iknowyou/back/internal/tools/crtsh/tool.go

package crtsh

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"sort"
	"strings"

	"github.com/anotherhadi/iknowyou/internal/tools"
)

const (
	name        = "crt.sh"
	description = "SSL/TLS certificate transparency log search via crt.sh — enumerates subdomains and certificates issued for a domain."
	link        = "https://crt.sh"
	icon        = ""
)

type Runner struct{}

func New() tools.ToolRunner {
	return &Runner{}
}

func (r *Runner) Name() string        { return name }
func (r *Runner) Description() string { return description }
func (r *Runner) Link() string        { return link }
func (r *Runner) Icon() string        { return icon }

func (r *Runner) InputTypes() []tools.InputType {
	return []tools.InputType{tools.InputTypeDomain}
}

type crtEntry struct {
	IssuerName     string `json:"issuer_name"`
	CommonName     string `json:"common_name"`
	NameValue      string `json:"name_value"`
	NotBefore      string `json:"not_before"`
	NotAfter       string `json:"not_after"`
	EntryTimestamp string `json:"entry_timestamp"`
}

func (r *Runner) Run(ctx context.Context, target string, _ tools.InputType, out chan<- tools.Event) error {
	defer close(out)

	params := url.Values{}
	params.Set("q", "%."+target)
	params.Set("output", "json")
	apiURL := "https://crt.sh/?" + params.Encode()
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, apiURL, nil)
	if err != nil {
		out <- tools.Event{Tool: name, Type: tools.EventTypeError, Payload: err.Error()}
		out <- tools.Event{Tool: name, Type: tools.EventTypeCount, Payload: 0}
		out <- tools.Event{Tool: name, Type: tools.EventTypeDone}
		return nil
	}
	req.Header.Set("Accept", "application/json")
	req.Header.Set("User-Agent", "Mozilla/5.0 (compatible; crtsh-scanner/1.0)")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		if ctx.Err() != nil {
			out <- tools.Event{Tool: name, Type: tools.EventTypeError, Payload: "scan cancelled"}
		} else {
			out <- tools.Event{Tool: name, Type: tools.EventTypeError, Payload: err.Error()}
		}
		out <- tools.Event{Tool: name, Type: tools.EventTypeCount, Payload: 0}
		out <- tools.Event{Tool: name, Type: tools.EventTypeDone}
		return nil
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		out <- tools.Event{Tool: name, Type: tools.EventTypeError, Payload: "failed to read response"}
		out <- tools.Event{Tool: name, Type: tools.EventTypeCount, Payload: 0}
		out <- tools.Event{Tool: name, Type: tools.EventTypeDone}
		return nil
	}

	if resp.StatusCode != http.StatusOK {
		msg := fmt.Sprintf("API error %d", resp.StatusCode)
		if resp.StatusCode == http.StatusBadGateway || resp.StatusCode == http.StatusServiceUnavailable || resp.StatusCode == http.StatusGatewayTimeout {
			msg = fmt.Sprintf("crt.sh is temporarily unavailable (%d), try again later", resp.StatusCode)
		}
		out <- tools.Event{Tool: name, Type: tools.EventTypeError, Payload: msg}
		out <- tools.Event{Tool: name, Type: tools.EventTypeCount, Payload: 0}
		out <- tools.Event{Tool: name, Type: tools.EventTypeDone}
		return nil
	}

	var entries []crtEntry
	if err := json.Unmarshal(body, &entries); err != nil {
		out <- tools.Event{Tool: name, Type: tools.EventTypeError, Payload: "failed to parse response"}
		out <- tools.Event{Tool: name, Type: tools.EventTypeCount, Payload: 0}
		out <- tools.Event{Tool: name, Type: tools.EventTypeDone}
		return nil
	}

	if len(entries) == 0 {
		out <- tools.Event{Tool: name, Type: tools.EventTypeCount, Payload: 0}
		out <- tools.Event{Tool: name, Type: tools.EventTypeDone}
		return nil
	}

	// Deduplicate subdomains from name_value fields
	seen := make(map[string]struct{})
	for _, e := range entries {
		for _, line := range strings.Split(e.NameValue, "\n") {
			line = strings.TrimSpace(line)
			if line != "" && !strings.HasPrefix(line, "*") {
				seen[line] = struct{}{}
			}
		}
	}

	subdomains := make([]string, 0, len(seen))
	for s := range seen {
		subdomains = append(subdomains, s)
	}
	sort.Strings(subdomains)

	var sb strings.Builder
	sb.WriteString(fmt.Sprintf("Found %d unique subdomains across %d certificate entries\n\n", len(subdomains), len(entries)))
	for _, s := range subdomains {
		sb.WriteString(s + "\n")
	}

	out <- tools.Event{Tool: name, Type: tools.EventTypeOutput, Payload: strings.TrimSpace(sb.String())}
	out <- tools.Event{Tool: name, Type: tools.EventTypeCount, Payload: len(subdomains)}
	out <- tools.Event{Tool: name, Type: tools.EventTypeDone}
	return nil
}