Rewrite ssl_asn1.c using new ASN.1 code.

Complete reimplementation of d2i_SSL_SESSION and i2d_SSL_SESSION using
new ASN.1 code and eliminating use of old ASN.1 macros.

Reviewed-by: Rich Salz <rsalz@openssl.org>

1 files changed, 275 insertions, 439 deletions

diff --git a/ssl/ssl_asn1.c b/ssl/ssl_asn1.c
index dd02b4171a..fb2a49556d 100644
--- a/ssl/ssl_asn1.c
+++ b/ssl/ssl_asn1.c
@@ -85,537 +85,373 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include "ssl_locl.h"
-#include <openssl/asn1_mac.h>
-#include <openssl/objects.h>
+#include <openssl/asn1t.h>
 #include <openssl/x509.h>
 
-typedef struct ssl_session_asn1_st {
-    ASN1_INTEGER version;
-    ASN1_INTEGER ssl_version;
-    ASN1_OCTET_STRING cipher;
-    ASN1_OCTET_STRING comp_id;
-    ASN1_OCTET_STRING master_key;
-    ASN1_OCTET_STRING session_id;
-    ASN1_OCTET_STRING session_id_context;
+typedef struct {
+    long version;
+    long ssl_version;
+    ASN1_OCTET_STRING *cipher;
+    ASN1_OCTET_STRING *comp_id;
+    ASN1_OCTET_STRING *master_key;
+    ASN1_OCTET_STRING *session_id;
 #ifndef OPENSSL_NO_KRB5
-    ASN1_OCTET_STRING krb5_princ;
-#endif                          /* OPENSSL_NO_KRB5 */
-    ASN1_INTEGER time;
-    ASN1_INTEGER timeout;
-    ASN1_INTEGER verify_result;
+    ASN1_OCTET_STRING *krb5_princ;
+#endif
+    ASN1_OCTET_STRING *key_arg;
+    long time;
+    long timeout;
+    X509 *peer;
+    ASN1_OCTET_STRING *session_id_context;
+    long verify_result;
 #ifndef OPENSSL_NO_TLSEXT
-    ASN1_OCTET_STRING tlsext_hostname;
-    ASN1_INTEGER tlsext_tick_lifetime;
-    ASN1_OCTET_STRING tlsext_tick;
-#endif                          /* OPENSSL_NO_TLSEXT */
-#ifndef OPENSSL_NO_PSK
-    ASN1_OCTET_STRING psk_identity_hint;
-    ASN1_OCTET_STRING psk_identity;
-#endif                          /* OPENSSL_NO_PSK */
+    ASN1_OCTET_STRING *tlsext_hostname;
+    long tlsext_tick_lifetime_hint;
+    ASN1_OCTET_STRING *tlsext_tick;
+#endif
+#ifndef OPENSSL_NO_TLSEXT
+    ASN1_OCTET_STRING *psk_identity_hint;
+    ASN1_OCTET_STRING *psk_identity;
+#endif
 #ifndef OPENSSL_NO_SRP
-    ASN1_OCTET_STRING srp_username;
-#endif                          /* OPENSSL_NO_SRP */
-    ASN1_INTEGER flags;
+    ASN1_OCTET_STRING *srp_username;
+#endif
+    long flags;
 } SSL_SESSION_ASN1;
 
