Allow user to specify the IP address epmd binds to

The IP address(es) epmd binds to can now be specified by the user,
either via epmd's new "-address" option or (if that's not used) by
setting the environment variable ERL_EPMD_ADDRESS. Multiple addresses
may be specified using a comma-separated list. If the loopback address
is not in this list, it will be added implicitly, so that the daemon can
be queried by an interactive epmd process.

7 files changed, 224 insertions, 111 deletions

diff --git a/erts/configure.in b/erts/configure.in
index 8c6f2ac076..fdaeb90d9c 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -1716,7 +1716,7 @@ AC_CHECK_FUNCS([getnameinfo getipnodebyname getipnodebyaddr gethostbyname2])
 
 AC_CHECK_FUNCS([ieee_handler fpsetmask finite isnan isinf res_gethostbyname dlopen \
 		pread pwrite writev memmove strerror strerror_r strncasecmp \
-		gethrtime localtime_r gmtime_r mmap mremap memcpy mallopt \
+		gethrtime localtime_r gmtime_r inet_pton mmap mremap memcpy mallopt \
 		sbrk _sbrk __sbrk brk _brk __brk \
 		flockfile fstat strlcpy strlcat setsid posix2time setlocale nl_langinfo poll])
 
diff --git a/erts/doc/src/epmd.xml b/erts/doc/src/epmd.xml
index f01cf90a36..f2ea325be7 100644
--- a/erts/doc/src/epmd.xml
+++ b/erts/doc/src/epmd.xml
@@ -116,6 +116,16 @@
 
     <p>These options are available when starting the actual name server. The name server is normally started automatically by the <c>erl</c> command (if not already available), but it can also be started at i.e. system start-up.</p>
     <taglist>
+    <tag><c><![CDATA[-address List]]></c></tag>
+    <item>
+    <p>Let this instance of <c>epmd</c> listen only on the
+      comma-separated list of IP addresses and on the loopback address
+      (which is implicitely added to the list if it has not been
+      specified). This can also be set using the
+      <c><![CDATA[ERL_EPMD_ADDRESS]]></c> environment variable, see the
+      section <seealso marker="#environment_variables">Environment
+      variables</seealso> below.</p>
+    </item>
     <tag><c><![CDATA[-port No]]></c></tag>
     <item>
       <p>Let this instance of epmd listen to another TCP port than
@@ -228,6 +238,15 @@
     <marker id="environment_variables"></marker>
     <title>Environment variables</title>
     <taglist>
+      <tag><c><![CDATA[ERL_EPMD_ADDRESS]]></c></tag>
+      <item>
+        <p>This environment variable may be set to a comma-separated
+          list of IP addresses, in which case the <c>epmd</c> daemon
+          will listen only on the specified address(es) and on the
+          loopback address (which is implicitely added to the list if it
+          has not been specified). The default behaviour is to listen on
+          all available IP addresses.</p>
+      </item>
       <tag><c><![CDATA[ERL_EPMD_PORT]]></c></tag>
       <item>
         <p>This environment variable can contain the port number epmd will use.
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 09c9cf6812..2fd804cd04 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -981,6 +981,15 @@
 	  add to the code path.
   	  See <seealso marker="kernel:code">code(3)</seealso>.</p>
       </item>
+      <tag><c><![CDATA[ERL_EPMD_ADDRESS]]></c></tag>
+      <item>
+        <p>This environment variable may be set to a comma-separated
+          list of IP addresses, in which case the
+          <seealso marker="epmd">epmd</seealso> daemon
+          will listen only on the specified address(es) and on the
+          loopback address (which is implicitely added to the list if it
+          has not been specified).</p>
+      </item>
       <tag><c><![CDATA[ERL_EPMD_PORT]]></c></tag>
       <item>
         <p>This environment variable can contain the port number to use when
diff --git a/erts/epmd/src/epmd.c b/erts/epmd/src/epmd.c
index 65ff0cd6b2..9ba1069663 100644
--- a/erts/epmd/src/epmd.c
+++ b/erts/epmd/src/epmd.c
@@ -33,6 +33,7 @@
 
