Milestone 5: deliver embedded RDP sessions and lifecycle hardening
This commit is contained in:
Keith Smith
362
third_party/FreeRDP/server/proxy/pf_channel.c
vendored
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362
third_party/FreeRDP/server/proxy/pf_channel.c
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/**
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* FreeRDP: A Remote Desktop Protocol Implementation
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*
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* Copyright 2022 David Fort <contact@hardening-consulting.com>
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <winpr/assert.h>
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#include <winpr/cast.h>
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#include <freerdp/freerdp.h>
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#include <freerdp/server/proxy/proxy_log.h>
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#include "proxy_modules.h"
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#include "pf_channel.h"
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#define TAG PROXY_TAG("channel")
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/** @brief a tracker for channel packets */
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struct sChannelStateTracker
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{
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pServerStaticChannelContext* channel;
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ChannelTrackerMode mode;
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wStream* currentPacket;
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size_t currentPacketReceived;
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size_t currentPacketSize;
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size_t currentPacketFragments;
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ChannelTrackerPeekFn peekFn;
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void* trackerData;
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proxyData* pdata;
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};
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WINPR_ATTR_NODISCARD
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static BOOL channelTracker_resetCurrentPacket(ChannelStateTracker* tracker)
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{
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WINPR_ASSERT(tracker);
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BOOL create = TRUE;
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if (tracker->currentPacket)
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{
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const size_t cap = Stream_Capacity(tracker->currentPacket);
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if (cap < 1ULL * 1000ULL * 1000ULL)
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create = FALSE;
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else
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Stream_Free(tracker->currentPacket, TRUE);
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}
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if (create)
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tracker->currentPacket = Stream_New(nullptr, 10ULL * 1024ULL);
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if (!tracker->currentPacket)
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return FALSE;
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Stream_ResetPosition(tracker->currentPacket);
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return TRUE;
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}
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ChannelStateTracker* channelTracker_new(pServerStaticChannelContext* channel,
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ChannelTrackerPeekFn fn, void* data)
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{
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ChannelStateTracker* ret = calloc(1, sizeof(ChannelStateTracker));
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if (!ret)
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return ret;
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WINPR_ASSERT(fn);
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ret->channel = channel;
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ret->peekFn = fn;
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if (!channelTracker_setCustomData(ret, data))
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goto fail;
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if (!channelTracker_resetCurrentPacket(ret))
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goto fail;
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return ret;
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fail:
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WINPR_PRAGMA_DIAG_PUSH
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WINPR_PRAGMA_DIAG_IGNORED_MISMATCHED_DEALLOC
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channelTracker_free(ret);
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WINPR_PRAGMA_DIAG_POP
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return nullptr;
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}
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PfChannelResult channelTracker_update(ChannelStateTracker* tracker, const BYTE* xdata, size_t xsize,
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UINT32 flags, size_t totalSize)
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{
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PfChannelResult result = PF_CHANNEL_RESULT_ERROR;
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BOOL firstPacket = (flags & CHANNEL_FLAG_FIRST) != 0;
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BOOL lastPacket = (flags & CHANNEL_FLAG_LAST) != 0;
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WINPR_ASSERT(tracker);
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WLog_VRB(TAG, "channelTracker_update(%s): sz=%" PRIuz " first=%d last=%d",
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tracker->channel->channel_name, xsize, firstPacket, lastPacket);
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if (flags & CHANNEL_FLAG_FIRST)
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{
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if (!channelTracker_resetCurrentPacket(tracker))
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return PF_CHANNEL_RESULT_ERROR;
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channelTracker_setCurrentPacketSize(tracker, totalSize);
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tracker->currentPacketReceived = 0;
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tracker->currentPacketFragments = 0;
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}
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{
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const size_t currentPacketSize = channelTracker_getCurrentPacketSize(tracker);
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if (tracker->currentPacketReceived + xsize > currentPacketSize)
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WLog_INFO(TAG, "cumulated size is bigger (%" PRIuz ") than total size (%" PRIuz ")",
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tracker->currentPacketReceived + xsize, currentPacketSize);
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}
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tracker->currentPacketReceived += xsize;
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tracker->currentPacketFragments++;
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switch (channelTracker_getMode(tracker))
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{
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case CHANNEL_TRACKER_PEEK:
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{