+ASN1_SEQUENCE(SSL_SESSION_ASN1) = {
+    ASN1_SIMPLE(SSL_SESSION_ASN1, version, LONG),
+    ASN1_SIMPLE(SSL_SESSION_ASN1, ssl_version, LONG),
+    ASN1_SIMPLE(SSL_SESSION_ASN1, cipher, ASN1_OCTET_STRING),
+    ASN1_SIMPLE(SSL_SESSION_ASN1, session_id, ASN1_OCTET_STRING),
+    ASN1_SIMPLE(SSL_SESSION_ASN1, master_key, ASN1_OCTET_STRING),
+#ifndef OPENSSL_NO_KRB5
+    ASN1_OPT(SSL_SESSION_ASN1, krb5_princ, ASN1_OCTET_STRING),
+#endif
+    ASN1_IMP_OPT(SSL_SESSION_ASN1, key_arg, ASN1_OCTET_STRING, 0),
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, time, ZLONG, 1),
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, timeout, ZLONG, 2),
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, peer, X509, 3),
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, session_id_context, ASN1_OCTET_STRING, 4),
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, verify_result, ZLONG, 5),
+#ifndef OPENSSL_NO_TLSEXT
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, tlsext_hostname, ASN1_OCTET_STRING, 6),
+#endif
+#ifndef OPENSSL_NO_PSK
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, psk_identity_hint, ASN1_OCTET_STRING, 7),
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, psk_identity, ASN1_OCTET_STRING, 8),
+#endif
+#ifndef OPENSSL_NO_TLSEXT
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, tlsext_tick_lifetime_hint, ZLONG, 9),
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, tlsext_tick, ASN1_OCTET_STRING, 10),
+#endif
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, comp_id, ASN1_OCTET_STRING, 11),
+#ifndef OPENSSL_NO_SRP
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, srp_username, ASN1_OCTET_STRING, 12),
+#endif
+    ASN1_EXP_OPT(SSL_SESSION_ASN1, flags, ZLONG, 13)
+} ASN1_SEQUENCE_END(SSL_SESSION_ASN1)
+
+IMPLEMENT_STATIC_ASN1_ENCODE_FUNCTIONS(SSL_SESSION_ASN1)
+
+/* Utility functions for i2d_SSL_SESSION */
+
+/* Initialise OCTET STRING from buffer and length */
+
+static void ssl_session_oinit(ASN1_OCTET_STRING **dest, ASN1_OCTET_STRING *os,
+                              unsigned char *data, size_t len)
+{
+    os->data = data;
+    os->length = len;
+    os->flags = 0;
+    *dest = os;
+}
+
+/* Initialise OCTET STRING from string */
+static void ssl_session_sinit(ASN1_OCTET_STRING **dest, ASN1_OCTET_STRING *os,
+                              char *data)
+{
+    if (data != NULL)
+        ssl_session_oinit(dest, os, (unsigned char *)data, strlen(data));
+    else
+        *dest = NULL;
+}
+
 int i2d_SSL_SESSION(SSL_SESSION *in, unsigned char **pp)
 {
-#define LSIZE2 (sizeof(long)*2)
-    int v1 = 0, v2 = 0, v3 = 0, v4 = 0, v5 = 0, v7 = 0, v8 = 0;
-    unsigned char buf[4], ibuf1[LSIZE2], ibuf2[LSIZE2];
-    unsigned char ibuf3[LSIZE2], ibuf4[LSIZE2], ibuf5[LSIZE2];
+
+    SSL_SESSION_ASN1 as;
+
+    ASN1_OCTET_STRING cipher;
+    unsigned char cipher_data[2];
+    ASN1_OCTET_STRING master_key, session_id, sid_ctx;
+
+#ifndef OPENSSL_NO_COMP
+    ASN1_OCTET_STRING comp_id;
+    unsigned char comp_id_data;
+#endif
+
 #ifndef OPENSSL_NO_TLSEXT
-    int v6 = 0, v9 = 0, v10 = 0;
-    unsigned char ibuf6[LSIZE2];
+    ASN1_OCTET_STRING tlsext_hostname, tlsext_tick;
 #endif
-#ifndef OPENSSL_NO_COMP
-    unsigned char cbuf;
-    int v11 = 0;
+
+#ifndef OPENSSL_NO_KRB5
+    ASN1_OCTET_STRING krb5_princ;
 #endif
+
 #ifndef OPENSSL_NO_SRP
-    int v12 = 0;
+    ASN1_OCTET_STRING srp_username;
+#endif
+
+#ifndef OPENSSL_NO_PSK
+    ASN1_OCTET_STRING psk_identity, psk_identity_hint;
 #endif
-    unsigned char fbuf[LSIZE2];
-    int v13 = 0;
+
     long l;
-    SSL_SESSION_ASN1 a;
-    M_ASN1_I2D_vars(in);
 
     if ((in == NULL) || ((in->cipher == NULL) && (in->cipher_id == 0)))
-        return (0);
-
-    /*
-     * Note that I cheat in the following 2 assignments.  I know that if the
-     * ASN1_INTEGER passed to ASN1_INTEGER_set is > sizeof(long)+1, the
-     * buffer will not be re-OPENSSL_malloc()ed. This is a bit evil but makes
-     * things simple, no dynamic allocation to clean up :-)
-     */
-    a.version.length = LSIZE2;
-    a.version.type = V_ASN1_INTEGER;
-    a.version.data = ibuf1;
-    ASN1_INTEGER_set(&(a.version), SSL_SESSION_ASN1_VERSION);
-
-    a.ssl_version.length = LSIZE2;
-    a.ssl_version.type = V_ASN1_INTEGER;
-    a.ssl_version.data = ibuf2;
-    ASN1_INTEGER_set(&(a.ssl_version), in->ssl_version);
-
-    a.cipher.type = V_ASN1_OCTET_STRING;
-    a.cipher.data = buf;
+        return 0;
+
+    memset(&as, 0, sizeof(as));
+
+    as.version = SSL_SESSION_ASN1_VERSION;
+    as.ssl_version = in->ssl_version;
 
     if (in->cipher == NULL)
         l = in->cipher_id;
     else
         l = in->cipher->id;
-    a.cipher.length = 2;
-    buf[0] = ((unsigned char)(l >> 8L)) & 0xff;
-    buf[1] = ((unsigned char)(l)) & 0xff;
+    cipher_data[0] = ((unsigned char)(l >> 8L)) & 0xff;
+    cipher_data[1] = ((unsigned char)(l)) & 0xff;
+
+    ssl_session_oinit(&as.cipher, &cipher, cipher_data, 2);
 
