Merge branch 'big-r81/epmd-nonfatal-loopback/OTP-17970' into maint-23

* big-r81/epmd-nonfatal-loopback/OTP-17970:
  epmd: don't fail if non-critical interfaces fail to bind

1 files changed, 18 insertions, 2 deletions

diff --git a/erts/epmd/src/epmd_srv.c b/erts/epmd/src/epmd_srv.c
index ad264585c6..362173a3f4 100644
--- a/erts/epmd/src/epmd_srv.c
+++ b/erts/epmd/src/epmd_srv.c
@@ -239,6 +239,7 @@ void run(EpmdVars *g)
   char socknamebuf[INET_ADDRSTRLEN];
 #endif
   int num_sockets = 0;
+  int nonfatal_sockets = 0;
   int i;
   int opt;
   unsigned short sport = g->port;
@@ -296,6 +297,14 @@ void run(EpmdVars *g)
       num_sockets++;
 #endif
 
+      /* IPv4 and/or IPv6 loopback may not be present, for example if
+       * the protocol stack is explicitly disabled in the kernel.  If
+       * any sockets to this point fail, log the error but do not exit
+       * with failure.  If any socket after this (explicitly
+       * configured via addresses) fails, then consider the error
+       * fatal. */
+      nonfatal_sockets = num_sockets;
+
 	  if ((tmp = strdup(g->addresses)) == NULL)
 	{
 	  dbg_perror(g,"cannot allocate memory");
@@ -411,7 +420,6 @@ void run(EpmdVars *g)
 	          epmd_cleanup_exit(g,1);
 	  }
 	}
-      g->listenfd[bound++] = listensock[i];
 
 #if HAVE_DECL_IPV6_V6ONLY
       opt = 1;
@@ -469,7 +477,14 @@ void run(EpmdVars *g)
               dbg_perror(g,"failed to bind on ipaddr %s",
                          epmd_ntop(&iserv_addr[num_sockets],
                                    socknamebuf, sizeof(socknamebuf)));
-              epmd_cleanup_exit(g,1);
+              if (i >= nonfatal_sockets)
+                  epmd_cleanup_exit(g,1);
+              else
+              {
+                  close(listensock[i]);
+                  continue;
+              }
+
 	    }
 	}
 
@@ -479,6 +494,7 @@ void run(EpmdVars *g)
                                socknamebuf, sizeof(socknamebuf)));
           epmd_cleanup_exit(g,1);
       }
+      g->listenfd[bound++] = listensock[i];
       select_fd_set(g, listensock[i]);
     }
   if (bound == 0) {