Support Unix sockets in hostfwd

QEMU has an issue open
(https://gitlab.com/qemu-project/qemu/-/issues/347) to forward a Unix
domain socket to guest TCP port. Both of these protocols support stream
modes of operation (and user-mode networking can only access the stream
anyway), so this patch enables Unix-to-TCP hostfwds.

Like with localhost hostfwds, the sotranslate_accept function will
translate a Unix domain socket connection to a TCP connection
originating from vhost_addr and a randomized ephemeral port.

Signed-off-by: Nicholas Ngai <nicholas@ngai.me>

1 files changed, 7 insertions, 12 deletions

diff --git a/src/socket.c b/src/socket.c
index 2c1b789..09ce6bf 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -769,18 +769,6 @@ struct socket *tcpx_listen(Slirp *slirp,
     socklen_t addrlen;
 
     DEBUG_CALL("tcpx_listen");
-    /* AF_INET6 addresses are bigger than AF_INET, so this is big enough. */
-    char addrstr[INET6_ADDRSTRLEN];
-    char portstr[6];
-    int ret;
-    ret = getnameinfo(haddr, haddrlen, addrstr, sizeof(addrstr), portstr, sizeof(portstr), NI_NUMERICHOST|NI_NUMERICSERV);
-    g_assert(ret == 0);
-    DEBUG_ARG("haddr = %s", addrstr);
-    DEBUG_ARG("hport = %s", portstr);
-    ret = getnameinfo(laddr, laddrlen, addrstr, sizeof(addrstr), portstr, sizeof(portstr), NI_NUMERICHOST|NI_NUMERICSERV);
-    g_assert(ret == 0);
-    DEBUG_ARG("laddr = %s", addrstr);
-    DEBUG_ARG("lport = %s", portstr);
     DEBUG_ARG("flags = %x", flags);
 
     /*
@@ -1041,6 +1029,13 @@ void sotranslate_accept(struct socket *so)
         }
         break;
 
+    case AF_UNIX:
+        /* Translate Unix socket to random ephemeral source port. */
+        so->so_ffamily = AF_INET;
+        so->so_faddr = slirp->vhost_addr;
+        so->so_fport = g_rand_int_range(slirp->grand, 49152, 65536);
+        break;
+
     default:
         break;
     }