 #ifndef OPENSSL_NO_COMP
     if (in->compress_meth) {
-        cbuf = (unsigned char)in->compress_meth;
-        a.comp_id.length = 1;
-        a.comp_id.type = V_ASN1_OCTET_STRING;
-        a.comp_id.data = &cbuf;
+        comp_id_data = (unsigned char)in->compress_meth;
+        ssl_session_oinit(&as.comp_id, &comp_id, &comp_id_data, 1);
     }
 #endif
 
-    a.master_key.length = in->master_key_length;
-    a.master_key.type = V_ASN1_OCTET_STRING;
-    a.master_key.data = in->master_key;
-
-    a.session_id.length = in->session_id_length;
-    a.session_id.type = V_ASN1_OCTET_STRING;
-    a.session_id.data = in->session_id;
+    ssl_session_oinit(&as.master_key, &master_key,
+                      in->master_key, in->master_key_length);
 
-    a.session_id_context.length = in->sid_ctx_length;
-    a.session_id_context.type = V_ASN1_OCTET_STRING;
-    a.session_id_context.data = in->sid_ctx;
+    ssl_session_oinit(&as.session_id, &session_id,
+                      in->session_id, in->session_id_length);
 
+    ssl_session_oinit(&as.session_id_context, &sid_ctx,
+                      in->sid_ctx, in->sid_ctx_length);
 #ifndef OPENSSL_NO_KRB5
     if (in->krb5_client_princ_len) {
-        a.krb5_princ.length = in->krb5_client_princ_len;
-        a.krb5_princ.type = V_ASN1_OCTET_STRING;
-        a.krb5_princ.data = in->krb5_client_princ;
+        ssl_session_oinit(&as.krb5_princ, &krb5_princ,
+                          in->krb5_client_princ, in->krb5_client_princ_len);
     }
 #endif                          /* OPENSSL_NO_KRB5 */
 
-    if (in->time != 0L) {
-        a.time.length = LSIZE2;
-        a.time.type = V_ASN1_INTEGER;
-        a.time.data = ibuf3;
-        ASN1_INTEGER_set(&(a.time), in->time);
-    }
+    as.time = in->time;
+    as.timeout = in->timeout;
+    as.verify_result = in->verify_result;
 
-    if (in->timeout != 0L) {
-        a.timeout.length = LSIZE2;
-        a.timeout.type = V_ASN1_INTEGER;
-        a.timeout.data = ibuf4;
-        ASN1_INTEGER_set(&(a.timeout), in->timeout);
-    }
+    as.peer = in->peer;
 
-    if (in->verify_result != X509_V_OK) {
-        a.verify_result.length = LSIZE2;
-        a.verify_result.type = V_ASN1_INTEGER;
-        a.verify_result.data = ibuf5;
-        ASN1_INTEGER_set(&a.verify_result, in->verify_result);
-    }
 #ifndef OPENSSL_NO_TLSEXT
-    if (in->tlsext_hostname) {
-        a.tlsext_hostname.length = strlen(in->tlsext_hostname);
-        a.tlsext_hostname.type = V_ASN1_OCTET_STRING;
-        a.tlsext_hostname.data = (unsigned char *)in->tlsext_hostname;
-    }
+    ssl_session_sinit(&as.tlsext_hostname, &tlsext_hostname,
+                      in->tlsext_hostname);
     if (in->tlsext_tick) {
-        a.tlsext_tick.length = in->tlsext_ticklen;
-        a.tlsext_tick.type = V_ASN1_OCTET_STRING;
-        a.tlsext_tick.data = (unsigned char *)in->tlsext_tick;
-    }
-    if (in->tlsext_tick_lifetime_hint > 0) {
-        a.tlsext_tick_lifetime.length = LSIZE2;
-        a.tlsext_tick_lifetime.type = V_ASN1_INTEGER;
-        a.tlsext_tick_lifetime.data = ibuf6;
-        ASN1_INTEGER_set(&a.tlsext_tick_lifetime,
-                         in->tlsext_tick_lifetime_hint);
+        ssl_session_oinit(&as.tlsext_tick, &tlsext_tick,
+                          in->tlsext_tick, in->tlsext_ticklen);
     }
+    if (in->tlsext_tick_lifetime_hint > 0)
+        as.tlsext_tick_lifetime_hint = in->tlsext_tick_lifetime_hint;
 #endif                          /* OPENSSL_NO_TLSEXT */
 #ifndef OPENSSL_NO_PSK
-    if (in->psk_identity_hint) {
-        a.psk_identity_hint.length = strlen(in->psk_identity_hint);
-        a.psk_identity_hint.type = V_ASN1_OCTET_STRING;
-        a.psk_identity_hint.data = (unsigned char *)(in->psk_identity_hint);
-    }
-    if (in->psk_identity) {
-        a.psk_identity.length = strlen(in->psk_identity);
-        a.psk_identity.type = V_ASN1_OCTET_STRING;
-        a.psk_identity.data = (unsigned char *)(in->psk_identity);
-    }
+    ssl_session_sinit(&as.psk_identity_hint, &psk_identity_hint,
+                      in->psk_identity_hint);
+    ssl_session_sinit(&as.psk_identity, &psk_identity, in->psk_identity);
 #endif                          /* OPENSSL_NO_PSK */
 #ifndef OPENSSL_NO_SRP
-    if (in->srp_username) {
-        a.srp_username.length = strlen(in->srp_username);
-        a.srp_username.type = V_ASN1_OCTET_STRING;
-        a.srp_username.data = (unsigned char *)(in->srp_username);
-    }
+    ssl_session_sinit(&as.srp_username, &srp_username, in->srp_username);
 #endif                          /* OPENSSL_NO_SRP */
 
