sock.c

LINUX1.0内核源代码,学习LINUX编程的一定要看。

/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		SOCK - AF_INET protocol family socket handler.
 *
 * Version:	@(#)sock.c	1.0.17	06/02/93
 *
 * Authors:	Ross Biro, <[e-mail]>
 *		Fred N. van Kempen, <[e-mail]>
 *		Florian La Roche, <[e-mail]>
 *
 * Fixes:
 *		Alan Cox	: 	Numerous verify_area() problems
 *		Alan Cox	:	Connecting on a connecting socket
 *					now returns an error for tcp.
 *		Alan Cox	:	sock->protocol is set correctly.
 *					and is not sometimes left as 0.
 *		Alan Cox	:	connect handles icmp errors on a
 *					connect properly. Unfortunately there
 *					is a restart syscall nasty there. I
 *					can't match BSD without hacking the C
 *					library. Ideas urgently sought!
 *		Alan Cox	:	Disallow bind() to addresses that are
 *					not ours - especially broadcast ones!!
 *		Alan Cox	:	Socket 1024 _IS_ ok for users. (fencepost)
 *		Alan Cox	:	sock_wfree/sock_rfree don't destroy sockets,
 *					instead they leave that for the DESTROY timer.
 *		Alan Cox	:	Clean up error flag in accept
 *		Alan Cox	:	TCP ack handling is buggy, the DESTROY timer
 *					was buggy. Put a remove_sock() in the handler
 *					for memory when we hit 0. Also altered the timer
 *					code. The ACK stuff can wait and needs major 
 *					TCP layer surgery.
 *		Alan Cox	:	Fixed TCP ack bug, removed remove sock
 *					and fixed timer/inet_bh race.
 *		Alan Cox	:	Added zapped flag for TCP
 *		Alan Cox	:	Move kfree_skb into skbuff.c and tidied up surplus code
 *		Alan Cox	:	for new sk_buff allocations wmalloc/rmalloc now call alloc_skb
 *		Alan Cox	:	kfree_s calls now are kfree_skbmem so we can track skb resources
 *		Alan Cox	:	Supports socket option broadcast now as does udp. Packet and raw need fixing.
 *		Alan Cox	:	Added RCVBUF,SNDBUF size setting. It suddenely occured to me how easy it was so...
 *		Rick Sladkey	:	Relaxed UDP rules for matching packets.
 *		C.E.Hawkins	:	IFF_PROMISC/SIOCGHWADDR support
 *	Pauline Middelink	:	Pidentd support
 *		Alan Cox	:	Fixed connect() taking signals I think.
 *		Alan Cox	:	SO_LINGER supported
 *		Alan Cox	:	Error reporting fixes
 *		Anonymous	:	inet_create tidied up (sk->reuse setting)
 *		Alan Cox	:	inet sockets don't set sk->type!
 *		Alan Cox	:	Split socket option code
 *		Alan Cox	:	Callbacks
 *		Alan Cox	:	Nagle flag for Charles & Johannes stuff
 *
 * To Fix:
 *
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>

#include <asm/segment.h>
#include <asm/system.h>

#include "inet.h"
#include "dev.h"
#include "ip.h"
#include "protocol.h"
#include "arp.h"
#include "route.h"
#include "tcp.h"
#include "udp.h"
#include "skbuff.h"
#include "sock.h"
#include "raw.h"
#include "icmp.h"


int inet_debug = DBG_OFF;		/* INET module debug flag	*/


#define min(a,b)	((a)<(b)?(a):(b))

extern struct proto packet_prot;


void
print_sk(struct sock *sk)
{
  if (!sk) {
	printk("  print_sk(NULL)\n");
	return;
  }
  printk("  wmem_alloc = %lu\n", sk->wmem_alloc);
  printk("  rmem_alloc = %lu\n", sk->rmem_alloc);
  printk("  send_head = %p\n", sk->send_head);
  printk("  state = %d\n",sk->state);
  printk("  wback = %p, rqueue = %p\n", sk->wback, sk->rqueue);
  printk("  wfront = %p\n", sk->wfront);
  printk("  daddr = %lX, saddr = %lX\n", sk->daddr,sk->saddr);
  printk("  num = %d", sk->num);
  printk(" next = %p\n", sk->next);
  printk("  write_seq = %ld, acked_seq = %ld, copied_seq = %ld\n",
	  sk->write_seq, sk->acked_seq, sk->copied_seq);
  printk("  rcv_ack_seq = %ld, window_seq = %ld, fin_seq = %ld\n",
	  sk->rcv_ack_seq, sk->window_seq, sk->fin_seq);
  printk("  prot = %p\n", sk->prot);
  printk("  pair = %p, back_log = %p\n", sk->pair,sk->back_log);
  printk("  inuse = %d , blog = %d\n", sk->inuse, sk->blog);
  printk("  dead = %d delay_acks=%d\n", sk->dead, sk->delay_acks);
  printk("  retransmits = %ld, timeout = %d\n", sk->retransmits, sk->timeout);
  printk("  cong_window = %d, packets_out = %d\n", sk->cong_window,
	  sk->packets_out);
  printk("  shutdown=%d\n", sk->shutdown);
}


