[Qemu-devel] [PATCH] Support for UDP unicast network backend

[Benjamin <mlspirat42@gmail.com>]

Follow-up of: 
http://www.mail-archive.com/qemu-devel@nongnu.org/msg81235.html

This enables connections between Qemu, Dynamips and VirtualBox guests.

Test it with:

qemu-system-i386 -netdev 
socket,id=gns3,udp=127.0.0.1:4243,localport=127.0.0.1:4242 -device 
e1000,netdev=gns3 /path/to/hard/drive/img1

qemu-system-i386 -netdev 
socket,id=gns3,udp=127.0.0.1:4242,localport=127.0.0.1:4243 -device 
e1000,netdev=gns3 /path/to/hard/drive/img2

You should be able to set up a network between these two hosts.

Any thoughts?

I noticed an interesting behavior of Qemu and I'd like to investigate.
When an IP address is assigned to an interface it sends a who-has ARP
request with its own address. Which is not what happens on my OS. What
would be the correct and standard behavior?

Signed-off-by: Benjamin MARSILI <marsil_b@epitech.eu>
---
  net.c           |   11 ++++++++-
  net/socket.c    |   66 
+++++++++++++++++++++++++++++++++++++++++++++++++++++-
  qemu-options.hx |    2 +
  3 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/net.c b/net.c
index cb52050..e70f1c8 100644
--- a/net.c
+++ b/net.c
@@ -1000,6 +1000,14 @@ static const struct {
                  .name = "localaddr",
                  .type = QEMU_OPT_STRING,
                  .help = "source address for multicast packets",
+            }, {
+                .name = "udp",
+                .type = QEMU_OPT_STRING,
+                .help = "UDP unicast address and port number",
+            }, {
+                .name = "localport",
+                .type = QEMU_OPT_STRING,
+                .help = "UDP unicast bind address and port number",
              },
              { /* end of list */ }
          },
@@ -1070,7 +1078,8 @@ int net_client_init(Monitor *mon, QemuOpts *opts, 
int is_netdev)
  #ifdef CONFIG_VDE
              strcmp(type, "vde") != 0 &&
  #endif
-            strcmp(type, "socket") != 0) {
+            strcmp(type, "socket") != 0 &&
+            strcmp(type, "udp") != 0) {
              qerror_report(QERR_INVALID_PARAMETER_VALUE, "type",
                            "a netdev backend type");
              return -1;
diff --git a/net/socket.c b/net/socket.c
index e9ef128..306e54b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -524,6 +524,52 @@ static int net_socket_mcast_init(VLANState *vlan,

  }

+static int net_socket_udp_init(VLANState *vlan,
+                                 const char *model,
+                                 const char *name,
+                                 const char *rhost,
+                                 const char *lhost)
+{
+    NetSocketState *s;
+    int fd, val, ret;
+    struct sockaddr_in laddr, raddr;
+
+    if (parse_host_port(&laddr, lhost) < 0)
+        return -1;
+
+    if (parse_host_port(&raddr, rhost) < 0)
+        return -1;
+
+    fd = qemu_socket(PF_INET, SOCK_DGRAM, 0);
+    if (fd < 0) {
+        perror("socket(PF_INET, SOCK_DGRAM)");
+        return -1;
+    }
+    val = 1;
+    ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
+                   (const char *)&val, sizeof(val));
+    if (ret < 0) {
+       perror("setsockopt(SOL_SOCKET, SO_REUSEADDR)");
+        return -1;
+    }
+    ret = bind(fd, (struct sockaddr *)&laddr, sizeof(laddr));
+    if (ret < 0) {
+        perror("bind");
+        return -1;
+    }
+
+    s = net_socket_fd_init(vlan, model, name, fd, 0);
+    if (!s)
+        return -1;
+
+    s->dgram_dst = raddr;
+
+    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
+             "socket: udp=%s:%d",
+             inet_ntoa(raddr.sin_addr), ntohs(raddr.sin_port));
+    return 0;
+}
+
  int net_init_socket(QemuOpts *opts,
                      Monitor *mon,
                      const char *name,
@@ -597,10 +643,26 @@ int net_init_socket(QemuOpts *opts,
          if (net_socket_mcast_init(vlan, "socket", name, mcast, 
localaddr) == -1) {
              return -1;
          }
+    } else if (qemu_opt_get(opts, "udp")) {
+        const char *udp, *localport;
+
+        if (qemu_opt_get(opts, "fd") ||
+            qemu_opt_get(opts, "connect") ||
+            qemu_opt_get(opts, "listen") ||
+            qemu_opt_get(opts, "mcast")) {
+            error_report("fd=, connect=, listen=, mcast=, localaddr= is 
invalid with udp=");
+            return -1;
+        }
+
+        udp = qemu_opt_get(opts, "udp");
+        localport = qemu_opt_get(opts, "localport");
+
+        if (net_socket_udp_init(vlan, "udp", name, udp, localport) == -1) {
+            return -1;
+        }
      } else {
-        error_report("-socket requires fd=, listen=, connect= or mcast=");
+        error_report("-socket requires fd=, listen=, connect=, mcast= 
or udp=");
          return -1;
      }
-
      return 0;
  }
diff --git a/qemu-options.hx b/qemu-options.hx
index 681eaf1..109feb0 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1217,6 +1217,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
      "-net 
socket[,vlan=n][,name=str][,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
      "                connect the vlan 'n' to multicast maddr and port\n"
      "                use 'localaddr=addr' to specify the host address 
to send packets from\n"
+    "-net 
socket[,vlan=n][,name=str][,fd=h][,udp=host:port][,localport=host:port]\n"
+    "                connect the vlan 'n' to another VLAN using an UDP 
tunnel\n"
  #ifdef CONFIG_VDE
      "-net 
vde[,vlan=n][,name=str][,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
      "                connect the vlan 'n' to port 'n' of a vde switch 
running\n"
-- 
1.7.3.5