-    if (in->flags) {
-        a.flags.length = LSIZE2;
-        a.flags.type = V_ASN1_INTEGER;
-        a.flags.data = fbuf;
-        ASN1_INTEGER_set(&a.flags, in->flags);
-    }
+    as.flags = in->flags;
 
-    M_ASN1_I2D_len(&(a.version), i2d_ASN1_INTEGER);
-    M_ASN1_I2D_len(&(a.ssl_version), i2d_ASN1_INTEGER);
-    M_ASN1_I2D_len(&(a.cipher), i2d_ASN1_OCTET_STRING);
-    M_ASN1_I2D_len(&(a.session_id), i2d_ASN1_OCTET_STRING);
-    M_ASN1_I2D_len(&(a.master_key), i2d_ASN1_OCTET_STRING);
-#ifndef OPENSSL_NO_KRB5
-    if (in->krb5_client_princ_len)
-        M_ASN1_I2D_len(&(a.krb5_princ), i2d_ASN1_OCTET_STRING);
-#endif                          /* OPENSSL_NO_KRB5 */
-    if (in->time != 0L)
-        M_ASN1_I2D_len_EXP_opt(&(a.time), i2d_ASN1_INTEGER, 1, v1);
-    if (in->timeout != 0L)
-        M_ASN1_I2D_len_EXP_opt(&(a.timeout), i2d_ASN1_INTEGER, 2, v2);
-    if (in->peer != NULL)
-        M_ASN1_I2D_len_EXP_opt(in->peer, i2d_X509, 3, v3);
-    M_ASN1_I2D_len_EXP_opt(&a.session_id_context, i2d_ASN1_OCTET_STRING, 4,
-                           v4);
-    if (in->verify_result != X509_V_OK)
-        M_ASN1_I2D_len_EXP_opt(&(a.verify_result), i2d_ASN1_INTEGER, 5, v5);
+    return i2d_SSL_SESSION_ASN1(&as, pp);
 
-#ifndef OPENSSL_NO_TLSEXT
-    if (in->tlsext_tick_lifetime_hint > 0)
-        M_ASN1_I2D_len_EXP_opt(&a.tlsext_tick_lifetime, i2d_ASN1_INTEGER, 9,
-                               v9);
-    if (in->tlsext_tick)
-        M_ASN1_I2D_len_EXP_opt(&(a.tlsext_tick), i2d_ASN1_OCTET_STRING, 10,
-                               v10);
-    if (in->tlsext_hostname)
-        M_ASN1_I2D_len_EXP_opt(&(a.tlsext_hostname), i2d_ASN1_OCTET_STRING, 6,
-                               v6);
-# ifndef OPENSSL_NO_COMP
-    if (in->compress_meth)
-        M_ASN1_I2D_len_EXP_opt(&(a.comp_id), i2d_ASN1_OCTET_STRING, 11, v11);
-# endif
-#endif                          /* OPENSSL_NO_TLSEXT */
-#ifndef OPENSSL_NO_PSK
-    if (in->psk_identity_hint)
-        M_ASN1_I2D_len_EXP_opt(&(a.psk_identity_hint), i2d_ASN1_OCTET_STRING,
-                               7, v7);
-    if (in->psk_identity)
-        M_ASN1_I2D_len_EXP_opt(&(a.psk_identity), i2d_ASN1_OCTET_STRING, 8,
-                               v8);
-#endif                          /* OPENSSL_NO_PSK */
-#ifndef OPENSSL_NO_SRP
-    if (in->srp_username)
-        M_ASN1_I2D_len_EXP_opt(&(a.srp_username), i2d_ASN1_OCTET_STRING, 12,
-                               v12);
-#endif                          /* OPENSSL_NO_SRP */
-    if (in->flags)
-        M_ASN1_I2D_len_EXP_opt(&(a.flags), i2d_ASN1_INTEGER, 13, v13);
+}
 
