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homograph warning #12068

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21510a8
feat: detect potential homoglyph attack and warn user
isaac-preyser Apr 2, 2026
a8f6117
Merge remote-tracking branch 'origin/homoglyph-warning' into homoglyp…
Douglas-MacGregor Apr 2, 2026
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81 changes: 46 additions & 35 deletions include/ghostty.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,9 @@ typedef SSIZE_T ssize_t;
#include <sys/types.h>
#endif

// Homoglyph URL report layout for `ghostty_runtime_confirm_read_clipboard_cb` only (stddef; no VT paste API).
#include "ghostty/vt/paste_homoglyph_report.h"

//-------------------------------------------------------------------
// Macros

Expand Down Expand Up @@ -84,6 +87,11 @@ typedef enum {
GHOSTTY_CLIPBOARD_REQUEST_OSC_52_WRITE,
} ghostty_clipboard_request_e;

typedef enum {
GHOSTTY_CLIPBOARD_CONFIRM_REASON_NONE,
GHOSTTY_CLIPBOARD_CONFIRM_REASON_MIXED_SCRIPT_URL,
} ghostty_clipboard_confirm_reason_e;

typedef enum {
GHOSTTY_MOUSE_RELEASE,
GHOSTTY_MOUSE_PRESS,
Expand Down Expand Up @@ -1001,11 +1009,14 @@ typedef void (*ghostty_runtime_wakeup_cb)(void*);
typedef bool (*ghostty_runtime_read_clipboard_cb)(void*,
ghostty_clipboard_e,
void*);

typedef void (*ghostty_runtime_confirm_read_clipboard_cb)(
void*,
const char*,
void*,
ghostty_clipboard_request_e);
ghostty_clipboard_request_e,
ghostty_clipboard_confirm_reason_e,
const ghostty_paste_homoglyph_report_t*);
typedef void (*ghostty_runtime_write_clipboard_cb)(void*,
ghostty_clipboard_e,
const ghostty_clipboard_content_s*,
Expand Down Expand Up @@ -1076,14 +1087,14 @@ GHOSTTY_API void ghostty_config_load_recursive_files(ghostty_config_t);
GHOSTTY_API void ghostty_config_finalize(ghostty_config_t);
GHOSTTY_API bool ghostty_config_get(ghostty_config_t, void*, const char*, uintptr_t);
GHOSTTY_API ghostty_input_trigger_s ghostty_config_trigger(ghostty_config_t,
const char*,
uintptr_t);
const char*,
uintptr_t);
GHOSTTY_API uint32_t ghostty_config_diagnostics_count(ghostty_config_t);
GHOSTTY_API ghostty_diagnostic_s ghostty_config_get_diagnostic(ghostty_config_t, uint32_t);
GHOSTTY_API ghostty_string_s ghostty_config_open_path(void);

GHOSTTY_API ghostty_app_t ghostty_app_new(const ghostty_runtime_config_s*,
ghostty_config_t);
ghostty_config_t);
GHOSTTY_API void ghostty_app_free(ghostty_app_t);
GHOSTTY_API void ghostty_app_tick(ghostty_app_t);
GHOSTTY_API void* ghostty_app_userdata(ghostty_app_t);
Expand All @@ -1100,7 +1111,7 @@ GHOSTTY_API void ghostty_app_set_color_scheme(ghostty_app_t, ghostty_color_schem
GHOSTTY_API ghostty_surface_config_s ghostty_surface_config_new();

