Add s_server and s_client async support

A new -async option is added which activates SSL_MODE_ASYNC. Also
SSL_WANT_ASYNC errors are handled appropriately.
Reviewed-by: NRich Salz <rsalz@openssl.org>

apps/s_client.c

@@ -182,6 +182,7 @@ extern int verify_error;
 extern int verify_return_error;
 extern int verify_quiet;
 
+static int async = 0;
 static int c_nbio = 0;
 static int c_tlsextdebug = 0;
 static int c_status_req = 0;
@@ -472,6 +473,7 @@ typedef enum OPTION_choice {
     OPT_CHAINCAFILE, OPT_VERIFYCAFILE, OPT_NEXTPROTONEG, OPT_ALPN,
     OPT_SERVERINFO, OPT_STARTTLS, OPT_SERVERNAME, OPT_JPAKE,
     OPT_USE_SRTP, OPT_KEYMATEXPORT, OPT_KEYMATEXPORTLEN, OPT_SMTPHOST,
+    OPT_ASYNC,
     OPT_V_ENUM,
     OPT_X_ENUM,
     OPT_S_ENUM,
@@ -557,6 +559,7 @@ OPTIONS s_client_options[] = {
      "types  Send empty ClientHello extensions (comma-separated numbers)"},
     {"alpn", OPT_ALPN, 's',
      "Enable ALPN extension, considering named protocols supported (comma-separated list)"},
+    {"async", OPT_ASYNC, '-', "Support asynchronous operation"},
     OPT_S_OPTIONS,
     OPT_V_OPTIONS,
     OPT_X_OPTIONS,
@@ -1061,6 +1064,9 @@ int s_client_main(int argc, char **argv)
         case OPT_KEYMATEXPORTLEN:
             keymatexportlen = atoi(opt_arg());
             break;
+        case OPT_ASYNC:
+            async = 1;
+            break;
         }
     }
     argc = opt_num_rest();
@@ -1199,6 +1205,9 @@ int s_client_main(int argc, char **argv)
         goto end;
     }
 
+    if (async)
+        SSL_CTX_set_mode(ctx, SSL_MODE_ASYNC);
+
     if (!config_ctx(cctx, ssl_args, ctx, 1, jpake_secret == NULL))
         goto end;
 
@@ -1883,6 +1892,11 @@ int s_client_main(int argc, char **argv)
                 write_ssl = 1;
                 read_tty = 0;
                 break;
+            case SSL_ERROR_WANT_ASYNC:
+                BIO_printf(bio_c_out, "write A BLOCK\n");
+                write_ssl = 1;
+                read_tty = 0;
+                break;
             case SSL_ERROR_WANT_READ:
                 BIO_printf(bio_c_out, "write R BLOCK\n");
                 write_tty = 0;
@@ -1965,6 +1979,13 @@ int s_client_main(int argc, char **argv)
                 read_ssl = 0;
                 write_tty = 1;
                 break;
+            case SSL_ERROR_WANT_ASYNC:
+                BIO_printf(bio_c_out, "read A BLOCK\n");
+                write_tty = 0;
+                read_ssl = 1;
+                if ((read_tty == 0) && (write_ssl == 0))
+                    write_ssl = 1;
+                break;
             case SSL_ERROR_WANT_WRITE:
                 BIO_printf(bio_c_out, "read W BLOCK\n");
                 write_ssl = 1;

apps/s_server.c

@@ -252,6 +252,8 @@ static int s_brief = 0;
 static char *keymatexportlabel = NULL;
 static int keymatexportlen = 20;
 
