#!/bin/bash
# Name: ipfn
# Version: 1.4.5
# Date: 2026-01-22
# Description: Fixed regex to correctly distinguish between addr:port and port:addr:port.

if [ "$(id -u)" -ne 0 ]; then
    exec sudo "$0" "$@"
fi

TABLE_NAME="ipf_wrapper"
VERSION="1.4.5"
PROTO="tcp"
FORCE_FLAG=false
SKIP_TEST=false
QUIET_MODE=false

# --- Functions ---

msg() { [[ "$QUIET_MODE" == false ]] && echo -e "$@"; }

init_nft() {
    nft add table inet "${TABLE_NAME}" 2>/dev/null
    nft add chain inet "${TABLE_NAME}" prerouting { type nat hook prerouting priority -100 \; } 2>/dev/null
    nft add chain inet "${TABLE_NAME}" output { type nat hook output priority -100 \; } 2>/dev/null
    nft add chain inet "${TABLE_NAME}" postrouting { type nat hook postrouting priority 100 \; } 2>/dev/null
    nft add chain inet "${TABLE_NAME}" forward { type filter hook forward priority 0 \; policy accept \; } 2>/dev/null
}

get_total_packets() {
    local uuid=$1
    local total=0
    local counts=$(nft list table inet "${TABLE_NAME}" 2>/dev/null | grep "$uuid" | grep -o 'packets [0-9]*' | awk '{print $2}')
    for c in $counts; do total=$((total + c)); done
    echo "$total"
}

test_connection() {
    local ip=$1
    local port=$2
    nc -z -v -w 1 "$ip" "$port" >/dev/null 2>&1
}

test_strict_handle() {
    local h=$1
    local info=$(nft -a list chain inet "${TABLE_NAME}" prerouting 2>/dev/null | grep "handle $h")
    [[ -z "$info" ]] && { echo -e "Handle $h \e[31mNOT FOUND\e[0m"; return; }
    
    local lp=$(echo "$info" | grep -o 'dport [0-9]*' | awk '{print $2}')
    local target=$(echo "$info" | grep -oE 'to ([0-9.]+|\[[0-9a-fA-F:]+\]):[0-9]+' | awk '{print $2}')
    local tip=$(echo "$target" | cut -d':' -f1 | tr -d '[]')
    local tp=$(echo "$target" | cut -d':' -f2)
    local uuid=$(echo "$info" | grep -o 'ipf-id:[a-z0-9-]*')
    local short_id=$(echo "$uuid" | cut -d':' -f2 | cut -c1-8)

    echo -n "Testing handle $h (Local :$lp -> Target $tip:$tp) [${short_id}]... "
    local count_before=$(get_total_packets "$uuid")
    
    if test_connection "$tip" "$tp"; then
        nc -z -v -w 1 127.0.0.1 "$lp" >/dev/null 2>&1
        sleep 0.1
        local count_after=$(get_total_packets "$uuid")
        if (( count_after > count_before )); then
            echo -e "\e[32mPASSED (Rule active & Target UP)\e[0m"
        else
            echo -e "\e[33mSKIPPED (Target UP, but blocked by prior rule)\e[0m"
        fi
    else
        nc -z -v -w 1 127.0.0.1 "$lp" >/dev/null 2>&1
        sleep 0.1
        local count_after=$(get_total_packets "$uuid")
        if (( count_after > count_before )); then
            echo -e "\e[33mOFFLINE (Rule matched, but Target Down)\e[0m"
        else
            echo -e "\e[31mFAILED (Target Down & Rule blocked)\e[0m"
        fi
    fi
}

