Split out DHE from tls_process_key_exchange()

Continuing from the previous commit. Refactor tls_process_key_exchange() to
split out into a separate function the DHE aspects.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

ssl/statem/statem_clnt.c

@@ -1393,6 +1393,102 @@ static int tls_process_ske_srp(SSL *s, PACKET *pkt, EVP_PKEY **pkey, int *al)
 #endif
 }
 
+static int tls_process_ske_dhe(SSL *s, PACKET *pkt, EVP_PKEY **pkey, int *al)
+{
+#ifndef OPENSSL_NO_DH
+    PACKET prime, generator, pub_key;
+    EVP_PKEY *peer_tmp = NULL;
+
+    DH *dh = NULL;
+    BIGNUM *p = NULL, *g = NULL, *bnpub_key = NULL;
+
+    if (!PACKET_get_length_prefixed_2(pkt, &prime)
+        || !PACKET_get_length_prefixed_2(pkt, &generator)
+        || !PACKET_get_length_prefixed_2(pkt, &pub_key)) {
+        *al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, SSL_R_LENGTH_MISMATCH);
+        return 0;
+    }
+
+    peer_tmp = EVP_PKEY_new();
+    dh = DH_new();
+
+    if (peer_tmp == NULL || dh == NULL) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+
+    p = BN_bin2bn(PACKET_data(&prime), PACKET_remaining(&prime), NULL);
+    g = BN_bin2bn(PACKET_data(&generator), PACKET_remaining(&generator),
+                  NULL);
+    bnpub_key = BN_bin2bn(PACKET_data(&pub_key), PACKET_remaining(&pub_key),
+                          NULL);
+    if (p == NULL || g == NULL || bnpub_key == NULL) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_BN_LIB);
+        goto err;
+    }
+
+    if (BN_is_zero(p) || BN_is_zero(g) || BN_is_zero(bnpub_key)) {
+        *al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, SSL_R_BAD_DH_VALUE);
+        goto err;
+    }
+
+    if (!DH_set0_pqg(dh, p, NULL, g)) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_BN_LIB);
+        goto err;
+    }
+    p = g = NULL;
+
+    if (!DH_set0_key(dh, bnpub_key, NULL)) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_BN_LIB);
+        goto err;
+    }
+    bnpub_key = NULL;
+
+    if (!ssl_security(s, SSL_SECOP_TMP_DH, DH_security_bits(dh), 0, dh)) {
+        *al = SSL_AD_HANDSHAKE_FAILURE;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, SSL_R_DH_KEY_TOO_SMALL);
+        goto err;
+    }
+
+    if (EVP_PKEY_assign_DH(peer_tmp, dh) == 0) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_EVP_LIB);
+        goto err;
+    }
+
+    s->s3->peer_tmp = peer_tmp;
+
+    /*
+     * FIXME: This makes assumptions about which ciphersuites come with
+     * public keys. We should have a less ad-hoc way of doing this
+     */
+    if (s->s3->tmp.new_cipher->algorithm_auth & (SSL_aRSA|SSL_aDSS))
+        *pkey = X509_get0_pubkey(s->session->peer);
+    /* else anonymous DH, so no certificate or pkey. */
+
+    return 1;
+
+ err:
+    BN_free(p);
+    BN_free(g);
+    BN_free(bnpub_key);
+    DH_free(dh);
+    EVP_PKEY_free(peer_tmp);
+
+    return 0;
+#else
+    SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_INTERNAL_ERROR);
+    *al = SSL_AD_INTERNAL_ERROR;
+    return 0;
+#endif
+}
+
 MSG_PROCESS_RETURN tls_process_key_exchange(SSL *s, PACKET *pkt)
 {
     EVP_MD_CTX *md_ctx;
@@ -1429,93 +1525,10 @@ MSG_PROCESS_RETURN tls_process_key_exchange(SSL *s, PACKET *pkt)
     } else if (alg_k & SSL_kSRP) {
