if.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define DEBUG 1
#define ETHER_MTU 1500
#define LOOPBACK_MTU 1536
#define ETHER_ADDR_LEN 6

typedef unsigned short ushort;
typedef unsigned char uchar;
typedef unsigned int uint;
typedef unsigned long ulong;
uchar hw_addr[6] = { 0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc };

struct gbuf {};

struct ifnet {
  struct ifnet *if_next;
  struct ifaddr *if_addrlist;
  uchar ifname[16]; // eth, wlan, le, lo
  short if_unit; // sub-unit for lower level driver.
  ushort if_index; // uniquely identifies the interface within the kernel and is used by the sysctl.
  short if_flags;
#define IFF_UP (1 << 0)
#define IFF_PROMISC (1 << 1)
#define IFF_RUNNING (1 << 2)
#define IFF_OACTIVE (1 << 3)
#define IFF_LOOPBACK (1 << 4)
  
  //short if_timer; watchdog timer.
  int if_pcount; // number of promiscuous listeners.
  // caddr_t if_bpf; // packet filter structure.
  
  struct ifdata {
    uchar ifi_type;
    uchar ifi_addrlen; // MAC = 6byte (48bit.)
    uchar ifi_hdrlen;
    ulong ifi_mtu;
    ulong ifi_metric;
    ulong ifi_ipackets; // packets received on interface.
    ulong ifi_ierrors; // input errors on interface.
    ulong ifi_opackets; // packets sent on interface.
    ulong ifi_oerrors; // output errors on interface.
    ulong ifi_collisions; // CSMA collisions.
    ulong ifi_ibytes; // bytes received.
    ulong ifi_obytes; // bytes sent.
    ulong ifi_iqdrops;
    ulong ifi_noproto; // packets destined for unsupported protocol.
    // ifi_imcasts, ifi_omcasts is not implemented.
  } if_data;
#define if_mtu if_data.ifi_mtu
#define if_type if_data.ifi_type
#define if_addrlen if_data.ifi_addrlen
#define if_hdrlen if_data.ifi_hdrlen
  // handles.
  int (*if_init)(int);
  // int (*if_output)(struct ifnet *, struct gbuf *, struct sockaddr *, struct rtentry *)
  int (*if_output)(struct ifnet *, struct gbuf *, struct sockaddr *);
  int (*if_start)(struct ifnet *); // initiate transmission of packets.
  int (*if_done)(struct ifnet *); // NOT USED.
  int (*if_ioctl)(struct ifnet *, int, caddr_t);
  int (*if_reset)(int);
  int (*if_watchdog)(int); // timctl_add_task().
  /*
   struct  ifqueue {
   struct gbuf *ifq_head;
   struct gbuf *ifq_tail;
   int ifq_len;
   int ifq_maxlen;
   int ifq_drops;
   } if_snd;
   */
};
// ifnet.ifdata.ifi_type
#define IFT_OTHER (1 << 0)
#define IFI_ETHER (1 << 1)
#define IFT_LOOP  (1 << 2)

struct xv6_sockaddr { uchar sa_len, sa_family; char sa_data[14]; };
struct xv6_osockaddr { ushort sa_family; char sa_data[14]; };

struct xv6_sockaddr_dl {
  uchar sdl_len; // total length of sockaddr.
  uchar sdl_family; // AF_LINK
  uchar sdl_index;
  uchar sdl_type;
  uchar sdl_nlen;
  uchar sdl_alen;
  uchar sdl_slen;
  char sdl_data[12];
};
struct xv6_in_addr { uchar addr[4]; };
// sockaddr.sa_family
#define AF_INET (1 << 0)
#define AF_LINK (1 << 1)
#define LLADDR(s) ((uint)((s)->sdl_data + (s)->sdl_nlen))

// ifnet.if_flags
struct ifaddr {
  struct ifnet *ifa_ifp;
  uint ifa_next;
  struct xv6_sockaddr ifa_addr;
  struct xv6_sockaddr ifa_netmask;
};

struct arpcom {
  struct ifnet ac_if;
  struct ifaddr ac_ifaddr;
  uchar ac_enaddr[6]; // MAC 48bit.
  struct xv6_in_addr ac_ipaddr; // copy of ipaddress.
};
#define NLE 3
struct ne2k_softc {
  struct arpcom sc_ac;
#define sc_if sc_ac.ac_if
#define sc_ifaddr sc_ac.ac_ifaddr
#define sc_addr sc_ac.ac_enaddr
} ne2k_softc[NLE];
struct loif {
  struct ifnet lo_ifnet;
} loif;
#define print_mac(hw) printf("%x:%x:%x:%x:%x:%x", hw[0], hw[1], hw[2], hw[3], hw[4], hw[5]);

