
if (!headerParser)
headerParser = new IMFHeader(reader);
if (!checkParse(*headerParser))
return Status::INCOMPLETE;
extractPartName(*headerParser);
delete headerParser;
headerParser = NULL;
state = PART_BODY;
return Status::DATA_AVAIL;
case PART_BODY: {
MString marker;
marker << "\r\n--";
marker << boundary;
char *bodyStart = buffer.getCursor();
int pos = buffer.find(marker);
if (pos < 0)
return Status::INCOMPLETE;
char *bodyEnd = buffer.getCursor();
if (!currentSkip && currentName.getLength() > 0)
storeValue(currentName, MString(ZString(bodyStart, bodyEnd - bodyStart)));
currentName = MString();
currentSkip = false;
state = PART_BOUNDARY;
return Status::DATA_AVAIL;
}
case PART_BOUNDARY:
if (!boundaryParser)
boundaryParser = new IMFBoundary(reader, boundary);
if (!checkParse(*boundaryParser))
return Status::INCOMPLETE;
{
bool last = boundaryParser->isLast();
delete boundaryParser;
boundaryParser = NULL;
if (last) {
state = DONE;
return Status::COMPLETE;
}
state = PART_HEADERS;
return Status::DATA_AVAIL;
}
case DONE:
return Status::COMPLETE;
}
throw coreutils::Exception("CGIFormData: unreachable state.");
}
void CGIFormData::storeValue(MString name, MString value) {
int index = nameCounts[name]++;
MString key = name;
key << ":";
key << MString(std::to_string(index));
data[key] = value;
}
MString CGIFormData::operator[](ZString name) {
if(formdata == NULL)
return MString();
return (*formdata).data[name];
MString key(name);
if (key.find(ZString(":")) == -1) {
key << ":0";
}
return data[key];
}
}