RFC4507 (including RFC4507bis) TLS stateless session resumption support
for OpenSSL.
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index e0ca4ac..6c78abe 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -111,10 +111,16 @@
#include <stdio.h>
#include <openssl/objects.h>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
#include "ssl_locl.h"
const char tls1_version_str[]="TLSv1" OPENSSL_VERSION_PTEXT;
+static int tls_decrypt_ticket(SSL *s, const unsigned char *tick, int ticklen,
+ const unsigned char *sess_id, int sesslen,
+ SSL_SESSION **psess);
+
SSL3_ENC_METHOD TLSv1_enc_data={
tls1_enc,
tls1_mac,
@@ -164,6 +170,7 @@
ret+=2;
if (ret>=limit) return NULL; /* this really never occurs, but ... */
+
if (s->tlsext_hostname != NULL)
{
/* Add TLS extension servername to the Client Hello message */
@@ -243,6 +250,27 @@
}
#endif /* OPENSSL_NO_EC */
+ if (!(SSL_get_options(s) & SSL_OP_NO_TICKET))
+ {
+ int ticklen;
+ if (s->session && s->session->tlsext_tick)
+ ticklen = s->session->tlsext_ticklen;
+ else
+ ticklen = 0;
+ /* Check for enough room 2 for extension type, 2 for len
+ * rest for ticket
+ */
+ if (limit - p - 4 - ticklen < 0)
+ return NULL;
+ s2n(TLSEXT_TYPE_session_ticket,ret);
+ s2n(ticklen,ret);
+ if (ticklen)
+ {
+ memcpy(ret, s->session->tlsext_tick, ticklen);
+ ret += ticklen;
+ }
+ }
+
if ((extdatalen = ret-p-2)== 0)
return p;
@@ -289,6 +317,14 @@
/* Currently the server should not respond with a SupportedCurves extension */
#endif /* OPENSSL_NO_EC */
+ if (s->tlsext_ticket_expected
+ && !(SSL_get_options(s) & SSL_OP_NO_TICKET))
+ {
+ if (limit - p - 4 < 0) return NULL;
+ s2n(TLSEXT_TYPE_session_ticket,ret);
+ s2n(0,ret);
+ }
+
if ((extdatalen = ret-p-2)== 0)
return p;
@@ -318,7 +354,10 @@
if (data+size > (d+n))
return 1;
-
+
+ if (s->tlsext_debug_cb)
+ s->tlsext_debug_cb(s, 0, type, data, size,
+ s->tlsext_debug_arg);
/* The servername extension is treated as follows:
- Only the hostname type is supported with a maximum length of 255.
@@ -472,9 +511,10 @@
#endif
}
#endif /* OPENSSL_NO_EC */
- data+=size;
+ /* session ticket processed earlier */
+ data+=size;
}
-
+
*p = data;
return 1;
}
@@ -501,6 +541,10 @@
if (data+size > (d+n))
return 1;
+ if (s->tlsext_debug_cb)
+ s->tlsext_debug_cb(s, 1, type, data, size,
+ s->tlsext_debug_arg);
+
if (type == TLSEXT_TYPE_server_name)
{
if (s->tlsext_hostname == NULL || size > 0)
@@ -540,6 +584,17 @@
#endif
}
#endif /* OPENSSL_NO_EC */
+
+ else if (type == TLSEXT_TYPE_session_ticket)
+ {
+ if ((SSL_get_options(s) & SSL_OP_NO_TICKET)
+ || (size > 0))
+ {
+ *al = TLS1_AD_UNSUPPORTED_EXTENSION;
+ return 0;
+ }
+ s->tlsext_ticket_expected = 1;
+ }
data+=size;
}
@@ -854,5 +909,144 @@
return 1;
}
}
-#endif
+/* Since the server cache lookup is done early on in the processing of client
+ * hello and other operations depend on the result we need to handle any TLS
+ * session ticket extension at the same time.
