feat(detectors): create azure_entra base package

feat(azure): finish pending items for review

pkg/detectors/azure_entra/common.go

@@ -0,0 +1,127 @@
+package azure_entra
+
+import (
+	"fmt"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/cache/simple"
+	"github.com/trufflesecurity/trufflehog/v3/pkg/context"
+	"golang.org/x/sync/singleflight"
+	"io"
+	"net/http"
+	"strings"
+
+	regexp "github.com/wasilibs/go-re2"
+
+	"github.com/trufflesecurity/trufflehog/v3/pkg/detectors"
+)
+
+const uuidStr = `[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}`
+
+var (
+	// Tenants can be identified with a UUID or an `*.onmicrosoft.com` domain.
+	//
+	// See:
+	// https://learn.microsoft.com/en-us/partner-center/account-settings/find-ids-and-domain-names#find-the-microsoft-azure-ad-tenant-id-and-primary-domain-name
+	// https://learn.microsoft.com/en-us/microsoft-365/admin/setup/domains-faq?view=o365-worldwide#why-do-i-have-an--onmicrosoft-com--domain
+	tenantIdPat = regexp.MustCompile(fmt.Sprintf(
+		//language=regexp
+		`(?i)(?:(?:login\.microsoftonline\.com/|(?:login|sts)\.windows\.net/|(?:t[ae]n[ae]nt(?:[ ._-]?id)?|\btid)(?:.|\s){0,60}?)(%s)|https?://(%s)|X-AnchorMailbox(?:.|\s){0,60}?@(%s))`,
+		uuidStr,
+		uuidStr,
+		uuidStr,
+	))
+	tenantOnMicrosoftPat = regexp.MustCompile(`([\w-]+\.onmicrosoft\.com)`)
+
+	clientIdPat = regexp.MustCompile(fmt.Sprintf(
+		`(?i)(?:(?:app(?:lication)?|client)(?:[ ._-]?id)?|username| -u)(?:.|\s){0,45}?(%s)`, uuidStr))
+)
+
+// FindTenantIdMatches returns a list of potential tenant IDs in the provided |data|.
+func FindTenantIdMatches(data string) map[string]struct{} {
+	uniqueMatches := make(map[string]struct{})
+
+	for _, match := range tenantIdPat.FindAllStringSubmatch(data, -1) {
+		var m string
+		if match[1] != "" {
+			m = strings.ToLower(match[1])
+		} else if match[2] != "" {
+			m = strings.ToLower(match[2])
+		} else if match[3] != "" {
+			m = strings.ToLower(match[3])
+		}
+		if _, ok := detectors.UuidFalsePositives[detectors.FalsePositive(m)]; ok {
+			continue
+		}
+		uniqueMatches[m] = struct{}{}
+	}
+	for _, match := range tenantOnMicrosoftPat.FindAllStringSubmatch(data, -1) {
+		uniqueMatches[match[1]] = struct{}{}
+	}
+	return uniqueMatches
+}
+
+// FindClientIdMatches returns a list of potential client UUIDs in the provided |data|.
+func FindClientIdMatches(data string) map[string]struct{} {
+	uniqueMatches := make(map[string]struct{})
+	for _, match := range clientIdPat.FindAllStringSubmatch(data, -1) {
+		m := strings.ToLower(match[1])
+		if _, ok := detectors.UuidFalsePositives[detectors.FalsePositive(m)]; ok {
+			continue
+		}
+		uniqueMatches[m] = struct{}{}
+	}
+	return uniqueMatches
+}
+
+var (
+	tenantCache = simple.NewCache[bool]()
+	tenantGroup singleflight.Group
+)
+
+// TenantExists returns whether the tenant exists according to Microsoft's well-known OpenID endpoint.
+func TenantExists(ctx context.Context, client *http.Client, tenant string) bool {
+	// Use cached value where possible.
+	if tenantExists, isCached := tenantCache.Get(tenant); isCached {
+		return tenantExists
+	}
+
+	// https://www.codingexplorations.com/blog/understanding-singleflight-in-golang-a-solution-for-eliminating-redundant-work
+	tenantExists, _, _ := tenantGroup.Do(tenant, func() (interface{}, error) {
+		result := queryTenant(ctx, client, tenant)
+		tenantCache.Set(tenant, result)
+		return result, nil
+	})
+
+	return tenantExists.(bool)
+}
+
+func queryTenant(ctx context.Context, client *http.Client, tenant string) bool {
+	logger := ctx.Logger().WithName("azure").WithValues("tenant", tenant)
+
+	tenantUrl := fmt.Sprintf("https://login.microsoftonline.com/%s/.well-known/openid-configuration", tenant)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, tenantUrl, nil)
+	if err != nil {
+		return false
+	}
+
+	res, err := client.Do(req)
+	if err != nil {
+		logger.Error(err, "Failed to check if tenant exists")
+		return false
+	}
+	defer func() {
+		_, _ = io.Copy(io.Discard, res.Body)
+		_ = res.Body.Close()
+	}()
+
+	switch res.StatusCode {
+	case http.StatusOK:
+		return true
+	case http.StatusBadRequest:
+		logger.V(4).Info("Tenant does not exist.")
+		return false
+	default:
+		bodyBytes, _ := io.ReadAll(res.Body)
+		logger.Error(nil, "WARNING: Unexpected response when checking if tenant exists", "status_code", res.StatusCode, "body", string(bodyBytes))
+		return false
+	}
+}