-    M_ASN1_I2D_seq_total();
+/* Utility functions for d2i_SSL_SESSION */
 
-    M_ASN1_I2D_put(&(a.version), i2d_ASN1_INTEGER);
-    M_ASN1_I2D_put(&(a.ssl_version), i2d_ASN1_INTEGER);
-    M_ASN1_I2D_put(&(a.cipher), i2d_ASN1_OCTET_STRING);
-    M_ASN1_I2D_put(&(a.session_id), i2d_ASN1_OCTET_STRING);
-    M_ASN1_I2D_put(&(a.master_key), i2d_ASN1_OCTET_STRING);
-#ifndef OPENSSL_NO_KRB5
-    if (in->krb5_client_princ_len)
-        M_ASN1_I2D_put(&(a.krb5_princ), i2d_ASN1_OCTET_STRING);
-#endif                          /* OPENSSL_NO_KRB5 */
-    if (in->time != 0L)
-        M_ASN1_I2D_put_EXP_opt(&(a.time), i2d_ASN1_INTEGER, 1, v1);
-    if (in->timeout != 0L)
-        M_ASN1_I2D_put_EXP_opt(&(a.timeout), i2d_ASN1_INTEGER, 2, v2);
-    if (in->peer != NULL)
-        M_ASN1_I2D_put_EXP_opt(in->peer, i2d_X509, 3, v3);
-    M_ASN1_I2D_put_EXP_opt(&a.session_id_context, i2d_ASN1_OCTET_STRING, 4,
-                           v4);
-    if (in->verify_result != X509_V_OK)
-        M_ASN1_I2D_put_EXP_opt(&a.verify_result, i2d_ASN1_INTEGER, 5, v5);
-#ifndef OPENSSL_NO_TLSEXT
-    if (in->tlsext_hostname)
-        M_ASN1_I2D_put_EXP_opt(&(a.tlsext_hostname), i2d_ASN1_OCTET_STRING, 6,
-                               v6);
-#endif                          /* OPENSSL_NO_TLSEXT */
-#ifndef OPENSSL_NO_PSK
-    if (in->psk_identity_hint)
-        M_ASN1_I2D_put_EXP_opt(&(a.psk_identity_hint), i2d_ASN1_OCTET_STRING,
-                               7, v7);
-    if (in->psk_identity)
-        M_ASN1_I2D_put_EXP_opt(&(a.psk_identity), i2d_ASN1_OCTET_STRING, 8,
-                               v8);
-#endif                          /* OPENSSL_NO_PSK */
-#ifndef OPENSSL_NO_TLSEXT
-    if (in->tlsext_tick_lifetime_hint > 0)
-        M_ASN1_I2D_put_EXP_opt(&a.tlsext_tick_lifetime, i2d_ASN1_INTEGER, 9,
-                               v9);
-    if (in->tlsext_tick)
-        M_ASN1_I2D_put_EXP_opt(&(a.tlsext_tick), i2d_ASN1_OCTET_STRING, 10,
-                               v10);
-#endif                          /* OPENSSL_NO_TLSEXT */
-#ifndef OPENSSL_NO_COMP
-    if (in->compress_meth)
-        M_ASN1_I2D_put_EXP_opt(&(a.comp_id), i2d_ASN1_OCTET_STRING, 11, v11);
-#endif
-#ifndef OPENSSL_NO_SRP
-    if (in->srp_username)
-        M_ASN1_I2D_put_EXP_opt(&(a.srp_username), i2d_ASN1_OCTET_STRING, 12,
-                               v12);
-#endif                          /* OPENSSL_NO_SRP */
-    if (in->flags)
-        M_ASN1_I2D_put_EXP_opt(&a.flags, i2d_ASN1_INTEGER, 13, v13);
-    M_ASN1_I2D_finish();
+/* BUF_strndup an OCTET STRING */
+
+static int ssl_session_strndup(char **pdst, ASN1_OCTET_STRING *src)
+{
+    if (*pdst) {
+        OPENSSL_free(*pdst);
+        *pdst = NULL;
+    }
+    if (src == NULL)
+        return 1;
+    *pdst = BUF_strndup((char *)src->data, src->length);
+    if (*pdst == NULL)
+        return 0;
+    return 1;
+}
+
+/* Copy an OCTET STRING, return error if it exceeds maximum length */
+
+static int ssl_session_memcpy(unsigned char *dst, unsigned int *pdstlen,
+                              ASN1_OCTET_STRING *src, int maxlen)
+{
+    if (src == NULL) {
+        *pdstlen = 0;
+        return 1;
+    }
+    if (src->length > maxlen)
+        return 0;
+    memcpy(dst, src->data, src->length);
+    *pdstlen = src->length;
+    return 1;
 }
 