// network structures.
struct ether_header {
  uchar ether_dhost[6];
  uchar ether_shost[6];
  ushort ether_type;
};
void ne2k_init();
void ne2k_reset();
void ne2k_ioctl();

// GLOBAL VARIABLES.
int if_index = 0;
struct ifnet *ifnet = NULL;

int int_count(int n) {
  int count = 0;
  if(n > 0) {
    while(n != 0) {
      ++count;
      n /= 10;
    }
  } else {
    count = 1;
  }
  return count;
}
struct ifnet *get_ifnet() { return ifnet; }
void if_ether_create(const char *if_pname, struct ifnet *ifn, struct ifaddr *ifn_ifaddr) {
  int i;
  ifn->if_next = NULL;
  memset(ifn->ifname, 0, 16);
  for(i = 0; i < strlen(if_pname) + int_count(if_index); i++) {
    if(i < strlen(if_pname)) {
      memcpy(ifn->ifname, if_pname, strlen(if_pname));
    } else {
      ifn->ifname[i] = '0' + if_index;
    }
  }
  ifn->if_index = if_index;
  ifn->if_unit = if_index;
  
  ifn->if_addrlist = ifn_ifaddr;
  ifn_ifaddr->ifa_ifp = ifn;
  ifn_ifaddr->ifa_next = NULL;
  
  struct xv6_sockaddr_dl *ifa_addr_dl = (struct xv6_sockaddr_dl *)&ifn_ifaddr->ifa_addr;
  struct xv6_sockaddr_dl *ifa_netmask_dl = (struct xv6_sockaddr_dl *)&ifn_ifaddr->ifa_netmask;
  
  ifa_addr_dl->sdl_len = 20;
  ifa_addr_dl->sdl_type = AF_LINK;
  ifa_addr_dl->sdl_index = 1;
  ifa_addr_dl->sdl_nlen = strlen(if_pname) + int_count(if_index); // ifa_addr_dl->sdl_nlen = 4 ("eth0").
  ifa_addr_dl->sdl_alen = ETHER_ADDR_LEN;
  memcpy(ifa_addr_dl->sdl_data, ifn->ifname, strlen(if_pname)+int_count(if_index));
  memcpy(ifa_addr_dl->sdl_data + strlen(if_pname) + int_count(if_index), hw_addr, ifa_addr_dl->sdl_alen);
  
  ifa_netmask_dl->sdl_len = 11;
  memcpy(ifa_netmask_dl->sdl_data, "\xff\xff\xff", 3);
}
#ifdef DEBUG
static void if_debug(const struct ifnet *ifn) {
  char nlen_buff[20];
  uchar alen_buff[6];
  memset(nlen_buff, 0, 20);
  memset(alen_buff, 0, 6);
  
  printf("<ifnet{} @ %p <ifname:\"%s\", if_index:%d, if_unit:%d, if_mtu:%d%s, if_next:%p>>\n",
         ifn, ifn->ifname, ifn->if_index, ifn->if_unit, ifn->if_mtu, (ifn->if_mtu == 1500 ? "(Ethernet)" : ""), ifn->if_next);
  if(ifn->if_addrlist != NULL) {
    printf("\t<ifaddr{} @ %p <ifa_ifp:<ifnet{} @ %p ifname:\"%s\">, ifa_next:%p>>\n",
           ifn->if_addrlist, ifn->if_addrlist->ifa_ifp, ifn->if_addrlist->ifa_ifp->ifname, ifn->if_addrlist->ifa_next);
    
    struct xv6_sockaddr_dl *ifa_addr_dl = (struct sockaddr_dl *)&ifn->if_addrlist->ifa_addr;
    struct xv6_sockaddr_dl *ifa_netmask_dl = (struct sockaddr_dl *)&ifn->if_addrlist->ifa_netmask;
    
