DNSDumpster MCP Server

Instructions

Implementation Reference

• server.py:230-340 (handler)

  The @mcp.tool() decorator registers the get_a_records tool, and the function implements its core logic: validates domain, fetches DNS records from DNSDumpster API, filters A records, and formats output with IP details, ASN info, and banner data (HTTP/HTTPS).

  @mcp.tool()
  async def get_a_records(domain: str, ctx: Context) -> str:
      """Get A records for a domain.
  
      Args:
          domain: The domain name to query (e.g., example.com)
          ctx: Request context
  
      Returns:
          Formatted string containing A records
      """
      if not domain:
          return "Error: Domain is required"
  
      # Validate domain
      if not is_valid_domain(domain):
          return "Error: Invalid domain name format"
  
      try:
          api_key = os.environ.get("DNSDUMPSTER_API_KEY")
          if not api_key:
              return "Error: API key not configured. Set DNSDUMPSTER_API_KEY environment variable."
  
          client = DNSDumpsterClient(api_key)
  
          try:
              ctx.info(f"Querying A records for {domain}")
              result = await client.get_dns_records(domain)
  
              if "a" not in result or not result["a"]:
                  return f"No A records found for {domain}"
  
              output_lines = [f"A Records for {domain}:"]
  
              for record in result["a"]:
                  host = record.get("host", "")
                  output_lines.append(f"\nHost: {host}")
  
                  for ip_info in record.get("ips", []):
                      ip = ip_info.get("ip", "")
                      country = ip_info.get("country", "Unknown")
                      asn = ip_info.get("asn", "")
                      asn_name = ip_info.get("asn_name", "")
                      asn_range = ip_info.get("asn_range", "")
  
                      output_lines.append(f"  IP: {ip}")
                      output_lines.append(f"  Country: {country}")
                      if asn:
                          output_lines.append(f"  ASN: {asn}")
                      if asn_name:
                          output_lines.append(f"  ASN Name: {asn_name}")
                      if asn_range:
                          output_lines.append(f"  ASN Range: {asn_range}")
  
                      # If banner information is available
                      if "banners" in ip_info:
                          output_lines.append("  Banners:")
                          banners = ip_info["banners"]
  
                          if "http" in banners:
                              http_banner = banners["http"]
                              output_lines.append("    HTTP:")
  
                              if "title" in http_banner:
                                  output_lines.append(
                                      f"      Title: {http_banner['title']}"
                                  )
  
                              if "server" in http_banner:
                                  output_lines.append(
                                      f"      Server: {http_banner['server']}"
                                  )
  
                              if "apps" in http_banner:
                                  output_lines.append(
                                      f"      Apps: {', '.join(http_banner['apps'])}"
                                  )
  
                          if "https" in banners:
                              https_banner = banners["https"]
                              output_lines.append("    HTTPS:")
  
                              if "title" in https_banner:
                                  output_lines.append(
                                      f"      Title: {https_banner['title']}"
                                  )
  
                              if "server" in https_banner:
                                  output_lines.append(
                                      f"      Server: {https_banner['server']}"
                                  )
  
                              if "apps" in https_banner:
                                  output_lines.append(
                                      f"      Apps: {', '.join(https_banner['apps'])}"
                                  )
  
                              if "cn" in https_banner:
                                  output_lines.append(f"      CN: {https_banner['cn']}")
  
                              if "alt_n" in https_banner:
                                  output_lines.append(
                                      f"      Alt Names: {', '.join(https_banner['alt_n'])}"
                                  )
  
              return "\n".join(output_lines)
          finally:
              await client.close()
  
      except Exception as e:
          return f"Error: {str(e)}"