 static void usage(EpmdVars *);
 static void run_daemon(EpmdVars*);
+static char* get_addresses(void);
 static int get_port_no(void);
 static int check_relaxed(void);
 #ifdef __WIN32__
@@ -133,6 +134,7 @@ int main(int argc, char** argv)
 {
     EpmdVars g_empd_vars;
     EpmdVars *g = &g_empd_vars;
+    int i;
 #ifdef __WIN32__
     WORD wVersionRequested;
     WSADATA wsaData;
@@ -158,8 +160,9 @@ int main(int argc, char** argv)
     g->argv = NULL;
 #endif
 
-    g->port  = get_port_no();
-    g->debug = 0;
+    g->addresses      = get_addresses();
+    g->port           = get_port_no();
+    g->debug          = 0;
 
     g->silent         = 0; 
     g->is_daemon      = 0;
@@ -168,12 +171,14 @@ int main(int argc, char** argv)
     g->delay_accept   = 0;
     g->delay_write    = 0;
     g->progname       = argv[0];
-    g->listenfd       = -1;
     g->conn           = NULL;
     g->nodes.reg = g->nodes.unreg = g->nodes.unreg_tail = NULL;
     g->nodes.unreg_count = 0;
     g->active_conn    = 0;
 
+    for (i = 0; i < MAX_LISTEN_SOCKETS; i++)
+	g->listenfd[i] = -1;
+
     argc--;
     argv++;
     while (argc > 0) {
@@ -208,6 +213,11 @@ int main(int argc, char** argv)
 	    else
 		usage(g);
 	    epmd_cleanup_exit(g,0);
+	} else if (strcmp(argv[0], "-address") == 0) {
+	    if (argc == 1)
+	      usage(g);
+	    g->addresses = argv[1];
+	    argv += 2; argc -= 2;
 	} else if (strcmp(argv[0], "-port") == 0) {
 	    if ((argc == 1) ||
 		((g->port = atoi(argv[1])) == 0))
@@ -252,13 +262,10 @@ int main(int argc, char** argv)
     /*
      * max_conn must not be greater than FD_SETSIZE.
      * (at least QNX crashes)
-     *
-     * More correctly, it must be FD_SETSIZE - 1, beacuse the
-     * listen FD is stored outside the connection array.
      */
   
     if (g->max_conn > FD_SETSIZE) {
-      g->max_conn = FD_SETSIZE - 1;
+      g->max_conn = FD_SETSIZE;
     }
 
     if (g->is_daemon)  {
@@ -393,11 +400,14 @@ static void run_daemon(EpmdVars *g)
 
 static void usage(EpmdVars *g)
 {
-    fprintf(stderr, "usage: epmd [-d|-debug] [DbgExtra...] [-port No] [-daemon]\n");
-    fprintf(stderr, "            [-relaxed_command_check]\n");
+    fprintf(stderr, "usage: epmd [-d|-debug] [DbgExtra...] [-address List]\n");
+    fprintf(stderr, "            [-port No] [-daemon] [-relaxed_command_check]\n");
     fprintf(stderr, "       epmd [-d|-debug] [-port No] [-names|-kill|-stop name]\n\n");
     fprintf(stderr, "See the Erlang epmd manual page for info about the usage.\n\n");
     fprintf(stderr, "Regular options\n");
+    fprintf(stderr, "    -address List\n");
+    fprintf(stderr, "        Let epmd listen only on the comma-separated list of IP\n");
+    fprintf(stderr, "        addresses (and on the loopback interface).\n");
     fprintf(stderr, "    -port No\n");
     fprintf(stderr, "        Let epmd listen to another port than default %d\n",
 	    EPMD_PORT_NO);
@@ -555,8 +565,9 @@ void epmd_cleanup_exit(EpmdVars *g, int exitval)
 	      epmd_conn_close(g,&g->conn[i]);
       free(g->conn);
   }
-  if(g->listenfd >= 0)
-      close(g->listenfd);
+  for(i=0; i < MAX_LISTEN_SOCKETS; i++)
+      if(g->listenfd[i] >= 0)
+          close(g->listenfd[i]);
   free_all_nodes(g);
   if(g->argv){
       for(i=0; g->argv[i] != NULL; ++i)
@@ -568,6 +579,10 @@ void epmd_cleanup_exit(EpmdVars *g, int exitval)
   exit(exitval);
 }
 
