There have been previous attempts to revert protocol tryout algorithm from v4,v3,v2 to previous v2,v4,v3 : https://www.spinics.net/lists/linux-nfs/msg89228.html Apart from GETADDR/NAT issue originating that proposed change, its possible that some legacy custom applications still use v2 of protocol with libtirpc. The change proposed here, introduces an environment variable "RPCB_V2FIRST" so that, if defined, old behaviour is used. This is more flexible and allow us to selectively pick what application reverts to old behaviour instead of a system-wide change. Example : $ tcpdump -s0 -i ens3 port 111 -w /tmp/capture.pcap &> /dev/null & [1] 13016 $ rpcinfo -T tcp 172.23.1.225 100005 &> /dev/null $ RPCB_V2FIRST=1 rpcinfo -T tcp 172.23.1.225 100005 &> /dev/null $ pkill tcpdump $ tshark -tad -nr /tmp/capture.pcap -Y portmap -T fields -e _ws.col.Info V4 GETADDR Call V4 GETADDR Reply (Call In 4) V2 GETPORT Call MOUNT(100005) V:0 TCP V2 GETPORT Reply (Call In 14) Port:20048 Signed-off-by: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx> --- man/rpcbind.3t | 2 ++ src/rpcb_clnt.c | 27 ++++++++++++++++++++++++--- tirpc/rpc/pmap_prot.h | 2 ++ 3 files changed, 28 insertions(+), 3 deletions(-) diff --git a/man/rpcbind.3t b/man/rpcbind.3t index ec492cc..4cb271b 100644 --- a/man/rpcbind.3t +++ b/man/rpcbind.3t @@ -187,6 +187,8 @@ in .El .Sh AVAILABILITY These functions are part of libtirpc. +.Sh ENVIRONMENT +If RPCB_V2FIRST is defined, rpcbind protocol version tryout algorithm changes from v4,v2,v3 to v2,v4,v3. .Sh SEE ALSO .Xr rpc_clnt_calls 3 , .Xr rpc_svc_calls 3 , diff --git a/src/rpcb_clnt.c b/src/rpcb_clnt.c index 0c34cb7..db3799e 100644 --- a/src/rpcb_clnt.c +++ b/src/rpcb_clnt.c @@ -818,7 +818,8 @@ error: * The algorithm used: If the transports is TCP or UDP, it first tries * version 4 (srv4), then 3 and then fall back to version 2 (portmap). * With this algorithm, we get performance as well as a plan for - * obsoleting version 2. + * obsoleting version 2. This behaviour is reverted to old algorithm + * if RPCB_V2FIRST environment var is defined * * For all other transports, the algorithm remains as 4 and then 3. * @@ -839,6 +840,10 @@ __rpcb_findaddr_timed(program, version, nconf, host, clpp, tp) #ifdef NOTUSED static bool_t check_rpcbind = TRUE; #endif + +#ifdef PORTMAP + static bool_t portmap_first = FALSE; +#endif CLIENT *client = NULL; RPCB parms; enum clnt_stat clnt_st; @@ -895,8 +900,18 @@ __rpcb_findaddr_timed(program, version, nconf, host, clpp, tp) parms.r_addr = (char *) &nullstring[0]; } - /* First try from start_vers(4) and then version 3 (RPCBVERS) */ + /* First try from start_vers(4) and then version 3 (RPCBVERS), except + * if env. var RPCB_V2FIRST is defined */ + +#ifdef PORTMAP + if (getenv(V2FIRST)) { + portmap_first = TRUE; + LIBTIRPC_DEBUG(3, ("__rpcb_findaddr_timed: trying v2-port first\n")); + goto portmap; + } +#endif +rpcbind: CLNT_CONTROL(client, CLSET_RETRY_TIMEOUT, (char *) &rpcbrmttime); for (vers = start_vers; vers >= RPCBVERS; vers--) { /* Set the version */ @@ -944,10 +959,16 @@ __rpcb_findaddr_timed(program, version, nconf, host, clpp, tp) } #ifdef PORTMAP /* Try version 2 for TCP or UDP */ + if (portmap_first) + goto error; /* we tried all versions if reached here */ +portmap: if (strcmp(nconf->nc_protofmly, NC_INET) == 0) { address = __try_protocol_version_2(program, version, nconf, host, tp); if (address == NULL) - goto error; + if (portmap_first) + goto rpcbind; + else + goto error; } #endif /* PORTMAP */ diff --git a/tirpc/rpc/pmap_prot.h b/tirpc/rpc/pmap_prot.h index 75354ce..7718b8b 100644 --- a/tirpc/rpc/pmap_prot.h +++ b/tirpc/rpc/pmap_prot.h @@ -84,6 +84,8 @@ #define PMAPPROC_DUMP ((u_long)4) #define PMAPPROC_CALLIT ((u_long)5) +#define V2FIRST "RPCB_V2FIRST" + struct pmap { long unsigned pm_prog; long unsigned pm_vers; -- 2.31.1
