Enable user-mode networking through SLIRP

.ci/test-netdev.sh

@@ -45,10 +45,13 @@ ASSERT expect <<DONE
         expect "riscv32 GNU/Linux" { send "ip l set eth0 up\n" } timeout { exit 3 }
         expect "# " { send "ip a add 192.168.10.2/24 dev eth0\n" }
         expect "# " { send "ping -c 3 192.168.10.1\n" }
-        expect "3 packets transmitted, 3 packets received, 0% packet loss" { } timeout { exit 4 }    
+        expect "3 packets transmitted, 3 packets received, 0% packet loss" { } timeout { exit 4 }
     } elseif { "$NETDEV" == "user" } {
-        # Test slirp configuration
-        expect "riscv32 GNU/Linux" { send "\x01"; send "x" } timeout { exit 3 }
+        expect "riscv32 GNU/Linux" { send "ip addr add 10.0.2.15/24 dev eth0\n" } timeout { exit 3 }
+        expect "# " { send "ip link set eth0 up\n"}
+        expect "# " { send "ip route add default via 10.0.2.2\n"}
+        expect "# " { send "ping -c 3 10.0.2.2\n" }
+        expect "3 packets transmitted, 3 packets received, 0% packet loss" { } timeout { exit 4 }
     }
 DONE
 }

.gitmodules

@@ -6,3 +6,7 @@
     path = mini-gdbstub
     url = https://github.com/RinHizakura/mini-gdbstub
     shallow = true
+[submodule "minislirp"]
+	path = minislirp
+	url = https://github.com/edubart/minislirp
+    shallow = true

Makefile

@@ -51,6 +51,7 @@ $(call set-feature, VIRTIONET)
 ifeq ($(call has, VIRTIONET), 1)
     OBJS_EXTRA += virtio-net.o
     OBJS_EXTRA += netdev.o
+	OBJS_EXTRA += slirp.o
 endif
 
 # virtio-snd
@@ -113,6 +114,17 @@ $(GDBSTUB_LIB): mini-gdbstub/Makefile
 	$(MAKE) -C $(dir $<)
 $(OBJS): $(GDBSTUB_LIB)
 
+ifeq ($(call has, VIRTIONET), 1)
+MINISLIRP_DIR := minislirp
+MINISLIRP_LIB := minislirp/src/libslirp.a
+LDFLAGS += $(MINISLIRP_LIB)
+$(MINISLIRP_DIR)/src/Makefile:
+	git submodule update --init $(MINISLIRP_DIR)
+$(MINISLIRP_LIB): $(MINISLIRP_DIR)/src/Makefile
+	$(MAKE) -C $(dir $<)
+$(OBJS): $(MINISLIRP_LIB)
+endif
+
 $(BIN): $(OBJS)
 	$(VECHO) "  LD\t$@\n"
 	$(Q)$(CC) -o $@ $^ $(LDFLAGS)
@@ -171,6 +183,7 @@ build-image:
 clean:
 	$(Q)$(RM) $(BIN) $(OBJS) $(deps)
 	$(Q)$(MAKE) -C mini-gdbstub clean
+	$(Q)$(MAKE) -C minislirp/src clean
 
 distclean: clean
 	$(Q)$(RM) riscv-harts.dtsi

device.h

@@ -1,6 +1,8 @@
 #pragma once
 
+#if SEMU_HAS(VIRTIONET)
 #include "netdev.h"
+#endif
 #include "riscv.h"
 #include "virtio.h"
 
@@ -120,6 +122,8 @@ void virtio_net_write(hart_t *core,
                       uint32_t value);
 void virtio_net_refresh_queue(virtio_net_state_t *vnet);
 
+void virtio_net_recv_from_peer(void *peer);
+
 bool virtio_net_init(virtio_net_state_t *vnet, const char *name);
 #endif /* SEMU_HAS(VIRTIONET) */
 

main.c

@@ -761,9 +761,38 @@ static int semu_run(emu_state_t *emu)
 
