ipcpd: Allow disabling of DNS

This allows someone to disable the use of DNS in the shim UDP. It also
adds a config file specific for the shim UDP (which holds the nsupdate
location). Certain defines were also moved to the global config file.

3 files changed, 79 insertions, 29 deletions

diff --git a/src/ipcpd/shim-udp/CMakeLists.txt b/src/ipcpd/shim-udp/CMakeLists.txt
index c71fa00b..a50fe8bd 100644
--- a/src/ipcpd/shim-udp/CMakeLists.txt
+++ b/src/ipcpd/shim-udp/CMakeLists.txt
@@ -1,5 +1,7 @@
-get_filename_component(CURRENT_SOURCE_PARENT_DIR ${CMAKE_CURRENT_SOURCE_DIR} DIRECTORY)
-get_filename_component(CURRENT_BINARY_PARENT_DIR ${CMAKE_CURRENT_BINARY_DIR} DIRECTORY)
+get_filename_component(CURRENT_SOURCE_PARENT_DIR
+  ${CMAKE_CURRENT_SOURCE_DIR} DIRECTORY)
+get_filename_component(CURRENT_BINARY_PARENT_DIR
+  ${CMAKE_CURRENT_BINARY_DIR} DIRECTORY)
 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
@@ -18,33 +20,47 @@ IF(NOT CMAKE_HAVE_GETHOSTBYNAME)
   IF (CMAKE_LIB_NSL_HAS_GETHOSTBYNAME)
     SET (X11_X_EXTRA_LIBS ${X11_X_EXTRA_LIBS} -lnsl)
   ELSE (CMAKE_LIB_NSL_HAS_GETHOSTBYNAME)
-    CHECK_LIBRARY_EXISTS("bsd" "gethostbyname" "" CMAKE_LIB_BSD_HAS_GETHOSTBYNAME)
+    CHECK_LIBRARY_EXISTS("bsd" "gethostbyname" ""
+      CMAKE_LIB_BSD_HAS_GETHOSTBYNAME)
     IF (CMAKE_LIB_BSD_HAS_GETHOSTBYNAME)
       SET (X11_X_EXTRA_LIBS ${X11_X_EXTRA_LIBS} -lbsd)
     ENDIF (CMAKE_LIB_BSD_HAS_GETHOSTBYNAME)
   ENDIF (CMAKE_LIB_NSL_HAS_GETHOSTBYNAME)
 ENDIF(NOT CMAKE_HAVE_GETHOSTBYNAME)
 
-# Find the nsupdate executable
-find_program(NSUPDATE_EXECUTABLE
-  NAMES nsupdate
-  DOC "The nsupdate tool that enables DDNS")
+# Enable DNS by default
+if (NOT DISABLE_DNS MATCHES True)
+  # Find the nsupdate executable
+  find_program(NSUPDATE_EXECUTABLE
+    NAMES nsupdate
+    DOC "The nsupdate tool that enables DDNS")
 
-if (${NSUPDATE_EXECUTABLE} STREQUAL "NSUPDATE_EXECUTABLE-NOTFOUND")
-  message(FATAL_ERROR "Could not find nsupdate, which is needed for DDNS")
-else()
-  message("-- Found nsupdate: ${NSUPDATE_EXECUTABLE}")
+  if (${NSUPDATE_EXECUTABLE} STREQUAL "NSUPDATE_EXECUTABLE-NOTFOUND")
+    message(FATAL_ERROR "Could not find nsupdate, which is needed for DDNS")
+  else()
+    message("-- Found nsupdate: ${NSUPDATE_EXECUTABLE}")
+  endif()
 endif()
 
+configure_file(
+  "${CMAKE_CURRENT_SOURCE_DIR}/shim_udp_config.h.in"
+  "${CMAKE_CURRENT_BINARY_DIR}/shim_udp_config.h")
+
 SET(IPCP_SHIM_UDP_TARGET ipcpd-shim-udp CACHE STRING "IPCP_SHIM_UDP_TARGET")
 
 set(SHIM_UDP_SOURCES
   # Add source files here
   ${CMAKE_CURRENT_SOURCE_DIR}/main.c)
 
-add_executable (ipcpd-shim-udp ${SHIM_UDP_SOURCES} ${IPCP_SOURCES})
+add_executable (ipcpd-shim-udp ${SHIM_UDP_SOURCES} ${IPCP_SOURCES}
+  "${CMAKE_CURRENT_BINARY_DIR}/shim_udp_config.h")
 target_link_libraries (ipcpd-shim-udp LINK_PUBLIC ouroboros)
 
+# Enable DNS by default
+if (NOT DISABLE_DNS MATCHES True)
+  MACRO_ADD_COMPILE_FLAGS(ipcpd-shim-udp -DCONFIG_OUROBOROS_ENABLE_DNS)
+endif()
+
 include(MacroAddCompileFlags)
 if (CMAKE_BUILD_TYPE MATCHES Debug)
   MACRO_ADD_COMPILE_FLAGS(ipcpd-shim-udp -DCONFIG_OUROBOROS_DEBUG)
diff --git a/src/ipcpd/shim-udp/main.c b/src/ipcpd/shim-udp/main.c
index e213f019..b45bee76 100644
--- a/src/ipcpd/shim-udp/main.c
+++ b/src/ipcpd/shim-udp/main.c
@@ -23,6 +23,7 @@
 #include <ouroboros/config.h>
 #include "ipcp.h"
 #include "flow.h"
+#include "shim_udp_config.h"
 #include <ouroboros/shm_du_map.h>
 #include <ouroboros/shm_ap_rbuff.h>
 #include <ouroboros/list.h>
@@ -31,6 +32,7 @@
 #include <ouroboros/dif_config.h>
 #include <ouroboros/sockets.h>
 #include <ouroboros/bitmap.h>
+#include <ouroboros/dev.h>
 