+static char* get_addresses(void)
+{
+    return getenv("ERL_EPMD_ADDRESS");
+}
 static int get_port_no(void)
 {
     char* port_str = getenv("ERL_EPMD_PORT");
diff --git a/erts/epmd/src/epmd_cli.c b/erts/epmd/src/epmd_cli.c
index 7c60ba0420..ac55ba6bb6 100644
--- a/erts/epmd/src/epmd_cli.c
+++ b/erts/epmd/src/epmd_cli.c
@@ -137,7 +137,7 @@ static int conn_to_epmd(EpmdVars *g)
 
     { /* store port number in unsigned short */
       unsigned short sport = g->port;
-      SET_ADDR_LOOPBACK(address, FAMILY, sport);
+      SET_ADDR(address, EPMD_ADDR_LOOPBACK, sport);
     }
 
     if (connect(connect_sock, (struct sockaddr*)&address, sizeof address) < 0) 
diff --git a/erts/epmd/src/epmd_int.h b/erts/epmd/src/epmd_int.h
index c2558d52a1..2a0de4df9c 100644
--- a/erts/epmd/src/epmd_int.h
+++ b/erts/epmd/src/epmd_int.h
@@ -168,42 +168,40 @@
 #if defined(HAVE_IN6) && defined(AF_INET6) && defined(EPMD6)
 
 #define EPMD_SOCKADDR_IN sockaddr_in6
-#define FAMILY      AF_INET6
-
-#define SET_ADDR_LOOPBACK(addr, af, port) do { \
-    memset((char*)&(addr), 0, sizeof(addr)); \
-    (addr).sin6_family = (af); \
-    (addr).sin6_flowinfo = 0; \
-    (addr).sin6_addr = in6addr_loopback; \
-    (addr).sin6_port = htons(port); \
+#define EPMD_IN_ADDR in6_addr
+#define EPMD_S_ADDR s6_addr
+#define EPMD_ADDR_LOOPBACK in6addr_loopback.s6_addr
+#define EPMD_ADDR_ANY in6addr_any.s6_addr
+#define FAMILY AF_INET6
+
+#define SET_ADDR(dst, addr, port) do { \
+    memset((char*)&(dst), 0, sizeof(dst)); \
+    memcpy((char*)&(dst).sin6_addr.s6_addr, (char*)&(addr), 16); \
+    (dst).sin6_family = AF_INET6; \
+    (dst).sin6_flowinfo = 0; \
+    (dst).sin6_port = htons(port); \
  } while(0)
 
-#define SET_ADDR_ANY(addr, af, port) do { \
-    memset((char*)&(addr), 0, sizeof(addr)); \
-    (addr).sin6_family = (af); \
-    (addr).sin6_flowinfo = 0; \
-    (addr).sin6_addr = in6addr_any; \
-    (addr).sin6_port = htons(port); \
- } while(0)
+#define IS_ADDR_LOOPBACK(addr) \
+    (memcmp((addr).s6_addr, in6addr_loopback.s6_addr, 16) == 0)
 
