gnutls_ext_raw_parse: introduced function

That function can be combined with callbacks like
gnutls_handshake_set_hook_function() for applications to
be able to process messages when necessary.

Resolves #382

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

8 files changed, 91 insertions, 14 deletions

diff --git a/lib/extv.c b/lib/extv.c
index 32dbc942fe..0abfd370fb 100644
--- a/lib/extv.c
+++ b/lib/extv.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2017 Red Hat, Inc.
+ * Copyright (C) 2017-2018 Red Hat, Inc.
  *
  * Author: Nikos Mavrogiannopoulos
  *
@@ -28,7 +28,7 @@
 /* Iterates through all extensions found, and calls the cb()
  * function with their data */
 int _gnutls_extv_parse(void *ctx,
-		       int (*cb)(void *ctx, uint16_t tls_id, const uint8_t *data, int data_size),
+		       gnutls_ext_raw_process_func cb,
 		       const uint8_t * data, int data_size)
 {
 	int next, ret;
@@ -75,7 +75,78 @@ int _gnutls_extv_parse(void *ctx,
 		return gnutls_assert_val(GNUTLS_E_UNEXPECTED_EXTENSIONS_LENGTH);
 
 	return 0;
+}
+
+#define HANDSHAKE_SESSION_ID_POS (34)
+/**
+ * gnutls_ext_raw_parse:
+ * @ctx: a pointer to pass to callback function
+ * @cb: callback function to process each extension found
+ * @data: TLS extension data
+ * @flags: should be zero or %GNUTLS_EXT_RAW_FLAG_CLIENT_HELLO
+ *
+ * This function iterates through the TLS extensions as passed in
+ * @data, passing the individual extension data to callback. The
+ * @data must conform to Extension extensions<0..2^16-1> format.
+ *
+ * If flags is %GNUTLS_EXT_RAW_FLAG_CLIENT_HELLO then this function
+ * will parse the extension data from the position, as if the packet in
+ * @data is a client hello (without record or handshake headers) -
+ * as provided by gnutls_handshake_set_hook_function().
+ *
+ * The return value of the callback will be propagated.
+ *
+ * Returns: %GNUTLS_E_SUCCESS on success, or an error code. On unknown
+ *   flags it returns %GNUTLS_E_INVALID_REQUEST.
+ *
+ * Since: 3.6.3
+ **/
+int gnutls_ext_raw_parse(void *ctx, gnutls_ext_raw_process_func cb,
+			 const gnutls_datum_t *data, unsigned int flags)
+{
+	if (flags & GNUTLS_EXT_RAW_FLAG_CLIENT_HELLO) {
+		ssize_t size = data->size;
+		size_t len;
+		uint8_t *p = data->data;
+
+		DECR_LEN(size, HANDSHAKE_SESSION_ID_POS);
+
+		if (p[0] != 0x03)
+			return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_VERSION_PACKET);
+
+		p += HANDSHAKE_SESSION_ID_POS;
+
+		/* skip session id */
+		DECR_LEN(size, 1);
+		len = p[0];
+		p++;
+		DECR_LEN(size, len);
+		p += len;
+
+		/* CipherSuites */
+		DECR_LEN(size, 2);
+		len = _gnutls_read_uint16(p);
+		p += 2;
+		DECR_LEN(size, len);
+		p += len;
+
+		/* legacy_compression_methods */
+		DECR_LEN(size, 1);
+		len = p[0];
+		p++;
+		DECR_LEN(size, len);
+		p += len;
+
+		if (size <= 0)
+			return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);
+
+		return _gnutls_extv_parse(ctx, cb, p, size);
+	}
+
+	if (flags != 0)
+		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
 
+	return _gnutls_extv_parse(ctx, cb, data->data, data->size);
 }
 
 /* Returns:
diff --git a/lib/extv.h b/lib/extv.h
index b5089efed5..9f13f7a2ce 100644
--- a/lib/extv.h
+++ b/lib/extv.h
@@ -30,7 +30,7 @@
  * calls the callback function for each of them. The ctx, flags
  * and parse_type are passed verbatim to callback. */
 int _gnutls_extv_parse(void *ctx,
-		       int (*cb)(void *ctx, uint16_t tls_id, const uint8_t *data, int data_size),
+		       gnutls_ext_raw_process_func cb,
 		       const uint8_t * data, int data_size);
 
 inline static
diff --git a/lib/hello_ext.c b/lib/hello_ext.c
index 4a4b2cc675..844b570061 100644
--- a/lib/hello_ext.c
+++ b/lib/hello_ext.c
@@ -195,7 +195,7 @@ typedef struct hello_ext_ctx_st {
 } hello_ext_ctx_st;
 
 static
-int hello_ext_parse(void *_ctx, uint16_t tls_id, const uint8_t *data, int data_size)
+int hello_ext_parse(void *_ctx, unsigned tls_id, const uint8_t *data, unsigned data_size)
 {
 	hello_ext_ctx_st *ctx = _ctx;
 	gnutls_session_t session = ctx->session;
diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
index dd123aaf4e..b9142519aa 100644
--- a/lib/includes/gnutls/gnutls.h.in
+++ b/lib/includes/gnutls/gnutls.h.in
@@ -2708,6 +2708,10 @@ typedef int (*gnutls_ext_pack_func) (gnutls_ext_priv_data_t data,
 typedef int (*gnutls_ext_unpack_func) (gnutls_buffer_t packed_data,
 				       gnutls_ext_priv_data_t *data);
 