GHOSTTY_API ghostty_surface_t ghostty_surface_new(ghostty_app_t,
const ghostty_surface_config_s*);
const ghostty_surface_config_s*);
GHOSTTY_API void ghostty_surface_free(ghostty_surface_t);
GHOSTTY_API void* ghostty_surface_userdata(ghostty_surface_t);
GHOSTTY_API ghostty_app_t ghostty_surface_app(ghostty_surface_t);
Expand All @@ -1116,48 +1127,48 @@ GHOSTTY_API void ghostty_surface_set_occlusion(ghostty_surface_t, bool);
GHOSTTY_API void ghostty_surface_set_size(ghostty_surface_t, uint32_t, uint32_t);
GHOSTTY_API ghostty_surface_size_s ghostty_surface_size(ghostty_surface_t);
GHOSTTY_API void ghostty_surface_set_color_scheme(ghostty_surface_t,
ghostty_color_scheme_e);
ghostty_color_scheme_e);
GHOSTTY_API ghostty_input_mods_e ghostty_surface_key_translation_mods(ghostty_surface_t,
ghostty_input_mods_e);
ghostty_input_mods_e);
GHOSTTY_API bool ghostty_surface_key(ghostty_surface_t, ghostty_input_key_s);
GHOSTTY_API bool ghostty_surface_key_is_binding(ghostty_surface_t,
ghostty_input_key_s,
ghostty_binding_flags_e*);
ghostty_input_key_s,
ghostty_binding_flags_e*);
GHOSTTY_API void ghostty_surface_text(ghostty_surface_t, const char*, uintptr_t);
GHOSTTY_API void ghostty_surface_preedit(ghostty_surface_t, const char*, uintptr_t);
GHOSTTY_API bool ghostty_surface_mouse_captured(ghostty_surface_t);
GHOSTTY_API bool ghostty_surface_mouse_button(ghostty_surface_t,
ghostty_input_mouse_state_e,
ghostty_input_mouse_button_e,
ghostty_input_mods_e);
ghostty_input_mouse_state_e,
ghostty_input_mouse_button_e,
ghostty_input_mods_e);
GHOSTTY_API void ghostty_surface_mouse_pos(ghostty_surface_t,
double,
double,
ghostty_input_mods_e);
double,
double,
ghostty_input_mods_e);
GHOSTTY_API void ghostty_surface_mouse_scroll(ghostty_surface_t,
double,
double,
ghostty_input_scroll_mods_t);
double,
double,
ghostty_input_scroll_mods_t);
GHOSTTY_API void ghostty_surface_mouse_pressure(ghostty_surface_t, uint32_t, double);
GHOSTTY_API void ghostty_surface_ime_point(ghostty_surface_t, double*, double*, double*, double*);
GHOSTTY_API void ghostty_surface_request_close(ghostty_surface_t);
GHOSTTY_API void ghostty_surface_split(ghostty_surface_t, ghostty_action_split_direction_e);
GHOSTTY_API void ghostty_surface_split_focus(ghostty_surface_t,
ghostty_action_goto_split_e);
ghostty_action_goto_split_e);
GHOSTTY_API void ghostty_surface_split_resize(ghostty_surface_t,
ghostty_action_resize_split_direction_e,
uint16_t);
ghostty_action_resize_split_direction_e,
uint16_t);
GHOSTTY_API void ghostty_surface_split_equalize(ghostty_surface_t);
GHOSTTY_API bool ghostty_surface_binding_action(ghostty_surface_t, const char*, uintptr_t);
GHOSTTY_API void ghostty_surface_complete_clipboard_request(ghostty_surface_t,
const char*,
void*,
bool);
const char*,
void*,
bool);
GHOSTTY_API bool ghostty_surface_has_selection(ghostty_surface_t);
GHOSTTY_API bool ghostty_surface_read_selection(ghostty_surface_t, ghostty_text_s*);
GHOSTTY_API bool ghostty_surface_read_text(ghostty_surface_t,
ghostty_selection_s,
ghostty_text_s*);
ghostty_selection_s,
ghostty_text_s*);
GHOSTTY_API void ghostty_surface_free_text(ghostty_surface_t, ghostty_text_s*);

#ifdef __APPLE__
Expand All @@ -1172,18 +1183,18 @@ GHOSTTY_API void ghostty_inspector_set_focus(ghostty_inspector_t, bool);
GHOSTTY_API void ghostty_inspector_set_content_scale(ghostty_inspector_t, double, double);
GHOSTTY_API void ghostty_inspector_set_size(ghostty_inspector_t, uint32_t, uint32_t);
GHOSTTY_API void ghostty_inspector_mouse_button(ghostty_inspector_t,
ghostty_input_mouse_state_e,
ghostty_input_mouse_button_e,
ghostty_input_mods_e);
ghostty_input_mouse_state_e,
ghostty_input_mouse_button_e,
ghostty_input_mods_e);
GHOSTTY_API void ghostty_inspector_mouse_pos(ghostty_inspector_t, double, double);
GHOSTTY_API void ghostty_inspector_mouse_scroll(ghostty_inspector_t,
double,
double,
ghostty_input_scroll_mods_t);
double,
double,
ghostty_input_scroll_mods_t);
GHOSTTY_API void ghostty_inspector_key(ghostty_inspector_t,
ghostty_input_action_e,
ghostty_input_key_e,
ghostty_input_mods_e);
ghostty_input_action_e,
ghostty_input_key_e,
ghostty_input_mods_e);
GHOSTTY_API void ghostty_inspector_text(ghostty_inspector_t, const char*);