+ */
+
+int tls1_process_ticket(SSL *s, unsigned char *session_id, int len,
+ const unsigned char *limit, SSL_SESSION **ret)
+ {
+ /* Point after session ID in client hello */
+ const unsigned char *p = session_id + len;
+ unsigned short i;
+ if ((s->version <= SSL3_VERSION) || !limit)
+ return 1;
+ if (p >= limit)
+ return -1;
+ /* Skip past cipher list */
+ n2s(p, i);
+ p+= i;
+ if (p >= limit)
+ return -1;
+ /* Skip past compression algorithm list */
+ i = *(p++);
+ p += i;
+ if (p > limit)
+ return -1;
+ /* Now at start of extensions */
+ if ((p + 2) >= limit)
+ return 1;
+ n2s(p, i);
+ while ((p + 4) <= limit)
+ {
+ unsigned short type, size;
+ n2s(p, type);
+ n2s(p, size);
+ if (p + size > limit)
+ return 1;
+ if (type == TLSEXT_TYPE_session_ticket)
+ {
+ /* If tickets disabled indicate cache miss which will
+ * trigger a full handshake
+ */
+ if (SSL_get_options(s) & SSL_OP_NO_TICKET)
+ return 0;
+ /* If zero length not client will accept a ticket
+ * and indicate cache miss to trigger full handshake
+ */
+ if (size == 0)
+ {
+ s->tlsext_ticket_expected = 1;
+ return 0; /* Cache miss */
+ }
+ return tls_decrypt_ticket(s, p, size, session_id, len,
+ ret);
+ }
+ p += size;
+ }
+ return 1;
+ }
+
+static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, int eticklen,
+ const unsigned char *sess_id, int sesslen,
+ SSL_SESSION **psess)
+ {
+ SSL_SESSION *sess;
+ unsigned char *sdec;
+ const unsigned char *p;
+ int slen, mlen;
+ unsigned char tick_hmac[EVP_MAX_MD_SIZE];
+ HMAC_CTX hctx;
+ EVP_CIPHER_CTX ctx;
+ /* Attempt to process session ticket, first conduct sanity and
+ * integrity checks on ticket.
+ */
+ mlen = EVP_MD_size(EVP_sha1());
+ eticklen -= mlen;
+ /* Need at least keyname + iv + some encrypted data */
+ if (eticklen < 48)
+ goto tickerr;
+ /* Check key name matches */
+ if (memcmp(etick, s->ctx->tlsext_tick_key_name, 16))
+ goto tickerr;
+fprintf(stderr, "Ticket match OK\n");
+ /* Check HMAC of encrypted ticket */
+ HMAC_CTX_init(&hctx);
+ HMAC_Init_ex(&hctx, s->ctx->tlsext_tick_hmac_key, 16,
+ EVP_sha1(), NULL);
+ HMAC_Update(&hctx, etick, eticklen);
+ HMAC_Final(&hctx, tick_hmac, NULL);
+ HMAC_CTX_cleanup(&hctx);
+ if (memcmp(tick_hmac, etick + eticklen, mlen))
+ goto tickerr;
+fprintf(stderr, "HMAC match OK\n");
+ /* Set p to start of IV */
+ p = etick + 16;
+ EVP_CIPHER_CTX_init(&ctx);
+ /* Attempt to decrypt session data */
+ EVP_DecryptInit_ex(&ctx, EVP_aes_128_cbc(), NULL,
+ s->ctx->tlsext_tick_aes_key, p);
+ /* Move p after IV to start of encrypted ticket, update length */
+ p += 16;
+ eticklen -= 32;
+ sdec = OPENSSL_malloc(eticklen);
+ if (!sdec)
+ {
+ EVP_CIPHER_CTX_cleanup(&ctx);
+ return -1;
+ }
+ EVP_DecryptUpdate(&ctx, sdec, &slen, p, eticklen);
+ if (EVP_DecryptFinal(&ctx, sdec + slen, &mlen) <= 0)
+ goto tickerr;
+fprintf(stderr, "Decrypt OK\n");
+ slen += mlen;
+ EVP_CIPHER_CTX_cleanup(&ctx);
+ p = sdec;
+
+ sess = d2i_SSL_SESSION(NULL, &p, slen);
+ OPENSSL_free(sdec);
+ if (sess)
+ {
+ /* The session ID if non-empty is used by some clients to
+ * detect that the ticket has been accepted. So we copy it to
+ * the session structure. If it is empty set length to zero
+ * as required by standard.
+ */
+ if (sesslen)
+ memcpy(sess->session_id, sess_id, sesslen);
+ sess->session_id_length = sesslen;
+ *psess = sess;
+ return 1;
+ }
+ /* If session decrypt failure indicate a cache miss and set state to
+ * send a new ticket
+ */
+ tickerr:
+ s->tlsext_ticket_expected = 1;
+ return 0;
+ }
+
+
+#endif