    printf("\t\t<sockaddr_dl{} @ %p <sdl_len:%d, sdl_nlen:%d, sdl_alen:%d, ",
           ifa_addr_dl, ifa_addr_dl->sdl_len, ifa_addr_dl->sdl_nlen, ifa_addr_dl->sdl_alen);
    memcpy(nlen_buff, ifa_addr_dl->sdl_data, ifa_addr_dl->sdl_nlen);
    printf("nlen: \"%s\", ", nlen_buff);
    memcpy(alen_buff, ifa_addr_dl->sdl_data + strlen(ifn->ifname), ifa_addr_dl->sdl_alen);
    printf("alen:");
    print_mac(alen_buff);
    printf(">>\n");
    printf("\t\t<sockaddr_dl{} @ %p <sdl_len:%d>>\n\n", ifa_netmask_dl, ifa_netmask_dl->sdl_len);
  }
}
#endif
void if_attach(struct ifnet *ifn) {
  struct ifnet **if_ptr = &ifnet;
  struct ifnet *prev_ifnet = NULL;
  
  while(*if_ptr != NULL) {
    prev_ifnet = *if_ptr;
    if_ptr = &((*if_ptr)->if_next);
  }
  *if_ptr = ifn;
  if(if_index > 0) {
    prev_ifnet->if_next = ifn;
    //printf("prev_ifnet : %p. prev_ifnet->if_next : %p\n", prev_ifnet, prev_ifnet->if_next);
  }
  ifn->if_index = ++if_index;
}
struct ifnet *ne2k_attach(const int dev_no) {
  struct ne2k_softc *ne2k_if = &ne2k_softc[dev_no];
  struct ifnet *ifp = &ne2k_if->sc_if;
  if_ether_create("eth", ifp, &ne2k_if->sc_ifaddr);
  
  ifp->if_mtu = ETHER_MTU;
  ifp->if_unit = dev_no;
  
  ifp->if_init = ne2k_init;
  ifp->if_reset = ne2k_reset;
  ifp->if_ioctl = ne2k_ioctl;
  if_attach(ifp);
  
#ifdef DEBUG
  printf("Called: if_attach(ifp), ifp -> ifnet{} @ %p\n", ifp);
  //if_debug(ifp);
#endif
  return ifp;
}
void ne2k_init() {}
void ne2k_reset() {}
void ne2k_ioctl() {
}

// For loopback device.
struct pdevinit {
  void (*pdev_attach)(int);
  int pdev_count;
};
void loioctl() {}
void looutput() {}

void loopattach(int pdev_count) {
  struct ifnet *ifp = &loif.lo_ifnet;
  memcpy(ifp->ifname, "lo0", 3);
  ifp->if_mtu = LOOPBACK_MTU;
  ifp->if_flags = IFF_LOOPBACK;
  ifp->if_ioctl = loioctl;
  ifp->if_output = looutput;
  ifp->if_hdrlen = 0;
  ifp->if_addrlen = 0;
  
  if_attach(ifp);
}

/*
 ioctl(2) call-trace Overview.
 ioctl()
 |
 soo_ioctl()
 |
 |--------------------|
 ifioctl   |         rtioctl
 |---|  pr_usrreq
 |  ifconf
 |-if_ioctl
 |-----------|
 ne2kioctl, loioctl
 */
struct xv6_ifconf {
  int ifc_len;
  union {
    uint ifcu_buf;
    struct ifreq *ifcu_req;
  } ifc_ifcu;
#define ifc_buf ifc_ifcu.ifcu_buf
#define ifc_req ifc_ifcu.ifcu_req
};
struct xv6_ifreq {
#define IFNAMESIZ 16
  char ifr_name[IFNAMESIZ];
  union {
    struct xv6_sockaddr ifru_addr;
    struct xv6_sockaddr ifru_dstaddr;
    struct xv6_sockaddr ifru_broadaddr;
    short ifru_flags;
    int ifru_metric;
    uint ifru_data;
  } ifr_ifru;
#define ifr_addr ifr_ifru.ifru_addr
#define ifr_dstaddr ifr_ifru.ifru_dstaddr
#define ifr_broadaddr ifr_ifru.ifru_broadaddr
#define ifr_flags ifr_ifru.ifru_flags
#define ifr_metric ifr_ifru.ifru_metric
#define ifr_data ifr_ifru.ifru_data
};
#define SIOCGIFCONF (1 << 0) // ifioctl -> ifconf(struct ifconf *)
#define SIOCGIFFLAGS (1 << 1) // ifioctl(struct ifreq *)
#define SIOCGIFMETRIC (1 << 2) // ifioctl(struct ifreq *)
#define SIOSGIFFLAGS (1 << 3) // ifioctl(struct ifreq *)
#define SIOCSIFFLAGS (1 << 4) // ifioctl(struct ifreq *)
#define SIOCSIFMETRIC (1 << 5) // ifioctl(struct ifreq *)

