net-mgmt/net-snmp: Fix the IPV6 MIB implementation

The implementations of var_tcp6() and var_udp6() on FreeBSD don't work
and fail to compile.  var_tcp6() also makes uses of kmem access, which
I'm trying to disable in snmpd.  Provide a patch to fix these problems.
This has been committed to the 5.9 branch upstream.

Readd mibII/ipv6 since it now compiles and works in my manual testing.
Also, simply remove the IPV6 option.  It has no effect, as --enable-ipv6
is the default.

Approved by:	zi
Sponsored by:	Klara, Inc.
Sponsored by:	Stormshield
Differential Revision:	https://reviews.freebsd.org/D45030

2 files changed, 129 insertions, 14 deletions

diff --git a/net-mgmt/net-snmp/Makefile b/net-mgmt/net-snmp/Makefile
index 9909de70e05f..71ad983bf18d 100644
--- a/net-mgmt/net-snmp/Makefile
+++ b/net-mgmt/net-snmp/Makefile
@@ -17,7 +17,7 @@ LICENSE_FILE=	${WRKSRC}/COPYING
 NOT_FOR_ARCHS=		mips mips64
 NOT_FOR_ARCHS_REASON=	SSP is currently broken on MIPS
 
-OPTIONS_DEFINE=	IPV6 MFD_REWRITES PERL PERL_EMBEDDED PYTHON DUMMY TKMIB \
+OPTIONS_DEFINE=	MFD_REWRITES PERL PERL_EMBEDDED PYTHON DUMMY TKMIB \
 		MYSQL AX_SOCKONLY UNPRIVILEGED SMUX DOCS JAIL AX_DISABLE_TRAP \
 		TLS NEWSYSLOG NOLIBPKG SCTP
 OPTIONS_DEFAULT=PERL PERL_EMBEDDED DUMMY SMUX NEWSYSLOG
@@ -54,7 +54,7 @@ CONFIGURE_ARGS+=--enable-shared --enable-internal-md5 \
 		--with-sys-location="${NET_SNMP_SYS_LOCATION}" \
 		--with-logfile="${NET_SNMP_LOGFILE}" \
 		--with-persistent-directory="${NET_SNMP_PERSISTENTDIR}" \
-		--with-gnu-ld --without-libwrap \
+		--with-gnu-ld --without-libwrap --enable-ipv6 \
 		--with-ldflags="-lm -lkvm -ldevstat -L${PKG_PREFIX}/lib -L${LOCALBASE}/lib ${LCRYPTO}"
 SUB_FILES=	pkg-message
 
@@ -129,14 +129,6 @@ CONFIGURE_ARGS+=--disable-snmptrapd-subagent
 CONFIGURE_ARGS+=--enable-agentx-dom-sock-only
 .endif
 
-.if ${PORT_OPTIONS:MIPV6}
-CONFIGURE_ARGS+=--enable-ipv6
-# --with-transport="UDPIPv6 TCPIPv6" --with-modules=mibII/ipv6"
-PLIST_SUB+=	WITH_IPV6=""
-.else
-PLIST_SUB+=	WITH_IPV6="@comment "
-.endif
-
 .if ${PORT_OPTIONS:MUNPRIVILEGED}
 CONFIGURE_ARGS+=--without-root-access
 .endif
@@ -153,10 +145,6 @@ NET_SNMP_LOGFILE?=	/var/log/snmpd.log
 NET_SNMP_PERSISTENTDIR?=/var/net-snmp
 NET_SNMP_WITH_MIB_MODULE_LIST+=	host disman/event-mib mibII/mta_sendmail mibII/tcpTable ucd-snmp/diskio
 
