?????Linux??TCP/IP???????????,??Linux ???????????? TCP/IP ??????? BSD ???????????????????????????????

1
?8? ??

• ?????Linux??TCP/IP???????????,??Linux
  ???????????? TCP/IP ??????? BSD
  ???????????????????????????????

2

• 8.1 ????
• 8.1.1 TCP/IP ????
• 8.1.2 TCP/IP ??????????
• 8.2 ???
• 8.2.1 ??????
• 8.2.2 ?????????????
• 8.2.3 ???????
• 8.2.4 ????????
• 8.3 ??????
• 8.3.1 ????????????
• 8.3.2 ???????????
• 8.3.3 ???????????
• 8.3.4 ?????????????

• 8.4 ????????
• 8.4.1 Linux????????
• 8.4.2 ??????
• 8.4.3 ??????
• 8.4.4 ??????
• 8.4.5 Socket???????
• 8.5 IP ?
• 8.5.1 ?? IP ???
• 8.5.2 ?? IP ???
• 8.5.3 ?????????
• 8.5.4 ??????
• 8.5.5 IP ??
• ?????

3

• 8.1 ????
• 8.1.1 TCP/IP ????
• TCP/IP ??? Internet ?????,?????????????TCP/
  IP ????????????,????????????IP(Internet
  Protocol)???????TCP(Transmission Control
  Protocol)????????UDP (User Datagram
  Protocol)?Internet??????ICMP(Internet Control
  Message Protocol)?
• ??????ARP(Address Resolution
  Protocol)???Linux?,?????socket???????????

4

• ? 8.1 TCP/IP ??????

TCP/IP ?????????????,?8.1?TCP/IP
?????????????,TCP/IP???????????,??????????????????
?????
5

• ?????(Network Interface Layer)????????????????????
  ?????,??????????,?????????????????????????????????
  ?????
• ???(Internet Layer)??????????(IP)?????????????????
  ??????IP????????????????????????????????????????
  ??????????????????????????
• IP?????????,?????????????????????????????
  ?????????????,????????????????????????Internet???
  ???ICMP,Internet?????IGMP???????ARP??

6

• ???(Transport Layer)??????????????????????????,???
  ?????????????????????????????????????????????????(
  Transmission Control Protocol, TCP)????????,??????
  ????????????(User Datagram Protocol,
  UDP)?????????,????????????
• ???(Application Layer)???????????????????,???????,
  ??????????SNMP(Simple Network Management
  Protocol)???????FTP(File Transfer
  Protocol)?????????SMTP(Simple Mail Transfer
  Protocol)??

7

• 8.1.2 TCP/IP ??????????
• ? 8.2 ??? TCP ?????????????????TCP ?? IP
  ????????????,??,IP ???????? TCP ??????UDP ??? IP
  ??????????,??????,???? IP ??????????? IP
  ???????????????????,?? IP ???????????,

8

• 8.1.2 TCP/IP ??????????
• ?????????????? IP ?????????????????????????????
  ????????,??????????????????????????,??,???????????
  ???????????????????,?????? TCP/IP ???????,???????
  IP ??,????

9

• 8.1.2 TCP/IP ??????????
• ?????????????????????,??????????????????,??
  Web ????????? 80???????,IP ??????????????

10

• 8.1.2 TCP/IP ??????????
• ?????????????????????,??????????????????,??
  Web ????????? 80???????,IP ??????????????

11

• IP ????????????????? IP ?????? 8.2 ?,IP
  ????????????????????????,IP ??????????????????????
  ??????????????????????,???????????????????????,???
  6 ?????,? 00-A0-0C-13-CC-78??????????????,???????
  ????????????????????? IP ?????,???????????,??,????
  ?????????????
• ??????????????????????? TCP/IP
  ????????????????????,???????????,??????????????,??
  ???????????Linux ???????,???? IP
  ??????????????????,Linux ??????? IP
  ?????????????(???)??????????????,?????????????????
  ???????????

12
? 8.3Linux ???????
? TCP/IP ???????,Linux ??????????TCP/IP
????????,Linux???????5??? 8.3 ??? Linux ????????
13

• (1) BSD socket???????BSD socket????,??socket?????
  struct socket?????????????????/net/socket.c
  /net/protocols.c ??
• (2) INET socket?BSD socket???????????????,????tcp
  /ip,????AF_INET???socket?,???????????,?????struct
  sock???
• ???????/net/ipv4/protocol.c?
  /net/ipv4/af_inet.c?/net/core/sock.c ??
• (3)TCP/UDP?????????,????struct
  inet_protocol?struct proto??????????????????/net/
  ipv4/udp.c?/net/ipv4/datagram.c?/net/ipv4/tcp.c?/n
  et/ipv4/tcp_input.c?/net/ipv4//tcp_output.c?
  /net/ipv4/tcp_minisocks.c?/net/ipv4/tcp_output.c?/
  net/ipv4/tcp_timer.c ??
• (4)IP?????????,????struct packet_type????????????
  /net/ipv4/ip_forward.c?ip_fragment.c?ip_input.c?i
  p_output.c ??
• (5)?????????????????struct net_device??,??????dev
  .c?,??????/driver/net????
• ????????????,????????,??????,???????

14

• 8.2 ???
• ?????(socket)????????????????I/O?????????
  ? ????,??socket??????socket??????socket????????
• 8.2.1 ??????
• ??????TCP/IP???????????????????????????????
  ?????????,?????????????????????
• ?????????????,??????????????????????????
  ?????????????????????,?????????????????
• Linux?BSD ???????????????
• 1. ??(stream)
• ??????????????????????????????????????IN
  ET????TCP????????? ?PF_INET?????,SOCK_STREAM??????
  ??????inet_stream_ops, ?????????tcp_prot?

15

• 2. ???(Datagram)
• ????????????????????????????,?????????????????
  ??????????????,????????????????????????????UDP????
  ??????????????(SOCK_DGRAM)??????????inet_dgram_ops
  ,?????????udp_prot?
• 3. ??(Raw)
• ?????????????????????????????(SOCK_RAW)???????
  ???inet_dgram_ops,?????????raw_prot?
• 4. ??????(Reliable Delivered Messages)
• ??????????????,??????????
• 5. ?????(Sequenced Packets)
• ?????????????,?????????????
• 6. ???(Packet)
• ??????BSD ?????,??Linux ??????????????????????
  ??

16

• 8.2.2?????????????
• ?????Unix????? (file descriptor)
  ?????????????
• Unix??????????I/O???,????????????????????
  ??????????????????????????????????????????????????
  ?????
• ??????????????,??????????????????open()??
  ?????????????????????????,????????????????????????
  ???????????????????
• ??,???????????????????,???????,??????????
  ?????,?????????,??????????????????????????????????
  ?????????????,???????????????????

17
1. BSD???
?8.1 BSD????????
?? ??
release ?????
bind ??????
connect ??????(TCP)?????????(UDP)
socketpair ?????????????
accept ????????
getname ??????
ioctl ??ioctl()??
listen ????????????
shutdown ??????????????
setsockopt ?????????
getsockopt ?????????
sendmsg ?????
recvmsg ?????
mmap ????????
sendpage ??????(????sendfile())
sk ??????sock,??????????
18

• ?Linux?,BSD?????????????(sockfs)?????????
  ?????????????????????????????????????????????,????
  ?,??????,?????????????????????????????????????sock
  et(family,type,protocol)??????????family,???type,?
  ??protocol?????,Linux?????????????????????????????
  ????????????,???????BSD???,??????????sockfs?????in
  ode?BSD?????????socket??????,??u.socket_i??????,u.
  socket_I?sockfs?????inode??????????
• ???BSD??????????????
• inode ??sockfs?inode????
• File ??sockfs????????
• State ??socket?????SS_FREE(???),SS_UNCNNECTE
  D(???),SS_CONNECTING(????),SS_CONNECTED(???),SS_DI
  SCONNECTING(??????)?
• Ops ????proto_ops????,????socket?????????????
  ???socket??????????????????????????????,?????????
  ??????????????????
• ?8.1 ???BSD?????????

