Elia Battiston | 4750d3c | 2022-07-14 13:24:56 +0000 | [diff] [blame] | 1 | package client |
| 2 | |
| 3 | import ( |
| 4 | "encoding/json" |
| 5 | "errors" |
| 6 | "sort" |
| 7 | "sync" |
| 8 | "time" |
| 9 | |
| 10 | "github.com/jcmturner/gokrb5/v8/messages" |
| 11 | "github.com/jcmturner/gokrb5/v8/types" |
| 12 | ) |
| 13 | |
| 14 | // Cache for service tickets held by the client. |
| 15 | type Cache struct { |
| 16 | Entries map[string]CacheEntry |
| 17 | mux sync.RWMutex |
| 18 | } |
| 19 | |
| 20 | // CacheEntry holds details for a cache entry. |
| 21 | type CacheEntry struct { |
| 22 | SPN string |
| 23 | Ticket messages.Ticket `json:"-"` |
| 24 | AuthTime time.Time |
| 25 | StartTime time.Time |
| 26 | EndTime time.Time |
| 27 | RenewTill time.Time |
| 28 | SessionKey types.EncryptionKey `json:"-"` |
| 29 | } |
| 30 | |
| 31 | // NewCache creates a new client ticket cache instance. |
| 32 | func NewCache() *Cache { |
| 33 | return &Cache{ |
| 34 | Entries: map[string]CacheEntry{}, |
| 35 | } |
| 36 | } |
| 37 | |
| 38 | // getEntry returns a cache entry that matches the SPN. |
| 39 | func (c *Cache) getEntry(spn string) (CacheEntry, bool) { |
| 40 | c.mux.RLock() |
| 41 | defer c.mux.RUnlock() |
| 42 | e, ok := (*c).Entries[spn] |
| 43 | return e, ok |
| 44 | } |
| 45 | |
| 46 | // JSON returns information about the cached service tickets in a JSON format. |
| 47 | func (c *Cache) JSON() (string, error) { |
| 48 | c.mux.RLock() |
| 49 | defer c.mux.RUnlock() |
| 50 | var es []CacheEntry |
| 51 | keys := make([]string, 0, len(c.Entries)) |
| 52 | for k := range c.Entries { |
| 53 | keys = append(keys, k) |
| 54 | } |
| 55 | sort.Strings(keys) |
| 56 | for _, k := range keys { |
| 57 | es = append(es, c.Entries[k]) |
| 58 | } |
| 59 | b, err := json.MarshalIndent(&es, "", " ") |
| 60 | if err != nil { |
| 61 | return "", err |
| 62 | } |
| 63 | return string(b), nil |
| 64 | } |
| 65 | |
| 66 | // addEntry adds a ticket to the cache. |
| 67 | func (c *Cache) addEntry(tkt messages.Ticket, authTime, startTime, endTime, renewTill time.Time, sessionKey types.EncryptionKey) CacheEntry { |
| 68 | spn := tkt.SName.PrincipalNameString() |
| 69 | c.mux.Lock() |
| 70 | defer c.mux.Unlock() |
| 71 | (*c).Entries[spn] = CacheEntry{ |
| 72 | SPN: spn, |
| 73 | Ticket: tkt, |
| 74 | AuthTime: authTime, |
| 75 | StartTime: startTime, |
| 76 | EndTime: endTime, |
| 77 | RenewTill: renewTill, |
| 78 | SessionKey: sessionKey, |
| 79 | } |
| 80 | return c.Entries[spn] |
| 81 | } |
| 82 | |
| 83 | // clear deletes all the cache entries |
| 84 | func (c *Cache) clear() { |
| 85 | c.mux.Lock() |
| 86 | defer c.mux.Unlock() |
| 87 | for k := range c.Entries { |
| 88 | delete(c.Entries, k) |
| 89 | } |
| 90 | } |
| 91 | |
| 92 | // RemoveEntry removes the cache entry for the defined SPN. |
| 93 | func (c *Cache) RemoveEntry(spn string) { |
| 94 | c.mux.Lock() |
| 95 | defer c.mux.Unlock() |
| 96 | delete(c.Entries, spn) |
| 97 | } |
| 98 | |
| 99 | // GetCachedTicket returns a ticket from the cache for the SPN. |
| 100 | // Only a ticket that is currently valid will be returned. |
| 101 | func (cl *Client) GetCachedTicket(spn string) (messages.Ticket, types.EncryptionKey, bool) { |
| 102 | if e, ok := cl.cache.getEntry(spn); ok { |
| 103 | //If within time window of ticket return it |
| 104 | if time.Now().UTC().After(e.StartTime) && time.Now().UTC().Before(e.EndTime) { |
| 105 | cl.Log("ticket received from cache for %s", spn) |
| 106 | return e.Ticket, e.SessionKey, true |
| 107 | } else if time.Now().UTC().Before(e.RenewTill) { |
| 108 | e, err := cl.renewTicket(e) |
| 109 | if err != nil { |
| 110 | return e.Ticket, e.SessionKey, false |
| 111 | } |
| 112 | return e.Ticket, e.SessionKey, true |
| 113 | } |
| 114 | } |
| 115 | var tkt messages.Ticket |
| 116 | var key types.EncryptionKey |
| 117 | return tkt, key, false |
| 118 | } |
| 119 | |
| 120 | // renewTicket renews a cache entry ticket. |
| 121 | // To renew from outside the client package use GetCachedTicket |
| 122 | func (cl *Client) renewTicket(e CacheEntry) (CacheEntry, error) { |
| 123 | spn := e.Ticket.SName |
| 124 | _, _, err := cl.TGSREQGenerateAndExchange(spn, e.Ticket.Realm, e.Ticket, e.SessionKey, true) |
| 125 | if err != nil { |
| 126 | return e, err |
| 127 | } |
| 128 | e, ok := cl.cache.getEntry(e.Ticket.SName.PrincipalNameString()) |
| 129 | if !ok { |
| 130 | return e, errors.New("ticket was not added to cache") |
| 131 | } |
| 132 | cl.Log("ticket renewed for %s (EndTime: %v)", spn.PrincipalNameString(), e.EndTime) |
| 133 | return e, nil |
| 134 | } |