Applied patch #1912, but had to make changes to get it to compile

src/api/sockets.c

@@ -1007,8 +1007,10 @@ int lwip_getsockopt (int s, int level, int optname, void *optval, socklen_t *opt
       /* UNIMPL case SO_SNDBUF: */
       /* UNIMPL case SO_RCVLOWAT: */
       /* UNIMPL case SO_SNDLOWAT: */
-      /* UNIMPL case SO_REUSEADDR: */
+#ifdef SO_REUSE
-      /* UNIMPL case SO_REUSEPORT: */
+      case SO_REUSEADDR:
+      case SO_REUSEPORT:
+#endif /* SO_REUSE */
       case SO_TYPE:
       /* UNIMPL case SO_USELOOPBACK: */
         if( *optlen < sizeof(int) ) {
@@ -1091,8 +1093,10 @@ int lwip_getsockopt (int s, int level, int optname, void *optval, socklen_t *opt
     /* UNIMPL case SO_DONTROUTE: */
     case SO_KEEPALIVE:
     /* UNIMPL case SO_OOBINCLUDE: */
-    /* UNIMPL case SO_REUSEADDR: */
+#ifdef SO_REUSE
-    /* UNIMPL case SO_REUSEPORT: */
+    case SO_REUSEADDR:
+    case SO_REUSEPORT:
+#endif /* SO_REUSE */
     /*case SO_USELOOPBACK: UNIMPL */
       *(int*)optval = sock->conn->pcb.tcp->so_options & optname;
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, optname=0x%x, ..) = %s\n", s, optname, (*(int*)optval?"on":"off")));
@@ -1192,8 +1196,10 @@ int lwip_setsockopt (int s, int level, int optname, const void *optval, socklen_
     /* UNIMPL case SO_SNDBUF: */
     /* UNIMPL case SO_RCVLOWAT: */
     /* UNIMPL case SO_SNDLOWAT: */
-    /* UNIMPL case SO_REUSEADDR: */
+#ifdef SO_REUSE
-    /* UNIMPL case SO_REUSEPORT: */
+    case SO_REUSEADDR:
+    case SO_REUSEPORT:
+#endif /* SO_REUSE */
     /* UNIMPL case SO_USELOOPBACK: */
       if( optlen < sizeof(int) ) {
         err = EINVAL;
@@ -1272,8 +1278,10 @@ int lwip_setsockopt (int s, int level, int optname, const void *optval, socklen_
     /* UNIMPL case SO_DONTROUTE: */
     case SO_KEEPALIVE:
     /* UNIMPL case SO_OOBINCLUDE: */
-    /* UNIMPL case SO_REUSEADDR: */
+#ifdef SO_REUSE
-    /* UNIMPL case SO_REUSEPORT: */
+    case SO_REUSEADDR:
+    case SO_REUSEPORT:
+#endif /* SO_REUSE */
     /* UNIMPL case SO_USELOOPBACK: */
       if ( *(int*)optval ) {
         sock->conn->pcb.tcp->so_options |= optname;

src/core/tcp.c

@@ -247,11 +247,14 @@ err_t
 tcp_bind(struct tcp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
 {
   struct tcp_pcb *cpcb;
+#ifdef SO_REUSE
+  int reuse_port_all_set = 1;
+#endif /* SO_REUSE */
 
