Refactor network device handling for flexible client support

chiangkd · chiangkd · commit 15f6f8ac2e22 · 2024-11-23T04:00:11.000+08:00
Separate network client handling to support various network backends,
such as Slirp, instead of hard-coding the TAP device. The '-netdev'
flag can now be used to specify the network client type, defaulting
to TAP if unspecified. Additionally, packet transfer functions are
now tailored to each client device, enabling more modular and
extensible network client development.
diff --git a/Makefile b/Makefile
@@ -31,6 +31,7 @@ ifeq ($(call has, VIRTIOBLK), 1)
     endif
 endif
 
+NETDEV ?= tap
 # virtio-net
 ENABLE_VIRTIONET ?= 1
 ifneq ($(UNAME_S),Linux)
@@ -39,6 +40,7 @@ endif
 $(call set-feature, VIRTIONET)
 ifeq ($(call has, VIRTIONET), 1)
     OBJS_EXTRA += virtio-net.o
+    OBJS_EXTRA += netdev.o
 endif
 
 BIN = semu
@@ -96,7 +98,7 @@ ext4.img:
 
 check: $(BIN) minimal.dtb $(KERNEL_DATA) $(INITRD_DATA) $(DISKIMG_FILE)
 	@$(call notice, Ready to launch Linux kernel. Please be patient.)
-	$(Q)./$(BIN) -k $(KERNEL_DATA) -c $(SMP) -b minimal.dtb -i $(INITRD_DATA) $(OPTS)
+	$(Q)./$(BIN) -k $(KERNEL_DATA) -c $(SMP) -b minimal.dtb -i $(INITRD_DATA) -n $(NETDEV) $(OPTS)
 
 build-image:
 	scripts/build-image.sh
diff --git a/device.h b/device.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "netdev.h"
 #include "riscv.h"
 #include "virtio.h"
 
@@ -101,7 +102,7 @@ typedef struct {
     uint32_t Status;
     uint32_t InterruptStatus;
     /* supplied by environment */
-    int tap_fd;
+    netdev_t peer;
     uint32_t *ram;
     /* implementation-specific */
     void *priv;
@@ -119,7 +120,7 @@ void virtio_net_write(hart_t *core,
                       uint32_t value);
 void virtio_net_refresh_queue(virtio_net_state_t *vnet);
 
-bool virtio_net_init(virtio_net_state_t *vnet);
+bool virtio_net_init(virtio_net_state_t *vnet, const char *name);
 #endif /* SEMU_HAS(VIRTIONET) */
 
 /* VirtIO-Block */
diff --git a/main.c b/main.c
@@ -440,19 +440,22 @@ static void handle_options(int argc,
                            char **dtb_file,
                            char **initrd_file,
                            char **disk_file,
+                           char **net_dev,
                            int *hart_count)
 {
-    *kernel_file = *dtb_file = *initrd_file = *disk_file = NULL;
+    *kernel_file = *dtb_file = *initrd_file = *disk_file = *net_dev = NULL;
 
     int optidx = 0;
     struct option opts[] = {
         {"kernel", 1, NULL, 'k'}, {"dtb", 1, NULL, 'b'},
         {"initrd", 1, NULL, 'i'}, {"disk", 1, NULL, 'd'},
-        {"smp", 1, NULL, 'c'},    {"help", 0, NULL, 'h'},
+        {"netdev", 1, NULL, 'n'}, {"smp", 1, NULL, 'c'},
+        {"help", 0, NULL, 'h'},
     };
 
     int c;
-    while ((c = getopt_long(argc, argv, "k:b:i:d:c:h", opts, &optidx)) != -1) {
+    while ((c = getopt_long(argc, argv, "k:b:i:d:n:c:h", opts, &optidx)) !=
+           -1) {
         switch (c) {
         case 'k':
             *kernel_file = optarg;
@@ -466,6 +469,9 @@ static void handle_options(int argc,
         case 'd':
             *disk_file = optarg;
             break;
+        case 'n':
+            *net_dev = optarg;
+            break;
         case 'c':
             *hart_count = atoi(optarg);
             break;
@@ -487,6 +493,9 @@ static void handle_options(int argc,
 
     if (!*dtb_file)
         *dtb_file = "minimal.dtb";
+
+    if (!*net_dev)
+        *net_dev = "tap";
 }
 
