GNU URL

gurl

#!/bin/bash

# Initialize options
follow_redirects=false
show_headers_only=false
silence_output=false

# Process options
while getopts "LsI" opt; do
  case $opt in
    L)
      follow_redirects=true
      ;;
    s)
      silence_output=true
      ;;
    I)
      show_headers_only=true
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
      ;;
  esac
done

# Shift off the options and flags processed by getopts
shift $((OPTIND-1))

# Initial URL
url_input=$1

follow_redirect() {
  local url="$1"
  # Remove protocol part
  local stripped_url="${url#http://}"
  stripped_url="${stripped_url#https://}"

  # Extract host and path
  local host="${stripped_url%%/*}"
  local path="${stripped_url#"$host"}"
  path="${path:-/}"  # Default path to '/' if empty

  # Determine protocol and port
  local protocol port
  if [[ "$url" == https://* ]]; then
    protocol="openssl s_client -quiet -ignore_unexpected_eof -connect"
    port="443"
  else
    protocol="/dev/tcp"
    port="80"
  fi

  # Make the request and capture the response
  if [ "$protocol" == "/dev/tcp" ]; then
    exec 3<>/dev/tcp/${host}/${port}
    echo -e "GET ${path} HTTP/1.1\r\nHost: ${host}\r\nConnection: close\r\n\r\n" >&3
    response=$(cat <&3)
  else
    response=$(echo -e "GET ${path} HTTP/1.1\r\nHost: ${host}\r\nConnection: close\r\n\r\n" | openssl s_client -quiet -ignore_unexpected_eof -connect "${host}:${port}" 2>/dev/null)
  fi

  # Parse status code and Location header
  local status=$(echo "$response" | grep -oE "HTTP/1.1 [0-9]+" | awk '{print $2}')
  local location=$(echo "$response" | grep -i "^Location:" | head -n 1 | cut -d' ' -f2)
  # Strip carriage return from the location
  location=$(echo "$location" | tr -d '\r')

  if $silence_output && ! $show_headers_only; then
    if [[ "$status" != "301" && "$status" != "302" ]]; then
      echo "$response" | tr -d '\r' | sed -n '/^$/,$p' # Print response body only
    fi
  else
    if $show_headers_only; then
      echo "$response" | grep -P "^(HTTP/1.1|[A-Za-z-]+:)"
    elif [[ "$status" == "301" || "$status" == "302" ]] && [ ! -z "$location" ]; then
      echo "Following redirect to $location" >&2
      follow_redirect "$location"
    else
      echo "$response"
    fi
  fi
}

follow_redirect "$url_input"