#ifdef __APPLE__
Expand Down
16 changes: 16 additions & 0 deletions include/ghostty/vt/paste.h
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@

#include <stdbool.h>
#include <stddef.h>
#include "ghostty/vt/paste_homoglyph_report.h"
#include <ghostty/vt/types.h>

#ifdef __cplusplus
Expand Down Expand Up @@ -92,6 +93,21 @@ GHOSTTY_API GhosttyResult ghostty_paste_encode(
size_t buf_len,
size_t* out_written);

GHOSTTY_API size_t ghostty_paste_homoglyph_suspicious_spans(const char* data,
size_t len,
ghostty_paste_homoglyph_span_t* out,
size_t max_out);


GHOSTTY_API int ghostty_paste_homoglyph_first_url_range(const char* data,
size_t len,
size_t* out_start,
size_t* out_end);

GHOSTTY_API int ghostty_paste_homoglyph_first_url_report(const char* data,
size_t len,
ghostty_paste_homoglyph_report_t* out);

#ifdef __cplusplus
}
#endif
Expand Down
39 changes: 39 additions & 0 deletions include/ghostty/vt/paste_homoglyph_report.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
/**
* @file paste_homoglyph_report.h
*
* Layout for mixed-script URL homoglyph data passed to embedders via
* `ghostty_runtime_confirm_read_clipboard_cb`. Shared with `paste.h` for the VT
* library; this header has no VT paste API and does not include `types.h`.
*/

#ifndef GHOSTTY_VT_PASTE_HOMOGLYPH_REPORT_H
#define GHOSTTY_VT_PASTE_HOMOGLYPH_REPORT_H

#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

/** UTF-8 byte range in paste data (`end` exclusive). */
typedef struct {
size_t start;
size_t end;
} ghostty_paste_homoglyph_span_t;

/** Max spans stored in `ghostty_paste_homoglyph_report_t::spans`. */
#define GHOSTTY_PASTE_HOMOGLYPH_REPORT_MAX_SPANS 128

typedef struct {
size_t url_start;
size_t url_end;
size_t span_total;
size_t span_written;
ghostty_paste_homoglyph_span_t spans[GHOSTTY_PASTE_HOMOGLYPH_REPORT_MAX_SPANS];
} ghostty_paste_homoglyph_report_t;

#ifdef __cplusplus
}
#endif

#endif /* GHOSTTY_VT_PASTE_HOMOGLYPH_REPORT_H */
23 changes: 16 additions & 7 deletions macos/Sources/Features/ClipboardConfirmation/ClipboardConfirmationController.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -12,13 +12,25 @@ class ClipboardConfirmationController: NSWindowController {
let surface: ghostty_surface_t
let contents: String
let request: Ghostty.ClipboardRequest
let confirmReason: Ghostty.ClipboardConfirmReason
let homoglyphHighlight: Ghostty.PasteHomoglyphURLHighlight?
let state: UnsafeMutableRawPointer?
weak private var delegate: ClipboardConfirmationViewDelegate?

init(surface: ghostty_surface_t, contents: String, request: Ghostty.ClipboardRequest, state: UnsafeMutableRawPointer?, delegate: ClipboardConfirmationViewDelegate) {
init(
surface: ghostty_surface_t,
contents: String,
request: Ghostty.ClipboardRequest,
confirmReason: Ghostty.ClipboardConfirmReason = .none,
homoglyphHighlight: Ghostty.PasteHomoglyphURLHighlight? = nil,
state: UnsafeMutableRawPointer?,
delegate: ClipboardConfirmationViewDelegate
) {
self.surface = surface
self.contents = contents
self.request = request
self.confirmReason = confirmReason
self.homoglyphHighlight = homoglyphHighlight
self.state = state
self.delegate = delegate
super.init(window: nil)
Expand All @@ -33,16 +45,13 @@ class ClipboardConfirmationController: NSWindowController {
override func windowDidLoad() {
guard let window = window else { return }