 
@@ -509,9 +518,10 @@ static int semu_start(int argc, char **argv)
     char *dtb_file;
     char *initrd_file;
     char *disk_file;
+    char *netdev;
     int hart_count = 1;
     handle_options(argc, argv, &kernel_file, &dtb_file, &initrd_file,
-                   &disk_file, &hart_count);
+                   &disk_file, &netdev, &hart_count);
 
     /* Initialize the emulator */
     emu_state_t emu;
@@ -573,7 +583,7 @@ static int semu_start(int argc, char **argv)
     emu.uart.in_fd = 0, emu.uart.out_fd = 1;
     capture_keyboard_input(); /* set up uart */
 #if SEMU_HAS(VIRTIONET)
-    if (!virtio_net_init(&(emu.vnet)))
+    if (!virtio_net_init(&(emu.vnet), netdev))
         fprintf(stderr, "No virtio-net functioned\n");
     emu.vnet.ram = emu.ram;
 #endif
diff --git a/netdev.c b/netdev.c
@@ -0,0 +1,80 @@
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "netdev.h"
+
+static int net_init_tap();
+static int net_init_slirp();
+
+static int (*const net_init_fun[NET_DEV_DRIVER_MAX])(const netdev_t *) = {
+    [NET_DEV_DRIVER_TAP] = net_init_tap,
+    [NET_DEV_DRIVER_USER] = net_init_slirp,
+};
+
+static const char *netdev_driver_lookup[] = {
+    [NET_DEV_DRIVER_TAP] = "tap",
+    [NET_DEV_DRIVER_USER] = "user",
+};
+
+static int find_net_dev_idx(const char *net_type, const char **netlookup)
+{
+    int i;
+    if (!net_type)
+        return -1;
+    for (i = 0; i < NET_DEV_DRIVER_MAX; i++) {
+        if (!strcmp(net_type, netlookup[i])) {
+            return i;
+        }
+    }
+    return -1;
+}
+
+static int net_init_tap(netdev_t *netdev)
+{
+    net_tap_options *tap;
+    tap = &netdev->op.tap;
+    tap->tap_fd = open("/dev/net/tun", O_RDWR);
+    if (tap->tap_fd < 0) {
+        fprintf(stderr, "failed to open TAP device: %s\n", strerror(errno));
+        return false;
+    }
+
+    /* Specify persistent tap device */
+    struct ifreq ifreq = {.ifr_flags = IFF_TAP | IFF_NO_PI};
+    strncpy(ifreq.ifr_name, "tap%d", sizeof(ifreq.ifr_name));
+    if (ioctl(tap->tap_fd, TUNSETIFF, &ifreq) < 0) {
+        fprintf(stderr, "failed to allocate TAP device: %s\n", strerror(errno));
+        return false;
+    }
+
+    fprintf(stderr, "allocated TAP interface: %s\n", ifreq.ifr_name);
+    assert(fcntl(tap->tap_fd, F_SETFL,
+                 fcntl(tap->tap_fd, F_GETFL, 0) | O_NONBLOCK) >= 0);
+    return 0;
+}
+
+static int net_init_slirp(netdev_t *netdev)
+{
+    // TBD: create slirp dev
+    return 0;
+}
+
+int netdev_init(netdev_t *netdev, const char *net_type)
+{
+    int dev_idx = find_net_dev_idx(net_type, netdev_driver_lookup);
+    if (dev_idx == -1)
+        return false;
+    else
+        netdev->type = dev_idx;
+
+    net_init_fun[netdev->type](netdev);
+
+    return true;
+}
diff --git a/netdev.h b/netdev.h
@@ -0,0 +1,27 @@
+#pragma once
+
+typedef enum {
+    NET_DEV_DRIVER_TAP,
+    NET_DEV_DRIVER_USER,
+    NET_DEV_DRIVER_MAX,
+} net_dev_driver_t;
+
+typedef struct {
+    int tap_fd;
+} net_tap_options;
+
+typedef struct {
+    /* TODO: Implement user option */
+    int temp;
+} net_user_options;
+
+typedef struct {
+    char *name;
+    net_dev_driver_t type;
+    union {
+        net_tap_options tap;
+        net_user_options user;
+    } op;
+} netdev_t;
+
+int netdev_init(netdev_t *nedtev, const char *net_type);
diff --git a/virtio-net.c b/virtio-net.c
@@ -62,11 +62,11 @@ static void virtio_net_update_status(virtio_net_state_t *vnet, uint32_t status)
         return;
 
