Android源码修改：dhcp兼容性漏洞修复

external\dhcpcd\dhcp.c
L1040：
修改前：

		/* Regardless of RFC2132, we should always send a hostname
		 * upto the first dot (the short hostname) as otherwise
		 * confuses some DHCP servers when updating DNS.
		 * The FQDN option should be used if a FQDN is required. */
		if (ifo->options & DHCPCD_HOSTNAME && ifo->hostname[0]) {
			*p++ = DHO_HOSTNAME;
			hp = strchr(ifo->hostname, '.');
			if (hp)
				len = hp - ifo->hostname;
			else
				len = strlen(ifo->hostname);
			*p++ = len;
			memcpy(p, ifo->hostname, len);
			p += len;
		}

 

修改后：

		/* Regardless of RFC2132, we should always send a hostname
		 * upto the first dot (the short hostname) as otherwise
		 * confuses some DHCP servers when updating DNS.
		 * The FQDN option should be used if a FQDN is required. */
		if (ifo->options & DHCPCD_HOSTNAME && ifo->hostname[0]) {
			*p++ = DHO_HOSTNAME;
			hp = strchr(ifo->hostname, '.');
			if (hp)
				len = hp - ifo->hostname;
			else
				len = strlen(ifo->hostname);
            if(len > 8)
                len = 8;//hostname too long may load dhcp fail on some router
			*p++ = len;
			memcpy(p, ifo->hostname, len);
			p += len;
		}