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wStream* currentPacket = channelTracker_getCurrentPacket(tracker);
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if (!Stream_EnsureRemainingCapacity(currentPacket, xsize))
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return PF_CHANNEL_RESULT_ERROR;
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Stream_Write(currentPacket, xdata, xsize);
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WINPR_ASSERT(tracker->peekFn);
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result = tracker->peekFn(tracker, firstPacket, lastPacket);
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}
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break;
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case CHANNEL_TRACKER_PASS:
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result = PF_CHANNEL_RESULT_PASS;
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break;
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case CHANNEL_TRACKER_DROP:
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result = PF_CHANNEL_RESULT_DROP;
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break;
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default:
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break;
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}
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if (lastPacket)
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{
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const size_t currentPacketSize = channelTracker_getCurrentPacketSize(tracker);
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channelTracker_setMode(tracker, CHANNEL_TRACKER_PEEK);
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if (tracker->currentPacketReceived != currentPacketSize)
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WLog_INFO(TAG, "cumulated size(%" PRIuz ") does not match total size (%" PRIuz ")",
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tracker->currentPacketReceived, currentPacketSize);
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}
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return result;
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}
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void channelTracker_free(ChannelStateTracker* t)
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{
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if (!t)
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return;
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Stream_Free(t->currentPacket, TRUE);
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free(t);
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}
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/**
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* Flushes the current accumulated tracker content, if it's the first packet, then
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* when can just return that the packet shall be passed, otherwise to have to refragment
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* the accumulated current packet.
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*/
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PfChannelResult channelTracker_flushCurrent(ChannelStateTracker* t, BOOL first, BOOL last,
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BOOL toBack)
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{
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proxyData* pdata = nullptr;
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pServerContext* ps = nullptr;
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pServerStaticChannelContext* channel = nullptr;
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UINT32 flags = CHANNEL_FLAG_FIRST;
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BOOL r = 0;
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const char* direction = toBack ? "F->B" : "B->F";
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const size_t currentPacketSize = channelTracker_getCurrentPacketSize(t);
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wStream* currentPacket = channelTracker_getCurrentPacket(t);
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WINPR_ASSERT(t);
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WLog_VRB(TAG, "channelTracker_flushCurrent(%s): %s sz=%" PRIuz " first=%d last=%d",
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t->channel->channel_name, direction, Stream_GetPosition(currentPacket), first, last);
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if (first)
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return PF_CHANNEL_RESULT_PASS;
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pdata = t->pdata;
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channel = t->channel;
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if (last)
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flags |= CHANNEL_FLAG_LAST;
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if (toBack)
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{
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proxyChannelDataEventInfo ev = WINPR_C_ARRAY_INIT;
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ev.channel_id = WINPR_ASSERTING_INT_CAST(UINT16, channel->front_channel_id);
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ev.channel_name = channel->channel_name;
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ev.data = Stream_Buffer(currentPacket);
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ev.data_len = Stream_GetPosition(currentPacket);
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ev.flags = flags;
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ev.total_size = currentPacketSize;
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if (!pdata->pc->sendChannelData)
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return PF_CHANNEL_RESULT_ERROR;
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return pdata->pc->sendChannelData(pdata->pc, &ev) ? PF_CHANNEL_RESULT_DROP
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: PF_CHANNEL_RESULT_ERROR;
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}
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ps = pdata->ps;
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r = ps->context.peer->SendChannelPacket(
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ps->context.peer, WINPR_ASSERTING_INT_CAST(UINT16, channel->front_channel_id),
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currentPacketSize, flags, Stream_Buffer(currentPacket), Stream_GetPosition(currentPacket));
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return r ? PF_CHANNEL_RESULT_DROP : PF_CHANNEL_RESULT_ERROR;
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}
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WINPR_ATTR_NODISCARD
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static PfChannelResult pf_channel_generic_back_data(proxyData* pdata,
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const pServerStaticChannelContext* channel,
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const BYTE* xdata, size_t xsize, UINT32 flags,
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size_t totalSize)
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{
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proxyChannelDataEventInfo ev = WINPR_C_ARRAY_INIT;
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WINPR_ASSERT(pdata);
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WINPR_ASSERT(channel);
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switch (channel->channelMode)
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{
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case PF_UTILS_CHANNEL_PASSTHROUGH:
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ev.channel_id = WINPR_ASSERTING_INT_CAST(UINT16, channel->back_channel_id);
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ev.channel_name = channel->channel_name;