 SSL_SESSION *d2i_SSL_SESSION(SSL_SESSION **a, const unsigned char **pp,
                              long length)
 {
-    int ssl_version = 0, i;
     long id;
-    ASN1_INTEGER ai, *aip;
-    ASN1_OCTET_STRING os, *osp;
-    M_ASN1_D2I_vars(a, SSL_SESSION *, SSL_SESSION_new);
-
-    aip = &ai;
-    osp = &os;
-
-    M_ASN1_D2I_Init();
-    M_ASN1_D2I_start_sequence();
-
-    ai.data = NULL;
-    ai.length = 0;
-    M_ASN1_D2I_get_x(ASN1_INTEGER, aip, d2i_ASN1_INTEGER);
-    if (ai.data != NULL) {
-        OPENSSL_free(ai.data);
-        ai.data = NULL;
-        ai.length = 0;
-    }
+    unsigned int tmpl;
+    const unsigned char *p = *pp;
+    SSL_SESSION_ASN1 *as = NULL;
+    SSL_SESSION *ret = NULL;
+
+    as = d2i_SSL_SESSION_ASN1(NULL, &p, length);
+    /* ASN.1 code returns suitable error */
+    if (as == NULL)
+        goto err;
 
-    /* we don't care about the version right now :-) */
-    M_ASN1_D2I_get_x(ASN1_INTEGER, aip, d2i_ASN1_INTEGER);
-    ssl_version = (int)ASN1_INTEGER_get(aip);
-    ret->ssl_version = ssl_version;
-    if (ai.data != NULL) {
-        OPENSSL_free(ai.data);
-        ai.data = NULL;
-        ai.length = 0;
+    if (0) {
+        i2d_SSL_SESSION_ASN1(NULL, NULL);
     }
 
-    os.data = NULL;
-    os.length = 0;
-    M_ASN1_D2I_get_x(ASN1_OCTET_STRING, osp, d2i_ASN1_OCTET_STRING);
-    if ((ssl_version >> 8) == SSL3_VERSION_MAJOR
-        || (ssl_version >> 8) == DTLS1_VERSION_MAJOR
-        || ssl_version == DTLS1_BAD_VER) {
-        if (os.length != 2) {
-            c.error = SSL_R_CIPHER_CODE_WRONG_LENGTH;
-            c.line = __LINE__;
+    if (!a || !*a) {
+        ret = SSL_SESSION_new();
+        if (ret == NULL)
             goto err;
-        }
-        id = 0x03000000L |
-            ((unsigned long)os.data[0] << 8L) | (unsigned long)os.data[1];
     } else {
-        c.error = SSL_R_UNKNOWN_SSL_VERSION;
-        c.line = __LINE__;
+        ret = *a;
+    }
+
+    if (as->version != SSL_SESSION_ASN1_VERSION) {
+        SSLerr(SSL_F_D2I_SSL_SESSION, SSL_R_UNKNOWN_SSL_VERSION);
         goto err;
     }
 
-    ret->cipher = NULL;
-    ret->cipher_id = id;
+    if ((as->ssl_version >> 8) != SSL3_VERSION_MAJOR
+        && (as->ssl_version >> 8) != DTLS1_VERSION_MAJOR
+        && as->ssl_version != DTLS1_BAD_VER) {
+        SSLerr(SSL_F_D2I_SSL_SESSION, SSL_R_UNSUPPORTED_SSL_VERSION);
+        goto err;
+    }
 
-    M_ASN1_D2I_get_x(ASN1_OCTET_STRING, osp, d2i_ASN1_OCTET_STRING);
-    i = SSL3_MAX_SSL_SESSION_ID_LENGTH;
+    ret->ssl_version = (int)as->ssl_version;
 
-    if (os.length > i)
-        os.length = i;
-    if (os.length > (int)sizeof(ret->session_id)) /* can't happen */
-        os.length = sizeof(ret->session_id);
+    if (as->cipher->length != 2) {
+        SSLerr(SSL_F_D2I_SSL_SESSION, SSL_R_CIPHER_CODE_WRONG_LENGTH);
+        goto err;
+    }
 
-    ret->session_id_length = os.length;
-    OPENSSL_assert(os.length <= (int)sizeof(ret->session_id));
-    memcpy(ret->session_id, os.data, os.length);
+    p = as->cipher->data;
+    id = 0x03000000L | ((unsigned long)p[0] << 8L) | (unsigned long)p[1];
 
-    M_ASN1_D2I_get_x(ASN1_OCTET_STRING, osp, d2i_ASN1_OCTET_STRING);
-    if (os.length > SSL_MAX_MASTER_KEY_LENGTH)
-        ret->master_key_length = SSL_MAX_MASTER_KEY_LENGTH;
-    else
-        ret->master_key_length = os.length;
-    memcpy(ret->master_key, os.data, ret->master_key_length);
+    ret->cipher = NULL;
+    ret->cipher_id = id;
 