   if (port == 0) {
     port = tcp_new_port();
   }
-
+#ifndef SO_REUSE
   /* Check if the address already is in use. */
   for(cpcb = (struct tcp_pcb *)tcp_listen_pcbs;
       cpcb != NULL; cpcb = cpcb->next) {
@@ -273,6 +276,102 @@ tcp_bind(struct tcp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
       }
     }
   }
+#else /* SO_REUSE */
+  /* Search through list of PCB's in LISTEN state. 
+     
+  If there is a PCB bound to specified port and IP_ADDR_ANY another PCB can be bound to the interface IP
+  or to the loopback address on the same port if SOF_REUSEADDR is set. Any combination of PCB's bound to 
+  the same local port, but to one address out of {IP_ADDR_ANY, 127.0.0.1, interface IP} at a time is valid.
+  But no two PCB's bound to same local port and same local address is valid.
+  
+  If SOF_REUSEPORT is set several PCB's can be bound to same local port and same local address also. But then 
+  all PCB's must have the SOF_REUSEPORT option set.
+  
+  When the two options aren't set and specified port is already bound, ERR_USE is returned saying that 
+  address is already in use. */
+  for(cpcb = (struct tcp_pcb *)tcp_listen_pcbs; cpcb != NULL; cpcb = cpcb->next) {
+    if(cpcb->local_port == port) {
+      if(ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
+        if(pcb->so_options & SOF_REUSEPORT) {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in listening PCB's: SO_REUSEPORT set and same address.\n"));
+          reuse_port_all_set = (reuse_port_all_set && (cpcb->so_options & SOF_REUSEPORT));
+        }
+        else {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in listening PCB's: SO_REUSEPORT not set and same address.\n"));
+          return ERR_USE;
+        }
+      }
+      else if((ip_addr_isany(ipaddr) && !ip_addr_isany(&(cpcb->local_ip))) ||
+              (!ip_addr_isany(ipaddr) && ip_addr_isany(&(cpcb->local_ip)))) {
+        if(!(pcb->so_options & SOF_REUSEADDR) && !(pcb->so_options & SOF_REUSEPORT)) {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in listening PCB's SO_REUSEPORT or SO_REUSEADDR not set and not the same address.\n"));
+          return ERR_USE;
+        }      
+        else {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in listening PCB's SO_REUSEPORT or SO_REUSEADDR set and not the same address.\n"));
+        }     
+      }
+    }
+  }
+
+  /* Search through list of PCB's in a state in which they can accept or send data. Same decription as for 
+     PCB's in state LISTEN applies to this PCB's regarding the options SOF_REUSEADDR and SOF_REUSEPORT. */
+  for(cpcb = tcp_active_pcbs; cpcb != NULL; cpcb = cpcb->next) {
+    if(cpcb->local_port == port) {
+      if(ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
+        if(pcb->so_options & SOF_REUSEPORT) {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in active PCB's SO_REUSEPORT set and same address.\n"));
+          reuse_port_all_set = (reuse_port_all_set && (cpcb->so_options & SOF_REUSEPORT));
+        }
+        else {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in active PCB's SO_REUSEPORT not set and same address.\n"));
+          return ERR_USE;
+        }
+      }
+      else if((ip_addr_isany(ipaddr) && !ip_addr_isany(&(cpcb->local_ip))) ||
+              (!ip_addr_isany(ipaddr) && ip_addr_isany(&(cpcb->local_ip)))) {
+        if(!(pcb->so_options & SOF_REUSEADDR) && !(pcb->so_options & SOF_REUSEPORT)) {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in active PCB's SO_REUSEPORT or SO_REUSEADDR not set and not the same address.\n"));
+          return ERR_USE;
+        }   
+        else {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in active PCB's SO_REUSEPORT or SO_REUSEADDR set and not the same address.\n"));
+        }        
+      }
+    }
+  }
+
+  /* Search through list of PCB's in TIME_WAIT state. If SO_REUSEADDR is set a bound combination [IP, port} 
+     can be rebound. The same applies when SOF_REUSEPORT is set. 
+     
+     If SOF_REUSEPORT is set several PCB's can be bound to same local port and same local address also. But then 
+     all PCB's must have the SOF_REUSEPORT option set.
+     
+     When the two options aren't set and specified port is already bound, ERR_USE is returned saying that 
+     address is already in use. */
+  for(cpcb = tcp_tw_pcbs; cpcb != NULL; cpcb = cpcb->next) {
+    if(cpcb->local_port == port) {
+      if(ip_addr_cmp(&(cpcb->local_ip), ipaddr)) {
+        if(!(pcb->so_options & SOF_REUSEADDR) && !(pcb->so_options & SOF_REUSEPORT)) {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in TIME_WAIT PCB's SO_REUSEPORT or SO_REUSEADDR not set and same address.\n"));
+          return ERR_USE;
+        }
+        else if(pcb->so_options & SOF_REUSEPORT) {
+          LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: in TIME_WAIT PCB's SO_REUSEPORT set and same address.\n"));
+          reuse_port_all_set = (reuse_port_all_set && (cpcb->so_options & SOF_REUSEPORT));
+        }
+      }
+    }
+  }
+
+  /* If SOF_REUSEPORT isn't set in all PCB's bound to specified port and local address specified then 
+     {IP, port} can't be reused. */
+  if(!reuse_port_all_set) {
+    LWIP_DEBUGF(TCP_DEBUG, ("tcp_bind: not all sockets have SO_REUSEPORT set.\n"));
+    return ERR_USE;
+  }
+#endif /* SO_REUSE */
+
   if (!ip_addr_isany(ipaddr)) {
     pcb->local_ip = *ipaddr;
   }

src/core/tcp_in.c

@@ -102,6 +102,11 @@ tcp_input(struct pbuf *p, struct netif *inp)
   u8_t hdrlen;
   err_t err;
 
