[PATCH iproute2] Fix segv on "-r" option if unknown rpc service

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

In init_service_resolver(), if getrpcbynumber() returned NULL, c->name
is pointing the undefined memory. So "-r" can segv for example.

So this patch uses "rpc.<r_prog>" format like the following if rpc
name is unresolved, instead of segv or raw port number.

	tcp   LISTEN  0  64  0.0.0.0:rpc.100227  0.0.0.0:*

[Or we would be able to set c->name = NULL to use raw port number]

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---
 misc/ss.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/misc/ss.c b/misc/ss.c
index ff985cd..866e278 100644
--- a/misc/ss.c	2022-08-25 16:22:06.454913793 +0900
+++ b/misc/ss.c	2022-09-18 02:48:24.212779850 +0900
@@ -1596,6 +1596,15 @@ static void init_service_resolver(void)
 		if (rpc) {
 			strncat(prog, rpc->r_name, 128 - strlen(prog));
 			c->name = strdup(prog);
+		} else {
+			const char fmt[] = "%s%u";
+			char *buf = NULL;
+			int len = snprintf(buf, 0, fmt, prog,
+					   rhead->rpcb_map.r_prog);
+			len++;
+			buf = malloc(len);
+			snprintf(buf, len, fmt, prog, rhead->rpcb_map.r_prog);
+			c->name = buf;
 		}
 
 		c->next = rlist;
_

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>