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https://issues.apache.org/jira/browse/GUACAMOLE-1514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17716442#comment-17716442
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Nick Couchman commented on GUACAMOLE-1514:
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[~gvalcaza]: Thanks for the detail in tracking this down. It'd be great if you
can open a pull request for at least the patch you attached, that would be
great. If you also find a way to implement those hooks that is compatible with
other RDP servers, that would be fine, too.
> Self-built guacd, Release 1.4.0, crashes when browser resolution is smaller
> than remote desktop resolution
> ----------------------------------------------------------------------------------------------------------
>
> Key: GUACAMOLE-1514
> URL: https://issues.apache.org/jira/browse/GUACAMOLE-1514
> Project: Guacamole
> Issue Type: Bug
> Components: guacamole-server, guacd, RDP
> Affects Versions: 1.4.0
> Reporter: Gabriel Joseph Valcázar Berdofe
> Priority: Major
> Attachments:
> 0001-rdp-gdi-resize-bitmap-buffer-to-match-server-s-displ.patch
>
>
> ||Component||Release||
> |guacd|1.4.0|
> |OS|Kubuntu 18.04|
> |FreeRDP|2.4.1|
> |RDP server|Weston 9.0.0 w/ RDP backend|
> I originally found this bug when testing a specific application which uses a
> rotated 800x1280 UI. Attempting to access the application via Guacamole
> always resulted in its RDP client crashing and resetting the connection with
> no additional information in the log, even with debug messages enabled. I
> then tried using different combinations of web browser and application sizes,
> and the client always crashes as long as the initial web browser size is
> smaller than the application's.
> Here's a guacd log using a small browser size and the 800x1280:
> {code:java}
> guacd[17516]: INFO: Connection ID is
> "$402f4aad-2d4a-4f07-86af-4fff9288e35c"
> guacd[17519]: DEBUG: Processing instruction: size
> guacd[17519]: DEBUG: Processing instruction: audio
> guacd[17519]: DEBUG: Processing instruction: video
> guacd[17519]: DEBUG: Processing instruction: image
> guacd[17519]: DEBUG: Processing instruction: timezone
> guacd[17519]: DEBUG: Parameter "console" omitted. Using default value of 0.
> guacd[17519]: DEBUG: Parameter "console-audio" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "disable-auth" omitted. Using default value
> of 0.
> guacd[17519]: INFO: No security mode specified. Defaulting to security
> mode negotiation with server.
> guacd[17519]: DEBUG: User resolution is 808x452 at 96 DPI
> guacd[17519]: DEBUG: Parameter "dpi" omitted. Using default value of 96.
> guacd[17519]: DEBUG: Using resolution of 808x452 at 96 DPI
> guacd[17519]: DEBUG: Parameter "force-lossless" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "read-only" omitted. Using default value of
> 0.
> guacd[17519]: DEBUG: Parameter "client-name" omitted. Using default value
> of "Guacamole RDP".
> guacd[17519]: DEBUG: Parameter "enable-theming" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "enable-font-smoothing" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "enable-full-window-drag" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "enable-desktop-composition" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "enable-menu-animations" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "disable-bitmap-caching" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "disable-offscreen-caching" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "disable-glyph-caching" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Glyph caching is currently universally disabled,
> regardless of the value of the "disable-glyph-caching" parameter, as glyph
> caching support is not considered stable by FreeRDP as of the FreeRDP 2.0.0
> release. See: https://issues.apache.org/jira/browse/GUACAMOLE-1191
> guacd[17519]: DEBUG: Parameter "disable-audio" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "enable-printing" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "printer-name" omitted. Using default value
> of "Guacamole Printer".
> guacd[17519]: DEBUG: Parameter "enable-drive" omitted. Using default value
> of 0.
> guacd[17519]: DEBUG: Parameter "drive-name" omitted. Using default value
> of "Guacamole Filesystem".
> guacd[17519]: DEBUG: Parameter "drive-path" omitted. Using default value
> of "".
> guacd[17519]: DEBUG: Parameter "create-drive-path" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "disable-download" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "disable-upload" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "timezone" omitted. Using default value of
> "Europe/Madrid".
> guacd[17519]: DEBUG: Parameter "enable-sftp" omitted. Using default value
> of 0.
> guacd[17519]: DEBUG: Parameter "sftp-hostname" omitted. Using default
> value of "10.101.2.164".
> guacd[17519]: DEBUG: Parameter "sftp-port" omitted. Using default value of
> "22".
> guacd[17519]: DEBUG: Parameter "sftp-username" omitted. Using default
> value of "".
> guacd[17519]: DEBUG: Parameter "sftp-password" omitted. Using default
> value of "".
> guacd[17519]: DEBUG: Parameter "sftp-passphrase" omitted. Using default
> value of "".
> guacd[17519]: DEBUG: Parameter "sftp-root-directory" omitted. Using
> default value of "/".
> guacd[17519]: DEBUG: Parameter "sftp-server-alive-interval" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "sftp-disable-download" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "sftp-disable-upload" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "recording-name" omitted. Using default
> value of "recording".