19
?? ??
close ?????
connect ????????????
disconnect ????
accept ??????
ioctl Ioctl
init ??INET?????
destroy ????
shutdown ????????????
setsockopt ??socket
getsockopt ??socket??
sendmsg ??
recvmsg ??
bind ??????
backlog_rcv ??????????????
hash ?INET??????hash?
unhash ????
get_port ?INET????????
2. INET???
?8.2 INET????? ???
20

• INET????struct sock??????????TCP/IP???BSD?
  ??????INET???????sk???BSD??????????????,??INET???
  ??TCP/IP???????????????????INET???,????????????IP?
  ?,?????????,???????????????????,?????????????
• INET?????????????????????proto????????,?8
  .2???????
• INET?????????BSD??????????????,?????,??BS
  D??????????INET???????
• sock??????80??,????????????????????????

21

• 3. ????????
• ??????????,??????????
• ?? socket()??????????(sockfs)????????????????
  ?????????????,??????????????????????,?????????????
  ????????????,???????????
• (1) ??????????socket_file_ops,
  ??????????(proto_ops)???,?????????????????(proto)?
  ???
• (2) ??????socket????,??????sock?????????????i
  node?u.socket_i?????????????????
• (3) ???????????????????, ??????????????????,?
  ??????????????????

22

• 8.2.3 ???????
• 1. sock_init
• ?2.2?2.4???????,init/main.c?start_kernel????kernel
  _thread???init??,?init?????????do_basic_setup???,?
  ?????net/socket.c???sock_init??,??????TCP/IP???,??
  ?ipx?????
• ???????,sock_init???????????
• for (i 0 i lt NPROTO i)net_familiesi
  NULLsk_init()proto_init()
• ??net_families?include/linux/net.h????
• struct net_proto_familyint familyint
  (create)(struct socket sock, int protocol)
  // These are counters for the number of different
  methods of each we supportshort
  authenticationshort encryptionshort
  encrypt_net
• ??????????,?create?callback???????,??AF_INET??????
  ???TCP/ICMP??????

23

• sk_init???net/core/sock.c??
• struct sock sk_alloc(int family, int priority,
  int zero_it)struct sock sk
  kmem_cache_alloc(sk_cachep, priority)if(sk)
  if (zero_it)memset(sk, 0, sizeof(struct
  sock))sk-gtfamily familyreturn sk
• proto_init?????????
• void _init proto_init(void)extern struct
  net_proto protocolsstruct net_proto propro
  protocolswhile (pro-gtname !
  NULL)(pro-gtinit_func)(pro)pro
• struct net_proto?include/linux/net.h?
• struct net_protoconst char name // Protocol
  namevoid (init_func)(struct net_proto ) //
  Bootstrap
• ?protocols???net/protocols.c???,??????????????,???
  ????AF_INET?AF_PACKET?????????inet_proto_init?pack
  et_proto_init ?

24

• 2. IPv4???PACKET??????
• ????IPv4???PACKET????????????PACKET??????????,????
  ??????,??PACKET??,?net/packet/af_packet.c????packe
  t_proto_init????
• void _init packet_proto_init(struct net_proto
  pro)sock_register(packet_family_ops)registe
  r_netdevice_notifier(packet_netdev_notifier)
• ???sock_register?????,?????net/socket.c????net_fam
  ilies???????
• int sock_register(struct net_proto_family
  ops)if (ops-gtfamily gt NPROTO)
  printk(KERN_CRIT "protocol d gt
  NPROTO(d)\n",ops-gtfamily, NPROTO)return
  -ENOBUFSnet_familiesops-gtfamilyopsreturn
  0

25

• ??packet_netdev_notifier??structnotifier_block,???
  ??include/linux/notifier.h?????
• struct notifier_blockint (notifier_call)(struc
  t notifier_block self, unsigned long, void
  )struct notifier_block nextint priority
  
• register_netdevice_notifier????net/core/dev.c?,??
  
• int register_netdevice_notifier(struct
  notifier_block nb)return notifier_chain_regist
  er(netdev_chain, nb)
• notifier_chain_register???include/linux/notifier.h
  ??
• extern _inline_ int notifier_chain_register(struc
  t notifier_block list, struct notifier_block
  n)while(list)if(n-gtpriority gt
  (list)-gtpriority)breaklist
  ((list)-gtnext)n-gtnext listlistnretu
  rn 0

26

• ????block????,??block?????block??????notifier
  _chain_register???,?????????netdev_chain??????????
  ?interface???????????????????ioctl???,????????????
  ?????????????register_netdevice_notifier?????netde
  v_notifier????,??????????notifier_call?????interfa
  ce??????
• inet_proto_init????net/ipv4/af_inet.c?,?????
  ifdef??????????????????CONFIG_NET_IPIP?CONFIG_NET
  _IPGRE?CONFIG_IP_FIREWALL?CONFIG_IP_MASQUERADE?CON
  FIG_IP_MROUTE ,???CONFIG_INET_RARP?CONFIG_PROC_FS?
  ??????,?????????

27

• (void) sock_register(inet_family_ops)for(p
  inet_protocol_base p ! NULL) struct
  inet_protocol tmp(struct inet_protocol
  )p-gtnextinet_add_protocol(p)printk("ss",p-gt
  name,tmp?", ""\n")p tmp
• arp_init()ip_init()tcp_v4_init(inet_family_op
  s)tcp_init()icmp_init(inet_family_ops)
• rarp_ioctl_hook rarp_ioctlproc_net_register(p
  roc_net_rarp)proc_net_register(proc_net_raw)p
  roc_net_register(proc_net_snmp)proc_net_registe
  r(proc_net_netstat)proc_net_register(proc_net_
  sockstat)proc_net_register(proc_net_tcp)proc_
  net_register(proc_net_udp)

28

• 3. struct inet_protocol?inet_add_protocol??
• struct inet_protocol??????include/net/protocol.h??
  ?
• struct inet_protocolint (handler)(struct
  sk_buff skb, unsigned short len)void
  (err_handler)(struct sk_buff skb, unsigned char
  dp, int len)struct inet_protocol
  nextunsigned char protocolunsigned char
  copy1void dataconst char name
• ??????????callback?????,??????????,???copy???????,
  data????????????

29

• inet_add_protocol???net/ipv4/protocol.c?
• void inet_add_protocol(struct inet_protocol
  prot)unsigned char hashstruct inet_protocol
  p2
• hash prot-gtprotocol (MAX_INET_PROTOS -
  1)prot -gtnext inet_protoshashinet_protosh
  ash protprot-gtcopy 0
• p2 (struct inet_protocol ) prot-gtnextwhile(p2
  ! NULL)if (p2-gtprotocol
  prot-gtprotocol)prot-gtcopy 1breakp2
  (struct inet_protocol ) p2-gtnext
• ?????????????hash?,??hash?????????,????hash???????
  ??????????

30

• ??????CONFIG_SYSCTL ,?arp_init????net/ipv4/arp.c?
  