         if (!tls_process_ske_srp(s, pkt, &pkey, &al))
             goto err;
+    } else if (alg_k & (SSL_kDHE | SSL_kDHEPSK)) {
+        if (!tls_process_ske_dhe(s, pkt, &pkey, &al))
+            goto err;
     }
-#ifndef OPENSSL_NO_DH
-    else if (alg_k & (SSL_kDHE | SSL_kDHEPSK)) {
-        PACKET prime, generator, pub_key;
-        EVP_PKEY *peer_tmp = NULL;
-
-        DH *dh = NULL;
-        BIGNUM *p = NULL, *g = NULL, *bnpub_key = NULL;
-
-        if (!PACKET_get_length_prefixed_2(pkt, &prime)
-            || !PACKET_get_length_prefixed_2(pkt, &generator)
-            || !PACKET_get_length_prefixed_2(pkt, &pub_key)) {
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, SSL_R_LENGTH_MISMATCH);
-            goto f_err;
-        }
-
-        peer_tmp = EVP_PKEY_new();
-        dh = DH_new();
-
-        if (peer_tmp == NULL || dh == NULL) {
-            al = SSL_AD_INTERNAL_ERROR;
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_MALLOC_FAILURE);
-            goto dherr;
-        }
-
-        p = BN_bin2bn(PACKET_data(&prime), PACKET_remaining(&prime), NULL);
-        g = BN_bin2bn(PACKET_data(&generator), PACKET_remaining(&generator),
-                      NULL);
-        bnpub_key = BN_bin2bn(PACKET_data(&pub_key), PACKET_remaining(&pub_key),
-                              NULL);
-        if (p == NULL || g == NULL || bnpub_key == NULL) {
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_BN_LIB);
-            goto dherr;
-        }
-
-        if (BN_is_zero(p) || BN_is_zero(g) || BN_is_zero(bnpub_key)) {
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, SSL_R_BAD_DH_VALUE);
-            goto dherr;
-        }
-
-        if (!DH_set0_pqg(dh, p, NULL, g)) {
-            al = SSL_AD_INTERNAL_ERROR;
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_BN_LIB);
-            goto dherr;
-        }
-        p = g = NULL;
-
-        if (!DH_set0_key(dh, bnpub_key, NULL)) {
-            al = SSL_AD_INTERNAL_ERROR;
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_BN_LIB);
-            goto dherr;
-        }
-        bnpub_key = NULL;
-
-        if (!ssl_security(s, SSL_SECOP_TMP_DH, DH_security_bits(dh), 0, dh)) {
-            al = SSL_AD_HANDSHAKE_FAILURE;
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, SSL_R_DH_KEY_TOO_SMALL);
-            goto dherr;
-        }
-
-        if (EVP_PKEY_assign_DH(peer_tmp, dh) == 0) {
-            al = SSL_AD_INTERNAL_ERROR;
-            SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_EVP_LIB);
-            goto dherr;
-        }
-
-        s->s3->peer_tmp = peer_tmp;
-
-        goto dhend;
- dherr:
-        BN_free(p);
-        BN_free(g);
-        BN_free(bnpub_key);
-        DH_free(dh);
-        EVP_PKEY_free(peer_tmp);
-        goto f_err;
- dhend:
-        /*
-         * FIXME: This makes assumptions about which ciphersuites come with
-         * public keys. We should have a less ad-hoc way of doing this
-         */
-        if (alg_a & (SSL_aRSA|SSL_aDSS))
-            pkey = X509_get0_pubkey(s->session->peer);
-        /* else anonymous DH, so no certificate or pkey. */
-    }
-#endif                          /* !OPENSSL_NO_DH */
-
 #ifndef OPENSSL_NO_EC
     else if (alg_k & (SSL_kECDHE | SSL_kECDHEPSK)) {
         PACKET encoded_pt;