Convert ssl3_client_hello() to CBB.

As part of this, change ssl_cipher_list_to_bytes() to take a CBB argument,
rather than a pointer/length. Some additional clean up/renames while here.

Based on a diff from doug@

1 files changed, 45 insertions, 36 deletions

diff --git a/src/lib/libssl/ssl_clnt.c b/src/lib/libssl/ssl_clnt.c
index 6343ec276d..33352705d1 100644
--- a/src/lib/libssl/ssl_clnt.c
+++ b/src/lib/libssl/ssl_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_clnt.c,v 1.20 2017/10/10 15:42:32 jsing Exp $ */
+/* $OpenBSD: ssl_clnt.c,v 1.21 2017/10/11 17:35:00 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -170,6 +170,7 @@
 #endif
 
 #include "bytestring.h"
+#include "ssl_tlsext.h"
 
 static int ca_dn_cmp(const X509_NAME * const *a, const X509_NAME * const *b);
 
@@ -662,12 +663,12 @@ end:
 int
 ssl3_client_hello(SSL *s)
 {
-        unsigned char   *bufend, *p, *d;
-        uint16_t         max_version;
-        size_t           outlen;
-        int              i;
+        CBB cbb, client_hello, session_id, cookie, cipher_suites;
+        CBB compression_methods;
+        uint16_t max_version;
+        size_t sl;
 
-        bufend = (unsigned char *)s->internal->init_buf->data + SSL3_RT_MAX_PLAIN_LENGTH;
+        memset(&cbb, 0, sizeof(cbb));
 
         if (S3I(s)->hs.state == SSL3_ST_CW_CLNT_HELLO_A) {
                 SSL_SESSION *sess = s->session;
@@ -695,7 +696,9 @@ ssl3_client_hello(SSL *s)
                 if (!SSL_IS_DTLS(s) || D1I(s)->send_cookie == 0)
                         arc4random_buf(s->s3->client_random, SSL3_RANDOM_SIZE);
 
-                d = p = ssl3_handshake_msg_start(s, SSL3_MT_CLIENT_HELLO);
+                if (!ssl3_handshake_msg_start_cbb(s, &cbb, &client_hello,
+                    SSL3_MT_CLIENT_HELLO))
+                        goto err;
 
                 /*
                  * Version indicates the negotiated version: for example from
@@ -727,27 +730,27 @@ ssl3_client_hello(SSL *s)
                  * client_version in client hello and not resetting it to
                  * the negotiated version.
                  */
-
-                *(p++) = s->client_version >> 8;
-                *(p++) = s->client_version & 0xff;
+                if (!CBB_add_u16(&client_hello, s->client_version))
+                        goto err;
 
                 /* Random stuff */
-                memcpy(p, s->s3->client_random, SSL3_RANDOM_SIZE);
-                p += SSL3_RANDOM_SIZE;
+                if (!CBB_add_bytes(&client_hello, s->s3->client_random,
+                    sizeof(s->s3->client_random)))
+                        goto err;
 
                 /* Session ID */
-                if (s->internal->new_session)
-                        i = 0;
-                else
-                        i = s->session->session_id_length;
-                *(p++) = i;
-                if (i != 0) {
-                        if (i > (int)sizeof(s->session->session_id)) {
+                if (!CBB_add_u8_length_prefixed(&client_hello, &session_id))
+                        goto err;
+                if (!s->internal->new_session &&
+                    s->session->session_id_length > 0) {
+                        sl = s->session->session_id_length;
+                        if (sl > sizeof(s->session->session_id)) {
                                 SSLerror(s, ERR_R_INTERNAL_ERROR);
                                 goto err;
                         }
-                        memcpy(p, s->session->session_id, i);
-                        p += i;
+                        if (!CBB_add_bytes(&session_id,
+                            s->session->session_id, sl))
+                                goto err;
                 }
 
                 /* DTLS Cookie. */
@@ -756,33 +759,37 @@ ssl3_client_hello(SSL *s)
                                 SSLerror(s, ERR_R_INTERNAL_ERROR);
                                 goto err;
                         }
-                        *(p++) = D1I(s)->cookie_len;
-                        memcpy(p, D1I(s)->cookie, D1I(s)->cookie_len);
-                        p += D1I(s)->cookie_len;
+                        if (!CBB_add_u8_length_prefixed(&client_hello, &cookie))
+                                goto err;
+                        if (!CBB_add_bytes(&cookie, D1I(s)->cookie,
+                            D1I(s)->cookie_len))
+                                goto err;
                 }
 
                 /* Ciphers supported */
-                if (!ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s), &p[2],
-                    bufend - &p[2], &outlen))
-                        goto err;
-                if (outlen == 0) {
+                if (!CBB_add_u16_length_prefixed(&client_hello, &cipher_suites))
+                        return 0;
+                if (!ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s),
+                    &cipher_suites)) {
                         SSLerror(s, SSL_R_NO_CIPHERS_AVAILABLE);
                         goto err;
                 }
-                s2n(outlen, p);
-                p += outlen;
 
-                /* add in (no) COMPRESSION */
-                *(p++) = 1;
-                *(p++) = 0; /* Add the NULL method */
+                /* Add in compression methods (null) */
+                if (!CBB_add_u8_length_prefixed(&client_hello,
+                    &compression_methods))
+                        goto err;
+                if (!CBB_add_u8(&compression_methods, 0))
+                        goto err;
 
-                /* TLS extensions*/
-                if ((p = ssl_add_clienthello_tlsext(s, p, bufend)) == NULL) {
+                /* TLS extensions */
+                if (!tlsext_clienthello_build(s, &client_hello)) {
                         SSLerror(s, ERR_R_INTERNAL_ERROR);
                         goto err;
                 }
 
-                ssl3_handshake_msg_finish(s, p - d);
+                if (!ssl3_handshake_msg_finish_cbb(s, &cbb))
+                        goto err;
 
                 S3I(s)->hs.state = SSL3_ST_CW_CLNT_HELLO_B;
         }
@@ -791,6 +798,8 @@ ssl3_client_hello(SSL *s)
         return (ssl3_handshake_write(s));
 
 err:
+        CBB_cleanup(&cbb);
+
         return (-1);
 }