• neigh_table_init(arp_tbl)dev_add_pack(arp_pack
  et_type)proc_net_register(proc_net_arp)
• ??????dev_add_pack???
• neigh_table_init???net/core/neighbour.c??
• void neigh_table_init(struct neigh_table
  tbl)unsigned long now jiffies
• tbl-gtparms.reachable_time neigh_rand_reach_time(
  tbl-gtparms.base_reachable_time)
• init_timer(tbl-gtgc_timer)tbl-gtgc_timer.data
  (unsigned long)tbltbl-gtgc_timer.function
  neigh_periodic_timertbl-gtgc_timer.expires now
  tbl-gtgc_interval tbl-gtparms.reachable_timead
  d_timer(tbl-gtgc_timer)
• init_timer(tbl-gtproxy_timer)tbl-gtproxy_timer.da
  ta (unsigned long)tbltbl-gtproxy_timer.function
  neigh_proxy_processskb_queue_head_init(tbl-gt
  proxy_queue)
• tbl-gtlast_flush nowtbl-gtlast_rand now
  tbl-gtparms.reachable_time20tbl-gtnext
  neigh_tablesneigh_tables tbl
• jiffies????????,?i386?????jiffies??50ms,????????ti
  mer,??????????timerlist???gc_timer???????????(garb
  age collect timer)???????arp?cache????,??????expir
  es??,????????????arp???proxy_timer??????????timer?
  function??????????,data????????????????

31

• ???dev_add_pack??,??net/core/dev.c??
• void dev_add_pack(struct packet_type pt)int
  hashifdef CONFIG_NET_FASTROUTE// Hack to
  detect packet socketif (pt-gtdata)
  netdev_fastroute_obstaclesdev_clear_fastrout
  e(pt-gtdev)endifif(pt-gttypehtons(ETH_P_ALL)
  )netdev_nitpt-gtnextptype_allptype_allpt
  elsehashntohs(pt-gttype)15pt-gtnext
  ptype_basehashptype_basehash pt
• ????????,???ptype_all,?????????????,?????hash????
  ???,???????????

32

• struct packet_type????include/linux/netdevice.h?,?
  ??????,??????????
• unsigned short type // This is really
  htons(ether_type)?struct device dev //
  NULL is wildcarded hereint (func) (struct
  sk_buff ,struct device , struct packet_type
  )void data // Private to the packet
  typestruct packet_type next
• ???func??????arp_packet_type??
• static struct packet_type arp_packet_type
  _constant_htons(ETH_P_ARP),NULL, // All
  devicesarp_rcv,NULL,NULL

33

• arp_init????????proc_net_register??,?????include/l
  inux/proc_fs.h?
• static inline int proc_net_register(struct
  proc_dir_entry x)return proc_register(proc_ne
  t, x)
• proc_register?fs/proc/root.c???,???????proc_net???
  ??????????????,??TCP??/proc???????????,????????/pr
  oc/net?????????????????????

34

• 4. ip_init??
• ip_init????net/ipv4/ip_output.c?
  (?????????CONFIG_PROC_FS,CONFIG_IP_MULTICAST?CONFI
  G_NET_CLS_ROUTE)
• _initfunc(void ip_init(void))dev_add_pack(ip_p
  acket_type)ip_rt_init()proc_net_register(proc
  _net_igmp)

35

• ip_rt_init????net/ipv4/route.c?????,????????
• _initfunc(void ip_rt_init(void))struct
  proc_dir_entry entdevinet_init()ip_fib_init()
  rt_periodic_timer.function rt_check_expire//
  All the timers, started at system startup
  tendto synchronize?Perturb it a
  bit.rt_periodic_timer.expires jiffies
  net_random()ip_rt_gc_interval
  ip_rt_gc_intervaladd_timer(rt_periodic_timer)
  
• proc_net_register((struct proc_dir_entry)
  PROC_NET_RTCACHE, 8, "rt_cache",S_IFREG
  S_IRUGO, 1, 0, 0,0, proc_net_inode_operations,r
  t_cache_get_info)ent create_proc_entry("net/
  rt_acct", 0, 0)ent-gtread_proc
  ip_rt_acct_read
• ????????????notifier???????????,???/proc??????????
  ????proc_net_register????????,?create_proc_entry??
  ?/proc/net????????rt_acct,????????(account)???ip_r
  t_acct_read????,????????????ip_rt_acct????????????
  ?

36

• devinet_init???net/ipv4/devinet.c?????,?????
• register_gifconf(PF_INET, inet_gifconf)register_
  netdevice_notifier(ip_netdev_notifier)
• register_netdevice_notifier????PACKET??????????,re
  gister_gifconf?????????SIOCGIFCONF????????????????
  ???PF_INET??,??????inet_gifconf???
• ????net/ipv4/devinet.c??inet_gifconf??,????????int
  erface???????,?????name?address????

37

• register_gifconf????net/core/dev.c?,??
• static gifconf_func_t gifconf_list NPROTO
• int register_gifconf(unsigned int family,
  gifconf_func_t gifconf)if (familygtNPROTO)re
  turn -EINVALgifconf_listfamily
  gifconfreturn 0
• dev_ioctl?????????interface?I/O???gifconf_list????
  ?dev_ifconf??????,?dev_ifconf???dev_ioctl???????in
  terface?ioctl??????????????????gifconf????gifconf?
  ?generous interface configure,???????????

38

• ip_fib_init????net/ipv4/fib_frontend.c?,??
• _initfunc(void ip_fib_init(void))proc_net_regis
  ter((struct proc_dir_entry) PROC_NET_ROUTE, 5,
  "route",S_IFREG S_IRUGO, 1, 0, 0,0,
  proc_net_inode_operations,fib_get_procinfo)
• fib_rules_init()register_netdevice_notifier(fib
  _netdev_notifier)register_inetaddr_notifier(fib
  _inetaddr_notifier)
• register_inetaddr_notifier??????register_netdevice
  _notifier??,????notifier_chain_register??????????,
  ???????interface?????????????net/ipv4/fib_rules.c?
  ?fib_rules_init????????register_netdevice_notifier
  ????fib_rules_notifier??????
• fib??IPv4 Forwarding Information
  Base,?IPv4??????

39

• 5. tcp_v4_init???
• ????net/ipv4/tcp_ipv4.c??tcp_v4_init??
• _initfunc(void tcp_v4_init(struct
  net_proto_family ops))int err
• tcp_inode.i_mode S_IFSOCKtcp_inode.i_sock
  1tcp_inode.i_uid 0tcp_inode.i_gid 0
• tcp_socket-gtinode tcp_inodetcp_socket-gtstate
  SS_UNCONNECTEDtcp_socket-gttypeSOCK_RAW
• if ((errops-gtcreate(tcp_socket,
  IPPROTO_TCP))lt0)panic("Failed to create the TCP
  control socket.\n")tcp_socket-gtsk-gtallocationGF
  P_ATOMICtcp_socket-gtsk-gtnum
  256tcp_socket-gtsk-gtip_ttl MAXTTL
• tcp_inode????inode??,?tcp_socket??tcp_inode.u.sock
  et_I,??????????????????

40

• tcp_socket??????,?????TCP???socket?????socke
  t,?TCP???????socket?,?socket????socket????????????
  ????SYN???RST,???????????SYN(???accept????socket)
  ?
• ??AF_INET??,ops-gtcreate?????net/ipv4/af_inet
  .c?inet_create??,??????????socket????????,????????
  ?
• ???socket?????,??????????????net/ipv4/tcp.c?
  ??tcp_init????????????hash??bucket????????????????
  
• tcp_openreq_cacheptcp_bucket_cacheptcp_timewait_
  cacheptcp_ehashtcp_bhash
• ??ehash??established hash, bhash??bind
  hash,????????????TCP_ESTABLISHED lt sk-gtstate lt
  TCP_CLOSE???SOCK??????????????????

