fixes #23956; bindUnix loses the last character on OpenBSD (#23961)

uses calculation as shown in
https://man7.org/linux/man-pages/man7/unix.7.html
> offsetof(struct sockaddr_un, sun_path) + strlen(sun_path) + 1

2 files changed, 4 insertions, 4 deletions

diff --git a/lib/pure/asyncnet.nim b/lib/pure/asyncnet.nim
index d8dc7a798..ee07e599e 100644
--- a/lib/pure/asyncnet.nim
+++ b/lib/pure/asyncnet.nim
@@ -687,7 +687,7 @@ when defined(posix) and not useNimNetLite:
 
       var socketAddr = makeUnixAddr(path)
       let ret = socket.fd.connect(cast[ptr SockAddr](addr socketAddr),
-                        (sizeof(socketAddr.sun_family) + path.len).SockLen)
+                        (offsetOf(socketAddr, sun_path) + path.len + 1).SockLen)
       if ret == 0:
         # Request to connect completed immediately.
         retFuture.complete()
@@ -705,7 +705,7 @@ when defined(posix) and not useNimNetLite:
     when not defined(nimdoc):
       var socketAddr = makeUnixAddr(path)
       if socket.fd.bindAddr(cast[ptr SockAddr](addr socketAddr),
-          (sizeof(socketAddr.sun_family) + path.len).SockLen) != 0'i32:
+          (offsetOf(socketAddr, sun_path) + path.len + 1).SockLen) != 0'i32:
         raiseOSError(osLastError())
 
 elif defined(nimdoc):
diff --git a/lib/pure/net.nim b/lib/pure/net.nim
index 7f6a36557..3324ed9b1 100644
--- a/lib/pure/net.nim
+++ b/lib/pure/net.nim
@@ -1321,7 +1321,7 @@ when defined(nimdoc) or (defined(posix) and not useNimNetLite):
     when not defined(nimdoc):
       var socketAddr = makeUnixAddr(path)
       if socket.fd.connect(cast[ptr SockAddr](addr socketAddr),
-          (sizeof(socketAddr.sun_family) + path.len).SockLen) != 0'i32:
+          (offsetOf(socketAddr, sun_path) + path.len + 1).SockLen) != 0'i32:
         raiseOSError(osLastError())
 
   proc bindUnix*(socket: Socket, path: string) =
@@ -1330,7 +1330,7 @@ when defined(nimdoc) or (defined(posix) and not useNimNetLite):
     when not defined(nimdoc):
       var socketAddr = makeUnixAddr(path)
       if socket.fd.bindAddr(cast[ptr SockAddr](addr socketAddr),
-          (sizeof(socketAddr.sun_family) + path.len).SockLen) != 0'i32:
+          (offsetOf(socketAddr, sun_path) + path.len + 1).SockLen) != 0'i32:
         raiseOSError(osLastError())
 
 when defineSsl: