From 3047681d4107d843be8d6943bc943a3d21307280 Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@anl.gov>
Date: Wed, 15 Jan 2025 15:29:50 -0600
Subject: [PATCH] Add a class method to cac for creating sockets

When EPICS_CAC_AVOID_LOW_FDS exists in the environment, all client
socket fds are renumbered to above FD_SETSIZE, allowing the client
library to play nice with applications like the CA gateway which use
select() for their own sockets.
---
 modules/ca/src/client/ca_client_context.cpp |  2 +-
 modules/ca/src/client/cac.cpp               | 15 +++++++++++++++
 modules/ca/src/client/cac.h                 |  2 ++
 modules/ca/src/client/tcpiiu.cpp            |  2 +-
 modules/ca/src/client/udpiiu.cpp            |  4 ++--
 5 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/modules/ca/src/client/ca_client_context.cpp b/modules/ca/src/client/ca_client_context.cpp
index 1e830fd080..e9155119c2 100644
--- a/modules/ca/src/client/ca_client_context.cpp
+++ b/modules/ca/src/client/ca_client_context.cpp
@@ -87,7 +87,7 @@ ca_client_context::ca_client_context ( bool enablePreemptiveCallback ) :
         }
     }
 
-    this->sock = epicsSocketCreate ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
+    this->sock = cac::SocketCreate ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
     if ( this->sock == INVALID_SOCKET ) {
         char sockErrBuf[64];
         epicsSocketConvertErrnoToString ( sockErrBuf, sizeof ( sockErrBuf ) );
diff --git a/modules/ca/src/client/cac.cpp b/modules/ca/src/client/cac.cpp
index fd641ad214..c47cc83495 100644
--- a/modules/ca/src/client/cac.cpp
+++ b/modules/ca/src/client/cac.cpp
@@ -385,6 +385,21 @@ unsigned cac::highestPriorityLevelBelow ( unsigned priority )
     return belowPriority;
 }
 
+SOCKET cac::SocketCreate (
+    int domain,
+    int type,
+    int protocol )
+{
+    SOCKET sock = epicsSocketCreate ( domain, type, protocol );
+#ifdef HAS_SOCK_RENUMBER
+    static bool renumber = getenv ( "EPICS_CAC_AVOID_LOW_FDS" );
+    if ( renumber ) {
+        sock = epicsSocketRenumber ( sock );
+    }
+#endif
+    return sock;
+}
+
 //
 // set the push pending flag on all virtual circuits
 //
diff --git a/modules/ca/src/client/cac.h b/modules/ca/src/client/cac.h
index 79dcbaa9be..795052b55d 100644
--- a/modules/ca/src/client/cac.h
+++ b/modules/ca/src/client/cac.h
@@ -204,6 +204,8 @@ class cac :
 
     const char * pLocalHostName ();
 
+    static SOCKET SocketCreate ( int domain, int type, int protocol );
+
 private:
     epicsSingleton < localHostName > :: reference _refLocalHostName;
     chronIntIdResTable < nciu > chanTable;
diff --git a/modules/ca/src/client/tcpiiu.cpp b/modules/ca/src/client/tcpiiu.cpp
index 30f6fad174..9d4472f485 100644
--- a/modules/ca/src/client/tcpiiu.cpp
+++ b/modules/ca/src/client/tcpiiu.cpp
@@ -717,7 +717,7 @@ tcpiiu::tcpiiu (
     if(!pCurData)
         throw std::bad_alloc();
 
-    this->sock = epicsSocketCreate ( AF_INET, SOCK_STREAM, IPPROTO_TCP );
+    this->sock = cac::SocketCreate ( AF_INET, SOCK_STREAM, IPPROTO_TCP );
     if ( this->sock == INVALID_SOCKET ) {
         freeListFree(this->cacRef.tcpSmallRecvBufFreeList, this->pCurData);
         char sockErrBuf[64];
diff --git a/modules/ca/src/client/udpiiu.cpp b/modules/ca/src/client/udpiiu.cpp
index d36e2c5b48..9d6e436973 100644
--- a/modules/ca/src/client/udpiiu.cpp
+++ b/modules/ca/src/client/udpiiu.cpp
@@ -168,7 +168,7 @@ udpiiu::udpiiu (
         envGetInetPortConfigParam ( &EPICS_CA_REPEATER_PORT,
                                     static_cast <unsigned short> (CA_REPEATER_PORT) );
 
-    this->sock = epicsSocketCreate ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
+    this->sock = cac::SocketCreate ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
     if ( this->sock == INVALID_SOCKET ) {
         char sockErrBuf[64];
         epicsSocketConvertErrnoToString (
@@ -594,7 +594,7 @@ void epicsStdCall caStartRepeaterIfNotInstalled ( unsigned repeaterPort )
         return;
     }
 
-    tmpSock = epicsSocketCreate ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
+    tmpSock = cac::SocketCreate ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
     if ( tmpSock != INVALID_SOCKET ) {
         ca_uint16_t port = static_cast < ca_uint16_t > ( repeaterPort );
         memset ( (char *) &bd, 0, sizeof ( bd ) );