Add slirp_add_unix()

Add a new function to forward to a unix socket.

Signed-off-by: Renzo Davoli <renzo@cs.unibo.it>
[ Marc-André - a bunch of cleanups ]
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

7 files changed, 84 insertions, 3 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5218a36..00d0ce2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,8 +9,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+ - New API function `slirp_add_unix`: add a forward rule to a Unix socket.
  - New API function `slirp_remove_guestfwd`: remove a forward rule previously
-   added by `slirp_add_exec` or `slirp_add_guestfwd`
+   added by `slirp_add_exec`, `slirp_add_unix` or `slirp_add_guestfwd`
 
 ### Changed
 
diff --git a/src/libslirp.h b/src/libslirp.h
index 3c8baba..ad93edf 100644
--- a/src/libslirp.h
+++ b/src/libslirp.h
@@ -138,9 +138,11 @@ int slirp_remove_hostfwd(Slirp *slirp, int is_udp, struct in_addr host_addr,
                          int host_port);
 int slirp_add_exec(Slirp *slirp, const char *cmdline,
                    struct in_addr *guest_addr, int guest_port);
+int slirp_add_unix(Slirp *slirp, const char *unixsock,
+                   struct in_addr *guest_addr, int guest_port);
 int slirp_add_guestfwd(Slirp *slirp, SlirpWriteCb write_cb, void *opaque,
                        struct in_addr *guest_addr, int guest_port);
-/* remove entries added by slirp_add_exec or slirp_add_guestfwd */
+/* remove entries added by slirp_add_exec, slirp_add_unix or slirp_add_guestfwd */
 int slirp_remove_guestfwd(Slirp *slirp, struct in_addr guest_addr,
                           int guest_port);
 
diff --git a/src/libslirp.map b/src/libslirp.map
index 20f9c8d..72aab91 100644
--- a/src/libslirp.map
+++ b/src/libslirp.map
@@ -25,5 +25,6 @@ SLIRP_4.1 {
 } SLIRP_4.0;
 
 SLIRP_4.2 {
+    slirp_add_unix;
     slirp_remove_guestfwd;
 } SLIRP_4.1;
diff --git a/src/misc.c b/src/misc.c
index 924eb0d..fa65b6d 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -4,6 +4,9 @@
  */
 
 #include "slirp.h"
+#ifdef G_OS_UNIX
+#include <sys/un.h>
+#endif
 
 inline void insque(void *a, void *b)
 {
@@ -50,6 +53,16 @@ struct gfwd_list *add_exec(struct gfwd_list **ex_ptr, const char *cmdline,
     return f;
 }
 
+struct gfwd_list *add_unix(struct gfwd_list **ex_ptr, const char *unixsock,
+                           struct in_addr addr, int port)
+{
+    struct gfwd_list *f = add_guestfwd(ex_ptr, NULL, NULL, addr, port);
+
+    f->ex_unix = g_strdup(unixsock);
+
+    return f;
+}
+
 int remove_guestfwd(struct gfwd_list **ex_ptr, struct in_addr addr, int port)
 {
     for (; *ex_ptr != NULL; ex_ptr = &((*ex_ptr)->ex_next)) {
@@ -224,6 +237,45 @@ int fork_exec(struct socket *so, const char *ex)
     return 1;
 }
 