+#define GNUTLS_EXT_RAW_FLAG_CLIENT_HELLO 1
+typedef int (*gnutls_ext_raw_process_func)(void *ctx, unsigned tls_id, const unsigned char *data, unsigned data_size);
+int gnutls_ext_raw_parse(void *ctx, gnutls_ext_raw_process_func cb,
+			 const gnutls_datum_t *data, unsigned int flags);
 
 /**
  * gnutls_ext_parse_type_t:
diff --git a/lib/libgnutls.map b/lib/libgnutls.map
index 5d7d7a5ace..07aaf714cc 100644
--- a/lib/libgnutls.map
+++ b/lib/libgnutls.map
@@ -1214,6 +1214,7 @@ GNUTLS_3_6_3
 	gnutls_certificate_set_ocsp_status_request_mem;
 	gnutls_certificate_get_ocsp_expiration;
 	gnutls_record_send2;
+	gnutls_ext_raw_parse;
 } GNUTLS_3_6_2;
 
 GNUTLS_FIPS140_3_4 {
diff --git a/lib/tls13/certificate.c b/lib/tls13/certificate.c
index 1d688de0b2..ad05f372c5 100644
--- a/lib/tls13/certificate.c
+++ b/lib/tls13/certificate.c
@@ -29,7 +29,7 @@
 #include "mbuffers.h"
 #include "ext/status_request.h"
 
-static int parse_cert_extension(void *ctx, uint16_t tls_id, const uint8_t *data, int data_size);
+static int parse_cert_extension(void *ctx, unsigned tls_id, const uint8_t *data, unsigned data_size);
 static int parse_cert_list(gnutls_session_t session, uint8_t * data, size_t data_size);
 
 int _gnutls13_recv_certificate(gnutls_session_t session)
@@ -309,7 +309,7 @@ typedef struct crt_cert_ctx_st {
 	unsigned idx;
 } crt_cert_ctx_st;
 
-static int parse_cert_extension(void *_ctx, uint16_t tls_id, const uint8_t *data, int data_size)
+static int parse_cert_extension(void *_ctx, unsigned tls_id, const uint8_t *data, unsigned data_size)
 {
 	crt_cert_ctx_st *ctx = _ctx;
 	gnutls_session_t session = ctx->session;
diff --git a/lib/tls13/certificate_request.c b/lib/tls13/certificate_request.c
index 959603f477..4e7c104afb 100644
--- a/lib/tls13/certificate_request.c
+++ b/lib/tls13/certificate_request.c
@@ -55,10 +55,11 @@ static unsigned is_algo_in_list(gnutls_pk_algorithm_t algo, gnutls_pk_algorithm_
 }
 
 static
-int parse_cert_extension(void *_ctx, uint16_t tls_id, const uint8_t *data, int data_size)
+int parse_cert_extension(void *_ctx, unsigned tls_id, const uint8_t *data, unsigned data_size)
 {
 	crt_req_ctx_st *ctx = _ctx;
 	gnutls_session_t session = ctx->session;
+	unsigned v;
 	int ret;
 
 	/* Decide which certificate to use if the signature algorithms extension
@@ -78,8 +79,8 @@ int parse_cert_extension(void *_ctx, uint16_t tls_id, const uint8_t *data, int d
 		if (data_size < 2)
 			return gnutls_assert_val(GNUTLS_E_TLS_PACKET_DECODING_ERROR);
 
-		ret = _gnutls_read_uint16(data);
-		if (ret != data_size-2)
+		v = _gnutls_read_uint16(data);
+		if (v != data_size-2)
 			return gnutls_assert_val(GNUTLS_E_TLS_PACKET_DECODING_ERROR);
 
 		data += 2;
@@ -111,12 +112,12 @@ int parse_cert_extension(void *_ctx, uint16_t tls_id, const uint8_t *data, int d
 			return gnutls_assert_val(GNUTLS_E_TLS_PACKET_DECODING_ERROR);
 		}
 
-		ret = _gnutls_read_uint16(data);
-		if (ret != data_size-2)
+		v = _gnutls_read_uint16(data);
+		if (v != data_size-2)
 			return gnutls_assert_val(GNUTLS_E_TLS_PACKET_DECODING_ERROR);
 
 		ctx->rdn = data+2;
-		ctx->rdn_size = ret;
+		ctx->rdn_size = v;
 	}
 
 	return 0;
diff --git a/lib/tls13/session_ticket.c b/lib/tls13/session_ticket.c
index 3dbec9260f..d5d62f433f 100644
--- a/lib/tls13/session_ticket.c
+++ b/lib/tls13/session_ticket.c
@@ -27,7 +27,7 @@
 #include "tls13/session_ticket.h"
 #include "auth/cert.h"
 
-static int parse_nst_extension(void *ctx, uint16_t tls_id, const uint8_t *data, int data_size);
+static int parse_nst_extension(void *ctx, unsigned tls_id, const uint8_t *data, unsigned data_size);
 
 int _gnutls13_recv_session_ticket(gnutls_session_t session, gnutls_buffer_st *buf)
 {
@@ -76,7 +76,7 @@ cleanup:
 	return ret;
 }
 
-static int parse_nst_extension(void *ctx, uint16_t tls_id, const uint8_t *data, int data_size)
+static int parse_nst_extension(void *ctx, unsigned tls_id, const uint8_t *data, unsigned data_size)
 {
 	/* ignore all extensions */
 	return 0;