TLS1.3 requires handling "spurious reads"

With TLS1.3 the socket can indicate data is available even when there is no application data. This commit ignores a 0-byte read when no data is required. Long-term, handling short reads/writes in TCP mode need to be handled completely differently, but that is a story for another day.

Signed-off-by: Erik Boasson <eb@ilities.com>

src/core/ddsi/include/ddsi/ddsi_tran.h

@@ -36,7 +36,7 @@ typedef struct ddsi_tran_qos * ddsi_tran_qos_t;
 
 /* Function pointer types */
 
-typedef ssize_t (*ddsi_tran_read_fn_t) (ddsi_tran_conn_t, unsigned char *, size_t, nn_locator_t *);
+typedef ssize_t (*ddsi_tran_read_fn_t) (ddsi_tran_conn_t, unsigned char *, size_t, bool, nn_locator_t *);
 typedef ssize_t (*ddsi_tran_write_fn_t) (ddsi_tran_conn_t, const nn_locator_t *, size_t, const os_iovec_t *, uint32_t);
 typedef int (*ddsi_tran_locator_fn_t) (ddsi_tran_base_t, nn_locator_t *);
 typedef bool (*ddsi_tran_supports_fn_t) (int32_t);
@@ -220,8 +220,8 @@ inline int ddsi_conn_locator (ddsi_tran_conn_t conn, nn_locator_t * loc) {
 inline ssize_t ddsi_conn_write (ddsi_tran_conn_t conn, const nn_locator_t *dst, size_t niov, const os_iovec_t *iov, uint32_t flags) {
   return conn->m_closed ? -1 : (conn->m_write_fn) (conn, dst, niov, iov, flags);
 }
-inline ssize_t ddsi_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, nn_locator_t *srcloc) {
+inline ssize_t ddsi_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, bool allow_spurious, nn_locator_t *srcloc) {
-  return conn->m_closed ? -1 : conn->m_read_fn (conn, buf, len, srcloc);
+  return conn->m_closed ? -1 : conn->m_read_fn (conn, buf, len, allow_spurious, srcloc);
 }
 bool ddsi_conn_peer_locator (ddsi_tran_conn_t conn, nn_locator_t * loc);
 void ddsi_conn_disable_multiplexing (ddsi_tran_conn_t conn);

src/core/ddsi/src/ddsi_raweth.c

@@ -63,7 +63,7 @@ static char *ddsi_raweth_to_string (ddsi_tran_factory_t tran, char *dst, size_t
   return dst;
 }
 
-static ssize_t ddsi_raweth_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, nn_locator_t *srcloc)
+static ssize_t ddsi_raweth_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, bool allow_spurious, nn_locator_t *srcloc)
 {
   int err;
   ssize_t ret;
@@ -71,6 +71,7 @@ static ssize_t ddsi_raweth_conn_read (ddsi_tran_conn_t conn, unsigned char * buf
   struct sockaddr_ll src;
   struct iovec msg_iov;
   socklen_t srclen = (socklen_t) sizeof (src);
+  (void) allow_spurious;
 
   msg_iov.iov_base = (void*) buf;
   msg_iov.iov_len = len;

src/core/ddsi/src/ddsi_tcp.c

@@ -395,7 +395,7 @@ static int err_is_AGAIN_or_WOULDBLOCK (int err)
   return 0;
 }
 
-static ssize_t ddsi_tcp_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, nn_locator_t *srcloc)
+static ssize_t ddsi_tcp_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, bool allow_spurious, nn_locator_t *srcloc)
 {
   ddsi_tcp_conn_t tcp = (ddsi_tcp_conn_t) conn;
   ssize_t (*rd) (ddsi_tcp_conn_t, void *, size_t, int * err) = ddsi_tcp_conn_read_plain;
@@ -436,10 +436,10 @@ static ssize_t ddsi_tcp_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, s
       {
         if (err_is_AGAIN_or_WOULDBLOCK (err))
         {
-          if (ddsi_tcp_select (tcp->m_sock, true, pos) == false)
+          if (allow_spurious && pos == 0)
-          {
+            return 0;
+          else if (ddsi_tcp_select (tcp->m_sock, true, pos) == false)
             break;
-          }
         }
         else
         {

src/core/ddsi/src/ddsi_tran.c

@@ -31,7 +31,7 @@ extern inline int ddsi_tran_locator (ddsi_tran_base_t base, nn_locator_t * loc);
 extern inline int ddsi_listener_locator (ddsi_tran_listener_t listener, nn_locator_t * loc);
 extern inline int ddsi_listener_listen (ddsi_tran_listener_t listener);
 extern inline ddsi_tran_conn_t ddsi_listener_accept (ddsi_tran_listener_t listener);
-extern inline ssize_t ddsi_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, nn_locator_t *srcloc);
+extern inline ssize_t ddsi_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, bool allow_spurious, nn_locator_t *srcloc);
 extern inline ssize_t ddsi_conn_write (ddsi_tran_conn_t conn, const nn_locator_t *dst, size_t niov, const os_iovec_t *iov, uint32_t flags);
 
 void ddsi_factory_add (ddsi_tran_factory_t factory)

src/core/ddsi/src/ddsi_udp.c

@@ -48,7 +48,7 @@ static struct ddsi_udp_config ddsi_udp_config_g;
 static struct ddsi_tran_factory ddsi_udp_factory_g;
 static os_atomic_uint32_t ddsi_udp_init_g = OS_ATOMIC_UINT32_INIT(0);
 
-static ssize_t ddsi_udp_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, nn_locator_t *srcloc)
+static ssize_t ddsi_udp_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, size_t len, bool allow_spurious, nn_locator_t *srcloc)
 {
   int err;
   ssize_t ret;
@@ -56,6 +56,7 @@ static ssize_t ddsi_udp_conn_read (ddsi_tran_conn_t conn, unsigned char * buf, s
   os_sockaddr_storage src;
   os_iovec_t msg_iov;
   socklen_t srclen = (socklen_t) sizeof (src);
+  (void) allow_spurious;
 
   msg_iov.iov_base = (void*) buf;
   msg_iov.iov_len = (os_iov_len_t)len; /* Windows uses unsigned, POSIX (except Linux) int */

src/core/ddsi/src/q_receive.c

@@ -2970,7 +2970,13 @@ static bool do_packet
 
     /* Read in DDSI header plus MSG_LEN sub message that follows it */
 
-    sz = ddsi_conn_read (conn, buff, stream_hdr_size, &srcloc);
+    sz = ddsi_conn_read (conn, buff, stream_hdr_size, true, &srcloc);
+    if (sz == 0)
+    {
+      /* Spurious read -- which at this point is still ok */
+      nn_rmsg_commit (rmsg);
+      return true;
+    }
 
     /* Read in remainder of packet */
 
@@ -2998,7 +3004,7 @@ static bool do_packet
       }
       else
       {
-        sz = ddsi_conn_read (conn, buff + stream_hdr_size, ml->length - stream_hdr_size, NULL);
+        sz = ddsi_conn_read (conn, buff + stream_hdr_size, ml->length - stream_hdr_size, false, NULL);
         if (sz > 0)
         {
           sz = (ssize_t) ml->length;
@@ -3010,7 +3016,7 @@ static bool do_packet
   {
     /* Get next packet */
 
-    sz = ddsi_conn_read (conn, buff, buff_len, &srcloc);
+    sz = ddsi_conn_read (conn, buff, buff_len, true, &srcloc);
   }
 
   if (sz > 0 && !gv.deaf)