Nmap路由信息获取--未完

方法一、读取/proc/net/route文件

用sscanf函数将读取内容按格式存储在不同变量中。

route_loop(route_t *r, route_handler callback, void *arg)
{
	FILE *fp;
	struct route_entry entry;
	char buf[BUFSIZ];
	int ret = 0;

	if ((fp = fopen(PROC_ROUTE_FILE, "r")) != NULL) {
		char ifbuf[16];
		int i, iflags, refcnt, use, metric, mss, win, irtt;
		uint32_t mask;
		
		while (fgets(buf, sizeof(buf), fp) != NULL) {
			i = sscanf(buf, "%16s %X %X %X %d %d %d %X %d %d %d\n",
			    ifbuf, &entry.route_dst.addr_ip,
			    &entry.route_gw.addr_ip, &iflags, &refcnt, &use,
			    &metric, &mask, &mss, &win, &irtt);//获取路由表各项信息
			
			if (i < 10 || !(iflags & RTF_UP))
				continue;
		
			entry.route_dst.addr_type = entry.route_gw.addr_type =
			    ADDR_TYPE_IP;
		
			if (addr_mtob(&mask, IP_ADDR_LEN,
				&entry.route_dst.addr_bits) < 0)//对mask的每一位进行是否为零的判断，IP_ADDR_LEN =4
				continue;
			
			entry.route_gw.addr_bits = IP_ADDR_BITS;
			
			if ((ret = callback(&entry, arg)) != 0)
				break;
		}
		fclose(fp);
	}
	if (ret == 0 && (fp = fopen(PROC_IPV6_ROUTE_FILE, "r")) != NULL) {
		char s[33], d[8][5], n[8][5];
		u_int slen, dlen;
		
		while (fgets(buf, sizeof(buf), fp) != NULL) {
			sscanf(buf, "%04s%04s%04s%04s%04s%04s%04s%04s %02x "
			    "%32s %02x %04s%04s%04s%04s%04s%04s%04s%04s ",
			    d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7],
			    &dlen, s, &slen,
			    n[0], n[1], n[2], n[3], n[4], n[5], n[6], n[7]);
			snprintf(buf, sizeof(buf), "%s:%s:%s:%s:%s:%s:%s:%s/%d",
			    d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7],
			    dlen);
			addr_aton(buf, &entry.route_dst);
			snprintf(buf, sizeof(buf), "%s:%s:%s:%s:%s:%s:%s:%s/%d",
			    n[0], n[1], n[2], n[3], n[4], n[5], n[6], n[7],
			    IP6_ADDR_BITS);
			addr_aton(buf, &entry.route_gw);
			
			if ((ret = callback(&entry, arg)) != 0)
				break;
		}
		fclose(fp);
	}
	return (ret);
}

int
addr_mtob(const void *mask, size_t size, uint16_t *bits)
{
	uint16_t n;
	u_char *p;
	int i, j;

	p = (u_char *)mask;
	
	for (n = i = 0; i < (int)size; i++, n += 8) {//每四位进行一次判断，如果不为 1111 1111，则直接跳出循环，
		if (p[i] != 0xff)                    //这使得下面的判断是从非零项开始
			break;
	}
	if (i != (int)size && p[i]) {
		for (j = 7; j > 0; j--, n++) {
			if ((p[i] & (1 << j)) == 0)//从高位开始判断，每一位是否为1，如果为0，则跳出循环
				break;
		}
	}*bit = n;//通过这个bit，应该就可以判断是A,B,C哪类地址了，如果是A类地址，默认子网掩码255.0.0.0，这时n = 8;

二、使用netlink