 #else /* Not IP v6 */
 
 #define EPMD_SOCKADDR_IN sockaddr_in
-#define FAMILY      AF_INET
-
-#define SET_ADDR_LOOPBACK(addr, af, port) do { \
-    memset((char*)&(addr), 0, sizeof(addr)); \
-    (addr).sin_family = (af); \
-    (addr).sin_addr.s_addr = htonl(INADDR_LOOPBACK); \
-    (addr).sin_port = htons(port); \
+#define EPMD_IN_ADDR in_addr
+#define EPMD_S_ADDR s_addr
+#define EPMD_ADDR_LOOPBACK htonl(INADDR_LOOPBACK)
+#define EPMD_ADDR_ANY htonl(INADDR_ANY)
+#define FAMILY AF_INET
+
+#define SET_ADDR(dst, addr, port) do { \
+    memset((char*)&(dst), 0, sizeof(dst)); \
+    (dst).sin_family = AF_INET; \
+    (dst).sin_addr.s_addr = (addr); \
+    (dst).sin_port = htons(port); \
  } while(0)
 
-#define SET_ADDR_ANY(addr, af, port) do { \
-    memset((char*)&(addr), 0, sizeof(addr)); \
-    (addr).sin_family = (af); \
-    (addr).sin_addr.s_addr = htonl(INADDR_ANY); \
-    (addr).sin_port = htons(port); \
- } while(0)
+#define IS_ADDR_LOOPBACK(addr) ((addr).s_addr == htonl(INADDR_LOOPBACK))
 
 #endif /* Not IP v6 */
 
@@ -231,6 +229,8 @@
 /* Maximum length of a node name == atom name */
 #define MAXSYMLEN 255
 
+#define MAX_LISTEN_SOCKETS 16
+
 #define INBUF_SIZE 1024
 #define OUTBUF_SIZE 1024
 
@@ -299,7 +299,8 @@ typedef struct {
   Connection *conn;
   Nodes nodes;
   fd_set orig_read_mask;
-  int listenfd;
+  int listenfd[MAX_LISTEN_SOCKETS];
+  char *addresses;
   char **argv;
 } EpmdVars;
 
diff --git a/erts/epmd/src/epmd_srv.c b/erts/epmd/src/epmd_srv.c
index ef471a473a..73b09e7299 100644
--- a/erts/epmd/src/epmd_srv.c
+++ b/erts/epmd/src/epmd_srv.c
@@ -24,6 +24,10 @@
 #include "epmd.h"     /* Renamed from 'epmd_r4.h' */
 #include "epmd_int.h"
 
+#ifndef INADDR_NONE
+#  define INADDR_NONE 0xffffffff
+#endif
+
 /*
  *  
  *  This server is a local name server for Erlang nodes. Erlang nodes can
@@ -79,90 +83,154 @@ static void print_names(EpmdVars*);
 
 void run(EpmdVars *g)
 {
-  int listensock;
+  struct EPMD_SOCKADDR_IN iserv_addr[MAX_LISTEN_SOCKETS];
+  int listensock[MAX_LISTEN_SOCKETS];
+  int num_sockets;
   int i;
   int opt;
-  struct EPMD_SOCKADDR_IN iserv_addr;
+  unsigned short sport = g->port;
 
   node_init(g);
   g->conn = conn_init(g);
 