void
print_skb(struct sk_buff *skb)
{
  if (!skb) {
	printk("  print_skb(NULL)\n");
	return;
  }
  printk("  prev = %p, next = %p\n", skb->prev, skb->next);
  printk("  sk = %p link3 = %p\n", skb->sk, skb->link3);
  printk("  mem_addr = %p, mem_len = %lu\n", skb->mem_addr, skb->mem_len);
  printk("  used = %d free = %d\n", skb->used,skb->free);
}



static int
sk_inuse(struct proto *prot, int num)
{
  struct sock *sk;

  for(sk = prot->sock_array[num & (SOCK_ARRAY_SIZE -1 )];
      sk != NULL;
      sk=sk->next) {
	if (sk->num == num) return(1);
  }
  return(0);
}


unsigned short
get_new_socknum(struct proto *prot, unsigned short base)
{
  static int start=0;

  /*
   * Used to cycle through the port numbers so the
   * chances of a confused connection drop.
   */
  int i, j;
  int best = 0;
  int size = 32767; /* a big num. */
  struct sock *sk;

  if (base == 0) base = PROT_SOCK+1+(start % 1024);
  if (base <= PROT_SOCK) {
	base += PROT_SOCK+(start % 1024);
  }

  /* Now look through the entire array and try to find an empty ptr. */
  for(i=0; i < SOCK_ARRAY_SIZE; i++) {
	j = 0;
	sk = prot->sock_array[(i+base+1) &(SOCK_ARRAY_SIZE -1)];
	while(sk != NULL) {
		sk = sk->next;
		j++;
	}
	if (j == 0) {
		start =(i+1+start )%1024;
		DPRINTF((DBG_INET, "get_new_socknum returning %d, start = %d\n",
							i + base + 1, start));
		return(i+base+1);
	}
	if (j < size) {
		best = i;
		size = j;
	}
  }

  /* Now make sure the one we want is not in use. */
  while(sk_inuse(prot, base +best+1)) {
	best += SOCK_ARRAY_SIZE;
  }
  DPRINTF((DBG_INET, "get_new_socknum returning %d, start = %d\n",
						best + base + 1, start));
  return(best+base+1);
}


void
put_sock(unsigned short num, struct sock *sk)
{
  struct sock *sk1;
  struct sock *sk2;
  int mask;

  DPRINTF((DBG_INET, "put_sock(num = %d, sk = %X\n", num, sk));
  sk->num = num;
  sk->next = NULL;
  num = num &(SOCK_ARRAY_SIZE -1);

  /* We can't have an interupt re-enter here. */
  cli();
  if (sk->prot->sock_array[num] == NULL) {
	sk->prot->sock_array[num] = sk;
	sti();
	return;
  }
  sti();
  for(mask = 0xff000000; mask != 0xffffffff; mask = (mask >> 8) | mask) {
	if ((mask & sk->saddr) &&
	    (mask & sk->saddr) != (mask & 0xffffffff)) {
		mask = mask << 8;
		break;
	}
  }
  DPRINTF((DBG_INET, "mask = %X\n", mask));

  cli();
  sk1 = sk->prot->sock_array[num];
  for(sk2 = sk1; sk2 != NULL; sk2=sk2->next) {
	if (!(sk2->saddr & mask)) {
		if (sk2 == sk1) {
			sk->next = sk->prot->sock_array[num];
			sk->prot->sock_array[num] = sk;
			sti();
			return;
		}
		sk->next = sk2;
		sk1->next= sk;
		sti();
		return;
	}
	sk1 = sk2;
  }

  /* Goes at the end. */
  sk->next = NULL;
  sk1->next = sk;
  sti();
}


static void
remove_sock(struct sock *sk1)
{
  struct sock *sk2;

  DPRINTF((DBG_INET, "remove_sock(sk1=%X)\n", sk1));
  if (!sk1) {
	printk("sock.c: remove_sock: sk1 == NULL\n");
	return;
  }

  if (!sk1->prot) {
	printk("sock.c: remove_sock: sk1->prot == NULL\n");
	return;
  }