+static int async = 0;
+
 #ifndef OPENSSL_NO_ENGINE
 static char *engine_id = NULL;
 #endif
@@ -402,6 +404,7 @@ static void s_server_init(void)
     s_msg = 0;
     s_quiet = 0;
     s_brief = 0;
+    async = 0;
 #ifndef OPENSSL_NO_ENGINE
     engine_id = NULL;
 #endif
@@ -805,7 +808,7 @@ typedef enum OPTION_choice {
     OPT_SECURITY_DEBUG, OPT_SECURITY_DEBUG_VERBOSE, OPT_STATE, OPT_CRLF,
     OPT_QUIET, OPT_BRIEF, OPT_NO_TMP_RSA, OPT_NO_DHE, OPT_NO_ECDHE,
     OPT_NO_RESUME_EPHEMERAL, OPT_PSK_HINT, OPT_PSK, OPT_SRPVFILE,
-    OPT_SRPUSERSEED, OPT_REV, OPT_WWW, OPT_UPPER_WWW, OPT_HTTP,
+    OPT_SRPUSERSEED, OPT_REV, OPT_WWW, OPT_UPPER_WWW, OPT_HTTP, OPT_ASYNC,
     OPT_SSL3,
     OPT_TLS1_2, OPT_TLS1_1, OPT_TLS1, OPT_DTLS, OPT_DTLS1,
     OPT_DTLS1_2, OPT_TIMEOUT, OPT_MTU, OPT_CHAIN, OPT_LISTEN,
@@ -914,6 +917,7 @@ OPTIONS s_server_options[] = {
     {"security_debug_verbose", OPT_SECURITY_DEBUG_VERBOSE, '-'},
     {"brief", OPT_BRIEF, '-'},
     {"rev", OPT_REV, '-'},
+    {"async", OPT_ASYNC, '-', "Operate in asynchronous mode"},
     OPT_S_OPTIONS,
     OPT_V_OPTIONS,
     OPT_X_OPTIONS,
@@ -1438,6 +1442,9 @@ int s_server_main(int argc, char *argv[])
         case OPT_KEYMATEXPORTLEN:
             keymatexportlen = atoi(opt_arg());
             break;
+        case OPT_ASYNC:
+            async = 1;
+            break;
         }
     }
     argc = opt_num_rest();
@@ -1650,6 +1657,9 @@ int s_server_main(int argc, char *argv[])
     else
         SSL_CTX_sess_set_cache_size(ctx, 128);
 
+    if (async)
+        SSL_CTX_set_mode(ctx, SSL_MODE_ASYNC);
+
 #ifndef OPENSSL_NO_SRTP
     if (srtp_profiles != NULL) {
         /* Returns 0 on success! */
@@ -1721,6 +1731,9 @@ int s_server_main(int argc, char *argv[])
         else
             SSL_CTX_sess_set_cache_size(ctx2, 128);
 
+        if (async)
+			SSL_CTX_set_mode(ctx2, SSL_MODE_ASYNC);
+
         if ((!SSL_CTX_load_verify_locations(ctx2, CAfile, CApath)) ||
             (!SSL_CTX_set_default_verify_paths(ctx2))) {
             ERR_print_errors(bio_err);
@@ -2281,6 +2294,9 @@ static int sv_body(char *hostname, int s, int stype, unsigned char *context)
                 switch (SSL_get_error(con, k)) {
                 case SSL_ERROR_NONE:
                     break;
+                case SSL_ERROR_WANT_ASYNC:
+                    BIO_printf(bio_s_out, "Write BLOCK (Async)\n");
+                    break;
                 case SSL_ERROR_WANT_WRITE:
                 case SSL_ERROR_WANT_READ:
                 case SSL_ERROR_WANT_X509_LOOKUP:
@@ -2345,6 +2361,7 @@ static int sv_body(char *hostname, int s, int stype, unsigned char *context)
                     if (SSL_pending(con))
                         goto again;
                     break;
+                case SSL_ERROR_WANT_ASYNC:
                 case SSL_ERROR_WANT_WRITE:
                 case SSL_ERROR_WANT_READ:
                     BIO_printf(bio_s_out, "Read BLOCK\n");
@@ -2423,6 +2440,8 @@ static int init_ssl_connection(SSL *con)
         }
     } else
 #endif
+
+    do {
         i = SSL_accept(con);
 
 #ifdef CERT_CB_TEST_RETRY
@@ -2435,6 +2454,7 @@ static int init_ssl_connection(SSL *con)
             }
         }
 #endif
+
 #ifndef OPENSSL_NO_SRP
         while (i <= 0 && SSL_get_error(con, i) == SSL_ERROR_WANT_X509_LOOKUP) {
             BIO_printf(bio_s_out, "LOOKUP during accept %s\n",
@@ -2450,6 +2470,7 @@ static int init_ssl_connection(SSL *con)
             i = SSL_accept(con);
         }
 #endif
+    } while (i < 0 && SSL_waiting_for_async(con));
 
     if (i <= 0) {
         if ((dtlslisten && i == 0)