ifconfig_main.c

自己改写的ifconfig代码程序

	//unsigned char mask;
	//unsigned char did_flags;
//#endif
	char interface[10]={0};							//add
	char addr[20];										//add
	char *p;
	char host[128];
	
	printf("input your IP address:\n");
	scanf("%s",&addr);
	strcpy(interface,"eth0   ");
	strcpy(*argv,strcat(interface,addr));							//add

	goterr = 0;
	did_flags = 0;
//#ifdef CONFIG_FEATURE_IFCONFIG_BROADCAST_PLUS
	sai_hostname = 0;
	sai_netmask = 0;
//#endif

	/* skip argv[0] */
	++argv;
	--argc;

/*#ifdef CONFIG_FEATURE_IFCONFIG_STATUS
	if ((argc > 0) && (((*argv)[0] == '-') && ((*argv)[1] == 'a') && !(*argv)[2])) {// ifconfig -a
		interface_opt_a = 1;
		--argc;
		++argv;
	}
#endif*/

	if (argc <= 1) {
/*#ifdef CONFIG_FEATURE_IFCONFIG_STATUS
		return display_interfaces(argc ? *argv : NULL);
#else
	//bb_error_msg_and_die
			("ifconfig was not compiled with interface status display support.");
#endif*/
	}

	/* Create a channel to the NET kernel. */
	sockfd = bb_xsocket(AF_INET, SOCK_DGRAM, 0);

	/* get interface name */
	//safe_strncpy(ifr.ifr_name, *argv, IFNAMSIZ);
	safe_strncpy(ifr.ifr_name, "eth0", IFNAMSIZ);

	/* Process the remaining arguments. */
	while (*++argv != (char *) NULL) {
		p = *argv;
		mask = N_MASK;
		if (*p == '-') {	/* If the arg starts with '-'... */
			++p;		/*    advance past it and */
			mask = M_MASK;	/*    set the appropriate mask. */
		}
		for (op = OptArray; op->name; op++) {	/* Find table entry. */
			if (strcmp(p, op->name) == 0) {	/* If name matches... */
				if ((mask &= op->flags)) {	/* set the mask and go. */
					goto FOUND_ARG;
				}
				/* If we get here, there was a valid arg with an */
				/* invalid '-' prefix. */
				++goterr;
				goto LOOP;
			}
		}

		/* We fell through, so treat as possible hostname. */
		a1op = Arg1Opt + (sizeof(Arg1Opt) / sizeof(Arg1Opt[0])) - 1;
		mask = op->arg_flags;
		goto HOSTNAME;

	  FOUND_ARG:
		if (mask & ARG_MASK) {
			mask = op->arg_flags;
			a1op = Arg1Opt + (op - OptArray);
			if (mask & A_NETMASK & did_flags) {
				//bb_show_usage();
			}
			if (*++argv == NULL) {
				if (mask & A_ARG_REQ) {
					//bb_show_usage();
				} else {
					--argv;
					mask &= A_SET_AFTER;	/* just for broadcast */
				}
			} else {	/* got an arg so process it */
			  HOSTNAME:
				did_flags |= (mask & (A_NETMASK|A_HOSTNAME));
				if (mask & A_CAST_HOST_COPY) {
//#ifdef CONFIG_FEATURE_IFCONFIG_HW
					if (mask & A_CAST_RESOLVE) {
//#endif


						safe_strncpy(host, *argv, (sizeof host));


						sai.sin_family = AF_INET;
						sai.sin_port = 0;
						if (!strcmp(host, "default")) {
							/* Default is special, meaning 0.0.0.0. */
							sai.sin_addr.s_addr = INADDR_ANY;
//#ifdef CONFIG_FEATURE_IFCONFIG_BROADCAST_PLUS
						} else if (((host[0] == '+') && !host[1]) && (mask & A_BROADCAST) &&
								   (did_flags & (A_NETMASK|A_HOSTNAME)) == (A_NETMASK|A_HOSTNAME)) {
							/* + is special, meaning broadcast is derived. */
							sai.sin_addr.s_addr = (~sai_netmask) | (sai_hostname & sai_netmask);
//#endif