 #define OUROBOROS_PREFIX "ipcpd/shim-udp"
 
@@ -74,19 +76,6 @@ struct ipcp * _ipcp;
  * the info
  */
 
-#define UNKNOWN_AP "__UNKNOWN_AP__"
-#define UNKNOWN_AE "__UNKNOWN_AE__"
-
-#define AP_MAX_FLOWS 256
-
-#ifndef DU_BUFF_HEADSPACE
-  #define DU_BUFF_HEADSPACE 128
-#endif
-
-#ifndef DU_BUFF_TAILSPACE
-  #define DU_BUFF_TAILSPACE 0
-#endif
-
 /* the shim needs access to these internals */
 struct shim_ap_data {
         instance_name_t *     api;
@@ -332,8 +321,11 @@ static void * ipcp_udp_listener()
                 }
 
                 /* echo back the packet */
-                while(send(fd, buf, strlen(buf), 0) < 0)
-                        ;
+                if (send(fd, buf, strlen(buf), 0) < 0) {
+                        LOG_ERR("Failed to echo back the packet.");
+                        close(fd);
+                        continue;
+                }
 
                 /* reply to IRM */
 
@@ -413,12 +405,16 @@ int ipcp_udp_bootstrap(struct dif_config * conf)
                   ipstr,
                   INET_ADDRSTRLEN);
 
-        if (conf->dns_addr != 0)
+        if (conf->dns_addr != 0) {
                 inet_ntop(AF_INET,
                           &conf->dns_addr,
                           dnsstr,
                           INET_ADDRSTRLEN);
-        else
+#ifndef CONFIG_OUROBOROS_ENABLE_DNS
+                LOG_WARN("DNS address ignored since shim-udp was "
+                         "compiled without DNS support.");
+#endif
+        } else
                 strcpy(dnsstr, "not set");
 
         shim_data(_ipcp)->ip_addr  = conf->ip_addr;
@@ -480,6 +476,7 @@ int ipcp_udp_bootstrap(struct dif_config * conf)
         return 0;
 }
 
+#ifdef CONFIG_OUROBOROS_ENABLE_DNS
 /* FIXME: Dependency on nsupdate to be removed in the end */
 static int ddns_send(char * cmd)
 {
@@ -524,15 +521,18 @@ static int ddns_send(char * cmd)
         close(pipe_fd[1]);
         return 0;
 }
+#endif
 
 int ipcp_udp_name_reg(char * name)
 {
+#ifdef CONFIG_OUROBOROS_ENABLE_DNS
         char ipstr[INET_ADDRSTRLEN];
         char dnsstr[INET_ADDRSTRLEN];
         /* max DNS name length + max IP length + command length */
         char cmd[100];
         uint32_t dns_addr;
         uint32_t ip_addr;
+#endif
 
         if (_ipcp->state != IPCP_ENROLLED) {
                 LOG_DBGF("Won't register with non-enrolled IPCP.");
@@ -549,6 +549,7 @@ int ipcp_udp_name_reg(char * name)
                 return -1;
         }
 
+#ifdef CONFIG_OUROBOROS_ENABLE_DNS
         /* register application with DNS server */
 
         dns_addr = shim_data(_ipcp)->dns_addr;
@@ -565,6 +566,7 @@ int ipcp_udp_name_reg(char * name)
                         return -1;
                 }
         }
+#endif
 
         LOG_DBG("Registered %s.", name);
 
@@ -573,16 +575,19 @@ int ipcp_udp_name_reg(char * name)
 
 int ipcp_udp_name_unreg(char * name)
 {
+#ifdef CONFIG_OUROBOROS_ENABLE_DNS
         char dnsstr[INET_ADDRSTRLEN];
         /* max DNS name length + max IP length + max command length */
         char cmd[100];
         uint32_t dns_addr;
+#endif
 
         if (strlen(name) > 24) {
                 LOG_ERR("DNS names cannot be longer than 24 chars.");
                 return -1;
         }
 
+#ifdef CONFIG_OUROBOROS_ENABLE_DNS
         /* unregister application with DNS server */
 
         dns_addr = shim_data(_ipcp)->dns_addr;
@@ -593,6 +598,7 @@ int ipcp_udp_name_unreg(char * name)
 
                 ddns_send(cmd);
         }
+#endif
 
         ipcp_data_del_reg_entry(_ipcp->data, name);
 
diff --git a/src/ipcpd/shim-udp/shim_udp_config.h.in b/src/ipcpd/shim-udp/shim_udp_config.h.in
new file mode 100644
index 00000000..00b0b910
--- /dev/null
+++ b/src/ipcpd/shim-udp/shim_udp_config.h.in
@@ -0,0 +1,28 @@
+/*
+ * Ouroboros - Copyright (C) 2016
+ *
+ * Configuration information specific for the shim UDP
+ *
+ *    Sander Vrijders <sander.vrijders@intec.ugent.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef OUROBOROS_SHIM_UDP_CONFIG
+#define OUROBOROS_SHIM_UDP_CONFIG
+
+#define NSUPDATE_EXEC "@NSUPDATE_EXECUTABLE@"
+
+#endif