inet.c

一个基于linux的TCP/IP协议栈的实现

/* inet.c
 * [e-mail]
 * 2006-10-20
 */

#include "net-support.h"
#include "util.h"
#include "af_inet.h"

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <errno.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>

struct addr {
	struct sockaddr_in addr;
	char *name;
	int host;
	struct addr *next;
};

static struct addr *MYINET_nn = NULL;

static int MYINET_rresolve(char *name, size_t len, struct sockaddr_in *sin,
             int numeric, unsigned int netmask)
{
	struct hostent *ent;
	struct netent *np;
	struct addr *pn;
	unsigned long ad, host_ad;
	int host = 0;

	if (sin->sin_family != MY_AF_INET) {
		fprintf(stderr, "rresolve: unsupport address family %d !\n", sin->sin_family);
		errno = EAFNOSUPPORT;
		return (-1);
	}
	ad = (unsigned long) sin->sin_addr.s_addr;

	if( ad == INADDR_ANY ){
		if( (numeric & 0x0FFF) == 0 ){
			if( numeric & 0x8000 )
				safe_strncpy( name, "default", len );
			else
				safe_strncpy(name, "*", len);
			return (0);
		}
	}
	if( numeric & 0x0FFF ){
		safe_strncpy( name, inet_ntoa(sin->sin_addr), len );
		return (0);
	}
	if ((ad & (~netmask)) != 0 || (numeric & 0x4000))
		host = 1;

	pn = MYINET_nn;
	while (pn != NULL) {
		if( pn->addr.sin_addr.s_addr == ad && pn->host == host ){
			safe_strncpy(name, pn->name, len);
			fprintf (stderr, "rresolve: found %s %08lx in cache\n", (host? "host": "net"), ad);
			return (0);
		}
		pn = pn->next;
	}

	host_ad = ntohl(ad);
	np = NULL;
	ent = NULL;
	if( host ){
		fprintf( stderr, "gethostbyaddr (%08lx)\n", ad );
		ent = gethostbyaddr((char *) & ad, 4, AF_INET);
		if( ent != NULL )
			safe_strncpy(name, ent->h_name, len);
	}else{
		fprintf (stderr, "getnetbyaddr (%08lx)\n", host_ad);
		np = getnetbyaddr(host_ad, MY_AF_INET);
		if( np != NULL )
			safe_strncpy(name, np->n_name, len);
	}
	if( (ent == NULL) && (np == NULL) )
		safe_strncpy(name, inet_ntoa(sin->sin_addr), len);
	pn = (struct addr *) malloc(sizeof(struct addr));
	pn->addr = *sin;
	pn->next = MYINET_nn;
	pn->host = host;
	pn->name = (char *) malloc(strlen(name) + 1);
	strcpy(pn->name, name);
	MYINET_nn = pn;
	return (0);
}

static char *MYINET_print(unsigned char *ptr)
{
	return ( inet_ntoa((*(struct in_addr *) ptr)) );
}

static char *MYINET_sprint(struct sockaddr *sap, int numeric)
{
	static char buff[128];

	if( sap->sa_family == 0xFFFF || sap->sa_family == 0 )
		return safe_strncpy(buff, "[NONE SET]", sizeof(buff));
	if( MYINET_rresolve(buff, sizeof(buff), (struct sockaddr_in *)sap,
							numeric, 0xffffff00) != 0)
		return (NULL);

	return (buff);
}

static int MYINET_resolve(char *name, struct sockaddr_in *sin, int hostfirst)
{
	struct hostent *hp;
	struct netent *np;

	sin->sin_family = MY_AF_INET;
	sin->sin_port = 0;

	if( !strcmp(name, "default") ){
		sin->sin_addr.s_addr = INADDR_ANY;
		return (1);
	}

	if( inet_aton(name, &sin->sin_addr) )
		return 0;

	if( hostfirst && (hp = gethostbyname(name)) != (struct hostent *) NULL ){
		memcpy( (char *) &sin->sin_addr, (char *) hp->h_addr_list[0], sizeof(struct in_addr) );
		return 0;
	}
	if( (np = getnetbyname(name)) != (struct netent *) NULL) {
		sin->sin_addr.s_addr = htonl(np->n_net);
		return 1;
	}
	if( hostfirst ){
    	errno = h_errno;
    	return -1;
    }

	if( (hp = gethostbyname(name)) == (struct hostent *) NULL ){
		errno = h_errno;
		return -1;
	}
	memcpy( (char *) &sin->sin_addr, (char *) hp->h_addr_list[0],
					sizeof(struct in_addr));
	return 0;
}

static int MYINET_getsock(char *bufp, struct sockaddr *sap)
{
	return 0;
}

static int MYINET_input(int type, char *bufp, struct sockaddr *sap)
{
	switch( type ){
		case 1:
			return ( MYINET_getsock(bufp, sap) );
		case 256:
			return ( MYINET_resolve(bufp, (struct sockaddr_in *) sap, 1) );
		default:
			return ( MYINET_resolve(bufp, (struct sockaddr_in *) sap, 0) );
	}
}

static void MYINET_reserror(char *text)
{
	herror(text);
}

static int MYINET_getnetmask(char *adr, struct sockaddr *m, char *name)
{
	struct sockaddr_in *mask = (struct sockaddr_in *) m;
	char *slash, *end;
	int prefix;

	if( (slash = strchr(adr, '/')) == NULL )
		return 0;
	*slash++ = '\0';
	prefix = strtoul( slash, &end, 0 );
	if( *end != '\0' )
		return -1;
	if( name ){
		sprintf(name, "/%d", prefix);
	}
	mask->sin_family = MY_AF_INET;
	mask->sin_addr.s_addr = htonl(~(0xffffffffU >> prefix));
	return 1;
}

struct aftype myinet_aftype =
{
	"myinet", NULL, MY_AF_INET, sizeof(unsigned long),
	MYINET_print, MYINET_sprint, MYINET_input, MYINET_reserror,
	NULL, NULL,
	MYINET_getnetmask,
	-1,
	NULL
};