  /* We can't have this changing out from under us. */
  cli();
  sk2 = sk1->prot->sock_array[sk1->num &(SOCK_ARRAY_SIZE -1)];
  if (sk2 == sk1) {
	sk1->prot->sock_array[sk1->num &(SOCK_ARRAY_SIZE -1)] = sk1->next;
	sti();
	return;
  }

  while(sk2 && sk2->next != sk1) {
	sk2 = sk2->next;
  }

  if (sk2) {
	sk2->next = sk1->next;
	sti();
	return;
  }
  sti();

  if (sk1->num != 0) DPRINTF((DBG_INET, "remove_sock: sock not found.\n"));
}


void
destroy_sock(struct sock *sk)
{
	struct sk_buff *skb;

  	DPRINTF((DBG_INET, "destroying socket %X\n", sk));
  	sk->inuse = 1;			/* just to be safe. */

  	/* Incase it's sleeping somewhere. */
  	if (!sk->dead) 
  		sk->write_space(sk);

  	remove_sock(sk);
  
  	/* Now we can no longer get new packets. */
  	delete_timer(sk);


	while ((skb = tcp_dequeue_partial(sk)) != NULL) 
  	{
  		IS_SKB(skb);
  		kfree_skb(skb, FREE_WRITE);
  	}

  /* Cleanup up the write buffer. */
  	for(skb = sk->wfront; skb != NULL; ) 
  	{
		struct sk_buff *skb2;

		skb2=(struct sk_buff *)skb->next;
		if (skb->magic != TCP_WRITE_QUEUE_MAGIC) {
			printk("sock.c:destroy_sock write queue with bad magic(%X)\n",
								skb->magic);
			break;
		}
		IS_SKB(skb);
		kfree_skb(skb, FREE_WRITE);
		skb = skb2;
  	}

  	sk->wfront = NULL;
  	sk->wback = NULL;

  	if (sk->rqueue != NULL) 
  	{
	  	while((skb=skb_dequeue(&sk->rqueue))!=NULL)
	  	{
		/*
		 * This will take care of closing sockets that were
		 * listening and didn't accept everything.
		 */
			if (skb->sk != NULL && skb->sk != sk) 
			{
				IS_SKB(skb);
				skb->sk->dead = 1;
				skb->sk->prot->close(skb->sk, 0);
			}
			IS_SKB(skb);
			kfree_skb(skb, FREE_READ);
		}
  	}
  	sk->rqueue = NULL;

  /* Now we need to clean up the send head. */
  	for(skb = sk->send_head; skb != NULL; ) 
  	{
		struct sk_buff *skb2;

		/*
		 * We need to remove skb from the transmit queue,
		 * or maybe the arp queue.
		 */
		cli();
		/* see if it's in a transmit queue. */
		/* this can be simplified quite a bit.  Look */
		/* at tcp.c:tcp_ack to see how. */
		if (skb->next != NULL) 
		{
			IS_SKB(skb);
			skb_unlink(skb);
		}
		skb->dev = NULL;
		sti();
		skb2 = (struct sk_buff *)skb->link3;
		kfree_skb(skb, FREE_WRITE);
		skb = skb2;
  	}	
  	sk->send_head = NULL;

  	/* And now the backlog. */
  	if (sk->back_log != NULL) 
  	{
		/* this should never happen. */
		printk("cleaning back_log. \n");
		cli();
		skb = (struct sk_buff *)sk->back_log;
		do 
		{
			struct sk_buff *skb2;
	
			skb2 = (struct sk_buff *)skb->next;
			kfree_skb(skb, FREE_READ);
			skb = skb2;
		}
		while(skb != sk->back_log);
		sti();
	}
	sk->back_log = NULL;

  /* Now if it has a half accepted/ closed socket. */
	if (sk->pair) 
	{
		sk->pair->dead = 1;
		sk->pair->prot->close(sk->pair, 0);
		sk->pair = NULL;
  	}

