LinkPort/internal/model/gateway_account.go

package model

import (
	"errors"
	"golang.org/x/crypto/ssh"
	"net/netip"
	"reflect"
	"strings"
	"time"
)

type GatewayAccount struct {
	TargetID              string   `json:"targetId,omitempty"`
	TargetAccountID       string   `json:"targetAccountId,omitempty"`
	ExpiresAt             string   `json:"expiresAt,omitempty"`
	RotationReminderDays  int      `json:"rotationReminderDays,omitempty"`
	ID                    string   `json:"id"`
	Username              string   `json:"username"`
	Password              string   `json:"password,omitempty"`
	Disabled              bool     `json:"disabled,omitempty"`
	AccessMode            string   `json:"accessMode,omitempty"`
	AllowCIDRs            []string `json:"allowCIDRs,omitempty"`
	AuthorizedKeys        []string `json:"authorizedKeys,omitempty"`
	AuthorizedKeysAssetID string   `json:"authorizedKeysAssetId,omitempty"`
}

// Redis and MongoDB gateways with no client accounts accept downstream
// connections without a local authentication step. Every other gateway,
// requires gateway authentication.
func (p Proxy) RequiresGatewayAuthentication() bool {
	return (p.Type != "redis" && p.Type != "mongodb") || len(p.GatewayAccounts) > 0
}

func (p Proxy) GatewayAccount(username string) (GatewayAccount, bool) {
	for _, a := range p.GatewayAccounts {
		if !a.Disabled && !credentialExpired(a.ExpiresAt, time.Now()) && a.Username == username {
			return a, true
		}
	}
	// Redis AUTH password authenticates the protocol's default user. An empty
	// configured username is the explicit password-only form of that identity.
	if p.Type == "redis" && username == "default" {
		for _, a := range p.GatewayAccounts {
			if !a.Disabled && !credentialExpired(a.ExpiresAt, time.Now()) && a.Username == "" {
				return a, true
			}
		}
	}
	return GatewayAccount{}, false
}
func (a GatewayAccount) Apply(p Proxy) Proxy {
	if a.TargetID != "" {
		t, ok := p.Targets[a.TargetID]
		if !ok && a.TargetID != p.TargetID {
			p = (Target{}).Apply(p)
			p.TargetCredentialError = ErrCredentialUnavailable
			return p
		}
		p.TargetAccountID = ""
		if ok {
			p = t.Apply(p)
		}
	}
	p = p.selectTargetAccount(a.TargetAccountID)
	if a.Disabled || credentialExpired(a.ExpiresAt, time.Now()) {
		p.TargetCredentialError = ErrCredentialUnavailable
	}
	p.GatewayUser, p.GatewayPassword = a.Username, a.Password
	p.AccessMode = a.AccessMode
	if p.AccessMode == "" && !IsSSH(p.Type) {
		p.AccessMode = "readwrite"
	}
	p.SSH.AuthorizedKeys = a.AuthorizedKeys
	return p
}

func (p Proxy) validateGatewayAccounts() error {
	if len(p.GatewayAccounts) > 32 {
		return errors.New("at most 32 gateway accounts")
	}
	ids, users := map[string]bool{}, map[string]bool{}
	for _, a := range p.GatewayAccounts {
		if err := validateCredentialExpiry(a.ExpiresAt, a.RotationReminderDays); err != nil {
			return err
		}
		if !accountIDPattern.MatchString(a.ID) || ids[a.ID] {
			return errors.New("invalid or duplicate gateway account id")
		}
		ids[a.ID] = true
		passwordOnlyRedis := p.Type == "redis" && a.Username == "" && a.Password != ""
		usernameKey := a.Username
		if p.Type == "redis" && usernameKey == "" {
			usernameKey = "default"
		}
		if (strings.TrimSpace(a.Username) == "" && !passwordOnlyRedis) || len(a.Username) > 128 || strings.ContainsAny(a.Username, "\r\n\x00") || users[usernameKey] {
			return errors.New("invalid or duplicate gateway username")
		}
		users[usernameKey] = true
		if a.Password == "" && (!IsSSH(p.Type) || (len(a.AuthorizedKeys) == 0 && a.AuthorizedKeysAssetID == "")) {
			return errors.New("gateway account password is required")
		}
		if a.AccessMode != "" && a.AccessMode != "readonly" && a.AccessMode != "readwrite" && a.AccessMode != "unrestricted" {
			return errors.New("invalid gateway account accessMode")
		}
		if a.AccessMode == "unrestricted" && p.Type != "mysql" {
			return errors.New("unrestricted accessMode is supported only for MySQL")
		}
		if a.AccessMode == "readonly" && p.Type != "mysql" && p.Type != "mongodb" {
			return errors.New("readonly is currently supported only for MySQL and MongoDB")
		}
		if IsSSH(p.Type) && a.AccessMode != "" {
			return errors.New("SSH has no accessMode")
		}
		for _, cidr := range a.AllowCIDRs {
			if _, e := netip.ParsePrefix(cidr); e != nil {
				if _, e = netip.ParseAddr(cidr); e != nil {
					return errors.New("invalid account source IP/CIDR")
				}
			}
		}
		for _, key := range a.AuthorizedKeys {
			if _, _, _, _, e := ssh.ParseAuthorizedKey([]byte(key)); e != nil {
				return errors.New("invalid gateway authorized key")
			}
		}
	}
	return nil
}
func mergeGatewaySecrets(current Proxy, patch map[string]any, out *Proxy) error {
	raw, present := patch["gatewayAccounts"]
	if !present {
		return nil
	}
	entries, ok := raw.([]any)
	if !ok || (len(entries) == 0 && out.Type != "tcp" && out.Type != "redis" && out.Type != "mongodb") {
		return errors.New("gatewayAccounts must contain at least one account")
	}
	byID := map[string]GatewayAccount{}
	for _, a := range current.GatewayAccounts {
		byID[a.ID] = a
	}
	for i, entry := range entries {
		fields, ok := entry.(map[string]any)
		if !ok {
			return errors.New("invalid gateway account")
		}
		if err := exactFields(fields, reflect.TypeOf(GatewayAccount{})); err != nil {
			return err
		}
		if _, ok := fields["password"]; !ok {
			out.GatewayAccounts[i].Password = byID[out.GatewayAccounts[i].ID].Password
		}
		old := byID[out.GatewayAccounts[i].ID]
		if old.AuthorizedKeysAssetID != "" && old.AuthorizedKeysAssetID != out.GatewayAccounts[i].AuthorizedKeysAssetID {
			out.GatewayAccounts[i].AuthorizedKeys = nil
		}
	}
	out.GatewayUser, out.GatewayPassword = "", ""
	return nil
}