burp_proxy.sh

#!/usr/bin/env bash

#########################################################################
# Proxy Manager Script
# 
# A utility to setup and manage proxy configurations for Burp Suite
# or other HTTP/HTTPS proxies for security testing and analysis.
#
#########################################################################

set -e          # Exit immediately if a command exits with non-zero status
set -u          # Treat unset variables as an error
set -o pipefail # Pipeline fails on any command error

#########################################################################
# Configuration variables with defaults (can be overridden by arguments)
#########################################################################
HOST="127.0.0.1"
PORT="8089"
CERT_PATH="/tmp"
DER_CERT=""
PEM_CERT=""
VERBOSE=false
LOG_FILE=""
COMMAND="setup"

#########################################################################
# Logging Functions
#########################################################################

# Log levels: INFO, WARN, ERROR, DEBUG
log() {
    local level="$1"
    local message="$2"
    local timestamp
    timestamp=$(date "+%Y-%m-%d %H:%M:%S")
    
    # Format the log message
    local formatted_message="[$timestamp] [$level] $message"
    
    # Print to stdout if verbose mode is enabled
    if [[ "$VERBOSE" == true || "$level" == "ERROR" ]]; then
        echo "$formatted_message"
    fi
    
    # Log to file if specified
    if [[ -n "$LOG_FILE" ]]; then
        echo "$formatted_message" >> "$LOG_FILE"
    fi
}

log_info() {
    log "INFO" "$1"
}

log_warn() {
    log "WARN" "$1"
}

log_error() {
    log "ERROR" "$1"
}

log_debug() {
    if [[ "$VERBOSE" == true ]]; then
        log "DEBUG" "$1"
    fi
}

#########################################################################
# Utility Functions
#########################################################################

# Check if a command exists
command_exists() {
    command -v "$1" >/dev/null 2>&1
}

# Validate required dependencies
validate_dependencies() {
    local missing_deps=false
    
    if ! command_exists curl; then
        log_error "Missing dependency: curl"
        missing_deps=true
    fi
    
    if ! command_exists openssl; then
        log_error "Missing dependency: openssl"
        missing_deps=true
    fi
    
    if [[ "$missing_deps" == true ]]; then
        log_error "Please install missing dependencies and try again."
        exit 1
    fi
}

# Setup certificate and PEM paths
setup_paths() {
    # If the paths weren't explicitly set via arguments
    if [[ -z "$DER_CERT" ]]; then
        DER_CERT="${CERT_PATH}/burp.cer"
    fi
    
    if [[ -z "$PEM_CERT" ]]; then
        PEM_CERT="${CERT_PATH}/cert.pem"
    fi
    
    # Create cert path if it doesn't exist
    if [[ ! -d "$CERT_PATH" ]]; then
        log_debug "Creating certificate directory: $CERT_PATH"
        mkdir -p "$CERT_PATH"
    fi
}

#########################################################################
# Main Functions
#########################################################################

# Function to download and convert certificate
setup_certificate() {
    log_info "Downloading certificate from $HOST:$PORT..."
    
    if ! curl --silent --show-error "$HOST:$PORT/cert" -o "$DER_CERT" 2>/dev/null; then
        log_error "Failed to download certificate from $HOST:$PORT"
        return 1
    fi
    
    log_info "Converting certificate to PEM format..."
    if ! openssl x509 -inform der -in "$DER_CERT" -out "$PEM_CERT" 2>/dev/null; then
        log_error "Certificate conversion failed"
        return 1
    fi
    
    log_info "Certificate setup successful"
    log_debug "Certificate path: $PEM_CERT"
    return 0
}

# Function to set up proxy environment variables
setup_proxy() {
    log_info "Setting up proxy environment variables..."
    
    # Verify certificate exists before setting up proxy
    if [[ ! -f "$PEM_CERT" ]]; then
        log_warn "Certificate not found at $PEM_CERT. Running certificate setup..."
        if ! setup_certificate; then
            log_error "Failed to set up certificate. Proxy setup aborted."
            return 1
        fi
    fi
    
    export HTTP_PROXY="http://$HOST:$PORT"
    export HTTPS_PROXY="http://$HOST:$PORT"
    export REQUESTS_CA_BUNDLE="$PEM_CERT"
    export SSL_CERT_FILE="$PEM_CERT"
    
    log_info "Proxy environment configured successfully"
    log_debug "HTTP_PROXY=$HTTP_PROXY"
    log_debug "HTTPS_PROXY=$HTTPS_PROXY"
    log_debug "REQUESTS_CA_BUNDLE=$REQUESTS_CA_BUNDLE"
    log_debug "SSL_CERT_FILE=$SSL_CERT_FILE"
    