-.if ${OPSYS} == FreeBSD
-NET_SNMP_WITHOUT_MIB_MODULE_LIST+=	mibII/ipv6
-.endif
-
 .if ${PORT_OPTIONS:MSCTP}
 NET_SNMP_WITH_MIB_MODULE_LIST+=	sctp-mib
 .endif
diff --git a/net-mgmt/net-snmp/files/patch-agent_mibgroup_mibII_ipv6.c b/net-mgmt/net-snmp/files/patch-agent_mibgroup_mibII_ipv6.c
new file mode 100644
index 000000000000..ad4ea51fe56a
--- /dev/null
+++ b/net-mgmt/net-snmp/files/patch-agent_mibgroup_mibII_ipv6.c
@@ -0,0 +1,127 @@
+--- agent/mibgroup/mibII/ipv6.c.orig	2023-08-15 20:32:01 UTC
++++ agent/mibgroup/mibII/ipv6.c
+@@ -5,9 +5,6 @@
+ 
+ #include <net-snmp/net-snmp-config.h>
+ #include <net-snmp/net-snmp-features.h>
+-/* For FreeBSD */
+-#define _WANT_INPCB 1
+-#define _WANT_TCPCB 1
+ #include <sys/types.h>
+ #include <sys/socket.h>
+ #ifdef HAVE_SYS_IOCTL_H
+@@ -1513,8 +1510,10 @@ var_udp6(register struct variable * vp,
+     int             result;
+     int             i, j;
+     caddr_t         p;
+-#if defined(openbsd4) || defined(freebsd3)
++#if defined(openbsd4)
+     static struct inpcb in6pcb, savpcb;
++#elif defined(freebsd3)
++    static struct xinpcb in6pcb, savpcb;
+ #else
+     static struct in6pcb in6pcb, savpcb;
+ #endif
+@@ -1614,8 +1613,7 @@ var_udp6(register struct variable * vp,
+         DEBUGMSGTL(("mibII/ipv6", "looping: p=%p\n", p));
+ 
+ #if defined(freebsd3)
+-	/* To do: fill in in6pcb properly. */
+-	memset(&in6pcb, 0, sizeof(in6pcb));
++	in6pcb = *(struct xinpcb *) xig;
+ #elif defined(darwin)
+ 	in6pcb = ((struct xinpcb *) xig)->xi_inp;
+ #else
+@@ -2108,12 +2106,18 @@ var_tcp6(register struct variable * vp,
+     int             result;
+     int             i, j;
+     caddr_t         p;
+-#if defined(openbsd4) || defined(freebsd3)
++#if defined(openbsd4)
+     static struct inpcb in6pcb, savpcb;
++#elif defined(freebsd3)
++    static struct xinpcb in6pcb;
++    static int      savstate;
+ #else
+     static struct in6pcb in6pcb, savpcb;
+ #endif
++#if !defined(freebsd3)
+     struct tcpcb    tcpcb;
++#endif
++    int             state;
+     int             found, savnameLen;
+ #if defined(__NetBSD__) && __NetBSD_Version__ >= 106250000 || defined(openbsd4)	/*1.6Y*/
+     struct inpcbtable tcbtable;
+@@ -2208,8 +2212,7 @@ var_tcp6(register struct variable * vp,
+         DEBUGMSGTL(("mibII/ipv6", "looping: p=%p\n", p));
+ 
+ #if defined(freebsd3)
+-	/* To do: fill in in6pcb properly. */
+-	memset(&in6pcb, 0, sizeof(in6pcb));
++	in6pcb = ((struct xtcpcb *) xig)->xt_inp;
+ #elif defined(dragonfly)
+ 	in6pcb = xtp->xt_inp;
+ #elif defined(darwin)
+@@ -2294,7 +2297,11 @@ var_tcp6(register struct variable * vp,
+ #endif
+         result = snmp_oid_compare(name, *length, newname, j);
+         if (exact && (result == 0)) {
++#if defined(freebsd3)
++                savstate = ((struct xtcpcb *) xig)->t_state;
++#else
+                 memcpy(&savpcb, &in6pcb, sizeof(savpcb));
++#endif
+                 savnameLen = j;
+                 memcpy(savname, newname, j * sizeof(oid));
+                 found++;
+@@ -2305,7 +2312,11 @@ var_tcp6(register struct variable * vp,
+              */
+             if ((savnameLen == 0) ||
+               (snmp_oid_compare(savname, savnameLen, newname, j) > 0)) {
++#if defined(freebsd3)
++                savstate = ((struct xtcpcb *) xig)->t_state;
++#else
+                 memcpy(&savpcb, &in6pcb, sizeof(savpcb));
++#endif
+                 savnameLen = j;
+                 memcpy(savname, newname, j * sizeof(oid));
+                 found++;
+@@ -2344,19 +2355,27 @@ var_tcp6(register struct variable * vp,
+         return NULL;
+     *length = savnameLen;
+     memcpy((char *) name, (char *) savname, *length * sizeof(oid));
++#if defined(freebsd3)
++    state = savstate;
++#elif defined(__NetBSD__) && __NetBSD_Version__ >= 999010400
+     memcpy(&in6pcb, &savpcb, sizeof(savpcb));
+-#if defined(__NetBSD__) && __NetBSD_Version__ >= 999010400
+     if (!NETSNMP_KLOOKUP(in6pcb.in6p_pcb.inp_ppcb, (char *) &tcpcb, sizeof(tcpcb))) {
+         DEBUGMSGTL(("mibII/ipv6", "klookup fail for tcb6.tcpcb at %p\n",
+                     in6pcb.in6p_pcb.inp_ppcb));
++	found = 0;
++	return NULL;
++    }
++    state = (int)tcpcb.t_state;
+ #else
++    memcpy(&in6pcb, &savpcb, sizeof(savpcb));
+     if (!NETSNMP_KLOOKUP(in6pcb.inp_ppcb, (char *) &tcpcb, sizeof(tcpcb))) {
+ 	DEBUGMSGTL(("mibII/ipv6", "klookup fail for tcb6.tcpcb at %p\n",
+ 		    in6pcb.inp_ppcb));
+-#endif
+ 	found = 0;
+ 	return NULL;
+     }
++    state = (int)tcpcb.t_state;
++#endif
+     *write_method = 0;
+     *var_len = sizeof(long);    /* default to 'long' results */
+ 
+@@ -2368,7 +2387,7 @@ var_tcp6(register struct variable * vp,
+     DEBUGMSGTL(("mibII/ipv6", "magic=%d\n", vp->magic));
+     switch (vp->magic) {
+     case IPV6TCPCONNSTATE:
+-        long_return = mapTcpState((int)tcpcb.t_state);
++        long_return = mapTcpState(state);
+         return (u_char *) & long_return;
+     default:
+         break;