switch request {
case .paste:
window.title = "Warning: Potentially Unsafe Paste"
case .osc_52_read, .osc_52_write:
window.title = "Authorize Clipboard Access"
}
window.title = request.windowTitle(confirmReason: confirmReason)

window.contentView = NSHostingView(rootView: ClipboardConfirmationView(
contents: contents,
request: request,
confirmReason: confirmReason,
homoglyphHighlight: homoglyphHighlight,
delegate: delegate
))
}
Expand Down
40 changes: 39 additions & 1 deletion macos/Sources/Features/ClipboardConfirmation/ClipboardConfirmationView.swift
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -31,12 +31,31 @@ struct ClipboardConfirmationView: View {
/// The type of the clipboard request
let request: Ghostty.ClipboardRequest

/// When request is paste, selects between default unsafe-paste copy and mixed-script URL copy.
let confirmReason: Ghostty.ClipboardConfirmReason

let homoglyphHighlight: Ghostty.PasteHomoglyphURLHighlight?

/// Optional delegate to get results. If this is nil, then this view will never close on its own.
weak var delegate: ClipboardConfirmationViewDelegate?

/// Used to track if we should rehide on disappear
@State private var cursorHiddenCount: UInt = 0

init(
contents: String,
request: Ghostty.ClipboardRequest,
confirmReason: Ghostty.ClipboardConfirmReason,
homoglyphHighlight: Ghostty.PasteHomoglyphURLHighlight? = nil,
delegate: ClipboardConfirmationViewDelegate?
) {
self.contents = contents
self.request = request
self.confirmReason = confirmReason
self.homoglyphHighlight = homoglyphHighlight
self.delegate = delegate
}

var body: some View {
VStack {
HStack {
Expand All @@ -46,14 +65,33 @@ struct ClipboardConfirmationView: View {
.padding()
.frame(alignment: .center)

Text(request.text())
Text(request.text(confirmReason: confirmReason))
.frame(maxWidth: .infinity, alignment: .leading)
.padding()
.multilineTextAlignment(.leading)
.lineLimit(6)
.fixedSize(horizontal: false, vertical: true)
}

if let highlight = homoglyphHighlight {
VStack(alignment: .leading, spacing: 8) {
Text("Suspicious URL (non-ascii characters are red and underlined)")
.font(.caption)
.foregroundStyle(.secondary)
Text(highlight.attributedLine())
.font(.system(.body, design: .monospaced))
.textSelection(.enabled)
.frame(maxWidth: .infinity, alignment: .leading)
}
.padding(.horizontal)
.padding(.bottom, 4)
.frame(maxWidth: .infinity, alignment: .leading)
}

TextEditor(text: .constant(contents))
.focusable(false)
.font(.system(.body, design: .monospaced))
.padding(.top, homoglyphHighlight != nil ? 2 : 0)

HStack {
Spacer()
Expand Down
6 changes: 6 additions & 0 deletions macos/Sources/Features/Terminal/BaseTerminalController.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1086,6 +1086,10 @@ class BaseTerminalController: NSWindowController,
guard let str = notification.userInfo?[Ghostty.Notification.ConfirmClipboardStrKey] as? String else { return }
guard let state = notification.userInfo?[Ghostty.Notification.ConfirmClipboardStateKey] as? UnsafeMutableRawPointer? else { return }
guard let request = notification.userInfo?[Ghostty.Notification.ConfirmClipboardRequestKey] as? Ghostty.ClipboardRequest else { return }
let rawReason = notification.userInfo?[Ghostty.Notification.ConfirmClipboardConfirmReasonKey] as? Int
let confirmReason = Ghostty.ClipboardConfirmReason(rawValue: rawReason ?? 0) ?? .none
let homoglyphHighlight =
notification.userInfo?[Ghostty.Notification.ConfirmClipboardHomoglyphPayloadKey] as? Ghostty.PasteHomoglyphURLHighlight

// If we already have a clipboard confirmation view up, we ignore this request.
// This shouldn't be possible...
Expand All @@ -1099,6 +1103,8 @@ class BaseTerminalController: NSWindowController,
surface: surface,
contents: str,
request: request,
confirmReason: confirmReason,
homoglyphHighlight: homoglyphHighlight,
state: state,
delegate: self
)
Expand Down
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