   dbg_printf(g,2,"try to initiate listening port %d", g->port);
-  
-  if ((listensock = socket(FAMILY,SOCK_STREAM,0)) < 0) {
-    dbg_perror(g,"error opening stream socket");
-    epmd_cleanup_exit(g,1);
-  }
-  g->listenfd = listensock;
+
+  if (g->addresses != NULL)
+    {
+      char *tmp;
+      char *token;
+      int loopback_ok = 0;
+
+      if ((tmp = (char *)malloc(strlen(g->addresses) + 1)) == NULL)
+	{
+	  dbg_perror(g,"cannot allocate memory");
+	  epmd_cleanup_exit(g,1);
+	}
+      strcpy(tmp,g->addresses);
+
+      for(token = strtok(tmp,", "), num_sockets = 0;
+	  token != NULL;
+	  token = strtok(NULL,", "), num_sockets++)
+	{
+	  struct EPMD_IN_ADDR addr;
+#ifdef HAVE_INET_PTON
+	  int ret;
+
+	  if ((ret = inet_pton(FAMILY,token,&addr)) == -1)
+	    {
+	      dbg_perror(g,"cannot convert IP address to network format");
+	      epmd_cleanup_exit(g,1);
+	    }
+	  else if (ret == 0)
+#elif !defined(EPMD6)
+	  if ((addr.EPMD_S_ADDR = inet_addr(token)) == INADDR_NONE)
+#endif
+	    {
+	      dbg_tty_printf(g,0,"cannot parse IP address \"%s\"",token);
+	      epmd_cleanup_exit(g,1);
+	    }
+
+	  if (IS_ADDR_LOOPBACK(addr))
+	    loopback_ok = 1;
+
+	  if (num_sockets - loopback_ok == MAX_LISTEN_SOCKETS - 1)
+	    {
+	      dbg_tty_printf(g,0,"cannot listen on more than %d IP addresses",
+			     MAX_LISTEN_SOCKETS);
+	      epmd_cleanup_exit(g,1);
+	    }
+
+	  SET_ADDR(iserv_addr[num_sockets],addr.EPMD_S_ADDR,sport);
+	}
+
+      free(tmp);
+
+      if (!loopback_ok)
+	{
+	  SET_ADDR(iserv_addr[num_sockets],EPMD_ADDR_LOOPBACK,sport);
+	  num_sockets++;
+	}
+    }
+  else
+    {
+      SET_ADDR(iserv_addr[0],EPMD_ADDR_ANY,sport);
+      num_sockets = 1;
+    }
+
+#if !defined(__WIN32__)
+  /* We ignore the SIGPIPE signal that is raised when we call write
+     twice on a socket closed by the other end. */
+  signal(SIGPIPE, SIG_IGN);
+#endif
 
   /*
    * Initialize number of active file descriptors.
    * Stdin, stdout, and stderr are still open.
-   * One for the listen socket.
    */
-  g->active_conn = 3+1;
+  g->active_conn = 3 + num_sockets;
+  g->max_conn -= num_sockets;
+
+  FD_ZERO(&g->orig_read_mask);
+
+  for (i = 0; i < num_sockets; i++)
+    {
+      if ((listensock[i] = socket(FAMILY,SOCK_STREAM,0)) < 0)
+	{
+	  dbg_perror(g,"error opening stream socket");
+	  epmd_cleanup_exit(g,1);
+	}
+      g->listenfd[i] = listensock[i];
   
-  /*
-   * Note that we must not enable the SO_REUSEADDR on Windows,
-   * because addresses will be reused even if they are still in use.
-   */
+      /*
+       * Note that we must not enable the SO_REUSEADDR on Windows,
+       * because addresses will be reused even if they are still in use.
+       */
   
 #if !defined(__WIN32__)
-  /* We ignore the SIGPIPE signal that is raised when we call write
-     twice on a socket closed by the other end. */
-  signal(SIGPIPE, SIG_IGN);
-
-  opt = 1;			/* Set this option */
-  if (setsockopt(listensock,SOL_SOCKET,SO_REUSEADDR,(char* ) &opt,
-		 sizeof(opt)) <0) {
-    dbg_perror(g,"can't set sockopt");
-    epmd_cleanup_exit(g,1);
-  }
+      opt = 1;
+      if (setsockopt(listensock[i],SOL_SOCKET,SO_REUSEADDR,(char* ) &opt,
+		     sizeof(opt)) <0)
+	{
+	  dbg_perror(g,"can't set sockopt");
+	  epmd_cleanup_exit(g,1);
+	}
 #endif
   