41

• ??net/ipv4/icmp.c??icmp_init????ICMP?????????
  ??,????ICMP,???tcp_v4_init???IPPROTO_TCP???IPPROTO
  _ICMP?proc_net_register?????????
• ??,?Linux IP?????????????????,??????????
• (1)dev_add_pack
• ??????????????,????????????????????????,????
  ??????copy?????ETH_P_ALL???????????????????ptype_a
  ll???ptype_base hash????
• (2)inet_add_protocol
• ???????IP??????,??TCP?UDP??
• (3)proc_net_register(?????proc_register)
• ?/proc/net???????????????????????????????

42

• 8.2.4 ????????
• ????????????????,????????????A,????????B,??A
  ??????????B??????,?"Hello",?B??????
• ??TCP????????,??????,?????UDP?????

43

• 1. ?????
• ???????,????????(socket),???????????????
• ...
• int sockfd
• sockfdsocket(AF_INET,SOCK_DGRAM,0)
• ...
• ???????,?????0x80????????,???????????Socket?
  ????????,???????????????,?sys_socketcall??????,???
  ?????????sys_socket?socket_bind????

44

• sys_socket??sock_create????struct
  socket??(?include/linux/net.h),???????????????????
  ?,????????????????(???inode,????????type????),????
  ??????????,?
• ...
• net_familiesfamily-gtcreate(sock, protocol)
• ...
• ?????????AF_INET,??????????inet_create()net_famil
  ies????,????????(net families)???,???????sock_regi
  ster???

45

• ?struct socket??????????????struct
  sock???,????????????????inet_create?????????,?????
  ???(??socket????????),???????
• ...
• if (sk-gtprot-gtinit)
• sk-gtprot-gtinit(sk)
• ...
• ?????SOCK_STREAM,???tcp_v4_init_sock???SOCK_D
  GRAM???socket?????????,??socket?????
• ?inet_create()????,?????sock_map_fd?????????
  ???????????????file???????????????????????
• ????????????????,????????????????????,?????
  ???????????

46

• 2. ????
• ???A??????,?????????(??sendto???????????)
• ...
• write(sockfd,"Hello",strlen("Hello"))
• ...
• write???????????sys_write,??????????????struc
  t file??????????(file????)???(file-gtf_mode
  FMODE_WRITE?true),????????????
• ...
• if (file-gtf_op (write file-gtf_op-gtwrite) !
  NULL)
• ret write(file, buf, count, file-gtf_pos)
• ...
• ??f_op??struct file_operations????,?sock_map
  _fd?????socket_file_ops,?????(/net/socket.c)

47

• static struct file_operations socket_file_ops
• llseek sock_lseek,
• read sock_read,
• write sock_write,
• poll sock_poll,
• ioctl sock_ioctl,
• mmap sock_mmap,
• open sock_no_open, // special open code to
  disallow
• open via /proc
• release sock_close,
• fasync sock_fasync,
• readv sock_readv,
• writev sock_writev
• ??wirte?????????sock_write,??????????????str
  uct msghdr,?????sock_sendmsg.?
• ...
• sock-gtops-gtsendmsg(sock, msg, size, scm)
• ...
• ????sock-gtops?inet_create()???????????UDP???
  ?,sock-gtops???inet_dgram_ops(?sock-gtops
  inet_dgram_ops),????net/ipv4/Af_inet.c?

48

• struct proto_ops inet_dgram_ops
• family PF_INET,
• release inet_release,
• bind inet_bind,
• connect inet_dgram_connect,
• socketpair sock_no_socketpair,
• accept sock_no_accept,
• getname inet_getname,
• poll datagram_poll,
• ioctl inet_ioctl,
• listen sock_no_listen,
• shutdown inet_shutdown,
• setsockopt inet_setsockopt,
• getsockopt inet_getsockopt,
• sendmsg inet_sendmsg,
• recvmsg inet_recvmsg,
• mmap sock_no_mmap,
• ?????inet_sendmsg()??,??????????????????

49

• ...
• sk-gtprot-gtsendmsg(sk, msg, size)
• ...
• ?????????????inet_create?
• ...
• protudp_prot
• ...
• ??udp_sendmsg???,????????????UDP?(???,?????)
  ,?????ip_route_output,??????????,??
• ...
• ip_build_xmit(sk,
• (sk-gtno_check UDP_CSUM_NOXMIT ?
• udp_getfrag_nosum
• udp_getfrag),
• ufh, ulen, ipc, rt, msg-gtmsg_flags)
• ...
• ip_build_xmit????????????sk_buff,???????IP???
  

50

• NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
• rt-gtu.dst.dev,output_maybe_reroute)
• ...
• ??????????????,????????????output_maybe_rero
  ute,?output_maybe_reroute?????
• return skb-gtdst-gtoutput(skb)
• ?????ip_route_output????,ip_route_output?????????,
  ???????skb-gtdst?(???ip_route_output_slow?rth-gtu.
  dst.outputip_output)?
• ??ip_output??,???????ip_finish_output????????
  ????????net_device??,?ip_finish_output?????????ip_
  route_output???????????????netfilter?NF_IP_POST_RO
  UTING??????,?????ip_finish_output2,???????
• ...
• hh-gthh_output(skb)
• ...
• ?????dev_queue_xmit,?????TCP/IP????,????????
  ???
• ?????????,??????

51

• ...
• dev-gthard_start_xmit(skb, dev)
• ...
• ?????????????????,?????????????,?????3c509??(
  ??????3c509.c),?????????(el3_probe),?
• ...
• dev-gthard_start_xmit el3_start_xmit
• ...
• ?????IO??,?????????????,?????????
• ???????????,???????,????????????????????????
  ???????????????(???TCP??)?

52

• 3. ????
• ???????????,?????????,??????????????????3c509?????
  ???el3_interrupt(???IRQ???????,????????request_ir
  q????)???????????????????IO??,?????(?IO?inw??),???
  ??????,??el3_rx(dev)??????
• ?el3_rx?,???????????struct sk_buff,???????,???????
  ??netif_rx(dev.c)????CPU???,???????????????????net
  if_rx?????????????sk_buff???????,????????,????????
  ,?????????????
• ...
• _skb_queue_tail(queue-gtinput_pkt_queue,skb)
• _cpu_raise_softirq(this_cpu, NET_RX_SOFTIRQ)
• ...
• ???????,???????????CPU??(??????????)????????schedu
  le()?,??????????,????????????

53

• ...
• if (softirq_active(this_cpu) softirq_mask(this_c
  pu))
• goto handle_softirq
• handle_softirq_back
• ...
• ...
• handle_softirq
• do_softirq()
• goto handle_softirq_back
• ...
• ???????,?????net_dev_init?,????????????net_rx
  _action
• ...
• open_softirq(NET_TX_SOFTIRQ, net_tx_action,
  NULL)
• ...
• ??????????????,?????????NET_TX_SOFTIRQ???,???
  ??net_rx_action?
• net_tx_action???2.2????net_bh???????,????????
  ???????,?????ptype_all,???????ptype_base16??????
  ?????????OSI7???????????????????????struct
  packet_type??,????????dev_add_pack????????ptype_al
  l?ptype_base??