list_rules() {
    [[ "$QUIET_MODE" == true ]] && return
    local highlight_uuid=$1
    init_nft
    msg "Forwarding Rules (ipfn):"
    printf "%-10s %-6s %-20s %-20s %-10s\n" "HANDLE" "PROTO" "LOCAL" "TARGET" "UUID"
    echo "-----------------------------------------------------------------------------------"
    nft -a list chain inet "${TABLE_NAME}" prerouting 2>/dev/null | grep "dnat" | while read -r line; do
        handle=$(echo "$line" | grep -o 'handle [0-9]*' | awk '{print $2}')
        proto=$(echo "$line" | grep -q "udp" && echo "udp" || echo "tcp")
        target=$(echo "$line" | grep -oE '([0-9.]+|\[[0-9a-fA-F:]+\]):[0-9]+' | head -n 1)
        lport=$(echo "$line" | grep -o 'dport [0-9]*' | awk '{print $2}')
        full_uuid=$(echo "$line" | grep -o 'ipf-id:[a-z0-9-]*' | cut -d':' -f2)
        if [[ -n "$highlight_uuid" && "$full_uuid" == "$highlight_uuid" ]]; then
            printf "\e[1;36m*%-9s %-6s %-20s %-20s %-10s\e[0m\n" "$handle" "$proto" ":$lport" "$target" "${full_uuid:0:8}"
        else
            printf " %-9s %-6s %-20s %-20s %-10s\n" "$handle" "$proto" ":$lport" "$target" "${full_uuid:0:8}"
        fi
    done
}

all_clear() {
    if [[ "$FORCE_FLAG" == false ]]; then
        echo -e "\e[33mWarning: This will delete ALL forwarding rules.\e[0m"
        read -p "Are you sure? (y/N): " confirm
        [[ ! "$confirm" =~ ^[yY]$ ]] && exit 0
    fi
    nft delete table inet "${TABLE_NAME}" 2>/dev/null
    init_nft; msg "All rules cleared successfully."; list_rules; exit 0 
}

# --- Flag Pre-processing ---

for arg in "$@"; do
    [[ "$arg" =~ q ]] && QUIET_MODE=true && FORCE_FLAG=true && SKIP_TEST=true
    [[ "$arg" =~ f ]] && FORCE_FLAG=true && SKIP_TEST=true
    [[ "$arg" == "-R" ]] && RESET_MODE=true
    [[ "$arg" == "--version" ]] && { echo "ipfn version ${VERSION}"; exit 0; }
done

if [[ "$RESET_MODE" == true ]]; then all_clear; fi
if [[ $# -eq 0 ]]; then list_rules; exit 0; fi

