Convert ssl3_get_server_kex_dhe() to CBS.

ok beck@

1 files changed, 19 insertions, 42 deletions

diff --git a/src/lib/libssl/s3_clnt.c b/src/lib/libssl/s3_clnt.c
index e9db8e27c2..8e02239392 100644
--- a/src/lib/libssl/s3_clnt.c
+++ b/src/lib/libssl/s3_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s3_clnt.c,v 1.140 2016/11/03 13:20:35 jsing Exp $ */
+/* $OpenBSD: s3_clnt.c,v 1.141 2016/11/04 15:05:29 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1094,68 +1094,47 @@ err:
 static int
 ssl3_get_server_kex_dhe(SSL *s, EVP_PKEY **pkey, unsigned char **pp, long *nn)
 {
+        CBS cbs, dhp, dhg, dhpk;
         BN_CTX *bn_ctx = NULL;
         SESS_CERT *sc = NULL;
         DH *dh = NULL;
-        int al, i, param_len;
-        unsigned char *p;
-        long alg_a, n;
+        long alg_a;
+        int al;
 
         alg_a = s->s3->tmp.new_cipher->algorithm_auth;
-        n = *nn;
-        p = *pp;
         sc = s->session->sess_cert;
 
+        if (*nn < 0)
+                goto err;
+
+        CBS_init(&cbs, *pp, *nn);
+
         if ((dh = DH_new()) == NULL) {
                 SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, ERR_R_DH_LIB);
                 goto err;
         }
-        if (2 > n)
+
+        if (!CBS_get_u16_length_prefixed(&cbs, &dhp))
                 goto truncated;
-        n2s(p, i);
-        param_len = i + 2;
-        if (param_len > n) {
-                al = SSL_AD_DECODE_ERROR;
-                SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_BAD_DH_P_LENGTH);
-                goto f_err;
-        }
-        if (!(dh->p = BN_bin2bn(p, i, NULL))) {
+        if ((dh->p = BN_bin2bn(CBS_data(&dhp), CBS_len(&dhp), NULL)) == NULL) {
                 SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, ERR_R_BN_LIB);
                 goto err;
         }
-        p += i;
 
-        if (param_len + 2 > n)
+        if (!CBS_get_u16_length_prefixed(&cbs, &dhg))
                 goto truncated;
-        n2s(p, i);
-        param_len += i + 2;
-        if (param_len > n) {
-                al = SSL_AD_DECODE_ERROR;
-                SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_BAD_DH_G_LENGTH);
-                goto f_err;
-        }
-        if (!(dh->g = BN_bin2bn(p, i, NULL))) {
+        if ((dh->g = BN_bin2bn(CBS_data(&dhg), CBS_len(&dhg), NULL)) == NULL) {
                 SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, ERR_R_BN_LIB);
                 goto err;
         }
-        p += i;
 
-        if (param_len + 2 > n)
+        if (!CBS_get_u16_length_prefixed(&cbs, &dhpk))
                 goto truncated;
-        n2s(p, i);
-        param_len += i + 2;
-        if (param_len > n) {
-                al = SSL_AD_DECODE_ERROR;
-                SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE,
-                    SSL_R_BAD_DH_PUB_KEY_LENGTH);
-                goto f_err;
-        }
-        if (!(dh->pub_key = BN_bin2bn(p, i, NULL))) {
+        if ((dh->pub_key = BN_bin2bn(CBS_data(&dhpk), CBS_len(&dhpk),
+            NULL)) == NULL) {
                 SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, ERR_R_BN_LIB);
                 goto err;
         }
-        p += i;
-        n -= param_len;
 
         /*
          * Check the strength of the DH key just constructed.
@@ -1176,16 +1155,14 @@ ssl3_get_server_kex_dhe(SSL *s, EVP_PKEY **pkey, unsigned char **pp, long *nn)
 
         sc->peer_dh_tmp = dh;
 
-        *nn = n;
-        *pp = p;
+        *nn = CBS_len(&cbs);
+        *pp = (unsigned char *)CBS_data(&cbs);
 
         return (1);
 
  truncated:
         al = SSL_AD_DECODE_ERROR;
         SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE, SSL_R_BAD_PACKET_LENGTH);
-
- f_err:
         ssl3_send_alert(s, SSL3_AL_FATAL, al);
 
  err: