vnsee-gui

#!/usr/bin/env bash
#
# vnsee-gui
#
# A simple GUI that allows the user to choose from available VNC servers
# and starts VNSee with the right arguments

set -euo pipefail

if ! command -v simple > /dev/null; then
    echo "Error: $0 needs the 'simple' program to work"
    echo "Please install it and try again"
    exit 1
fi

if ! command -v vnsee > /dev/null; then
    echo "Error: $0 needs the 'vnsee' program to work"
    echo "Please install it and try again"
    exit 1
fi

has_nmap=1

if ! command -v nmap > /dev/null; then
    has_nmap=0
    echo "Warning: The 'nmap' program is not installed"
    echo "Auto-detection of available servers will not work"
    echo
fi

# Awk script for extracting host/port pairs from Nmap
open_port_suffix="\/open\/tcp"
read -r -d '' nmap_open_port_awk << AWK || true
    /Host:.*Ports:/{
        host = \$2;
        while (match(\$0, /[0-9]+$open_port_suffix/)) {
            port = substr(\$0, RSTART, RLENGTH);
            sub(/$open_port_suffix/, "", port);
            print host " " port;
            \$0 = substr(\$0, RSTART + RLENGTH);
        }
    }
AWK

# Scan for VNC servers listening over the USB network
#
# Output:
#
# Lines in the `IP PORT` format where, each line corresponds
# to a server that was found.
scan-servers-usb() {
    if [[ $has_nmap = 0 ]]; then
        return
    fi
    local usb_subnet
    usb_subnet="$(ip -f inet addr show usb0 | awk '/inet/{print $2}')"
    nmap "$usb_subnet" -p5900-5905 -oG - | awk "$nmap_open_port_awk"
}

# Helpers for building a UI scene
reset() {
    scene=("@fontsize 42")
}

add() {
    scene+=("@$*")
}

ui() {
    scene+=("[$*]")
}

# Update interface and wait for user input
wait-for-input() {
    (
        for line in "${scene[@]}"; do
            echo "$line"
        done
    ) | simple
}

# Display a selectable list of options
#
# Params:
#
#   $1 - Identifier prefix for each option
#   $2 - Starting X coordinate
#   $3 - Starting Y coordinate
#   $… - Options to display
#
# Output:
#
# Sets the next_y variable to the next available Y coordinate.
display-options() {
    local id="$1"
    local x_start="$2"
    local y_start="$3"

    if [[ $# -lt 4 ]]; then
        ui label "$x_start" "$y_start" 450 50 "(None)"
        ((y_start += 60))
    else
        for ((i = 4; i <= "$#"; i++)); do
            ui "button:$id-$((i - 4))" "$x_start" "$y_start" 450 50 "> ${!i}"
            ((y_start += 60))
        done
    fi

    y_next="$y_start"
}

# History of last used servers
server_history_file="$HOME/.cache/vnsee-gui/history"

if [[ ! -f $server_history_file ]]; then
    mkdir -p "$(dirname "$server_history_file")"
    touch "$server_history_file"
fi

# Add an entry to the history of last used servers (or move it up in the list)
#
# Params:
#
#   $1 - IP address of the server to add to the list
#   $1 - Port of the server
save-history() {
    mapfile -t histsrvs < "$server_history_file"
    output=("$1 $2")

    for srv in "${histsrvs[@]}"; do
        if [[ $srv != "$1 $2" ]]; then
            output+=("$srv")
        fi
    done

    (
        for line in "${output[@]:0:5}"; do
            echo "$line"
        done
    ) > "$server_history_file"
}

read -r -d '' help_message << MSG || true
Please choose a server to connect to.
If you’re connected via USB to a computer running a VNC server, it should show up below. You can also input the address of a specific server.
MSG

# Initial scene for configuring VNSee
#
# Output:
#
#   - First line: Chosen IP address and port number
#   - Second line: Flags to pass to VNSee
#
# Exit code:
#
# 0 if the user chose a server, 1 to quit
configure-vnsee() {
    # Scan for VNC servers over USB
    mapfile -t usbsrvs < <(scan-servers-usb)