						} else if (inet_aton(host, &sai.sin_addr) == 0) {
							/* It's not a dotted quad. */
							struct hostent *hp;
							if ((hp = gethostbyname(host)) == (struct hostent *)NULL) {
								++goterr;
								continue;
							}
							memcpy((char *) &sai.sin_addr, (char *) hp->h_addr_list[0],
							sizeof(struct in_addr));
						}
//#ifdef CONFIG_FEATURE_IFCONFIG_BROADCAST_PLUS
						if (mask & A_HOSTNAME) {
							sai_hostname = sai.sin_addr.s_addr;
						}
						if (mask & A_NETMASK) {
							sai_netmask = sai.sin_addr.s_addr;
						}
//#endif
						p = (char *) &sai;
//#ifdef CONFIG_FEATURE_IFCONFIG_HW
					} else {	/* A_CAST_HOST_COPY_IN_ETHER */
						/* This is the "hw" arg case. */
						if (strcmp("ether", *argv) || (*++argv == NULL)) {
						//	bb_show_usage();
						}
						safe_strncpy(host, *argv, (sizeof host));
						if (in_ether(host, &sa)) {
							//bb_error_msg("invalid hw-addr %s", host);
							++goterr;
							continue;
						}
						p = (char *) &sa;
					}
//#endif
					memcpy((((char *) (&ifr)) + a1op->ifr_offset),
						   p, sizeof(struct sockaddr));
				} else {
					unsigned long i = strtoul(*argv, NULL, 0);

					p = ((char *) (&ifr)) + a1op->ifr_offset;
//#ifdef CONFIG_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
					if (mask & A_MAP_TYPE) {
						if (ioctl(sockfd, SIOCSIFMAP, &ifr) < 0) {
							++goterr;
							continue;
						}
						if ((mask & A_MAP_UCHAR) == A_MAP_UCHAR) {
							*((unsigned char *) p) = i;
						} else if (mask & A_MAP_USHORT) {
							*((unsigned short *) p) = i;
						} else {
							*((unsigned long *) p) = i;
						}
					} else
//#endif
					if (mask & A_CAST_CHAR_PTR) {
						*((caddr_t *) p) = (caddr_t) i;
					} else {	/* A_CAST_INT */
						*((int *) p) = i;
					}
				}

				if (ioctl(sockfd, a1op->selector, &ifr) < 0) {
					perror(a1op->name);
					++goterr;
					continue;
				}
//#ifdef QUESTIONABLE_ALIAS_CASE
				if (mask & A_COLON_CHK) {
					/*
					 * Don't do the set_flag() if the address is an alias with
					 * a - at the end, since it's deleted already! - Roman
					 *
					 * Should really use regex.h here, not sure though how well
					 * it'll go with the cross-platform support etc.
					 */
					char *ptr;
					short int found_colon = 0;

					for (ptr = ifr.ifr_name; *ptr; ptr++) {
						if (*ptr == ':') {
							found_colon++;
						}
					}

					if (found_colon && *(ptr - 1) == '-') {
						continue;
					}
				}
//#endif
			}
			if (!(mask & A_SET_AFTER)) {
				continue;
			}
			mask = N_SET;
		}

		if (ioctl(sockfd, SIOCGIFFLAGS, &ifr) < 0) {
			perror("SIOCGIFFLAGS");
			++goterr;
		} else {
			selector = op->selector;
			if (mask & SET_MASK) {
				ifr.ifr_flags |= selector;
			} else {
				ifr.ifr_flags &= ~selector;
			}
			if (ioctl(sockfd, SIOCSIFFLAGS, &ifr) < 0) {
				perror("SIOCSIFFLAGS");
				++goterr;
			}
		}
	  LOOP:
		continue;
	}					/* end of while-loop */

	if(ENABLE_FEATURE_CLEAN_UP) close(sockfd);
	return goterr;
}

//#ifdef CONFIG_FEATURE_IFCONFIG_HW
/* Input an Ethernet address and convert to binary. */
static int in_ether(char *bufp, struct sockaddr *sap)
{
	char *ptr;
	int i, j;
	unsigned char val;
	unsigned char c;

	sap->sa_family = ARPHRD_ETHER;
	ptr = sap->sa_data;

	i = 0;
	do {
		j = val = 0;

		/* We might get a semicolon here - not required. */
		if (i && (*bufp == ':')) {
			bufp++;
		}

		do {
			c = *bufp;
			if (((unsigned char)(c - '0')) <= 9) {
				c -= '0';
			} else if (((unsigned char)((c|0x20) - 'a')) <= 5) {
				c = (c|0x20) - ('a'-10);
			} else if (j && (c == ':' || c == 0)) {
				break;
			} else {
				return -1;
			}
			++bufp;
			val <<= 4;
			val += c;
		} while (++j < 2);
		*ptr++ = val;
	} while (++i < ETH_ALEN);

	return (int) (*bufp);	/* Error if we don't end at end of string. */
}
//#endif

char * safe_strncpy(char *dst, const char *src, size_t size)
{
	dst[size-1] = '\0';
	return strncpy(dst, src, size-1);
}

int bb_xsocket(int domain, int type, int protocol)
{
	int r = socket(domain, type, protocol);
	if (r < 0)
		
	return r;
}