From 2c7659ec930277981b6333b5b3aff7840d11933c Mon Sep 17 00:00:00 2001
From: Dirk Engling <erdgeist@erdgeist.org>
Date: Sun, 25 Oct 2026 18:51:51 +0100
Subject: Decouple config parsing from binding and worker spawning

* Options are parsed now into a listener description list before
  binding them at once and starting the workers later
* UDP workers can now be configured per connection
* socket reuse is now done more sensibly, mcast sockets always
  reused
* Hold-off logic after spawning udp workers removed
---
 ot_socket.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

(limited to 'ot_socket.c')

diff --git a/ot_socket.c b/ot_socket.c
index e26ad52..84020ca 100644
--- a/ot_socket.c
+++ b/ot_socket.c
@@ -15,8 +15,6 @@
 #include "ot_ip.h"
 #include "ot_socket.h"
 
-int g_socket_reuseport;
-
 static void sockaddr_from_ip(struct sockaddr_in6 *sa, const ot_ip6 ip, uint16_t port) {
   memset(sa, 0, sizeof(*sa));
   sa->sin6_family = AF_INET6;
@@ -75,37 +73,43 @@ static int socket_v6(int type) {
   return s;
 }
 
-static int socket_bind_v6(int s, const ot_ip6 ip, uint16_t port) {
-  struct sockaddr_in6 sa;
-  int                 one = 1;
+/* The only place in the tree that needs to know what a kernel calls this */
+static void socket_set_sharing(int s, socket_sharing sharing) {
+  int one = 1;
 
   setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 #ifdef SO_REUSEPORT
-  if (g_socket_reuseport)
+  if (sharing == SOCKET_SHARED)
     setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 #endif
+}
+
+static int socket_bind_v6(int s, const ot_ip6 ip, uint16_t port, socket_sharing sharing) {
+  struct sockaddr_in6 sa;
+
+  socket_set_sharing(s, sharing);
 
   sockaddr_from_ip(&sa, ip, port);
   return bind(s, (struct sockaddr *)&sa, sizeof(sa));
 }
 
-int socket_tcp_listen(const ot_ip6 ip, uint16_t port) {
+int socket_tcp_listen(const ot_ip6 ip, uint16_t port, socket_sharing sharing) {
   int s = socket_v6(SOCK_STREAM);
 
   if (s == -1)
     return -1;
-  if (socket_bind_v6(s, ip, port) == -1 || listen(s, SOMAXCONN) == -1)
+  if (socket_bind_v6(s, ip, port, sharing) == -1 || listen(s, SOMAXCONN) == -1)
     return close_and_fail(s);
 
   return s;
 }
 
-int socket_udp_bind(const ot_ip6 ip, uint16_t port) {
+int socket_udp_bind(const ot_ip6 ip, uint16_t port, socket_sharing sharing) {
   int s = socket_v6(SOCK_DGRAM);
 
   if (s == -1)
     return -1;
-  if (socket_bind_v6(s, ip, port) == -1)
+  if (socket_bind_v6(s, ip, port, sharing) == -1)
     return close_and_fail(s);
 
   return s;
@@ -117,7 +121,7 @@ int socket_tcp_connect(const ot_ip6 srcip, uint16_t srcport, const ot_ip6 dstip,
 
   if (s == -1)
     return -1;
-  if (socket_bind_v6(s, srcip, srcport) == -1)
+  if (socket_bind_v6(s, srcip, srcport, SOCKET_EXCLUSIVE) == -1)
     return close_and_fail(s);
 
   sockaddr_from_ip(&sa, dstip, dstport);
@@ -187,18 +191,16 @@ static void sockaddr4_from_ip(struct sockaddr_in *sa, const ot_ip6 ip, uint16_t
   memcpy(&sa->sin_addr, ip + sizeof(ip_v4mapped_prefix), 4);
 }
 
+/* A multicast group is meant to have several listeners, so these are always
+   shared */
 static int socket_v4_bind(const ot_ip6 ip, uint16_t port) {
   struct sockaddr_in sa;
-  int                s, one = 1;
+  int                s;
 
   if ((s = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
     return -1;
 
-  setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
-#ifdef SO_REUSEPORT
-  if (g_socket_reuseport)
-    setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
-#endif
+  socket_set_sharing(s, SOCKET_SHARED);
 
   sockaddr4_from_ip(&sa, ip, port);
   if (bind(s, (struct sockaddr *)&sa, sizeof(sa)) == -1)
-- 
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