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--- ifreq_ethtool [2018/09/02 06:21] – created rpjday
+++ ifreq_ethtool [2018/09/02 06:56] (current) – [Userspace and struct ifreq] rpjday
@@ Line 3: / Line 3: @@
 Notes on ''ethtool'' and underlying kernel hooks/code.
-Links:
+General links:
   * [[https://git.kernel.org/pub/scm/network/ethtool/ethtool.git/|ethtool git repo]]
+Kernel source links:
+  * [[https://github.com/torvalds/linux/tree/master/include|include/]]
+    * [[https://github.com/torvalds/linux/tree/master/include/uapi|uapi/]]
+      * [[https://github.com/torvalds/linux/tree/master/include/uapi/linux|linux/]]
+        * [[https://github.com/torvalds/linux/blob/master/include/uapi/linux/if.h|if.h]] (for ''struct ifreq'')
+        * [[https://github.com/torvalds/linux/blob/master/include/uapi/linux/sockios.h|sockios.h]] (for ''SIOCETHTOOL''}
+        * [[https://github.com/torvalds/linux/blob/master/include/uapi/linux/ethtool.h|ethtool.h]]
+===== Userspace and struct ifreq =====
+From ethtool's ''internal.h'':
+<code>
+/* Context for sub-commands */
+struct cmd_context {
+        const char *devname;    /* net device name */
+        int fd;                 /* socket suitable for ethtool ioctl */
+        struct ifreq ifr;       /* ifreq suitable for ethtool ioctl */
+        int argc;               /* number of arguments to the sub-command */
+        char **argp;            /* arguments to the sub-command */
+};
+</code>
+and from ''ethtool.c'', the wrapper for ioctl calls:
+<code>
+#ifndef TEST_ETHTOOL
+int send_ioctl(struct cmd_context *ctx, void *cmd)
+{
+        ctx->ifr.ifr_data = cmd;
+        return ioctl(ctx->fd, SIOCETHTOOL, &ctx->ifr);
+}
+#endif
+</code>
+From ''if.h'':
+<code>
+/* for compatibility with glibc net/if.h */
+#if __UAPI_DEF_IF_IFREQ
+struct ifreq {
+#define IFHWADDRLEN     6
+        union
+        {
+                char    ifrn_name[IFNAMSIZ];            /* if name, e.g. "en0" */
+        } ifr_ifrn;
+        union {
+                struct  sockaddr ifru_addr;
+                struct  sockaddr ifru_dstaddr;
+                struct  sockaddr ifru_broadaddr;
+                struct  sockaddr ifru_netmask;
+                struct  sockaddr ifru_hwaddr;
+                short   ifru_flags;
+                int     ifru_ivalue;
+                int     ifru_mtu;
+                struct  ifmap ifru_map;
+                char    ifru_slave[IFNAMSIZ];   /* Just fits the size */
+                char    ifru_newname[IFNAMSIZ];
+                void *  ifru_data;
+                struct  if_settings ifru_settings;
+        } ifr_ifru;
+};
+#endif /* __UAPI_DEF_IF_IFREQ */
+#define ifr_name        ifr_ifrn.ifrn_name      /* interface name       */
+#define ifr_hwaddr      ifr_ifru.ifru_hwaddr    /* MAC address          */
+#define ifr_addr        ifr_ifru.ifru_addr      /* address              */
+#define ifr_dstaddr     ifr_ifru.ifru_dstaddr   /* other end of p-p lnk */
+#define ifr_broadaddr   ifr_ifru.ifru_broadaddr /* broadcast address    */
+#define ifr_netmask     ifr_ifru.ifru_netmask   /* interface net mask   */
+#define ifr_flags       ifr_ifru.ifru_flags     /* flags                */
+#define ifr_metric      ifr_ifru.ifru_ivalue    /* metric               */
+#define ifr_mtu         ifr_ifru.ifru_mtu       /* mtu                  */
+#define ifr_map         ifr_ifru.ifru_map       /* device map           */
+#define ifr_slave       ifr_ifru.ifru_slave     /* slave device         */
+#define ifr_data        ifr_ifru.ifru_data      /* for use by interface */
+#define ifr_ifindex     ifr_ifru.ifru_ivalue    /* interface index      */
+#define ifr_bandwidth   ifr_ifru.ifru_ivalue    /* link bandwidth       */
+#define ifr_qlen        ifr_ifru.ifru_ivalue    /* Queue length         */
+#define ifr_newname     ifr_ifru.ifru_newname   /* New name             */
+#define ifr_settings    ifr_ifru.ifru_settings  /* Device/proto settings*/
+</code>