-  /* In rare cases select returns because there is someone
-     to accept but the request is withdrawn before the
-     accept function is called. We set the listen socket
-     to be non blocking to prevent us from being hanging
-     in accept() waiting for the next request. */
+      /* In rare cases select returns because there is someone
+	 to accept but the request is withdrawn before the
+	 accept function is called. We set the listen socket
+	 to be non blocking to prevent us from being hanging
+	 in accept() waiting for the next request. */
 #if (defined(__WIN32__) || defined(NO_FCNTL))
-  opt = 1;
-  if (ioctl(listensock, FIONBIO, &opt) != 0) /* Gives warning in VxWorks */
+      opt = 1;
+      /* Gives warning in VxWorks */
+      if (ioctl(listensock[i], FIONBIO, &opt) != 0)
 #else
-  opt = fcntl(listensock, F_GETFL, 0);
-  if (fcntl(listensock, F_SETFL, opt | O_NONBLOCK) == -1)
+      opt = fcntl(listensock[i], F_GETFL, 0);
+      if (fcntl(listensock[i], F_SETFL, opt | O_NONBLOCK) == -1)
 #endif /* __WIN32__ || VXWORKS */
-    dbg_perror(g,"failed to set non-blocking mode of listening socket %d",
-	       listensock);
+	dbg_perror(g,"failed to set non-blocking mode of listening socket %d",
+		   listensock[i]);
 
-  { /* store port number in unsigned short */
-    unsigned short sport = g->port;
-    SET_ADDR_ANY(iserv_addr, FAMILY, sport);
-  }
-  
-  if(bind(listensock,(struct sockaddr*) &iserv_addr, sizeof(iserv_addr)) < 0 )
-    {
-      if (errno == EADDRINUSE)
-	{
-	  dbg_tty_printf(g,1,"there is already a epmd running at port %d",
-			 g->port);
-	  epmd_cleanup_exit(g,0);
-	}
-      else
+      if (bind(listensock[i], (struct sockaddr*) &iserv_addr[i],
+	  sizeof(iserv_addr[i])) < 0)
 	{
-	  dbg_perror(g,"failed to bind socket");
-	  epmd_cleanup_exit(g,1);
+	  if (errno == EADDRINUSE)
+	    {
+	      dbg_tty_printf(g,1,"there is already a epmd running at port %d",
+			     g->port);
+	      epmd_cleanup_exit(g,0);
+	    }
+	  else
+	    {
+	      dbg_perror(g,"failed to bind socket");
+	      epmd_cleanup_exit(g,1);
+	    }
 	}
+      listen(listensock[i],SOMAXCONN);
+      FD_SET(listensock[i],&g->orig_read_mask);
     }
 
-  dbg_printf(g,2,"starting");
-
-  listen(listensock, SOMAXCONN);
-
-
-  FD_ZERO(&g->orig_read_mask);
-  FD_SET(listensock,&g->orig_read_mask);
-
   dbg_tty_printf(g,2,"entering the main select() loop");
 
  select_again:
@@ -198,17 +266,18 @@ void run(EpmdVars *g)
 	  sleep(g->delay_accept);
 	}
 
-	if (FD_ISSET(listensock,&read_mask)) {
-	  if (do_accept(g, listensock) && g->active_conn < g->max_conn) {
-	    /*
-	     * The accept() succeeded, and we have at least one file
-	     * descriptor still free, which means that another accept()
-	     * could succeed. Go do do another select(), in case there
-	     * are more incoming connections waiting to be accepted.
-	     */
-	    goto select_again;
+	for (i = 0; i < num_sockets; i++)
+	  if (FD_ISSET(listensock[i],&read_mask)) {
+	    if (do_accept(g, listensock[i]) && g->active_conn < g->max_conn) {
+	      /*
+	       * The accept() succeeded, and we have at least one file
+	       * descriptor still free, which means that another accept()
+	       * could succeed. Go do do another select(), in case there
+	       * are more incoming connections waiting to be accepted.
+	       */
+	      goto select_again;
+	    }
 	  }
-	}
 	  
 	/* Check all open streams marked by select for data or a
 	   close.  We also close all open sockets except ALIVE