> guacd[17519]: DEBUG: Parameter "recording-exclude-output" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "recording-exclude-mouse" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "recording-exclude-touch" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "recording-include-keys" omitted. Using
> default value of 0.
> guacd[17519]: DEBUG: Parameter "create-recording-path" omitted. Using
> default value of 0.
> guacd[17519]: INFO: Resize method: none
> guacd[17519]: DEBUG: Parameter "enable-touch" omitted. Using default value
> of 0.
> guacd[17519]: DEBUG: Parameter "enable-audio-input" omitted. Using default
> value of 0.
> guacd[17519]: DEBUG: Parameter "gateway-port" omitted. Using default value
> of 443.
> guacd[17519]: DEBUG: Parameter "disable-copy" omitted. Using default value
> of 0.
> guacd[17519]: DEBUG: Parameter "disable-paste" omitted. Using default
> value of 0.
> guacd[17519]: INFO: No clipboard line-ending normalization specified.
> Defaulting to preserving the format of all line endings.
> guacd[17519]: DEBUG: Parameter "wol-send-packet" omitted. Using default
> value of 0.
> guacd[17519]: INFO: User "@367f8cf8-3120-42c1-8f48-9839a2a1d808" joined
> connection "$402f4aad-2d4a-4f07-86af-4fff9288e35c" (1 users now present)
> guacd[17519]: DEBUG: Client is using protocol version "VERSION_1_3_0"
> guacd[17519]: INFO: Loading keymap "base"
> guacd[17519]: INFO: Loading keymap "en-us-qwerty"
> guacd[17519]: DEBUG: freerdp_connect:freerdp_set_last_error_ex resetting
> error state
> guacd[17519]: DEBUG: Support for CLIPRDR (clipboard redirection)
> registered. Awaiting channel connection.
> guacd[17519]: DEBUG: Support for static channel "rdpdr" loaded.
> guacd[17519]: DEBUG: Support for static channel "rdpsnd" loaded.
> guacd[17519]: DEBUG: Local framebuffer format PIXEL_FORMAT_BGRX32
> guacd[17519]: DEBUG: Remote framebuffer format PIXEL_FORMAT_BGR24
> guacd[17519]: DEBUG: primitives autodetect, using optimized
> guacd[17519]: DEBUG:
> freerdp_tcp_is_hostname_resolvable:freerdp_set_last_error_ex resetting error
> state
> guacd[17519]: DEBUG: freerdp_tcp_connect:freerdp_set_last_error_ex
> resetting error state
> guacd[17519]: DEBUG: CLIPRDR (clipboard redirection) channel connected.
> guacd[17519]: DEBUG: SVC "rdpdr" connected.
> guacd[17519]: DEBUG: SVC "rdpsnd" connected.
> guacd[17519]: DEBUG: Server resized display to 800x1280
> guacd[17519]: DEBUG: tpdu length 0 > tpkt header length 0
> ...
> guacd[17519]: DEBUG: tpdu length 0 > tpkt header length 0
> guacd[17516]: INFO: Connection "$402f4aad-2d4a-4f07-86af-4fff9288e35c"
> removed. {code}
> After debugging FreeRDP, I found the root cause of the issue: the guacamole
> RDP component initializes FreeRDP's gdi bitmap buffer using the web browser's
> initial resolution (in the log above, "Using resolution of 808x452 at 96
> DPI"). Then, guacamole receives the server's desktop resolution ("Server
> resized display to 800x1280"), but the bitmap buffer is not resized
> accordingly. Once guacamole's FreeRDP receives the server's bitmap and copies
> it to gdi's buffer, one of three things can happen:
> * The browser and desktop resolutions are the same ->the bitmap fits
> perfectly
> * The browser is larger than the desktop -> the bitmap fits with room to
> spare
> * The browser is smaller than the desktop -> the bitmap {*}doesn't fit{*},
> and eventually, there is an *out of bounds* memcpy that causes
> FreeRDP/guacamole to crash.
> In my case, the crash happens in this part of the _freerdp_image_copy()_
> function in FreeRDP. As soon as the loop surpasses the web browser's height,
> guacamole crashes (in the case of the log above, since the browser has a
> height of {*}452{*}, the crash happens in iteration {*}453{*}):
> {code:java}
> for (y = 0; y < (INT32)nHeight; y++)
> {
> const BYTE* srcLine =
> &pSrcData[(y + nYSrc) * nSrcStep * srcVMultiplier +
> srcVOffset];
> BYTE* dstLine = &pDstData[(y + nYDst) * nDstStep *
> dstVMultiplier + dstVOffset];
> memcpy(&dstLine[xDstOffset], &srcLine[xSrcOffset],
> copyDstWidth);
> } {code}
> Thankfully, FreeRDP's gdi API has a function that allows to resize the bitmap
> buffer on the fly. By calling said function from guacamole when it receives
> the server's resolution ("Server resized display to 800x1280"), I was able to
> circumvent the issue. I'm not sure if this fix has other implications, but
> I'm attaching a patch for it.
> Also, I don't know if this issue is specific to my client/server combination,
> but I haven't seen the gdi buffer being resized anywhere else in the code, so
> we might as well do so if we have the chance.
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