54

• ??packet_type??type??ETH_P_ALL?,?????ptype_a
  ll???,???ip_packet_type,????ptype_base16????????
  ????????????ETH_P_ALL????,?????????????,?????????
  ???????
• skb-gtprotocol??el3_rx????,??????????????????
  ??,??????,????ETH_P_IP,???net_tx_action?,???IP????
  ??????ip_packet_type ????,??????ip_recv()?
• pt_prev-gtfunc(????ip_recv)?????atomic_inc(s
  kb-gtusers)??(?2.2??????????skb_clone,????),???????
  sk_buff??????????????????????????????sk_buff?(????
  )???kfree_skb,?kfree_skb?????????????????,????????
  ????(_kfree_skb),????????1?

55

• ??net/ipv4/ip_input.c????ip_recv???????????
  ????????(???????????????),???????????????2.4???,??
  ?????????,??????ip_recv??????,???????ip_recv??????
  ???ip_rcv_finish????ip_rcv_finish?,??????IP??(????
  ?)?IP?,??????ip_route_input????,???????skb-gtdst???
  ???????????????????????????,?????????????????????
  ???????????,???ip_local_deliver(/net/ipv4/ip_inpu
  t.c),????ip_forward(/net/ipv4/ip_forward.c)?skb-gtd
  st-gtinput???????????????????
• ??????????,????ip_local_deliver?????????????
  ??,???????????????,??ip_local_deliver??????????,??
  ????(???sk_buff???),??????
• ???????netfilter????????????,???/net/ipv4/ip
  _input.c?ip_local_deliver_finish??

56

• ???(?TCP?UDP?RAW)????????inet_protos?(??inet
  _add_protocol)?ip_local_deliver_finish???IP???????
  ????(?iph-gtprotocol),??????????????,???udp,???ippr
  ot-gthandler????udp_rcv??
• ???????????socket???????struct
  socket/struct sock???udp_rcv???udp_v4_lookup??????
  ???sock,?????????udp_queue_rcv_skb(/net/ipv4/udp.c
  )??????sock_queue_rcv_skb??,????sk_buff??????,????
  ??????

57

• ...
• kb_set_owner_r(skb, sk)
• skb_queue_tail(sk-gtreceive_queue, skb)
• if (!sk-gtdead)
• sk-gtdata_ready(sk,skb-gtlen)
• return 0
• ...
• sk-gtdata_ready????sock????????(sock_init_data)
• ...
• sk-gtdata_readysock_def_readable
• ...
• ????????
• ??B??????,??????
• ...
• read(sockfd,buff,sizeof(buff))
• ...
• ?????????????sys_read(fs/read_write.c)??????
  ?write???,?????udp_recvmsg?????skb_recv_datagram,?
  ????????,?socket???????,?????(signal_pending(curre
  nt)),??data_ready???????????????(wake_up_interrupt
  ible(sk-gtsleep))?

58

• 8.3 ??????
• ??????,???????????(sk_buff)?????????,?????????????
  ?sk_buff???,??????????????????
• 8.3.1 ????????????

Linux?????????????,?????????????????????????
?,Linux?????????????????????????????,????????????
?????????? ???????????????????,??????????????
????????,????????????????,??,??????????????,??????
??????????????,???????????????????????????????????
?????,????????????????????????,????????,??????????
???,Linux ????????(sk_buff)????????????????Linux??
???????????????????????????????sk_buff,sk_buff
????????????,?????????????????????????????????????
buffer??sk_buffs? ???????,???????????????
sk_buffs??????????????????
? 8.4 Linux ???????(sk_buff)
59
8.3.2 ???????????
? 8.5 sk_buff ???????
???? ??
Head ??????????????sk_buff ???????????,??????????
data ???????????????????????? sk_buff ???????????
tail ??????????????? data ????,??????????? sk_buff ???????????
end ????????????? head ????,sk_buff ?????,???????????
?? 8.4 ??,?? sk_buff ?????????4?????????????????
???,???????????????????,? 8.5 ????????????
60
sk_buff ???????,len ? truesize,?????????????
?????????????sk_buff ?????????????????????????????
??????,???????????? sk_buff ???? data ? tail
??,?????? 8.6 ??? ? sk_buff ?????,?????????
sk_buff ?????????????????????????????????????
sk_buff ???????? ? 8.6 sk_buff ???????????
???? ??
push ???? data ????????????? len ??????????????,?????????????????????
pull ???? push ???????,?? data ??????????,??? len ?????????????????????????????
put ???? tail ????????????? len ??????????????,?????????????????????
trim ???? put ???????,?? tail ??????????,??? len ?????????????????????????????
61

• 8.3.3 ???????????
• ??sk_buff???????????? ????????
  ????????sk_buffs???????,??????????????
  ????????????????????,????????????????
• ???????
• void append_frame(char buf,int len)
• struct sk_buff skb alloc_skb(len,GFP_ATOMIC)
  
• if (skb NULL)
• my_dropped
• else
• skb_put(skb,len)
• memcpy(skb-gtdata,data,len)
• skb_append(my_list,skb)
• void process_queue(void)
• struct sk_buff skb
• while ((skb skb_dequeue(my_list)) ! NULL)
• process_data(skb)

62
? net/core/dev.c ?? netif_rx() ? net_bh()
????????,??????????????????,????????
skb_put() ??????????memcpy?????
???????????????,?????skb_push????????,??????????8.
5??
? 8.5
skb_put?skb_push ??skb_reserve()????????,?????????
????????? skb alloc_skb(lenheadspace,GFP_KERNE
L) skb_reserve(skb,headspace) skb_put(skb,len)
memcpy_fromfs(skb-gtdata,data,len) pass_to_m_proto
col(skb)
63

• ???????
• (1) skb_dequeue()
• struct sk_buff _skb_dequeue(struct sk_buff_head
  list)
• ????????????,??????????? ??? skb_queue_head ?
  skb_queue_tail ??????????
• (2) skb_queue_head()
• void skb_queue_head(struct sk_buff_head
  list,struct sk_buff newsk)
• ????????????????
• (3) skb_queue_tail()
• void skb_queue_tail(struct sk_buff_head
  list,struct sk_buff newsk)
• ????????????????
• (4) skb_unlink()
• void skb_unlink(struct sk_buff skb)
• ?????????????????????,???????????

64

• (5) skb_insert skb_append
• void skb_insert(struct sk_buff old,struct
  sk_buff newsk)
• void skb_append(struct sk_buff old,struct
  sk_buff newsk)
• ????????????????????,??????????????????????
• (6) alloc_skb()
• define alloc_skb(size,priority)
• (struct sk_buff ) kmalloc(size,priority)
• ????????sk_buff? ???????? skb-gtfree1 ???????
• (7) kfree_skb()
• void kfree_skb(struct sk_buff skb)
• ??????sk_buff?
• (8) skb_clone()
• struct sk_buff skb_clone(struct sk_buff
  skb,int gfp_mask)
• ???sk_buff???,?????????
• (9) skb_copy()
• int skb_copy_datagram(struct sk_buff skb,int
  offset,
• char to,int size)
• ????sk_buff????

65

• 8.3.4 ?????????????
• sock_queue_rcv_skb() ????????????????????
• sk my_find_socket(whatever)
• if (sock_queue_rcv_skb(sk,skb) -1)
• myproto_stats?dropped
• kfree_skb(skb,FREE_READ)
• return
• ?????????????socket? ?????????,???????
• ????,sock_alloc_send_skb() ????????,??????
• skbsock_alloc_send_skb(sk,????)
• if(skb NULL)
• return -err
• skb-gtsk sk
• skb_reserve(skb,headroom)
• skb_put(skb,len)
• memcpy(skb-gtdata,data,len)
• protocol_do_something(skb)
• ???????? skb-gtsk sk,sock_alloc_send_skb()
  ?????????socket,????????kfree_skb()?,??sk?????????
  ???????????,????????????

