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@

4 files changed, 64 insertions, 93 deletions

diff --git a/lib/libssl/ssl_clnt.c b/lib/libssl/ssl_clnt.c
index 6343ec276d6..33352705d18 100644
--- a/lib/libssl/ssl_clnt.c
+++ b/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);
 }
 
diff --git a/lib/libssl/ssl_lib.c b/lib/libssl/ssl_lib.c
index b91ba7f0f39..c7ae2a9631a 100644
--- a/lib/libssl/ssl_lib.c
+++ b/lib/libssl/ssl_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_lib.c,v 1.171 2017/10/10 16:51:38 jsing Exp $ */
+/* $OpenBSD: ssl_lib.c,v 1.172 2017/10/11 17:35:00 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1380,51 +1380,40 @@ SSL_get_shared_ciphers(const SSL *s, char *buf, int len)
 }
 
 int
-ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *sk, unsigned char *p,
-    size_t maxlen, size_t *outlen)
+ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *ciphers, CBB *cbb)
 {
 	SSL_CIPHER *cipher;
-	int ciphers = 0;
-	CBB cbb;
+	int num_ciphers = 0;
 	int i;
 
-	*outlen = 0;
-
-	if (sk == NULL)
-		return (0);
-
-	if (!CBB_init_fixed(&cbb, p, maxlen))
-		goto err;
+	if (ciphers == NULL)
+		return 0;
 
-	for (i = 0; i < sk_SSL_CIPHER_num(sk); i++) {
-		cipher = sk_SSL_CIPHER_value(sk, i);
+	for (i = 0; i < sk_SSL_CIPHER_num(ciphers); i++) {
+		if ((cipher = sk_SSL_CIPHER_value(ciphers, i)) == NULL)
+			return 0;
 
 		/* Skip TLS v1.2 only ciphersuites if lower than v1.2 */
 		if ((cipher->algorithm_ssl & SSL_TLSV1_2) &&
 		    (TLS1_get_client_version(s) < TLS1_2_VERSION))
 			continue;
 
-		if (!CBB_add_u16(&cbb, ssl3_cipher_get_value(cipher)))
-			goto err;
+		if (!CBB_add_u16(cbb, ssl3_cipher_get_value(cipher)))
+			return 0;
 
-		ciphers++;
+		num_ciphers++;
 	}
 
 	/* Add SCSV if there are other ciphers and we're not renegotiating. */
-	if (ciphers > 0 && !s->internal->renegotiate) {
-		if (!CBB_add_u16(&cbb, SSL3_CK_SCSV & SSL3_CK_VALUE_MASK))
-			goto err;
+	if (num_ciphers > 0 && !s->internal->renegotiate) {
+		if (!CBB_add_u16(cbb, SSL3_CK_SCSV & SSL3_CK_VALUE_MASK))
+			return 0;
 	}
 
-	if (!CBB_finish(&cbb, NULL, outlen))
-		goto err;
+	if (!CBB_flush(cbb))
+		return 0;
 
 	return 1;
-
- err:
-	CBB_cleanup(&cbb);
-
-	return 0;
 }
 
 STACK_OF(SSL_CIPHER) *
diff --git a/lib/libssl/ssl_locl.h b/lib/libssl/ssl_locl.h
index 2ce4b056000..92667ec125e 100644
--- a/lib/libssl/ssl_locl.h
+++ b/lib/libssl/ssl_locl.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_locl.h,v 1.197 2017/10/11 16:51:39 jsing Exp $ */
+/* $OpenBSD: ssl_locl.h,v 1.198 2017/10/11 17:35:00 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1064,9 +1064,8 @@ int ssl_cipher_id_cmp(const SSL_CIPHER *a, const SSL_CIPHER *b);
 SSL_CIPHER *OBJ_bsearch_ssl_cipher_id(SSL_CIPHER *key, SSL_CIPHER const *base, int num);
 int ssl_cipher_ptr_id_cmp(const SSL_CIPHER * const *ap,
     const SSL_CIPHER * const *bp);
+int ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *ciphers, CBB *cbb);
 STACK_OF(SSL_CIPHER) *ssl_bytes_to_cipher_list(SSL *s, CBS *cbs);
-int ssl_cipher_list_to_bytes(SSL *s, STACK_OF(SSL_CIPHER) *sk,
-    unsigned char *p, size_t maxlen, size_t *outlen);
 STACK_OF(SSL_CIPHER) *ssl_create_cipher_list(const SSL_METHOD *meth,
     STACK_OF(SSL_CIPHER) **pref, STACK_OF(SSL_CIPHER) **sorted,
     const char *rule_str);
@@ -1286,9 +1285,6 @@ uint16_t tls1_ec_nid2curve_id(const int nid);
 int tls1_check_curve(SSL *s, const uint16_t curve_id);
 int tls1_get_shared_curve(SSL *s);
 
-unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p,
-    unsigned char *limit);
-
 int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **data,
     unsigned char *d, int n, int *al);
 int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **data,
diff --git a/lib/libssl/t1_lib.c b/lib/libssl/t1_lib.c
index 8526ca167b9..1cef08d0946 100644
--- a/lib/libssl/t1_lib.c
+++ b/lib/libssl/t1_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: t1_lib.c,v 1.138 2017/10/11 16:51:39 jsing Exp $ */
+/* $OpenBSD: t1_lib.c,v 1.139 2017/10/11 17:35:00 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -661,29 +661,6 @@ tls12_get_req_sig_algs(SSL *s, unsigned char **sigalgs, size_t *sigalgs_len)
 	*sigalgs_len = sizeof(tls12_sigalgs);
 }
 
-unsigned char *
-ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned char *limit)
-{
-	size_t len;
-	CBB cbb;
-
-	if (p >= limit)
-		return NULL;
-
-	if (!CBB_init_fixed(&cbb, p, limit - p))
-		return NULL;
-	if (!tlsext_clienthello_build(s, &cbb)) {
-		CBB_cleanup(&cbb);
-		return NULL;
-	}
-	if (!CBB_finish(&cbb, NULL, &len)) {
-		CBB_cleanup(&cbb);
-		return NULL;
-	}
-
-	return (p + len);
-}
-
 int
 ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
     int n, int *al)