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1. BUG #19039: UNREACHABLE_CODE: Remove unreachable code in network_send - replace with assertion

   PG Bug reporting form <noreply@postgresql.org> — 2025-09-02T07:06:18Z

   The following bug has been logged on the website:
   
   Bug reference:      19039
   Logged by:          Eugeny Goryachev
   Email address:      gorcom2012@gmail.com
   PostgreSQL version: 17.4
   Operating system:   Ubuntu
   Description:        
   
   I found unreachable code in the network_send function in
   src/backend/utils/adt/network.c.
   The current check:
   
   if (nb < 0)
       nb = 0;
   
   is unreachable because the ip_addrsize(addr) function can only return one of
   two possible values:
   
       - 4 for IPv4 addresses (AF_INET);
       - 16 for IPv6 addresses (AF_INET6).
   
   These are the only address families supported by PostgreSQL's inet datatype,
   and the network input functions validate all addresses before they reach
   this code path.
   
   Replace the unreachable defensive code with an assertion that documents this
   invariant:
   
   diff --git a/src/backend/utils/adt/network.c
   b/src/backend/utils/adt/network.c
   index 640fc37dc83..3f83fbe85df 100644
   --- a/src/backend/utils/adt/network.c
   +++ b/src/backend/utils/adt/network.c
   @@ -279,8 +279,7 @@ network_send(inet *addr, bool is_cidr)
           pq_sendbyte(&buf, ip_bits(addr));
           pq_sendbyte(&buf, is_cidr);
           nb = ip_addrsize(addr);
   -       if (nb < 0)
   -               nb = 0;
   +       Assert(nb >= 0);
           pq_sendbyte(&buf, nb);
           addrptr = (char *) ip_addr(addr);
           for (i = 0; i < nb; i++)
   
   

2. Re: BUG #19039: UNREACHABLE_CODE: Remove unreachable code in network_send - replace with assertion

   Daniel Gustafsson <daniel@yesql.se> — 2025-09-02T11:54:06Z

   > On 2 Sep 2025, at 09:06, PG Bug reporting form <noreply@postgresql.org> wrote:
   
   > if (nb < 0)
   >    nb = 0;
   > 
   > is unreachable because the ip_addrsize(addr) function can only return one of
   > two possible values:
   
   Thanks for the report, this has already been fixed in f27eb0325b7b.
   
   --
   Daniel Gustafsson