66

• 8.4 ????????
• ?Linux?,????????????????????(packet)???????
• 8.4.1 Linux????????
• ????????????????????,???????????????,???????
  ????,??????????????????????????????????????????lin
  ux/net/core???,??linux/net/core/dev.c????????
• Linux??TCP/IP,IPX,X.25,AppleTalk????,???????
  ?????linux/net/???????????????TCP/IP
  (IPv4)??,??????linux/net/ipv4?,??linux/net/ipv4/af
  _inet.c?????????

67
???????????linux/net/socket.c?????Socket????????
???????????????linux/net/socket.c? 1. ????
?
8.6 ????????? ???Linux?????????????(???????
)??drivers/net/skeleton.c ????????????????????????
?????????????????????,????????????,?netif_rx()??,?
????????????????????????????????????????????,??8.6
???
68
2. ???? ???Linux??????????,?????????????????
???????????(??????)?
ethn ????
trn ???
sln SLIP??
pppn PPP??
plipn PLIP??
tunln IP IP????
nrn NetROM ????
isdnn ISDN??
dummyn ???
lo ??????
69

• 3. ????
• ??register_netdev(struct device )??????
  struct device ??????????? ?????????struct
  device??????????????? unregister_netdev(struct
  device ) ???????????,??????????????????,?????????
  ,???? struct device dev_get(const char
  name)?????????????,??????,????????????????
• ???????????
• int register_my_device(void)
• int i 0
• for(i 0i lt 100i)
• sprintf(mydevice?name,"mydevd",i)
• if(dev_get(mydevice?name) NULL)
• if(register_netdev(mydevice) ! 0)
• return -EIO
• return 0
• printk("100 mydevs loaded? Unable to load more?
• ")
• return -ENFILE

70

• 4. ????????
• ????????????? struct device
  ?,????????????????? struct device???????
• ?????(name)?????????,????????,???????????eth
  n???,????????????
• ??????(Bus Interface Parameters)????????????
  ??????
• ?????(Protocol Layer Variables)???????????
  mtu??

71

• 8.4.2 ??????
• ??????????????????,??include/linux/if_arp.h?
  28?????ARP??????????????????????????????????,?????
  ????????,???????????????????????????????3c501?????
  ???(???linux/drivers/net/3c501.c)??,??????????
• ?????????????????????,?????????????

72

• ??????????,?linux/drivers/net/3c501.c?el_sta
  rt_xmit() ???????3Com3c501???????????,????????????
  ????????,?????????
• ??????????????????,??????????,?????????linux
  /drivers/net/3c501.c?el_interrupt()????,??????????
  ???????,??????????????,????????????el_interrupt()?
  ???????????????,??????????el_receive()?el_receive(
  )????????????,???????????????????(dev_alloc_skb(
  )),?????????????????,??????net/core/dev.c??????net
  if_rx(),???????
• ????????????????,????????????????,??????????
  ??????????

73

• ???????,???????????net/core/dev.c???netif_rx
  ()?????,????????????????????,?????????????????????
  ?,??????????????????????
• ???????????????????????????????????,????????
  ???????,??????????????????????dev_base??,??linux/i
  nclude/linux/netdevice.h ????structnet_device
  dev_base?????????????????????????,?????????(?incl
  ude/linux/netdevice.h????)?net_device??,??????????
  ?????????????

74

• struct net_device
• open()
• stop()
• hard_start_xmit()
• hard_header()
• rebuild_header()
• set_mac_address()
• do_ioctl()
• set_config()
• hard_header_cache()
• header_cache_update()
• change_mtu()
• tx_timeout()
• hard_header_parse()
• neigh_setup()
• accept_fastpath()

75

• ????????????????????,????dev_base???????,????
  ???????????net_device?????????????dev_base????????
  ????linux/drivers/net/net_init.c????register_netde
  v(dev_3c50)????????????net_device????????????????
  ????/drivers/net/3c501.c??el1_probe1()????
• el1_probe1()
• dev-gtopen el_open
• dev-gthard_start_xmit el_start_xmit
• dev-gttx_timeout el_timeout
• dev-gtwatchdog_timeo HZ
• dev-gtstop el1_close
• dev-gtget_stats el1_get_stats
• dev-gtset_multicast_list set_multicast_list
• ether_setup(dev)
• ?????????drivers/net/net_init.c??ether_setup
  (dev)????
• ??dev-gthard_start_xmit el_start_xmit,??????
  ?????????????dev-gthard_start_xmit?????,el_start_x
  mit????????????????????

76

• 8.4.3 ??????
• ??????????????????,?????????????????????????
  ???????????????
• ???????????net/core/dev.c?dev_queue_xmit()??
  ????????????????IP,??ARP??,???????????????????,???
  ?????????????dev_queue_xmit()?????????dev-gthard_st
  art_xmit(),dev-gthard_start_xmit()?????????????????
  ?????,??dev-gthard_start_xmit()???????el_start_xmit
  ()?

77

• ???????,?????????net/core/dev.c
  ????netif_rx()???????????,????????????????????????
  ?????,???????????????????????????????????????,??,?
  ?dev_base?????????????????????????????????????
  net/core/dev.c ?static struct packet_ptype_base16
  ?????????????????????????,?????????????
• ????,IP?????????ip_rcv()???,?ARP?????arp_rcv
  ()?,???????????????????????????

78

• ??????????????????????,?????net/core/dev.c??
  dev_add_pack()???dev_remove_pack()???Ip?????net/ip
  v4/ip_output.c ???????void _init ip_init(void)???
• dev_add_pack(ip_packet_type)

79

• ?????????net/core/dev.c ????netif_rx()??????
  ??????,?????????,??????????,????????cpu_raise_soft
  irq (this_cpu?NET_RX_SOFTIRQ)???????,
  ?open_softirq(NET_RX_SOFTIRQ, net_rx_action,
  NULL)????,NET_RX_SOFTIRQ???????????net/core/dev.c?
  ?net_rx_action()?net_rx_action()?????????????ptype
  _base16????????,?????????????,????????????,?????
  ?????,???????????net_rx_action()??pt_prev-gtfunc()?
  ?????????IP????,ptype_baseETH_P_IP-gtfunc()(ip_rc
  v()),??????????IP???

80

• 8.4.4 ??????
• ??????????????????linux/include/linux/socket
  .h?,Linux?BSD Socket?????32???????,??PF_INET??????
  TCP/IP???(IPv4, ????????IPv4)???????????,?????????
  ????TCP/IP?????????inux/net/ipv4/????,linux/net/ip
  v4/af_inet.c?????????
• ?Linux2.4.x??,???TCP/IP???????IGMP?TCP?UDP?I
  CMP?ARP?IP?????????,IP?ARP????????????????????,???
  ?????????(core)???????????????(TCP?UDP?IGMP?ICMP)?
  ??????IP???,???IP??????,????IP??????,???????Socket
  ???????????????IP?????????,??????????,????????????
  ???????

81

• ?IP????,??????(core) ?????IP????,??ptype_bas
  eETH_P_IP???IP???????IP???ip_packet_type-gtip_rcv
  ()?????????IP?,????IP???????ip_rcv()(linux/net/ipv
  4/ip_input.c)??????ip_rcv()??????IP???????checksum
  ?????,????????????????????ip_rcv_finish()(???????
  NF_HOOK????)???,ip_rcv_finish()????????IP????????I
  P??????????,??????????????????????/linux/net/ipv4/
  route.c???ip_route_input()??????????,??????????
• (1)???????(???????TCP,UDP,IGMP???????)
• (2)?????????(????NAT??????)
• (3)?????????(??????)