+#ifdef SO_REUSE
+  struct tcp_pcb *pcb_temp;
+  int reuse = 0;
+  int reuse_port = 0;
+#endif /* SO_REUSE */
 
   PERF_START;
 
@@ -174,7 +179,17 @@ tcp_input(struct pbuf *p, struct netif *inp)
   /* Demultiplex an incoming segment. First, we check if it is destined
      for an active connection. */
   prev = NULL;
+
+#ifdef SO_REUSE
+  pcb_temp = tcp_active_pcbs;
+  
+ again_1:
+  
+  /* Iterate through the TCP pcb list for a fully matching pcb */
+  for(pcb = pcb_temp; pcb != NULL; pcb = pcb->next) {
+#else  /* SO_REUSE */
   for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {
+#endif  /* SO_REUSE */
     LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
     LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
     LWIP_ASSERT("tcp_input: active pcb->state != LISTEN", pcb->state != LISTEN);
@@ -183,6 +198,32 @@ tcp_input(struct pbuf *p, struct netif *inp)
        ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)) &&
        ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest))) {
 
+#ifdef SO_REUSE
+      if(pcb->so_options & SOF_REUSEPORT) {
+        if(reuse) {
+          /* We processed one PCB already */
+          LWIP_DEBUGF(TCP_INPUT_DEBUG,("tcp_input: second or later PCB and SOF_REUSEPORT set.\n"));
+        } else {
+          /* First PCB with this address */
+          LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: first PCB and SOF_REUSEPORT set.\n"));
+          reuse = 1;
+        }
+        
+        reuse_port = 1; 
+        p->ref++;
+        
+        /* We want to search on next socket after receiving */
+        pcb_temp = pcb->next;
+        
+        LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: reference counter on PBUF set to %i\n", p->ref));
+      } else  {
+        if(reuse) {
+          /* We processed one PCB already */
+          LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: second or later PCB but SOF_REUSEPORT not set !\n"));
+        }
+      }
+#endif /* SO_REUSE */
+
       /* Move this PCB to the front of the list so that subsequent
    lookups will be faster (we exploit locality in TCP segment
    arrivals). */
@@ -327,8 +368,25 @@ tcp_input(struct pbuf *p, struct netif *inp)
     tcp_debug_print_state(pcb->state);
 #endif /* TCP_DEBUG */
 #endif /* TCP_INPUT_DEBUG */
+#ifdef SO_REUSE
+    /* First socket should receive now */
+    if(reuse_port) {
+      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: searching next PCB.\n"));
+      reuse_port = 0;
+      
+      /* We are searching connected sockets */
+      goto again_1;
+    }
+#endif /* SO_REUSE */
 
   } else {
+#ifdef SO_REUSE
+    if(reuse) {
+      LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: freeing PBUF with reference counter set to %i\n", p->ref));
+      pbuf_free(p);
+      goto end;
+    }
+#endif /* SO_REUSE */
     /* If no matching PCB was found, send a TCP RST (reset) to the
        sender. */
     LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_input: no PCB match found, resetting.\n"));
@@ -343,7 +401,9 @@ tcp_input(struct pbuf *p, struct netif *inp)
     }
     pbuf_free(p);
   }
-
+#ifdef SO_REUSE
+ end:
+#endif /* SO_REUSE */
   LWIP_ASSERT("tcp_input: tcp_pcbs_sane()", tcp_pcbs_sane());
   PERF_STOP("tcp_input");
 }

src/core/udp.c

@@ -163,6 +163,13 @@ udp_input(struct pbuf *p, struct netif *inp)
   struct ip_hdr *iphdr;
   u16_t src, dest;
 
+#ifdef SO_REUSE
+  struct udp_pcb *pcb_temp;
+  int reuse = 0;
+  int reuse_port_1 = 0;
+  int reuse_port_2 = 0;
+#endif /* SO_REUSE */
+  
   PERF_START;
 