-    os.length = 0;
+    if (!ssl_session_memcpy(ret->session_id, &ret->session_id_length,
+                            as->session_id, SSL3_MAX_SSL_SESSION_ID_LENGTH))
+        goto err;
+
+    if (!ssl_session_memcpy(ret->master_key, &tmpl,
+                            as->master_key, SSL_MAX_MASTER_KEY_LENGTH))
+        goto err;
+
+    ret->master_key_length = tmpl;
 
 #ifndef OPENSSL_NO_KRB5
-    os.length = 0;
-    M_ASN1_D2I_get_opt(osp, d2i_ASN1_OCTET_STRING, V_ASN1_OCTET_STRING);
-    if (os.data) {
-        if (os.length > SSL_MAX_KRB5_PRINCIPAL_LENGTH)
-            ret->krb5_client_princ_len = 0;
-        else
-            ret->krb5_client_princ_len = os.length;
-        memcpy(ret->krb5_client_princ, os.data, ret->krb5_client_princ_len);
-        OPENSSL_free(os.data);
-        os.data = NULL;
-        os.length = 0;
-    } else
-        ret->krb5_client_princ_len = 0;
+    if (!ssl_session_memcpy(ret->krb5_client_princ, &ret->krb5_client_princ_len,
+                            as->krb5_princ, SSL_MAX_PRINCIPAL_LENGTH))
+        goto err;
 #endif                          /* OPENSSL_NO_KRB5 */
 
-    M_ASN1_D2I_get_IMP_opt(osp, d2i_ASN1_OCTET_STRING, 0,
-                           V_ASN1_OCTET_STRING);
-    if (os.data != NULL)
-        OPENSSL_free(os.data);
-
-    ai.length = 0;
-    M_ASN1_D2I_get_EXP_opt(aip, d2i_ASN1_INTEGER, 1);
-    if (ai.data != NULL) {
-        ret->time = ASN1_INTEGER_get(aip);
-        OPENSSL_free(ai.data);
-        ai.data = NULL;
-        ai.length = 0;
-    } else
+    if (as->time != 0)
+        ret->time = as->time;
+    else
         ret->time = (unsigned long)time(NULL);
 
-    ai.length = 0;
-    M_ASN1_D2I_get_EXP_opt(aip, d2i_ASN1_INTEGER, 2);
-    if (ai.data != NULL) {
-        ret->timeout = ASN1_INTEGER_get(aip);
-        OPENSSL_free(ai.data);
-        ai.data = NULL;
-        ai.length = 0;
-    } else
+    if (as->timeout != 0)
+        ret->timeout = as->timeout;
+    else
         ret->timeout = 3;
 
-    if (ret->peer != NULL) {
-        X509_free(ret->peer);
-        ret->peer = NULL;
-    }
-    M_ASN1_D2I_get_EXP_opt(ret->peer, d2i_X509, 3);
+    X509_free(ret->peer);
+    ret->peer = as->peer;
+    as->peer = NULL;
 
-    os.length = 0;
-    os.data = NULL;
-    M_ASN1_D2I_get_EXP_opt(osp, d2i_ASN1_OCTET_STRING, 4);
+    if (!ssl_session_memcpy(ret->sid_ctx, &ret->sid_ctx_length,
+                            as->session_id_context, SSL_MAX_SID_CTX_LENGTH))
+        goto err;
 
-    if (os.data != NULL) {
-        if (os.length > SSL_MAX_SID_CTX_LENGTH) {
-            c.error = SSL_R_BAD_LENGTH;
-            c.line = __LINE__;
-            goto err;
-        } else {
-            ret->sid_ctx_length = os.length;
-            memcpy(ret->sid_ctx, os.data, os.length);
-        }
-        OPENSSL_free(os.data);
-        os.data = NULL;
-        os.length = 0;
-    } else
-        ret->sid_ctx_length = 0;
-
-    ai.length = 0;
-    M_ASN1_D2I_get_EXP_opt(aip, d2i_ASN1_INTEGER, 5);
-    if (ai.data != NULL) {
-        ret->verify_result = ASN1_INTEGER_get(aip);
-        OPENSSL_free(ai.data);
-        ai.data = NULL;
-        ai.length = 0;
-    } else
-        ret->verify_result = X509_V_OK;
+    /* NB: this defaults to zero which is X509_V_OK */
+    ret->verify_result = as->verify_result;
 
 #ifndef OPENSSL_NO_TLSEXT
-    os.length = 0;
-    os.data = NULL;
-    M_ASN1_D2I_get_EXP_opt(osp, d2i_ASN1_OCTET_STRING, 6);
-    if (os.data) {
-        ret->tlsext_hostname = BUF_strndup((char *)os.data, os.length);
-        OPENSSL_free(os.data);
-        os.data = NULL;
-        os.length = 0;
-    } else
-        ret->tlsext_hostname = NULL;
+    if (!ssl_session_strndup(&ret->tlsext_hostname, as->tlsext_hostname))
+        goto err;
 #endif                          /* OPENSSL_NO_TLSEXT */
 
