[Qemu-devel] [Patch] Add -net dump option

[Tristan Gingold]

Hi,

latest version of the patch inlined.

Signed-off-by: Tristan Gingold <address@hidden>

Thanks,
Tristan.


Index: vl.c
===================================================================
--- vl.c        (revision 6685)
+++ vl.c        (working copy)
@@ -3987,6 +3987,8 @@
            "                Use group 'groupname' and mode 'octalmode' to 
change default\n"
            "                ownership and permissions for communication 
port.\n"
 #endif
+           "-net dump[,vlan=n][,file=f][,len=n]\n"
+           "                dump traffic on vlan 'n' to file 'f' (max n bytes 
per packet)\n"
            "-net none       use it alone to have zero network devices; if no 
-net option\n"
            "                is provided, the default is '-net nic -net user'\n"
 #ifdef CONFIG_SLIRP
Index: net.c
===================================================================
--- net.c       (revision 6685)
+++ net.c       (working copy)
@@ -27,6 +27,7 @@
 #include "sysemu.h"
 #include "qemu-timer.h"
 #include "qemu-char.h"
+#include "qemu-log.h"
 #include "audio/audio.h"
 
 #include <unistd.h>
@@ -324,14 +325,14 @@
     return strdup(buf);
 }
 
-VLANClientState *qemu_new_vlan_client(VLANState *vlan,
-                                      const char *model,
-                                      const char *name,
-                                      IOReadHandler *fd_read,
-                                      IOCanRWHandler *fd_can_read,
-                                      void *opaque)
+static VLANClientState *qemu_new_vlan_client_common(VLANState *vlan,
+                                                   const char *model,
+                                                   const char *name,
+                                                   IOReadHandler *fd_read,
+                                                   IOCanRWHandler *fd_can_read,
+                                                   void *opaque)
 {
-    VLANClientState *vc, **pvc;
+    VLANClientState *vc;
     vc = qemu_mallocz(sizeof(VLANClientState));
     vc->model = strdup(model);
     if (name)
@@ -343,14 +344,58 @@
     vc->opaque = opaque;
     vc->vlan = vlan;
 
-    vc->next = NULL;
+    return vc;
+}
+
+VLANClientState *qemu_new_vlan_client(VLANState *vlan,
+                                      const char *model,
+                                      const char *name,
+                                      IOReadHandler *fd_read,
+                                      IOCanRWHandler *fd_can_read,
+                                      void *opaque)
+{
+    VLANClientState *vc, **pvc;
+
+    vc = qemu_new_vlan_client_common(vlan, model, name, fd_read, fd_can_read,
+                                    opaque);
+    /* Append but before last_client.  */
     pvc = &vlan->first_client;
-    while (*pvc != NULL)
+    while (*pvc != NULL) {
+       if ((*pvc)->last_client) {
+           vc->next = *pvc;
+           break;
+       }
         pvc = &(*pvc)->next;
+    }
     *pvc = vc;
     return vc;
 }
 
+static VLANClientState *qemu_new_vlan_client_tail(VLANState *vlan,
+                                                 const char *model,
+                                                 const char *name,
+                                                 IOReadHandler *fd_read,
+                                                 IOCanRWHandler *fd_can_read,
+                                                 void *opaque)
+{
+    VLANClientState *vc, **pvc;
+
+    vc = qemu_new_vlan_client_common(vlan, model, name, fd_read, fd_can_read,
+                                    opaque);
+    vc->last_client = 1;
+    pvc = &vlan->first_client;
+    while (*pvc != NULL) {
+       if ((*pvc)->last_client) {
+           fprintf(stderr, "Multiple vlan last client (%s and %s)\n",
+                   (*pvc)->name, name);
+           exit(1);
+       }
+        pvc = &(*pvc)->next;
+    }
+    *pvc = vc;
+    return vc;
+}
+
 void qemu_del_vlan_client(VLANClientState *vc)
 {
     VLANClientState **pvc = &vc->vlan->first_client;
@@ -516,8 +561,8 @@
         slirp_inited = 1;
         slirp_init(slirp_restrict, slirp_ip);
     }
-    slirp_vc = qemu_new_vlan_client(vlan, model, name,
-                                    slirp_receive, NULL, NULL);
+    slirp_vc = qemu_new_vlan_client_tail(vlan, model, name,
+                                        slirp_receive, NULL, NULL);
     slirp_vc->info_str[0] = '\0';
     return 0;
 }
@@ -1088,6 +1133,91 @@
 }
 #endif
 