    # Create proxy status file for reference
    echo "HOST=$HOST" > "$CERT_PATH/proxy_status"
    echo "PORT=$PORT" >> "$CERT_PATH/proxy_status"
    echo "TIMESTAMP=$(date +%s)" >> "$CERT_PATH/proxy_status"
    
    return 0
}

# Function to unset proxy environment variables
unset_proxy() {
    log_info "Unsetting proxy environment variables..."
    
    unset HTTP_PROXY
    unset HTTPS_PROXY
    unset REQUESTS_CA_BUNDLE
    unset SSL_CERT_FILE
    
    # Remove proxy status file if it exists
    if [[ -f "$CERT_PATH/proxy_status" ]]; then
        rm -f "$CERT_PATH/proxy_status"
    fi
    
    log_info "Proxy environment variables unset successfully"
    return 0
}

# Function to check proxy status
check_status() {
    if [[ -f "$CERT_PATH/proxy_status" ]]; then
        log_info "Proxy is currently ACTIVE with the following configuration:"
        cat "$CERT_PATH/proxy_status"
        
        # Check if certificate file exists
        if [[ -f "$PEM_CERT" ]]; then
            log_info "Certificate file: $PEM_CERT (exists)"
        else
            log_warn "Certificate file: $PEM_CERT (missing)"
        fi
        
        # Test connectivity to proxy
        if curl --silent --connect-timeout 3 -x "$HOST:$PORT" http://example.com >/dev/null 2>&1; then
            log_info "Proxy connectivity test: SUCCESS"
        else
            log_warn "Proxy connectivity test: FAILED - Proxy may be unreachable"
        fi
    else
        log_info "Proxy is currently NOT ACTIVE"
    fi
}

# Function to display help information
show_help() {
    cat << EOF
Usage: $(basename "$0") [OPTIONS] COMMAND

A utility to manage HTTP/HTTPS proxy configuration for security testing.

Commands:
  setup    Setup proxy and certificate (default command)
  unset    Remove proxy environment variables
  status   Check current proxy status
  help     Show this help message

Options:
  -h, --host HOST        Proxy host (default: $HOST)
  -p, --port PORT        Proxy port (default: $PORT)
  -c, --cert-path PATH   Path to store certificates (default: $CERT_PATH)
  -d, --der FILE         Path to save DER certificate
  -o, --pem FILE         Path to save PEM certificate
  -v, --verbose          Enable verbose output
  -l, --log FILE         Log to specified file
  --help                 Display this help message

Examples:
  $(basename "$0") setup                   # Setup with default settings
  $(basename "$0") -h 192.168.1.100 -p 8080 setup  # Custom host and port
  $(basename "$0") unset                   # Remove proxy configuration
  $(basename "$0") status                  # Check proxy status
  $(basename "$0") -v -c /path/to/certs setup     # Verbose mode with custom cert path

Environment Variables:
  After running setup, the script sets the following environment variables:
  - HTTP_PROXY
  - HTTPS_PROXY
  - REQUESTS_CA_BUNDLE
  - SSL_CERT_FILE
  
  These variables affect programs running in the same shell session.
  For system-wide configuration, consider modifying your profile files.

Note: This script must be sourced (not executed) to affect the current shell:
  source $(basename "$0") setup
  . $(basename "$0") setup
EOF
}

# Parse command line arguments
parse_args() {
    while [[ $# -gt 0 ]]; do
        case "$1" in
            -h|--host)
                HOST="$2"
                shift 2
                ;;
            -p|--port)
                PORT="$2"
                shift 2
                ;;
            -c|--cert-path)
                CERT_PATH="$2"
                shift 2
                ;;
            -d|--der)
                DER_CERT="$2"
                shift 2
                ;;
            -o|--pem)
                PEM_CERT="$2"
                shift 2
                ;;
            -v|--verbose)
                VERBOSE=true
                shift
                ;;
            -l|--log)
                LOG_FILE="$2"
                shift 2
                ;;
            --help)
                show_help
                exit 0
                ;;
            setup|unset|status|help)
                COMMAND="$1"
                shift
                ;;
            *)
                log_error "Unknown option: $1"
                show_help
                exit 1
                ;;
        esac
    done
}

#########################################################################
# Main Execution
#########################################################################

main() {
    # Parse command line arguments
    parse_args "$@"
    
    # Validate dependencies
    validate_dependencies
    
    # Setup paths
    setup_paths
    
    # Process command
    case "$COMMAND" in
        setup)
            setup_certificate && setup_proxy
            ;;
        unset)
            unset_proxy
            ;;
        status)
            check_status
            ;;
        help)
            show_help
            ;;
        *)
            log_error "Unknown command: $COMMAND"
            show_help
            exit 1
            ;;
    esac
}

# Main execution
# No direct source detection needed - just run the main function
# This works in both zsh and bash
main "$@"