# --- Main Loop ---

while [[ $# -gt 0 ]]; do
    case "$1" in
        -h|--help) 
            echo "Usage: ipfn [OPTIONS] [RULES]"
            echo "Tests: -t 5 (handle), -t :80 (port), -t 1.1.1.1:80 (direct), -t 80:1.1.1.1:80 (full)"
            exit 0 ;;
        -L|-l) list_rules; exit 0 ;;
        -*[d]*)
            h_str=$(echo "$1" | sed -E 's/^-q?d?f?//')
            [[ -z "$h_str" ]] && { h_str="$2"; shift; }
            if [[ "$h_str" == "all" || "$h_str" == "*" ]]; then all_clear; fi
            handles=()
            IFS=',' read -r -a parts <<< "$h_str"
            for part in "${parts[@]}"; do
                if [[ "$part" =~ ^:([0-9]+)$ ]]; then
                    p="${BASH_REMATCH[1]}"
                    for h in $(nft -a list chain inet "${TABLE_NAME}" prerouting 2>/dev/null | grep "dport $p" | grep -o 'handle [0-9]*' | awk '{print $2}'); do handles+=("$h"); done
                else handles+=("$part"); fi
            done
            for h in "${handles[@]}"; do
                uuid=$(nft -a list chain inet "${TABLE_NAME}" prerouting 2>/dev/null | grep "handle $h" | grep -o 'ipf-id:[a-z0-9-]*')
                [[ -z "$uuid" ]] && continue
                for c in prerouting output forward postrouting; do
                    nft -a list chain inet "${TABLE_NAME}" "$c" 2>/dev/null | grep "$uuid" | grep -o 'handle [0-9]*' | awk '{print $2}' | while read -r rh; do
                        nft delete rule inet "${TABLE_NAME}" "$c" handle "$rh"
                    done
                done
                msg "Deleted handle $h"
            done
            list_rules; exit 0 ;;
        -t*)
            h_str="${1#-t}"; [[ -z "$h_str" && -n "$2" ]] && { h_str="$2"; shift; }
            # 1. port:addr:port
            if [[ "$h_str" =~ ^([0-9]+):([0-9\.]+):([0-9]+)$ ]]; then
                lp=${BASH_REMATCH[1]}; tip=${BASH_REMATCH[2]}; tp=${BASH_REMATCH[3]}
                echo -n "Checking Target $tip:$tp... "
                test_connection "$tip" "$tp" && echo -e "\e[32mUP\e[0m" || echo -e "\e[31mDOWN\e[0m"
                echo -n "Checking Local :$lp... "
                nc -z -v -w 1 127.0.0.1 "$lp" >/dev/null 2>&1 && echo -e "\e[32mOPEN\e[0m" || echo -e "\e[31mCLOSED\e[0m"
            # 2. addr:port
            elif [[ "$h_str" =~ ^([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+):([0-9]+)$ ]]; then
                tip=${BASH_REMATCH[1]}; tp=${BASH_REMATCH[2]}
                echo -n "Checking Target $tip:$tp... "
                test_connection "$tip" "$tp" && echo -e "\e[32mUP\e[0m" || echo -e "\e[31mDOWN\e[0m"
            # 3. :port or port:
            elif [[ "$h_str" =~ ^:([0-9]+)$ || "$h_str" =~ ^([0-9]+):$ ]]; then
                p="${BASH_REMATCH[1]}${BASH_REMATCH[2]}"
                echo -n "Checking Local :$p... "
                nc -z -v -w 1 127.0.0.1 "$p" >/dev/null 2>&1 && echo -e "\e[32mOK\e[0m" || echo -e "\e[31mOFFLINE\e[0m"
            # 4. handle
            elif [[ "$h_str" =~ ^[0-9]+$ ]]; then
                test_strict_handle "$h_str"
            else
                top_h=$(nft -a list chain inet "${TABLE_NAME}" prerouting 2>/dev/null | grep "dnat" | head -n 1 | grep -o 'handle [0-9]*' | awk '{print $2}')
                [[ -n "$top_h" ]] && test_strict_handle "$top_h" || msg "Error: No rules to test."
            fi
            exit 0 ;;
        [0-9]*)
            init_nft; raw="$1"
            if [[ "$raw" =~ ^([0-9]+):([0-9\.]+):([0-9]+)$ ]]; then lp=${BASH_REMATCH[1]}; tip=${BASH_REMATCH[2]}; tp=${BASH_REMATCH[3]}
            elif [[ "$raw" =~ ^([0-9]+):([0-9]+)$ ]]; then lp=${BASH_REMATCH[1]}; tip="127.0.0.1"; tp=${BASH_REMATCH[2]}
            elif [[ "$raw" =~ ^([0-9]+)$ ]]; then lp=${BASH_REMATCH[1]}; tip="127.0.0.1"; tp=${BASH_REMATCH[1]}
            fi
            u_raw=$(cat /proc/sys/kernel/random/uuid); u="ipf-id:$u_raw"; fam="ip"; [[ "$tip" =~ : ]] && fam="ip6"
            nft insert rule inet "${TABLE_NAME}" prerouting "$PROTO" dport "$lp" counter dnat $fam to "$tip:$tp" comment "\"$u\""
            nft insert rule inet "${TABLE_NAME}" output "$PROTO" dport "$lp" counter dnat $fam to "$tip:$tp" comment "\"$u\""
            nft insert rule inet "${TABLE_NAME}" forward $fam daddr "$tip" "$PROTO" dport "$tp" ct state new,established,related accept comment "\"$u\""
            nft insert rule inet "${TABLE_NAME}" forward $fam saddr "$tip" "$PROTO" sport "$tp" ct state established,related accept comment "\"$u\""
            nft insert rule inet "${TABLE_NAME}" forward iifname "lo" accept comment "\"$u\""
            nft insert rule inet "${TABLE_NAME}" postrouting $fam daddr "$tip" "$PROTO" dport "$tp" masquerade comment "\"$u\""
            list_rules "$u_raw"
            if [[ "$SKIP_TEST" == false ]]; then
                new_h=$(nft -a list chain inet "${TABLE_NAME}" prerouting 2>/dev/null | grep "$u_raw" | grep -o 'handle [0-9]*' | awk '{print $2}')
                echo ""; test_strict_handle "$new_h"
            fi
            exit 0 ;;
        *) msg "Error: Unknown option '$1'"; exit 1 ;;
    esac
    shift
done