openssl s_server: print the accepting address and socket

The line saying ACCEPT is extended with a space followed by the the
address and port combination on which s_server accepts connections.
The address is written in such a way that s_client should be able to
accepts as argument for the '-connect' option.
Reviewed-by: NAndy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5843)

apps/s_apps.h

@@ -22,9 +22,8 @@
 
 typedef int (*do_server_cb)(int s, int stype, int prot, unsigned char *context);
 int do_server(int *accept_sock, const char *host, const char *port,
-              int family, int type, int protocol,
-              do_server_cb cb,
-              unsigned char *context, int naccept);
+              int family, int type, int protocol, do_server_cb cb,
+              unsigned char *context, int naccept, BIO *bio_s_out);
 #ifdef HEADER_X509_H
 int verify_callback(int ok, X509_STORE_CTX *ctx);
 #endif

apps/s_server.c

@@ -2095,8 +2095,6 @@ int s_server_main(int argc, char *argv[])
     if (max_early_data >= 0)
         SSL_CTX_set_max_early_data(ctx, max_early_data);
 
-    BIO_printf(bio_s_out, "ACCEPT\n");
-    (void)BIO_flush(bio_s_out);
     if (rev)
         server_cb = rev_body;
     else if (www)
@@ -2109,7 +2107,7 @@ int s_server_main(int argc, char *argv[])
         unlink(host);
 #endif
     do_server(&accept_socket, host, port, socket_family, socket_type, protocol,
-              server_cb, context, naccept);
+              server_cb, context, naccept, bio_s_out);
     print_stats(bio_s_out, ctx);
     ret = 0;
  end:
@@ -2673,9 +2671,6 @@ static int sv_body(int s, int stype, int prot, unsigned char *context)
     }
     BIO_printf(bio_s_out, "CONNECTION CLOSED\n");
     OPENSSL_clear_free(buf, bufsize);
-    if (ret >= 0)
-        BIO_printf(bio_s_out, "ACCEPT\n");
-    (void)BIO_flush(bio_s_out);
     return ret;
 }
 
@@ -3284,8 +3279,6 @@ static int www_body(int s, int stype, int prot, unsigned char *context)
     SSL_set_shutdown(con, SSL_SENT_SHUTDOWN | SSL_RECEIVED_SHUTDOWN);
 
  err:
-    if (ret >= 0)
-        BIO_printf(bio_s_out, "ACCEPT\n");
     OPENSSL_free(buf);
     BIO_free_all(io);
     return ret;

apps/s_socket.c

@@ -204,7 +204,7 @@ out:
  */
 int do_server(int *accept_sock, const char *host, const char *port,
               int family, int type, int protocol, do_server_cb cb,
-              unsigned char *context, int naccept)
+              unsigned char *context, int naccept, BIO *bio_s_out)
 {
     int asock = 0;
     int sock;
@@ -283,6 +283,34 @@ int do_server(int *accept_sock, const char *host, const char *port,
     BIO_ADDRINFO_free(res);
     res = NULL;
 
+    {
+        union BIO_sock_info_u info;
+        char *hostname = NULL;
+        char *service = NULL;
+        int success = 0;
+
+        if ((info.addr = BIO_ADDR_new()) != NULL
+            && BIO_sock_info(asock, BIO_SOCK_INFO_ADDRESS, &info)
+            && (hostname = BIO_ADDR_hostname_string(info.addr, 1)) != NULL
+            && (service = BIO_ADDR_service_string(info.addr, 1)) != NULL
+            && BIO_printf(bio_s_out,
+                          strchr(hostname, ':') == NULL
+                          ? /* IPv4 */ "ACCEPT %s:%s\n"
+                          : /* IPv6 */ "ACCEPT [%s]:%s\n",
+                          hostname, service) > 0)
+            success = 1;
+
+        (void)BIO_flush(bio_s_out);
+        OPENSSL_free(hostname);
+        OPENSSL_free(service);
+        BIO_ADDR_free(info.addr);
+        if (!success) {
+            BIO_closesocket(asock);
+            ERR_print_errors(bio_err);
+            goto end;
+        }
+    }
+
     if (accept_sock != NULL)
         *accept_sock = asock;
     for (;;) {