內(nèi)核與用戶態(tài)通信(setsockopt)

1、filter提供了nf_register_sockopt()和nf_unregister_sockopt()來動態(tài)登記或取消sockopt命令字；打開一個網(wǎng)絡(luò)socket后可以使用setgetsockopt(2)可實現(xiàn)用戶空間與內(nèi)核的通信，本質(zhì)和ioctl差不多，區(qū)別在于setgetsockopt不用新建設(shè)備，直接利用系統(tǒng)已有的socket類型就可以進行，可用setsockopt函數(shù)向內(nèi)核寫數(shù)據(jù)，用getsockopt向內(nèi)核讀數(shù)據(jù)。mo

2、dule.c:#include#include#include#include#include#include#include#defineSOCKET_OPS_BASE128#defineSOCKET_OPS_SET(SOCKET_OPS_BASE)#defineSOCKET_OPS_GET(SOCKET_OPS_BASE)#defineSOCKET_OPS_MAX(SOCKET_OPS_BASE1)#defineKMSG“amess

3、agefromkernel“#defineKMSG_LENsizeof(“amessagefromkernel“)MODULE_LICENSE(“GPL“)staticintrecv_msg(structsockskintcmdvoid__useruserunsignedintlen)intret=0printk(KERN_INFO“sockopt:recv_msg()n“)if(cmd==SOCKET_OPS_SET)umsg[64]

4、intlen=sizeof()64memset(umsg0len)ret=copy_from_user(umsguserlen)printk(“recv_msg:umsg=%s.ret=%dn“umsgret)return0staticintsend_msg(structsockskintcmdvoid__useruserint#include#include#include#include#defineSOCKET_OPS_BASE1

5、28#defineSOCKET_OPS_SET(SOCKET_OPS_BASE)#defineSOCKET_OPS_GET(SOCKET_OPS_BASE)#defineSOCKET_OPS_MAX(SOCKET_OPS_BASE1)#defineUMSG“amessagefromuserspace“#defineUMSG_LENsizeof(“amessagefromuserspace“)kmsg[64]intmain(void)in

6、tsockfdintlenintretsockfd=socket(AF_ISOCK_RAWIPPROTO_RAW)if(sockfd0)printf(“cannotcreateasocketn“)return1callfunctionrecv_msg()ret=setsockopt(sockfdIPPROTO_IPSOCKET_OPS_SETUMSGUMSG_LEN)printf(“setsockopt:ret=%d.msg=%sn“r