 #ifndef OPENSSL_NO_PSK
-    os.length = 0;
-    os.data = NULL;
-    M_ASN1_D2I_get_EXP_opt(osp, d2i_ASN1_OCTET_STRING, 7);
-    if (os.data) {
-        ret->psk_identity_hint = BUF_strndup((char *)os.data, os.length);
-        OPENSSL_free(os.data);
-        os.data = NULL;
-        os.length = 0;
-    } else
-        ret->psk_identity_hint = NULL;
-
-    os.length = 0;
-    os.data = NULL;
-    M_ASN1_D2I_get_EXP_opt(osp, d2i_ASN1_OCTET_STRING, 8);
-    if (os.data) {
-        ret->psk_identity = BUF_strndup((char *)os.data, os.length);
-        OPENSSL_free(os.data);
-        os.data = NULL;
-        os.length = 0;
-    } else
-        ret->psk_identity = NULL;
-#endif                          /* OPENSSL_NO_PSK */
+    if (!ssl_session_strndup(&ret->psk_identity_hint, as->psk_identity_hint))
+        goto err;
+    if (!ssl_session_strndup(&ret->psk_identity, as->psk_identity))
+        goto err;
+#endif
 
 #ifndef OPENSSL_NO_TLSEXT
-    ai.length = 0;
-    M_ASN1_D2I_get_EXP_opt(aip, d2i_ASN1_INTEGER, 9);
-    if (ai.data != NULL) {
-        ret->tlsext_tick_lifetime_hint = ASN1_INTEGER_get(aip);
-        OPENSSL_free(ai.data);
-        ai.data = NULL;
-        ai.length = 0;
-    } else
-        ret->tlsext_tick_lifetime_hint = 0;
-    os.length = 0;
-    os.data = NULL;
-    M_ASN1_D2I_get_EXP_opt(osp, d2i_ASN1_OCTET_STRING, 10);
-    if (os.data) {
-        ret->tlsext_tick = os.data;
-        ret->tlsext_ticklen = os.length;
-        os.data = NULL;
-        os.length = 0;
-    } else
+    ret->tlsext_tick_lifetime_hint = as->tlsext_tick_lifetime_hint;
+    if (as->tlsext_tick) {
+        ret->tlsext_tick = as->tlsext_tick->data;
+        ret->tlsext_ticklen = as->tlsext_tick->length;
+        as->tlsext_tick->data = NULL;
+    } else {
         ret->tlsext_tick = NULL;
+    }
 #endif                          /* OPENSSL_NO_TLSEXT */
 #ifndef OPENSSL_NO_COMP
-    os.length = 0;
-    os.data = NULL;
-    M_ASN1_D2I_get_EXP_opt(osp, d2i_ASN1_OCTET_STRING, 11);
-    if (os.data) {
-        ret->compress_meth = os.data[0];
-        OPENSSL_free(os.data);
-        os.data = NULL;
+    if (as->comp_id) {
+        if (as->comp_id->length != 1) {
+            SSLerr(SSL_F_D2I_SSL_SESSION, SSL_R_BAD_LENGTH);
+            goto err;
+        }
+        ret->compress_meth = as->comp_id->data[0];
+    } else {
+        ret->compress_meth = 0;
     }
 #endif
 
 #ifndef OPENSSL_NO_SRP
-    os.length = 0;
-    os.data = NULL;
-    M_ASN1_D2I_get_EXP_opt(osp, d2i_ASN1_OCTET_STRING, 12);
-    if (os.data) {
-        ret->srp_username = BUF_strndup((char *)os.data, os.length);
-        OPENSSL_free(os.data);
-        os.data = NULL;
-        os.length = 0;
-    } else
-        ret->srp_username = NULL;
+    if (!ssl_session_strndup(&ret->srp_username, as->srp_username))
+        goto err;
 #endif                          /* OPENSSL_NO_SRP */
-    ai.length = 0;
-    M_ASN1_D2I_get_EXP_opt(aip, d2i_ASN1_INTEGER, 13);
-    if (ai.data != NULL) {
-        ret->flags = ASN1_INTEGER_get(aip);
-        OPENSSL_free(ai.data);
-        ai.data = NULL;
-        ai.length = 0;
-    } else
-        ret->flags = 0;
-
-    M_ASN1_D2I_Finish(a, SSL_SESSION_free, SSL_F_D2I_SSL_SESSION);
+    /* Flags defaults to zero which is fine */
+    ret->flags = as->flags;
+
+    M_ASN1_free_of(as, SSL_SESSION_ASN1);
+
+    if ((a != NULL) && (*a == NULL))
+        *a = ret;
+    *pp = p;
+    return ret;
+
+    err:
+    M_ASN1_free_of(as, SSL_SESSION_ASN1);
+    if ((a == NULL) || (*a != ret))
+        SSL_SESSION_free(ret);
+    return NULL;
 }