 #ifdef UDP_STATS
@@ -200,8 +207,18 @@ udp_input(struct pbuf *p, struct netif *inp)
     ip4_addr3(&iphdr->dest), ip4_addr4(&iphdr->dest), ntohs(udphdr->dest),
     ip4_addr1(&iphdr->src), ip4_addr2(&iphdr->src),
     ip4_addr3(&iphdr->src), ip4_addr4(&iphdr->src), ntohs(udphdr->src)));
+
+#ifdef SO_REUSE
+  pcb_temp = udp_pcbs;
+  
+ again_1:
+  
+  /* Iterate through the UDP pcb list for a fully matching pcb */
+  for(pcb = pcb_temp; pcb != NULL; pcb = pcb->next) {
+#else  /* SO_REUSE */ 
   /* Iterate through the UDP pcb list for a fully matching pcb */
   for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
+#endif  /* SO_REUSE */ 
     /* print the PCB local and remote address */
     LWIP_DEBUGF(UDP_DEBUG, ("pcb (%u.%u.%u.%u, %u) --- (%u.%u.%u.%u, %u)\n",
       ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
@@ -221,6 +238,27 @@ udp_input(struct pbuf *p, struct netif *inp)
        (ip_addr_isany(&pcb->local_ip) ||
        /* PCB local IP address matches UDP destination IP address? */
         ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
+#ifdef SO_REUSE
+      if(pcb->so_options & SOF_REUSEPORT) {
+        if(reuse) {
+          /* We processed one PCB already */
+          LWIP_DEBUGF(UDP_DEBUG, ("udp_input: second or later PCB and SOF_REUSEPORT set.\n"));
+        } else {
+          /* First PCB with this address */
+          LWIP_DEBUGF(UDP_DEBUG, ("udp_input: first PCB and SOF_REUSEPORT set.\n"));
+          reuse = 1;
+        }
+        
+        reuse_port_1 = 1; 
+        p->ref++;
+        LWIP_DEBUGF(UDP_DEBUG, ("udp_input: reference counter on PBUF set to %i\n", p->ref));
+      } else {
+        if(reuse) {
+          /* We processed one PCB already */
+          LWIP_DEBUGF(UDP_DEBUG, ("udp_input: second or later PCB but SOF_REUSEPORT not set !\n"));
+        }
+      }
+#endif /* SO_REUSE */
       break;
     }
   }
@@ -228,7 +266,16 @@ udp_input(struct pbuf *p, struct netif *inp)
   if (pcb == NULL) {
     /* Iterate through the UDP PCB list for a pcb that matches
        the local address. */
+
+#ifdef SO_REUSE
+    pcb_temp = udp_pcbs;
+    
+  again_2:
+
+    for(pcb = pcb_temp; pcb != NULL; pcb = pcb->next) {
+#else  /* SO_REUSE */ 
     for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
+#endif  /* SO_REUSE */ 
       LWIP_DEBUGF(UDP_DEBUG, ("pcb (%u.%u.%u.%u, %u) --- (%u.%u.%u.%u, %u)\n",
         ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
         ip4_addr3(&pcb->local_ip), ip4_addr4(&pcb->local_ip), pcb->local_port,
@@ -242,7 +289,28 @@ udp_input(struct pbuf *p, struct netif *inp)
         (ip_addr_isany(&pcb->local_ip) ||
         /* ...matching interface address? */
         ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
-         break;
+#ifdef SO_REUSE
+        if(pcb->so_options & SOF_REUSEPORT) {
+          if(reuse) {
+            /* We processed one PCB already */
+            LWIP_DEBUGF(UDP_DEBUG, ("udp_input: second or later PCB and SOF_REUSEPORT set.\n"));
+          } else {
+            /* First PCB with this address */
+            LWIP_DEBUGF(UDP_DEBUG, ("udp_input: first PCB and SOF_REUSEPORT set.\n"));
+            reuse = 1;
+          }
+          
+          reuse_port_2 = 1; 
+          p->ref++;
+          LWIP_DEBUGF(UDP_DEBUG, ("udp_input: reference counter on PBUF set to %i\n", p->ref));
+        } else {
+          if(reuse) {
+            /* We processed one PCB already */
+            LWIP_DEBUGF(UDP_DEBUG, ("udp_input: second or later PCB but SOF_REUSEPORT not set !\n"));
+          }
+        }
+#endif /* SO_REUSE */
+        break;
       }
     }
   }
@@ -291,7 +359,33 @@ udp_input(struct pbuf *p, struct netif *inp)
     if (pcb != NULL) {
       snmp_inc_udpindatagrams();
       pcb->recv(pcb->recv_arg, pcb, p, &(iphdr->src), src);
+#ifdef SO_REUSE
+      /* First socket should receive now */
+      if(reuse_port_1 || reuse_port_2) {
+        /* We want to search on next socket after receiving */
+        pcb_temp = pcb->next;
+        
+        if(reuse_port_1) {
+          /* We are searching connected sockets */
+          reuse_port_1 = 0;
+          reuse_port_2 = 0;
+          goto again_1;
+        } else {
+          /* We are searching unconnected sockets */
+          reuse_port_1 = 0;
+          reuse_port_2 = 0;
+          goto again_2;
+        }
+      }
+#endif /* SO_REUSE */ 
     } else {
+#ifdef SO_REUSE
+      if(reuse) {
+        LWIP_DEBUGF(UDP_DEBUG, ("udp_input: freeing PBUF with reference counter set to %i\n", p->ref));
+        pbuf_free(p);
+        goto end;
+      }
+#endif /* SO_REUSE */
       LWIP_DEBUGF(UDP_DEBUG | DBG_TRACE, ("udp_input: not for us.\n"));
 