     /* Emulate */
     while (!emu->stopped) {
-        ret = semu_step(emu);
-        if (ret)
-            return ret;
+#if SEMU_HAS(VIRTIONET)
+        int i = 0;
+        if (emu->vnet.peer.type == NETDEV_IMPL_user && boot_complete) {
+            net_user_options_t *usr = (net_user_options_t *) emu->vnet.peer.op;
+
+            uint32_t timeout = -1;
+            usr->pfd_len = 1;
+            slirp_pollfds_fill_socket(usr->slirp, &timeout,
+                                      semu_slirp_add_poll_socket, usr);
+
+            /* Poll the internal pipe for incoming data. If data is
+             * available (POLL_IN), process it and forward it to the
+             * virtio-net device.
+             */
+            int pollout = poll(usr->pfd, usr->pfd_len, 1);
+            if (usr->pfd[0].revents & POLLIN) {
+                virtio_net_recv_from_peer(usr->peer);
+            }
+            slirp_pollfds_poll(usr->slirp, (pollout <= 0),
+                               semu_slirp_get_revents, usr);
+            for (i = 0; i < SLIRP_POLL_INTERVAL; i++) {
+                ret = semu_step(emu);
+                if (ret)
+                    return ret;
+            }
+        } else
+#endif
+        {
+            ret = semu_step(emu);
+            if (ret)
+                return ret;
+        }
     }
 
     /* unreachable */

netdev.c

@@ -8,6 +8,7 @@
 #include <string.h>
 #include <sys/ioctl.h>
 
+#include "device.h"
 #include "netdev.h"
 
 static int net_init_tap();
@@ -55,9 +56,19 @@ static int net_init_tap(netdev_t *netdev)
     return 0;
 }
 
-static int net_init_user(netdev_t *netdev UNUSED)
+static int net_init_user(netdev_t *netdev)
 {
-    /* TODO: create slirp dev */
+    net_user_options_t *usr = (net_user_options_t *) netdev->op;
+    memset(usr, 0, sizeof(*usr));
+    usr->peer = container_of(netdev, virtio_net_state_t, peer);
+    if (pipe(usr->channel) < 0)
+        return false;
+    assert(fcntl(usr->channel[SLIRP_READ_SIDE], F_SETFL,
+                 fcntl(usr->channel[SLIRP_READ_SIDE], F_GETFL, 0) |
+                     O_NONBLOCK) >= 0);
+
+    net_slirp_init(usr);
+
     return 0;
 }
 

netdev.h

@@ -1,6 +1,11 @@
 #pragma once
 
-#include <stdbool.h>
+#include <poll.h>
+#include <unistd.h>
+
+#include "minislirp/src/libslirp.h"
+#include "utils.h"
+
 
 /* clang-format off */
 #define SUPPORTED_DEVICES   \
@@ -18,10 +23,34 @@ typedef struct {
     int tap_fd;
 } net_tap_options_t;
 
+/* SLIRP */
+#define SLIRP_POLL_INTERVAL 100000
+#define SLIRP_READ_SIDE 0
+#define SLIRP_WRITE_SIDE 1
 typedef struct {
-    /* TODO: Implement user option */
+    semu_timer_t timer;
+    Slirp *slirp;
+    SlirpTimerId id;
+    void *cb_opaque;
+    void (*cb)(void *opaque);
+    int64_t expire_timer_msec;
+} slirp_timer;
+
+typedef struct {
+    Slirp *slirp;
+    int channel[2];
+    int pfd_len;
+    int pfd_size;
+    struct pollfd *pfd;
+    slirp_timer *timer;
+    void *peer;
 } net_user_options_t;
 
+Slirp *slirp_create(net_user_options_t *usr, SlirpConfig *cfg);
+int net_slirp_init(net_user_options_t *usr);
+int semu_slirp_add_poll_socket(slirp_os_socket fd, int events, void *opaque);
+int semu_slirp_get_revents(int idx, void *opaque);
+
 typedef struct {
     char *name;
     netdev_impl_t type;