82

• ?????????,ip_route_input()????net/ipv4/route
  .c?ip_route_input_slow(),?ip_route_input_slow()???
  rth-gtu.dst.inputip_local_deliver,?????IP????????,
  ?????????????????????????,???ip_rcv_finish()?ip_rc
  v_finish()?????skb-gtdst-gtinput(skb),????????ip_loc
  al_deliver()??,ip_local_deliver()??????ip_local_de
  liver_finish()?????????????
• ???????(core)??????ptype_base16???????????
  ?????????,?/linux/net/ipv4/protocol.c?,??????????
  ?????struct net_protocolinet_protosMAX_INET_PROT
  OS,?????????IP????????????(IGMP,TCP,UDP,ICMP)????
  ??????????TCP???????

83

• linux/net/ipv4/protocol.c line67
• static struct inet_protocol tcp_protocol
• handlertcp_v4_rcv,// ???????
• err_handlertcp_v4_err,// ???????
• nextIPPROTO_PREVIOUS,
• protocolIPPROTO_TCP,
• name"TCP"
• ???????linux/net/ipv4/protocol.c,IP?????????
  ?????????TCP???linux/net/ipv4/protocol.c???,??????
  ?????????igmp_rcv()?udp_rcv()?icmp_rcv()??????????
  ?,???inet_protosMAX_INET_PROTOS???????????inet_a
  dd_protocol()???,???????inet_del_protocol()????ine
  t_protosMAX_INET_PROTOS???????linux/net/ipv4/af_
  inet.c inet_init()????????
• inet_init()
• printk(KERN_INFO "IP Protocols")
• for (p inet_protocol_base p ! NULL)
• struct inet_protocol tmp (struct inet_protocol
  ) p-gtnext
• inet_add_protocol(p)// ????
• printk("ss",p-gtname,tmp?", ""\n")
• p tmp

84

• ???Linux??????????????, ??linux?????dmesg???
  ????????????
• IP Protocols ICMP,UDP,TCP,IGMP
• ??,??inet_protos ????ICMP?UDP?TCP?IGMP????
  ?inet_protocol????,???????????????????
• Linux 2.4.x?linux/include/linux/socket.h????
  32????BSDsocket??,????TCP/IP?IPX/SPX?X.25?,???????
  ????????TCP/IP????TCP????????,???UDP??????????????
  ????,??????????????,???????socket?????
• ?BSD socket????????,????????????????????????
  ?????TCP?????????

85

• sock_descriptor socket(AF_INET,SOCK_STREAM,0)
• connect(sock_descriptor, ??,)
• send(sock_descriptor,hello world)
• recv(sock_descriptor,buffer,1024,0)
• ??????????Inet??,?TCP/IP??,????????????,????
  ??TCP??,?????????socket?????????
• ????,??socket?????????????(???AF_INET),???32
  ??????????????????,????????,????????????????????,?
  ????????????????,Inet???????TCP???

86

• ???????????????,??????????????,?????????????
  ?????????????,????????????,??????????linux/net/soc
  ket.c???????
• staticstructnet_proto_family net_familiesNPROTO
  
• ??????????,net_families2?TCP/IP??,net_fami
  lies3?X.25??,???????????,?include/linux/socket.h
  ??????????????net_proto_family?ops???,????????????
  ????????????????ops???????sock_register()(linux/ne
  t/socket.c)???????,??TCP/IP???????????
• int _init inet_init(void) (net/ipv4/af_inet.c)
• (void) sock_register(inet_family_ops)
• ????AF_INET(??????2),?????net_failies2
  ?????????

87

• ????????,??????????????????????????????????,
  ??????????????????TCP/IP????,?????????
  net/ipv4/af_inet.c??struct list_head
  inetswSOCK_MAX???????????????????,????net/ipv4/a
  f_inet.c???????inetsw_array
• static struct inet_protosw inetsw_array
• typeSOCK_STREAM,
• protocolIPPROTO_TCP,
• prottcp_prot,
• opsinet_stream_ops,
• capability-1,
• no_check0,
• flagsINET_PROTOSW_PERMANENT,
• ,
• typeSOCK_DGRAM,
• protocolIPPROTO_UDP,
• protudp_prot,
• opsinet_dgram_ops,
• capability-1,
• no_checkUDP_CSUM_DEFAULT,

88

• ????,SOCK_STREAM????TCP??,SOCK_DGRAM????UDP?
  ?,SOCK_RAW????IP???????????inet_register_protosw()
  ?inetsw_array?????????inetswSOCK_MAX??????inet_i
  nit() (net/ipv4/af_inet.c) ?????????
• ???????????socket,???accept?send()?connect()
  ?release()?bind()????????????ops?prot?????????????
  TCP??
• typeSOCK_STREAM,
• protocolIPPROTO_TCP,
• prottcp_prot,
• opsinet_stream_ops,
• capability-1,
• no_check0,
• flagsINET_PROTOSW_PERMANENT,
• ,
• ???? tcp_prot???

89

• struct proto tcp_prot
• name"TCP",
• closetcp_close,
• connecttcp_v4_connect,
• disconnecttcp_disconnect,
• accepttcp_accept,
• ioctltcp_ioctl,
• inittcp_v4_init_sock,
• destroytcp_v4_destroy_sock,
• shutdowntcp_shutdown,
• setsockopttcp_setsockopt,
• getsockopttcp_getsockopt,
• sendmsgtcp_sendmsg,
• recvmsgtcp_recvmsg,
• backlog_rcvtcp_v4_do_rcv,
• hashtcp_v4_hash,
• unhashtcp_unhash,
• get_porttcp_v4_get_port,

90

• 8.4.5 Socket???????
• ????socket()?bind()?connect()?accept?send()?
  release()???linux/net/socket.c?????,??????????????
  ???????sys_????
• ?????socket()?????,Socket(AF_INET,SOCK_STREA
  M,0)?????sys_socket(),sys_socket()????socket_creat
  ()socket_creat()???????????????net_families????
  ?????,???????????????????????,??????????create()??
  ??????????AF_INET,inet_creat()?????,?inet_creat()?
  ??????inetswSOCK_MAX???????,??????????socket,??S
  OCK_STREAM,TCP?????,
• inet_creat()
• answerinetsw ????????
• sock-gtops answer-gtops
• sk-gtprot answer-gtprot

91

• 8.5 IP ?
• 8.5.1 ?? IP ???
• ???? device ??????? dev_base
  ??,???????????,?????????????? dev_base ???????
  device ???????????? device ???????????,?????????,?
  ??????????????????????????????,???????????????????
  ????????????????????????,????????????? sk_buff
  ??????????????????,???? sk_buff ??????? backlog
  ??????? backlog ???????,???? sk_buff ???????????
  sk_buff ??? backlog ???,?????????????????,????????
  ?????????????

92

• ??????????????????,??,?????????????????????,
  ?????,??????????? sk_buff ??? backlog
  ??????????????????????????????
• ? Linux ??????????,?????? ptype_all ???
  ptype_base ?????? packet_type ??????????packet_typ
  e ????????????????????????????????????????????????
  ???packet_type ??????????? ptype_all??????????????
  ???,?????? ptype_all ???ptype_base
  ??????,??????????????,????????????????????????????
  ????????,??????????????? sk_buff ????????
  packet_type ?????packet_type ????????(??????????),
  ??,????????????? sk_buff,sk_buff??????????????????
  ???

93

• 8.5.2 ?? IP ???
• ????????????,?????????(??????)???????????,????????
  ?? sk_buff ????????,?????????????,???????????????
• sk_buff ??????????????,??,IP ??????????????,??????
  ???????????????????????? PPP ??????????,??????????
  ???????????????,? PPP ??????????????????????????,?
  ??????????,??????????????????????