+typedef struct DumpState {
+    VLANClientState *tcpdump_vc;
+    FILE *tcpdump_file;
+    int tcpdump_caplen;
+} DumpState;
+
+#define TCPDUMP_MAGIC          0xa1b2c3d4
+
+struct pcap_file_hdr {
+    uint32_t magic;
+    uint16_t version_major;
+    uint16_t version_minor;
+    int32_t thiszone;
+    uint32_t sigfigs;
+    uint32_t snaplen;
+    uint32_t linktype;
+};
+
+struct pcap_sf_pkthdr {
+    struct {
+       int32_t tv_sec;
+       int32_t tv_usec;
+    } ts;
+    uint32_t caplen;
+    uint32_t len;
+};
+    
+static void tcpdump_receive(void *opaque, const uint8_t *buf, int size)
+{
+    DumpState *ds = (DumpState *)opaque;
+    struct pcap_sf_pkthdr hdr;
+    int64_t ts;
+    int caplen;
+
+    /* Early return in case of previous error.  */
+    if (ds->tcpdump_file == NULL)
+       return;
+
+    ts = muldiv64 (qemu_get_clock(vm_clock),1000000, ticks_per_sec);
+    caplen = size > ds->tcpdump_caplen ? ds->tcpdump_caplen : size;
+
+    hdr.ts.tv_sec = ts / 1000000000LL;
+    hdr.ts.tv_usec = ts % 1000000;
+    hdr.caplen = caplen;
+    hdr.len = size;
+    if (fwrite(&hdr, sizeof(hdr), 1, ds->tcpdump_file) != 1
+       || fwrite(buf, caplen, 1, ds->tcpdump_file) != 1) {
+       qemu_log("-net dump write error - stop dump\n");
+       fclose(ds->tcpdump_file);
+       ds->tcpdump_file = NULL;
+    }
+}
+
+static int net_tcpdump_init(VLANState *vlan, const char *device,
+                           const char *name, const char *filename, int len)
+{
+    struct pcap_file_hdr hdr;
+    DumpState *ds;
+
+    ds = qemu_malloc (sizeof (DumpState));
+    ds->tcpdump_file = fopen(filename, "wb");
+    if (!ds->tcpdump_file) {
+       fprintf(stderr, "-net dump: can't open %s\n", filename);
+       exit(1);
+    }
+
+    ds->tcpdump_caplen = len;
+
+    hdr.magic = TCPDUMP_MAGIC;
+    hdr.version_major = 2;
+    hdr.version_minor = 4;
+    hdr.thiszone = 0;
+    hdr.sigfigs = 0;
+    hdr.snaplen = ds->tcpdump_caplen;
+    hdr.linktype = 1;
+
+    fwrite(&hdr, sizeof(hdr), 1, ds->tcpdump_file);
+
+    ds->tcpdump_vc = qemu_new_vlan_client(vlan, device, name,
+                                         tcpdump_receive, NULL, ds);
+    snprintf(ds->tcpdump_vc->info_str, sizeof(ds->tcpdump_vc->info_str),
+            "tcpdump to %s (len=%d)", filename, len);
+    return 0;
+}
+
 /* network connection */
 typedef struct NetSocketState {
     VLANClientState *vc;
@@ -1762,6 +1892,20 @@
        ret = net_vde_init(vlan, device, name, vde_sock, vde_port, vde_group, 
vde_mode);
     } else
 #endif
+    if (!strcmp(device, "dump")) {
+       int len = 64;
+        if (get_param_value(buf, sizeof(buf), "len", p) > 0) {
+            len = strtol(buf, NULL, 0);
+       }
+
+        if (!get_param_value(buf, sizeof(buf), "file", p)) {
+           if (vlan_id == 0)
+               strcpy(buf, "qemu.tcpdump");
+           else
+               snprintf(buf, sizeof(buf), "qemu-vlan%d.tcpdump", vlan_id);
+        }
+        ret = net_tcpdump_init(vlan, device, name, buf, len);
+    } else
     {
         fprintf(stderr, "Unknown network device: %s\n", device);
         if (name)
Index: net.h
===================================================================
--- net.h       (revision 6685)
+++ net.h       (working copy)
@@ -19,6 +19,9 @@
     IOCanRWHandler *fd_can_read;
     LinkStatusChanged *link_status_changed;
     int link_down;
+    /* If set this client must be the last in the VLAN (currently set only
+       by slirp).  */
+    int last_client;
     void *opaque;
     struct VLANClientState *next;
     struct VLANState *vlan;
Index: qemu-doc.texi
===================================================================
--- qemu-doc.texi       (revision 6685)
+++ qemu-doc.texi       (working copy)
@@ -742,6 +742,11 @@
 qemu linux.img -net nic -net vde,sock=/tmp/myswitch
 @end example
 
address@hidden -net dump[,address@hidden,address@hidden,address@hidden
+Dump network traffic on VLAN @var{n} to file @var{file} (@file{qemu.tcpdump} by
+default).  At most @var{len} bytes (64 by default) by packet are stored.  The
+dump can be analyzed with tools such as tcpdump.
+
 @item -net none
 Indicate that no network devices should be configured. It is used to
 override the default configuration (@option{-net nic -net user}) which