  /*
   * Now if everything is gone we can free the socket
   * structure, otherwise we need to keep it around until
   * everything is gone.
   */
	  if (sk->rmem_alloc == 0 && sk->wmem_alloc == 0) 
	  {
		kfree_s((void *)sk,sizeof(*sk));
	  } 
	  else 
	  {
		/* this should never happen. */
		/* actually it can if an ack has just been sent. */
		DPRINTF((DBG_INET, "possible memory leak in socket = %X\n", sk));
		sk->destroy = 1;
		sk->ack_backlog = 0;
		sk->inuse = 0;
		reset_timer(sk, TIME_DESTROY, SOCK_DESTROY_TIME);
  	}
  	DPRINTF((DBG_INET, "leaving destroy_sock\n"));
}


static int
inet_fcntl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
  struct sock *sk;

  sk = (struct sock *) sock->data;
  if (sk == NULL) {
	printk("Warning: sock->data = NULL: %d\n" ,__LINE__);
	return(0);
  }

  switch(cmd) {
	case F_SETOWN:
		/*
		 * This is a little restrictive, but it's the only
		 * way to make sure that you can't send a sigurg to
		 * another process.
		 */
		if (!suser() && current->pgrp != -arg &&
				current->pid != arg) return(-EPERM);
		sk->proc = arg;
		return(0);
	case F_GETOWN:
		return(sk->proc);
	default:
		return(-EINVAL);
  }
}

/*
 *	Set socket options on an inet socket.
 */
 
static int inet_setsockopt(struct socket *sock, int level, int optname,
		    char *optval, int optlen)
{
  	struct sock *sk = (struct sock *) sock->data;  
	if (level == SOL_SOCKET)
		return sock_setsockopt(sk,level,optname,optval,optlen);
	if (sk->prot->setsockopt==NULL)
		return(-EOPNOTSUPP);
	else
		return sk->prot->setsockopt(sk,level,optname,optval,optlen);
}




static int inet_getsockopt(struct socket *sock, int level, int optname,
		    char *optval, int *optlen)
{
  	struct sock *sk = (struct sock *) sock->data;  	
  	if (level == SOL_SOCKET) 
  		return sock_getsockopt(sk,level,optname,optval,optlen);
  	if(sk->prot->getsockopt==NULL)  	
  		return(-EOPNOTSUPP);
  	else
  		return sk->prot->getsockopt(sk,level,optname,optval,optlen);
}

/*
 *	This is meant for all protocols to use and covers goings on
 *	at the socket level. Everything here is generic.
 */

int sock_setsockopt(struct sock *sk, int level, int optname,
		char *optval, int optlen)
{
	int val;
	int err;
	struct linger ling;

  	if (optval == NULL) 
  		return(-EINVAL);

  	err=verify_area(VERIFY_READ, optval, sizeof(int));
  	if(err)
  		return err;
  	
  	val = get_fs_long((unsigned long *)optval);
  	switch(optname) 
  	{
		case SO_TYPE:
		case SO_ERROR:
		  	return(-ENOPROTOOPT);

		case SO_DEBUG:	
			sk->debug=val?1:0;
		case SO_DONTROUTE:	/* Still to be implemented */
			return(0);
		case SO_BROADCAST:
			sk->broadcast=val?1:0;
			return 0;
		case SO_SNDBUF:
			if(val>32767)
				val=32767;
			if(val<256)
				val=256;
			sk->sndbuf=val;
			return 0;
		case SO_LINGER:
			err=verify_area(VERIFY_READ,optval,sizeof(ling));
			if(err)
				return err;
			memcpy_fromfs(&ling,optval,sizeof(ling));
			if(ling.l_onoff==0)
				sk->linger=0;
			else
			{
				sk->lingertime=ling.l_linger;
				sk->linger=1;
			}
			return 0;
		case SO_RCVBUF:
			if(val>32767)
				val=32767;
			if(val<256)
				val=256;
			sk->rcvbuf=val;
			return(0);

		case SO_REUSEADDR:
			if (val) 
				sk->reuse = 1;
			else 
				sk->reuse = 0;
			return(0);

		case SO_KEEPALIVE:
			if (val)
				sk->keepopen = 1;
			else 
				sk->keepopen = 0;
			return(0);

	 	case SO_OOBINLINE:
			if (val) 
				sk->urginline = 1;
			else 
				sk->urginline = 0;
			return(0);

	 	case SO_NO_CHECK:
			if (val) 
				sk->no_check = 1;
			else 
				sk->no_check = 0;
			return(0);

		 case SO_PRIORITY:
			if (val >= 0 && val < DEV_NUMBUFFS) 
			{
				sk->priority = val;
			} 
			else 
			{
				return(-EINVAL);
			}
			return(0);

		default:
		  	return(-ENOPROTOOPT);
  	}
}


int sock_getsockopt(struct sock *sk, int level, int optname,
		   char *optval, int *optlen)
{		
  	int val;
  	int err;
  	struct linger ling;

  	switch(optname) 
  	{
		case SO_DEBUG:		
			val = sk->debug;
			break;
		
		case SO_DONTROUTE:	/* One last option to implement */
			val = 0;
			break;
		
		case SO_BROADCAST:
			val= sk->broadcast;