// For SIOCGIFCONF (cmd in ifconf() will be ignored...)
/*
  struct ifconf ifc;
  uchar ifconf_buf[36 * 2];
  int s;
  ifc.ifc_len = 36 * 2;
  ifc.ifc_buf = ifconf_buf;
  if(ioctl(s, SIOCGIFCONF, &ifc) < 0) exit(1);

0   ifr_name[]   16     ifr_addr        36
|----------------------------------------|
|e|t|h|0|--------|20|18|1|6|3|6|0|e|t|h|0| 36byte
|l|o|0|----------|20|18|3|24|3|0|0|l|o|0 | 36byte
*/
int ifconf(const int cmd, void *data) {
  struct xv6_ifconf *ifc = (struct xv6_ifconf *)data;
  struct ifnet *ifp = ifnet;
  struct ifaddr *ifa;
  return 1;
}
struct ifnet *if_unit(const char *if_name) {
  struct ifnet *ifp;
  for(ifp = ifnet; ifp->if_next != NULL; ifp = ifp->if_next) {
    if(strcmp(ifp->ifname, if_name) == 0) {
      break;
    } else {
      ifp = ifp->if_next;
    }
  }
  return ifp;
}
void if_down(struct ifnet *ifp) {
  struct ifaddr *ifa;
  ifp->if_flags &= ~IFF_UP;
  for(ifa = ifp->if_addrlist; ifa != NULL; ifa = ifa->ifa_next) {
    // pfctlinput(PRC_IFDOWN, ifa->ifa_addr);
    // todo: pfctlinput gives an oppotunity to notify the each of protocol which uses this interface that the interface state is 'down'.
  }
  // todo: if_qflush(&ifp->if_snd);
}
void if_up(struct ifnet *ifp) {
  ifp->if_flags |= IFF_UP;
  // rt_ifmsg(ifp);
}
int ifioctl(const int cmd, void *data) {
  struct ifnet *ifp;
  struct xv6_ifreq *ifr;
  if(cmd == SIOCGIFCONF) {
    return (ifconf(cmd, data));
  }
  ifr = (struct xv6_ifreq *)data;
  ifp = if_unit(ifr->ifr_name);
  if(ifp == NULL) {
#ifdef DEBUG
    printf("Error\n");
#endif
  }
  switch(cmd) {
    case SIOCGIFFLAGS:
      ifr->ifr_flags = ifp->if_flags;
      break;
    case SIOCGIFFLAGS:
      ifr->ifr_metric = ifp->if_metric;
      break;
    case SIOSCIFFLAGS:
      // todo: SIOSCIFFLAGS, SIOCSIFMETRIC use receive-blocking like splimp(), splx().
      //       should consider how to design these blocking-calls.
      break;
  }
  return 0;
}

int main(void) {
  /*
   struct ifnet ifnet_eth0;
   struct ifaddr if_addr_eth0;
   if_create("eth", &ifnet_eth0, &if_addr_eth0);
   */
  struct ifnet *ifp;
  ne2k_attach(0);
  
  // Loopback
  struct pdevinit pdevinit[] = {{ loopattach, 1 }, { 0, 0 }};
  struct pdevinit *pdev;
  for(pdev = pdevinit; pdev->pdev_attach != NULL; pdev++) (*pdev->pdev_attach)(pdev->pdev_count);
  
  /*
   ifp = if_unit("eth0");
   if_debug(ifp);
   */
  ifp = get_ifnet();
  while(ifp != NULL) {
    if_debug(ifp);
    ifp = ifp->if_next;
  }
  return 0;
}