94

• ??????? IP ???,IP ????????? IP
  ?????????????????????? IP ??,??????? rtable
  ????????????????????? IP ???????? device
  ?????????????????????????????????,????????????????
  ????????????,???????? 8.2,????????????????????????
  ???????,????????????????????????? IP
  ???,????????????????????????????????? ARP
  ????,?????,?????????? ARP ????????????????????????
  ?????????,??????????? IP ??????? ARP ???????

95

• 8.5.3 ?????????
• ????????????????,???????????????????????????
  ????????,IP ????????????????????????????????????,I
  P ???????????,??????????????
• ? IP ????????,IP ? IP ????????? IP
  ????????,??????? device ?????????? mtu
  ??,????????????(?????)?????? mtu ??????? IP
  ??????,????? IP ??????????(mtu ?????)????????
  sk_buff ??,??? IP ?????????,?????? IP
  ????????????????????? IP ?????????? IP ????
  sk_buff,??????

96

• IP ?????????????????,?? IP
  ?????????????,??????,???????????????? IP ????,IP
  ???????????????????????????,IP ?????? ipq
  ????,???????????? IP ????? ipqueue ???????? IP
  ?????,IP ????? ipq ????,?????? ipfrag
  ???????????? ipq ?????????????IP ??????????????
  IP ?????,???????????? IP ???????????????,?????????
  sk_buff ??????????????????????????????,ipq ?????
  ipfrag ???,?????????????,??,?????????????????????

97

• 8.5.4??????
• IP?????????????????????????,IP??????????,??
  ???????????????????????,??? IP ????????????,??????
  ??? IP ???? sk_buff ?????????????,IP ?????????IP
  ?????????????,????,?????????????????????????,Linux
  ????????????????????????????,????????????????????
  ???????????????????,????????? ARP ????? IP
  ??????????
• ARP ??????????ARP ???? ARP ???ARP
  ?????????? IP ??,? ARP ????????? IP ??????????ARP
  ????????,??,???????,????????????????? ARP
  ?????,??? IP ?????????? ARP ??,??????????? ARP
  ????

98
? 8.7 arp_table ????????
?? ??
?????? ? ARP ???????????
?????? ? ARP ???????????
?? ??????????,??????????
IP ?? ??????? IP ???
???? ?????????
??? ???????????
??? ?? timer_list ?????,???? ARP ????????
???? ? ARP ?????????
sk_buff ?? ????? IP ??? sk_buff ????
Linux ?? ARP ???????? arp_table
?????,??????????? IP ???????????????????? IP
?????,???????????? arp_table ???????????? 8.7 ???
99

• ARP ???????(? arp_tables ??)??,???????
  arp_table ????????????????,???????????????? IP
  ??????????????????????,?????????????? arp_table
  ??????,Linux ??????????????,???? arp_table ???
  hh_cache ??????
• ??????? IP ?????,???????? arp_table ??,ARP
  ???? ARP ????????????????? arp_talbe
  ??,??????????? sk_buff ? arp_table ??? sk_buff
  ???????????????? IP ??? sk_buff ??,??? sk_buff
  ??????????,????????? ARP ??????UDP ???????????,?
  TCP ???????? TCP ??????????? IP
  ???????????????,arp_table ??????????,???? sk_buff
  ??????????????????????? sk_buff ????

100

• ARP ??????????? IP ??? ARP ???ARP ?????????
  packet_type ??????????????,??,???????? ARP
  ????????? ARP ????????? ARP ???,???????????
  device ???????????? ARP ?????
• ?????????????ARP?????????????????,??????????
  ????????????????????????(neighbor
  cache)?,?????????arp cache??????????arp?????neighb
  or cache?????????/proc/net/arp?
• ??neighbor cache????????neighbour?????????h
  a,?????????????????????????hh_cache?????,hh_cache?
  ??????????????????????????????????,??????????????
  ????????????????

101

• ??????????????,? IP ??????????????????,?
  DHCP ???,????? IP ????????????? ARP ?????????,
  ARP ??????????????? arp_table ????????????????????
  ??,????????????????????????? arp_table
  ???????,????????????????? ARP ??????,????
  arp_table ?????????????????????,? ARP
  ???????????,?????????,??????????? ARP ?????

102

• 8.5.5 IP ??
• IP???????????????????????????????????????
  ,?????????????????????? IP ????,??????????????????
  ????????,?????????????????????????????,???????????
  ???????IP ?????????????????????????????????,??????
  ??????,??????????????? IP ????????????????????????
  ?????,?????,????????? IP ????????????,????????????
  ???,??????????????????????

103

• ?????? BSD ?????? IOCTL ????????????????????
  ??????INET ?????????????????????? IP
  ???????????????,????????????????????????????,?????
  ?????????????????,??????????????? IP
  ???????????????????????????????(gated)?????,???
  BSD ?????? IOCTL ????????
• ???OSPF??BGP???????,????????????????????????
  ??????????,????????????????????????????,??????????
  ,??????????
• Linux?????????????????????(Routing
  Infomation Base,RIB),??????????(Forwarding
  Infomation Base,FIB)?

104

• 1. ????
• ????????????,????????FIB?????????????,??????
  ?????????,????????????????????????????,??????????
  ??????????,???????????????????????/proc/net/rt_cac
  he??????
• ????? IP ???,???????????????????????,???????
  ???????????????????????????,IP ??????????,????????
  ???????????????????,??????????,??????????????????

105

• ?????????? (ip_rt_hash_table),??????????
  rtable ??????????????????? IP ????????????????????
  ????????? IP ???????????,???????????????? rtable
  ???????,??? IP ???????? IP ???????? device
  ????,?????????????????????????????????????????????
  (? jiffies ??)?????????,?????????????????????????
  ?????????,?????????????????????? rtable
  ??????,??????????????????????????????,??? rtable
  ????,????????????,?????????? rtable
  ?????????????????,??????????????????????????????,?
  ?,???????,???????

106

• ?????????????????rt_hash_table??????????IP
  ??????????,?????????????????,Linux???????????????,
  ?????????????????????????????????
• 2. ???????
• ?????(Forwarding Infomation
  Base,FIB)????????,???????????????????????FIB??????
  ???,?????????????????FIB???????????,??????????????
  ???
• ? 8.7??????????????????????????????,????????
  ????????,?????????????????????? IP
  ???,????????????,?????????????????????????????????
  ?????
• ?? IP ????? fib_zone ?????????? fib_zones
  ???????????? fib_zone,?????????? IP
  ????????????????????? fib_node ? fib_info
  ??????,?????????? fib_zone ??????fz_list
  ???????????????,?????????????? fib_node ?????

107
(No Transcript)
108

• ????? IP ??,????????,?????????????????????
  IP ????????????????????????,????,?????????????,???
  ????????????????????????? metric,????????????????,
  ??? metric ????????,??????? IP ????,??? metric
  ???,??????

109

• ?????
• 1. ??????????????????????
• 2. ?????????????,????????????????
• 3. ??????????,???????????????????NOS???,??,NOS????
  ???????
• 4.???????????????????????????????????????
• 5.???????????????????????
• 6.???????,NOS???????????????,NOS?????????
• 7.??????????NOS???????????
• 8.??????send??????(??)????????????????

110

• 9.??????,????????????
• 10.RPC???????????????????????????????
• 11.?????????????(??????,????????,????????????????
  ?lt??,????,?????,????,?????gt)
• 13.socket?????????????
• 14.????socket????????????????
• 15.????????????????????????
• 16.??????,???????????????(??)????????????