From 5ae9cc6536a41337cc8272f3ea8a9bd6123a2742 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Thu, 10 Jul 2025 20:10:17 -0700
Subject: [PATCH] gethostbyname -> getaddrinfo

Prefer reentrant DNS API
---
 modules/libcom/src/osi/os/posix/osdSock.c | 57 ++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

diff --git a/modules/libcom/src/osi/os/posix/osdSock.c b/modules/libcom/src/osi/os/posix/osdSock.c
index 0d873e628..41f6580f0 100644
--- a/modules/libcom/src/osi/os/posix/osdSock.c
+++ b/modules/libcom/src/osi/os/posix/osdSock.c
@@ -41,6 +41,13 @@
 #  define SOCK_CLOEXEC (0)
 #endif
 
+#if defined(AI_PASSIVE) && !defined(__rtems__)
+#  define USE_INFO
+#else
+#  define USE_BY
+#endif
+
+#ifdef USE_BY
 /*
  * Protect some routines which are not thread-safe
  */
@@ -60,7 +67,7 @@ static void unlockInfo (void)
 {
     epicsMutexUnlock (infoMutex);
 }
-
+#endif
 
 static size_t nAttached;
 
@@ -164,6 +171,7 @@ LIBCOM_API void epicsStdCall epicsSocketDestroy ( SOCKET s )
     }
 }
 
+#ifdef USE_BY
 /*
  * ipAddrToHostName
  * On many systems, gethostbyaddr must be protected by a
@@ -214,6 +222,53 @@ LIBCOM_API int epicsStdCall hostToIPAddr
     unlockInfo ();
     return ret;
 }
+#endif
 
+#ifdef USE_INFO
 
+unsigned epicsStdCall ipAddrToHostName(const struct in_addr *pAddr, char *pBuf, unsigned bufSize)
+{
+    osiSockAddr query;
 
+    if(!bufSize)
+        return 0; // non-sense
+
+    memset(&query, 0, sizeof(query));
+    query.ia.sin_family = AF_INET;
+    query.ia.sin_addr = *pAddr;
+
+    int ret = getnameinfo(&query.sa, sizeof(query), pBuf, bufSize, NULL, 0, NI_NAMEREQD);
+    if(ret==0) {
+        ret = strlen (pBuf);
+
+    } else { // lookup fails
+        ret = 0; // indicate failure to caller
+    }
+    return ret;
+}
+
+int epicsStdCall hostToIPAddr(const char *pHostName, struct in_addr *pIPA)
+{
+    struct addrinfo hint, *result = NULL;
+
+    memset(&hint, 0, sizeof(hint));
+    hint.ai_family = AF_INET;
+
+    int ret = getaddrinfo(pHostName, NULL, &hint, &result);
+    if(ret==0) {
+        const struct addrinfo *ai;
+        ret = -1;
+        for(ai = result; ai; ai = ai->ai_next) {
+            assert(ai->ai_family==AF_INET); // ensured by hint
+            const struct sockaddr_in *answer = (const struct sockaddr_in*)ai->ai_addr;
+            *pIPA = answer->sin_addr;
+            ret = 0;
+            break;
+        }
+    }
+    if(result) {
+        freeaddrinfo(result);
+    }
+    return ret;
+}
+#endif