       /* No match was found, send ICMP destination port unreachable unless
@@ -457,9 +551,13 @@ udp_bind(struct udp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
 {
   struct udp_pcb *ipcb;
   u8_t rebind;
+#ifdef SO_REUSE
+  int reuse_port_all_set = 1;
+#endif /* SO_REUSE */
   LWIP_DEBUGF(UDP_DEBUG | DBG_TRACE | 3, ("udp_bind(ipaddr = "));
   ip_addr_debug_print(UDP_DEBUG, ipaddr);
   LWIP_DEBUGF(UDP_DEBUG | DBG_TRACE | 3, (", port = %u)\n", port));
+
   rebind = 0;
   /* Check for double bind and rebind of the same pcb */
   for (ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
@@ -470,6 +568,8 @@ udp_bind(struct udp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
       /* pcb already in list, just rebind */
       rebind = 1;
     }
+
+#ifndef SO_REUSE
 /* this code does not allow upper layer to share a UDP port for
    listening to broadcast or multicast traffic (See SO_REUSE_ADDR and
    SO_REUSE_PORT under *BSD). TODO: See where it fits instead, OR
@@ -486,8 +586,52 @@ udp_bind(struct udp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
       return ERR_USE;
     }
 #endif
+
+#else /* SO_REUSE */
+      /* Search through list of PCB's. 
+         
+      If there is a PCB bound to specified port and IP_ADDR_ANY another PCB can be bound to the interface IP
+      or to the loopback address on the same port if SOF_REUSEADDR is set. Any combination of PCB's bound to 
+      the same local port, but to one address out of {IP_ADDR_ANY, 127.0.0.1, interface IP} at a time is valid.
+      But no two PCB's bound to same local port and same local address is valid.
+      
+      If SOF_REUSEPORT is set several PCB's can be bound to same local port and same local address also. But then 
+      all PCB's must have the SOF_REUSEPORT option set.
+      
+      When the two options aren't set and specified port is already bound, ERR_USE is returned saying that 
+      address is already in use. */
+    else if (ipcb->local_port == port) {
+      if(ip_addr_cmp(&(ipcb->local_ip), ipaddr)) {
+        if(pcb->so_options & SOF_REUSEPORT) {
+          LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: in UDP PCB's SO_REUSEPORT set and same address.\n"));
+          reuse_port_all_set = (reuse_port_all_set && (ipcb->so_options & SOF_REUSEPORT));
+        }
+        else {
+          LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: in UDP PCB's SO_REUSEPORT not set and same address.\n"));
+          return ERR_USE;
+        }
+      }
+      else if((ip_addr_isany(ipaddr) && !ip_addr_isany(&(ipcb->local_ip))) ||
+              (!ip_addr_isany(ipaddr) && ip_addr_isany(&(ipcb->local_ip)))) {
+        if(!(pcb->so_options & SOF_REUSEADDR) && !(pcb->so_options & SOF_REUSEPORT)) {
+          LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: in UDP PCB's SO_REUSEPORT or SO_REUSEADDR not set and not the same address.\n"));
+          return ERR_USE;
+        }           
+      }
+    }
+#endif /* SO_REUSE */
+
   }
-  /* bind local address */
+
+#ifdef SO_REUSE
+  /* If SOF_REUSEPORT isn't set in all PCB's bound to specified port and local address specified then 
+     {IP, port} can't be reused. */
+  if(!reuse_port_all_set) {
+    LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: not all sockets have SO_REUSEPORT set.\n"));
+    return ERR_USE;
+  }
+#endif /* SO_REUSE */
+
   ip_addr_set(&pcb->local_ip, ipaddr);
   /* no port specified? */
   if (port == 0) {

src/include/lwip/opt.h

@@ -325,6 +325,14 @@ a lot of data that needs to be copied, this should be set high. */
 #define DEFAULT_THREAD_PRIO             1
 #endif
 
+
+/* ---------- Socket Options ---------- */
+/* Enable SO_REUSEADDR and SO_REUSEPORT options */ 
+#ifndef SO_REUSE
+# define SO_REUSE 1
+#endif                                                                        
+
+
 /* ---------- Statistics options ---------- */
 #ifndef LWIP_STATS
 #define LWIP_STATS                      1