     /* Reset */
-    int tap_fd = vnet->tap_fd;
+    netdev_t peer = vnet->peer;
     uint32_t *ram = vnet->ram;
     void *priv = vnet->priv;
     memset(vnet, 0, sizeof(*vnet));
-    vnet->tap_fd = tap_fd, vnet->ram = ram;
+    vnet->peer = peer, vnet->ram = ram;
     vnet->priv = priv;
 }
 
@@ -113,6 +113,64 @@ static bool vnet_iovec_read(struct iovec **vecs,
     return n && !*nvecs;
 }
 
+static ssize_t handle_read(netdev_t *netdev,
+                           virtio_net_queue_t *queue,
+                           struct iovec *iovs_cursor,
+                           size_t niovs)
+{
+    ssize_t plen = 0;
+    switch (netdev->type) {
+    case NET_DEV_DRIVER_TAP:
+        plen = readv(netdev->op.tap.tap_fd, iovs_cursor, niovs);
+        if (plen < 0 && (errno == EWOULDBLOCK || errno == EAGAIN)) {
+            queue->fd_ready = false;
+            return -1;
+        }
+        if (plen < 0) {
+            plen = 0;
+            fprintf(stderr, "[VNET] could not read packet: %s\n",
+                    strerror(errno));
+        }
+        break;
+    case NET_DEV_DRIVER_USER:
+        /* TODO: handle read  */
+        break;
+    default:
+        break;
+    }
+
+    return plen;
+}
+
+static ssize_t handle_write(netdev_t *netdev,
+                            virtio_net_queue_t *queue,
+                            struct iovec *iovs_cursor,
+                            size_t niovs)
+{
+    ssize_t plen = 0;
+    switch (netdev->type) {
+    case NET_DEV_DRIVER_TAP:
+        plen = writev(netdev->op.tap.tap_fd, iovs_cursor, niovs);
+        if (plen < 0 && (errno == EWOULDBLOCK || errno == EAGAIN)) {
+            queue->fd_ready = false;
+            return -1;
+        }
+        if (plen < 0) {
+            plen = 0;
+            fprintf(stderr, "[VNET] could not write packet: %s\n",
+                    strerror(errno));
+        }
+        break;
+    case NET_DEV_DRIVER_USER:
+        /* TODO: handle slirp_input */
+        break;
+    default:
+        break;
+    }
+
+    return plen;
+}
+
 /* Require existing 'desc_idx' to use as iteration variable, and input
  * 'buffer_idx'.
  */
@@ -186,18 +244,10 @@ static bool vnet_iovec_read(struct iovec **vecs,
                                 virtio_header, sizeof(virtio_header));         \
             }                                                                  \
                                                                                \
-            ssize_t plen =                                                     \
-                VERB##v(vnet->tap_fd, buffer_iovs_cursor, buffer_niovs);       \
-            if (plen < 0 && (errno == EWOULDBLOCK || errno == EAGAIN)) {       \
-                queue->fd_ready = false;                                       \
+            ssize_t plen = handle_##VERB(&vnet->peer, queue,                   \
+                                         buffer_iovs_cursor, buffer_niovs);    \
+            if (plen < 0)                                                      \
                 break;                                                         \
-            }                                                                  \
-            if (plen < 0) {                                                    \
-                plen = 0;                                                      \
-                fprintf(stderr, "[VNET] could not " #VERB " packet: %s\n",     \
-                        strerror(errno));                                      \
-            }                                                                  \
-                                                                               \
             /* consume from available queue, write to used queue */            \
             queue->last_avail++;                                               \
             ram[queue->QueueUsed + 1 + (new_used % queue->QueueNum) * 2] =     \
@@ -223,15 +273,25 @@ void virtio_net_refresh_queue(virtio_net_state_t *vnet)
         (vnet->Status & VIRTIO_STATUS__DEVICE_NEEDS_RESET))
         return;
 
