Add Okta users driver and name resolver

The driver lists GET /api/v1/users (limit=200) on the customer's org
host and follows the RFC 5988 Link header, pinning pagination to the
configured host so a response cannot redirect the crawl off-tenant.
User status maps to the three-valued Active flag (SUSPENDED and
DEPROVISIONED are inactive); ExternalID is the stable Okta user id.

The name resolver reads /api/v1/org and returns ("", nil) on any
non-2xx so a read-only token lacking org-settings read does not loop
the source-name worker.

The org domain is operator-supplied and feeds the URL host, so it is
the one SSRF-sensitive input: NormalizeOktaDomain validates and
strips it on the write path and IsValidOktaDomain re-checks it at
driver construction, on top of the transport's SSRF protection.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/accessreview/drivers/okta.go

@@ -0,0 +1,222 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package drivers
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"go.probo.inc/probo/pkg/coredata"
+	"go.probo.inc/probo/pkg/rfc5988"
+)
+
+// OktaDriver lists the users of a single Okta org. The org is identified by
+// its bare domain host (e.g. "acme.okta.com") supplied with the API token —
+// Okta has no central API gateway, so every request targets that org's own
+// host. The connection's transport attaches the `Authorization: SSWS <token>`
+// header (see connector.APIKeyConnection); the driver only sets Accept.
+type OktaDriver struct {
+	httpClient *http.Client
+	domain     string
+}
+
+var _ Driver = (*OktaDriver)(nil)
+
+type oktaUser struct {
+	ID        string      `json:"id"`
+	Status    string      `json:"status"`
+	Created   string      `json:"created"`
+	LastLogin string      `json:"lastLogin"`
+	Profile   oktaProfile `json:"profile"`
+}
+
+type oktaProfile struct {
+	FirstName   string `json:"firstName"`
+	LastName    string `json:"lastName"`
+	DisplayName string `json:"displayName"`
+	Email       string `json:"email"`
+	Login       string `json:"login"`
+	Title       string `json:"title"`
+}
+
+// oktaUsersPageLimit is Okta's maximum page size for GET /api/v1/users.
+const oktaUsersPageLimit = "200"
+
+func NewOktaDriver(httpClient *http.Client, domain string) *OktaDriver {
+	return &OktaDriver{
+		httpClient: httpClient,
+		domain:     domain,
+	}
+}
+
+func (d *OktaDriver) ListAccounts(ctx context.Context) ([]AccountRecord, error) {
+	endpoint := url.URL{
+		Scheme:   "https",
+		Host:     d.domain,
+		Path:     "/api/v1/users",
+		RawQuery: url.Values{"limit": {oktaUsersPageLimit}}.Encode(),
+	}
+
+	next := endpoint.String()
+
+	var records []AccountRecord
+
+	for range maxPaginationPages {
+		users, linkNext, err := d.fetchUsersPage(ctx, next)
+		if err != nil {
+			return nil, err
+		}
+
+		for _, u := range users {
+			email := u.Profile.Email
+			if email == "" {
+				email = u.Profile.Login
+			}
+
+			if email == "" {
+				continue
+			}
+
+			record := AccountRecord{
+				Email:       email,
+				FullName:    oktaFullName(u.Profile),
+				JobTitle:    u.Profile.Title,
+				Active:      oktaActive(u.Status),
+				MFAStatus:   coredata.MFAStatusUnknown,
+				AuthMethod:  coredata.AccessEntryAuthMethodUnknown,
+				AccountType: coredata.AccessEntryAccountTypeUser,
+				ExternalID:  u.ID,
+			}
+
+			if t, ok := parseOktaTimestamp(u.Created); ok {
+				record.CreatedAt = &t
+			}
+
+			if t, ok := parseOktaTimestamp(u.LastLogin); ok {
+				record.LastLogin = &t
+			}
+
+			records = append(records, record)
+		}
+
+		if linkNext == "" {
+			return records, nil
+		}
+
+		next = linkNext
+	}
+
+	return nil, fmt.Errorf("cannot list all okta accounts: %w", ErrPaginationLimitReached)
+}
+
+func (d *OktaDriver) fetchUsersPage(ctx context.Context, endpoint string) ([]oktaUser, string, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+	if err != nil {
+		return nil, "", fmt.Errorf("cannot create okta users request: %w", err)
+	}
+
+	req.Header.Set("Accept", "application/json")
+
+	httpResp, err := d.httpClient.Do(req)
+	if err != nil {
+		return nil, "", fmt.Errorf("cannot execute okta users request: %w", err)
+	}
+
+	defer func() {
+		_ = httpResp.Body.Close()
+	}()
+
+	if httpResp.StatusCode < 200 || httpResp.StatusCode >= 300 {
+		return nil, "", fmt.Errorf("cannot fetch okta users: unexpected status %d", httpResp.StatusCode)
+	}
+
+	var users []oktaUser
+	if err := json.NewDecoder(httpResp.Body).Decode(&users); err != nil {
+		return nil, "", fmt.Errorf("cannot decode okta users response: %w", err)
+	}
+
+	// Okta emits one Link header per relation (self, next), so Header.Get
+	// would return only the first. Join all of them before scanning for
+	// rel="next".
+	next, err := d.nextPageURL(strings.Join(httpResp.Header.Values("Link"), ", "))
+	if err != nil {
+		return nil, "", err
+	}
+
+	return users, next, nil
+}
+
+// nextPageURL returns the rel="next" pagination URL from an Okta Link header,
+// or "" when the list is exhausted. It pins pagination to the configured org
+// host: a `next` link pointing at any other host is rejected rather than
+// followed, so the response cannot redirect the crawl off-tenant.
+func (d *OktaDriver) nextPageURL(linkHeader string) (string, error) {
+	raw := rfc5988.FindByRel(linkHeader, "next")
+	if raw == "" {
+		return "", nil
+	}
+
+	u, err := url.Parse(raw)
+	if err != nil {
+		return "", fmt.Errorf("cannot parse okta next-page link")
+	}
+
+	if !strings.EqualFold(u.Hostname(), d.domain) {
+		return "", fmt.Errorf("cannot follow okta next-page link: host mismatch")
+	}
+
+	return u.String(), nil
+}
+
+func oktaFullName(p oktaProfile) string {
+	if p.DisplayName != "" {
+		return p.DisplayName
+	}
+
+	return strings.TrimSpace(strings.Join([]string{p.FirstName, p.LastName}, " "))
+}
+
+// oktaActive maps an Okta user status to the three-valued Active flag.
+// SUSPENDED and DEPROVISIONED are the explicitly disabled/deactivated states;
+// every other status (ACTIVE, PROVISIONED, STAGED, RECOVERY, PASSWORD_EXPIRED,
+// LOCKED_OUT) is a usable account. An empty status leaves Active nil.
+func oktaActive(status string) *bool {
+	if status == "" {
+		return nil
+	}
+
+	active := status != "SUSPENDED" && status != "DEPROVISIONED"
+
+	return &active
+}
+
+func parseOktaTimestamp(value string) (time.Time, bool) {
+	if value == "" {
+		return time.Time{}, false
+	}
+
+	for _, layout := range []string{time.RFC3339Nano, time.RFC3339} {
+		if t, err := time.Parse(layout, value); err == nil {
+			return t, true
+		}
+	}
+
+	return time.Time{}, false
+}