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ev.data = xdata;
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ev.data_len = xsize;
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ev.flags = flags;
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ev.total_size = totalSize;
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if (!pf_modules_run_filter(pdata->module, FILTER_TYPE_CLIENT_PASSTHROUGH_CHANNEL_DATA,
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pdata, &ev))
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return PF_CHANNEL_RESULT_DROP; /* Silently drop */
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return PF_CHANNEL_RESULT_PASS;
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case PF_UTILS_CHANNEL_INTERCEPT:
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/* TODO */
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case PF_UTILS_CHANNEL_BLOCK:
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default:
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return PF_CHANNEL_RESULT_DROP;
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}
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}
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WINPR_ATTR_NODISCARD
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static PfChannelResult pf_channel_generic_front_data(proxyData* pdata,
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const pServerStaticChannelContext* channel,
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const BYTE* xdata, size_t xsize, UINT32 flags,
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size_t totalSize)
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{
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proxyChannelDataEventInfo ev = WINPR_C_ARRAY_INIT;
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WINPR_ASSERT(pdata);
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WINPR_ASSERT(channel);
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switch (channel->channelMode)
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{
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case PF_UTILS_CHANNEL_PASSTHROUGH:
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ev.channel_id = WINPR_ASSERTING_INT_CAST(UINT16, channel->front_channel_id);
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ev.channel_name = channel->channel_name;
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ev.data = xdata;
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ev.data_len = xsize;
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ev.flags = flags;
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ev.total_size = totalSize;
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if (!pf_modules_run_filter(pdata->module, FILTER_TYPE_SERVER_PASSTHROUGH_CHANNEL_DATA,
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pdata, &ev))
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return PF_CHANNEL_RESULT_DROP; /* Silently drop */
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return PF_CHANNEL_RESULT_PASS;
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case PF_UTILS_CHANNEL_INTERCEPT:
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/* TODO */
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case PF_UTILS_CHANNEL_BLOCK:
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default:
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return PF_CHANNEL_RESULT_DROP;
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}
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}
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BOOL pf_channel_setup_generic(pServerStaticChannelContext* channel)
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{
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WINPR_ASSERT(channel);
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channel->onBackData = pf_channel_generic_back_data;
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channel->onFrontData = pf_channel_generic_front_data;
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return TRUE;
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}
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BOOL channelTracker_setMode(ChannelStateTracker* tracker, ChannelTrackerMode mode)
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{
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WINPR_ASSERT(tracker);
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tracker->mode = mode;
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return TRUE;
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}
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ChannelTrackerMode channelTracker_getMode(ChannelStateTracker* tracker)
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{
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WINPR_ASSERT(tracker);
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return tracker->mode;
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}
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BOOL channelTracker_setPData(ChannelStateTracker* tracker, proxyData* pdata)
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{
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WINPR_ASSERT(tracker);
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tracker->pdata = pdata;
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return TRUE;
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}
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proxyData* channelTracker_getPData(ChannelStateTracker* tracker)
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{
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WINPR_ASSERT(tracker);
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return tracker->pdata;
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}
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wStream* channelTracker_getCurrentPacket(ChannelStateTracker* tracker)
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{
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WINPR_ASSERT(tracker);
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return tracker->currentPacket;
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}
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BOOL channelTracker_setCustomData(ChannelStateTracker* tracker, void* data)
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{
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WINPR_ASSERT(tracker);
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tracker->trackerData = data;
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return TRUE;
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}
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void* channelTracker_getCustomData(ChannelStateTracker* tracker)
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{
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WINPR_ASSERT(tracker);
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return tracker->trackerData;
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}
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size_t channelTracker_getCurrentPacketSize(ChannelStateTracker* tracker)
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{
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WINPR_ASSERT(tracker);
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return tracker->currentPacketSize;
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}
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BOOL channelTracker_setCurrentPacketSize(ChannelStateTracker* tracker, size_t size)
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{
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WINPR_ASSERT(tracker);
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tracker->currentPacketSize = size;
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return TRUE;
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}
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