    # Read history of last used servers
    mapfile -t histsrvs < "$server_history_file"

    # Manual address entry
    manual_ip=10.11.99.2
    manual_port=5900

    # Set to the user-selected server
    selected_server=

    # Input flags
    declare -A input_state=()
    input_state[buttons]=1
    input_state[pen]=1
    input_state[touch]=1

    while true; do
        reset

        add justify center
        y_next=80
        ui label 80 "$y_next" 1248 50 "VNSee"

        add justify left
        ui button:quit 80 "$y_next" 200 50 "Quit"
        ((y_next += 150))
        ui paragraph 80 "$y_next" 1248 200 "$help_message"

        ((y_next += 300))
        ui label 80 "$y_next" 200 50 Servers listening over USB:
        ((y_next += 50))
        display-options usbsrv 80 "$y_next" "${usbsrvs[@]}"

        ((y_next += 100))
        ui label 80 "$y_next" 200 50 Last used servers:
        ((y_next += 50))
        display-options histsrv 80 "$y_next" "${histsrvs[@]}"

        ((y_next += 100))
        ui label 80 "$y_next" 200 50 Enter new address:
        ((y_next += 50))
        ui textinput:manualip 80 "$y_next" 450 50 "$manual_ip"
        ui textinput:manualport 580 "$y_next" 200 50 "$manual_port"
        ui button:manualsrv 830 "$y_next" 200 50 Connect

        ((y_next += 150))
        ui label 80 "$y_next" 200 50 Input settings:

        for kind in buttons pen touch; do
            ((y_next += 60))

            if ((${input_state[$kind]})); then
                state="enabled"
                action="Disable"
            else
                state="disabled"
                action="Enable"
            fi

            ui label 80 "$y_next" 450 50 "$kind $state"
            ui "button:toggle$kind" 530 "$y_next" 200 50 "$action"
        done

        result="$(wait-for-input)"

        if [[ $result =~ ^input: ]]; then
            input="${result#input: }"

            if [[ $input =~ ^manualip\ : ]]; then
                manual_ip="${input#manualip : }"
            elif [[ $input =~ ^manualport\ : ]]; then
                manual_port="${input#manualport : }"
            fi
        elif [[ $result =~ ^selected: ]]; then
            button="${result#selected: }"

            if [[ $button =~ ^usbsrv- ]]; then
                index="${button#usbsrv-}"
                selected_server="${usbsrvs[index]}"
                break
            elif [[ $button =~ ^histsrv- ]]; then
                index="${button#histsrv-}"
                selected_server="${histsrvs[index]}"
                break
            elif [[ $button = manualsrv ]]; then
                selected_server="$manual_ip $manual_port"
                break
            elif [[ $button =~ ^toggle ]]; then
                kind="${button#toggle}"
                input_state[$kind]=$((1 - ${input_state[$kind]}))
            elif [[ $button == quit ]]; then
                return 1
            fi
        fi
    done

    echo "$selected_server"

    for kind in buttons pen touch; do
        if ! ((${input_state[$kind]})); then
            echo -n "--no-$kind "
        fi
    done

    echo
    return 0
}

# Show a waiting screen while VNSee connects to a server
#
# Params:
#
#   $1 - IP address of the server we’re connecting to
#   $1 - Port of the server
please-wait() {
    reset
    add timeout 1
    add padding_x 15%
    add padding_y 15%

    ui label 0 0 200 50 Please wait
    ui label 0 50 200 100 Connecting to "$1":"$2"…
    wait-for-input
}

# Show error logs after VNSee exits
#
# Params:
#
#   $1 - Path to the file containing the VNSee error log
show-errors() {
    reset
    add padding_x 15%
    add padding_y 15%

    y_next=0
    ui label 0 0 200 50 VNSee error:

    ((y_next += 100))
    while IFS="" read -r line; do
        ui label 0 "$y_next" 450 50 "$line"
        ((y_next += 50))
    done < "$1"

    add justify center
    ((y_next += 50))
    ui button 0 "$y_next" 985 50 Back
    wait-for-input
}

session_log_file=/tmp/vnsee.log

while true; do
    {
        read -ra server_address
        read -ra flags
    } < <(configure-vnsee)
    save-history "${server_address[0]}" "${server_address[1]}"
    please-wait "${server_address[0]}" "${server_address[1]}"
    vnsee "${server_address[0]}" "${server_address[1]}" "${flags[@]}" \
        2> "$session_log_file" \
        || show-errors "$session_log_file"
done