-    struct pollfd pfd = {vnet->tap_fd, POLLIN | POLLOUT, 0};
-    poll(&pfd, 1, 0);
-    if (pfd.revents & POLLIN) {
-        vnet->queues[VNET_QUEUE_RX].fd_ready = true;
-        virtio_net_try_rx(vnet);
-    }
-    if (pfd.revents & POLLOUT) {
-        vnet->queues[VNET_QUEUE_TX].fd_ready = true;
-        virtio_net_try_tx(vnet);
+    net_dev_driver_t dev_type = vnet->peer.type;
+    switch (dev_type) {
+    case NET_DEV_DRIVER_TAP:
+        struct pollfd pfd = {vnet->peer.op.tap.tap_fd, POLLIN | POLLOUT, 0};
+        poll(&pfd, 1, 0);
+        if (pfd.revents & POLLIN) {
+            vnet->queues[VNET_QUEUE_RX].fd_ready = true;
+            virtio_net_try_rx(vnet);
+        }
+        if (pfd.revents & POLLOUT) {
+            vnet->queues[VNET_QUEUE_TX].fd_ready = true;
+            virtio_net_try_tx(vnet);
+        }
+        break;
+    case NET_DEV_DRIVER_USER:
+        /* TODO: handle slirp input/output */
+        break;
+    default:
+        break;
     }
 }
 
@@ -433,7 +493,7 @@ void virtio_net_write(hart_t *vm,
     }
 }
 
-bool virtio_net_init(virtio_net_state_t *vnet)
+bool virtio_net_init(virtio_net_state_t *vnet, const char *name)
 {
     if (vnet_dev_cnt >= VNET_DEV_CNT_MAX) {
         fprintf(stderr,
@@ -444,23 +504,10 @@ bool virtio_net_init(virtio_net_state_t *vnet)
     /* Allocate memory for the private member */
     vnet->priv = &vnet_configs[vnet_dev_cnt++];
 
-    vnet->tap_fd = open("/dev/net/tun", O_RDWR);
-    if (vnet->tap_fd < 0) {
-        fprintf(stderr, "failed to open TAP device: %s\n", strerror(errno));
+    if (!netdev_init(&vnet->peer, name)) {
+        fprintf(stderr, "Fail to init net device %s\n", name);
         return false;
     }
 
-    /* Specify persistent tap device */
-    struct ifreq ifreq = {.ifr_flags = IFF_TAP | IFF_NO_PI};
-    strncpy(ifreq.ifr_name, TAP_INTERFACE, sizeof(ifreq.ifr_name));
-    if (ioctl(vnet->tap_fd, TUNSETIFF, &ifreq) < 0) {
-        fprintf(stderr, "failed to allocate TAP device: %s\n", strerror(errno));
-        return false;
-    }
-
-    fprintf(stderr, "allocated TAP interface: %s\n", ifreq.ifr_name);
-    assert(fcntl(vnet->tap_fd, F_SETFL,
-                 fcntl(vnet->tap_fd, F_GETFL, 0) | O_NONBLOCK) >= 0);
-
     return true;
 }
