From 75d638ac9cc613f39ec4513d3dc2e43a6f909da1 Mon Sep 17 00:00:00 2001 From: Thijs Schreijer Date: Sun, 30 Aug 2026 12:58:43 +0200 Subject: fix(udp): receive(0) tests and bad call to getnameinfo --- src/udp.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'src/udp.c') diff --git a/src/udp.c b/src/udp.c index 712ad50..a782699 100644 --- a/src/udp.c +++ b/src/udp.c @@ -277,6 +277,7 @@ static int meth_receivefrom(lua_State *L) { lua_pushliteral(L, "out of memory"); return 2; } + memset(&addr, 0, sizeof(addr)); err = socket_recvfrom(&udp->sock, dgram, wanted, &got, (SA *) &addr, &addr_len, tm); /* Unlike TCP, recv() of zero is not closed, but a zero-length packet. */ @@ -286,6 +287,17 @@ static int meth_receivefrom(lua_State *L) { if (wanted > sizeof(buf)) free(dgram); return 2; } + /* a zero-length request may be satisfied by some kernels (notably + * Darwin/BSD) without ever touching the sender's address -- only + * resolve it when the OS actually reported one, instead of feeding + * getnameinfo() a garbage/zeroed sockaddr. */ + if (addr.ss_family != AF_INET && addr.ss_family != AF_INET6) { + lua_pushlstring(L, dgram, got); + lua_pushnil(L); + lua_pushnil(L); + if (wanted > sizeof(buf)) free(dgram); + return 3; + } err = getnameinfo((struct sockaddr *)&addr, addr_len, addrstr, INET6_ADDRSTRLEN, portstr, 6, NI_NUMERICHOST | NI_NUMERICSERV); if (err) { -- cgit v1.2.3-55-g6feb