+int open_unix(struct socket *so, const char *unixpath)
+{
+#ifdef G_OS_UNIX
+    struct sockaddr_un sa;
+    int s;
+
+    DEBUG_CALL("open_unix");
+    DEBUG_ARG("so = %p", so);
+    DEBUG_ARG("unixpath = %s", unixpath);
+
+    memset(&sa, 0, sizeof(sa));
+    sa.sun_family = AF_UNIX;
+    if (g_strlcpy(sa.sun_path, unixpath, sizeof(sa.sun_path)) >= sizeof(sa.sun_path)) {
+        g_critical("Bad unix path: %s", unixpath);
+        return 0;
+    }
+
+    s = slirp_socket(PF_UNIX, SOCK_STREAM, 0);
+    if (s < 0) {
+        g_critical("open_unix(): %s", strerror(errno));
+        return 0;
+    }
+
+    if (connect(s, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+        g_critical("open_unix(): %s", strerror(errno));
+        closesocket(s);
+        return 0;
+    }
+
+    so->s = s;
+    slirp_set_nonblock(so->s);
+    so->slirp->cb->register_poll_fd(so->s, so->slirp->opaque);
+
+    return 1;
+#else
+    g_assert_not_reached();
+#endif
+}
+
 char *slirp_connection_info(Slirp *slirp)
 {
     GString *str = g_string_new(NULL);
diff --git a/src/misc.h b/src/misc.h
index 6ff7f54..841b0a7 100644
--- a/src/misc.h
+++ b/src/misc.h
@@ -14,6 +14,7 @@ struct gfwd_list {
     struct in_addr ex_addr; /* Server address */
     int ex_fport; /* Port to telnet to */
     char *ex_exec; /* Command line of what to exec */
+    char *ex_unix; /* unix socket */
     struct gfwd_list *ex_next;
 };
 
@@ -53,6 +54,7 @@ struct slirp_quehead {
 void slirp_insque(void *, void *);
 void slirp_remque(void *);
 int fork_exec(struct socket *so, const char *ex);
+int open_unix(struct socket *so, const char *unixsock);
 
 struct gfwd_list *add_guestfwd(struct gfwd_list **ex_ptr, SlirpWriteCb write_cb,
                                void *opaque, struct in_addr addr, int port);
@@ -60,6 +62,9 @@ struct gfwd_list *add_guestfwd(struct gfwd_list **ex_ptr, SlirpWriteCb write_cb,
 struct gfwd_list *add_exec(struct gfwd_list **ex_ptr, const char *cmdline,
                            struct in_addr addr, int port);
 
+struct gfwd_list *add_unix(struct gfwd_list **ex_ptr, const char *unixsock,
+                           struct in_addr addr, int port);
+
 int remove_guestfwd(struct gfwd_list **ex_ptr, struct in_addr addr, int port);
 
 #endif
diff --git a/src/slirp.c b/src/slirp.c
index 1abbce5..e82e7e8 100644
--- a/src/slirp.c
+++ b/src/slirp.c
@@ -368,6 +368,7 @@ void slirp_cleanup(Slirp *slirp)
     for (e = slirp->guestfwd_list; e; e = next) {
         next = e->ex_next;
         g_free(e->ex_exec);
+        g_free(e->ex_unix);
         g_free(e);
     }
 
@@ -1049,6 +1050,22 @@ int slirp_add_exec(Slirp *slirp, const char *cmdline,
     return 0;
 }
 
+int slirp_add_unix(Slirp *slirp, const char *unixsock,
+                   struct in_addr *guest_addr, int guest_port)
+{
+#ifdef G_OS_UNIX
+    if (!check_guestfwd(slirp, guest_addr, guest_port)) {
+        return -1;
+    }
+
+    add_unix(&slirp->guestfwd_list, unixsock, *guest_addr, htons(guest_port));
+    return 0;
+#else
+    g_warn_if_reached();
+    return -1;
+#endif
+}
+
 int slirp_add_guestfwd(Slirp *slirp, SlirpWriteCb write_cb, void *opaque,
                        struct in_addr *guest_addr, int guest_port)
 {
diff --git a/src/tcp_subr.c b/src/tcp_subr.c
index 3ccea96..382aa38 100644
--- a/src/tcp_subr.c
+++ b/src/tcp_subr.c
@@ -948,7 +948,10 @@ int tcp_ctl(struct socket *so)
                     return 1;
                 }
                 DEBUG_MISC(" executing %s", ex_ptr->ex_exec);
-                return fork_exec(so, ex_ptr->ex_exec);
+                if (ex_ptr->ex_unix)
+                    return open_unix(so, ex_ptr->ex_unix);
+                else
+                    return fork_exec(so, ex_ptr->ex_exec);
             }
         }
     }