请帮助我。
经过2天的长篇大论后，我找不到答案。请帮我
我对socket编程很新，我写了一个小代码来转发tcp层的数据包，因为我使用了ip_queue和netlinks与NETLINK_FIREWALL协议。
我所做的是
iptables -I OUTPUT -j QUEUE -p udp --destination-port 19989
我按命令提示跑了
我的代码是（只接收数据包不多）
只是它避免了远程的icmp错误和打印包信息而没有传递到应用程序层。
1 #include<asm/types.h>
2 #include<sys/socket.h>
3 #include<linux/netlink.h>
4 #include<linux/netfilter_ipv4/ip_queue.h>
5 #include<stdio.h>
6 #include<stdlib.h>
7 #include<netinet/in.h>
8 #include<arpa/inet.h>
9 #include<netdb.h>
10 #include<linux/ip.h>
11 #include<linux/icmp.h>
12 #include<string.h>
13 #include<unistd.h>
14
15 int nl_sock_fd = 0;
16 struct sockaddr_nl nl_addr;
17 int seq = 0;
18 struct ipq_mode_msg* modeMessage;
19 struct ipq_verdict_msg *ver_data = NULL;
20 struct nlmsghdr* netlinkHeader =NULL;
21 struct ipq_packet_msg* packet = NULL;
22 char buf1[128] ={0};
23 char buf[4096] = {0};
24 char buf2[8192] = {0};
25
26 int addrSize;
27 int len,i;
28
29
30 int main(int argc, char *argv[])
31 {
32 int iter= 0;
33
34 /******* create and set the values for netlink sockets*************/
35 if((nl_sock_fd = socket( AF_NETLINK, SOCK_RAW, NETLINK_FIREWALL))<0)
36 {
37 printf("socket creation failed!\n");
38 return ;
39 }
40 printf("socket fd =%d\n", nl_sock_fd);
41
42 // Set up the kernels address structure:
43 memset(&nl_addr, 0, sizeof( struct sockaddr_nl ) );
44 nl_addr.nl_family = AF_NETLINK;
45 nl_addr.nl_pid = 0; // The with address 0 in netlink /getpid();
46 nl_addr.nl_groups = 0; // we dont need any multicast groups
47 nl_addr.nl_pad = 0;
48 if(bind(nl_sock_fd, (struct sockaddr*)&nl_addr, sizeof(nl_addr))<0)
49 {
50 printf("bind failed");
51 }
52 /******************* set mode values ***************************/
53 memset(buf1, 0, 128 );
54 netlinkHeader = (struct nlmsghdr*)buf1;
55 netlinkHeader->nlmsg_len = NLMSG_LENGTH(sizeof(struct ipq_mode_msg));
56 //NLMSG_LENGTH size of the ancilliary data
57 netlinkHeader->nlmsg_type = IPQM_MODE; //IPQM Packet
58 netlinkHeader->nlmsg_flags = NLM_F_REQUEST; //request message
59 netlinkHeader->nlmsg_seq = seq++; //to allow response correlation
60 netlinkHeader->nlmsg_pid = getpid();
61
62 // modeMessage=(struct ipq_mode_msg*)NLMSG_DATA(netlinkHeader);
63 modeMessage=NLMSG_DATA(netlinkHeader);
64 //NLMSG_DATA returns a pointer to the ancilliary data which it contains
65 modeMessage->value = IPQ_COPY_PACKET; //copy metadata and range 0 is entire packet
66 modeMessage->range = 0; // copy the entire payload
67
68 if(sendto( nl_sock_fd, (void*)buf1, netlinkHeader->nlmsg_len, 0, (struct sockaddr*)&nl_addr, s izeof(struct sockaddr_nl) ) < 0 )
69 {
70 printf("unable to set netlink mode ...\n");
71 exit(0);
72 }
73 printf("portion of data sent to netlink\n");
74 for(iter = 0; iter < 24; iter++ )
75 {
76 printf(" %x",(unsigned int)buf1[iter]);
77 if(!(iter%10) && iter !=0)
78 printf("\n");
79 }
80 printf("\n");
81
82 /*********** receiving msg ******************/
83 printf("socket is up and waiting for messages....\n");
84
85 while(1)
86 {
87 //struct nlmsghdr* netlinkHeader = buf1;
88
89 //netlinkHeader = buf1;
90 printf(" iam at recvfrom \n");
91 len = recvfrom(nl_sock_fd, buf2, NLMSG_LENGTH(sizeof(struct ipq_packet_msg)), 0, (struct soc kaddr*)&nl_addr, &addrSize );
92 printf(" NLMSG_LENGTH = %d\n",NLMSG_LENGTH(sizeof(struct ipq_packet_msg)));
93 if( len < 0 )
94 {
95 printf("unable to recive packet from the kernel\n");
96 return 0;
97 }
98
99 netlinkHeader = ( struct nlmsghdr* ) buf2;
100
101 printf("message received with pid=%d \n", nl_addr.nl_pid);
102
103 if( netlinkHeader->nlmsg_type == NLMSG_ERROR )
104 {
105 struct nlmsgerr* pError = (struct nlmsgerr*)NLMSG_DATA( netlinkHeader );
106 if( pError->error != 0 ) // Error number 0 is an acknowledgement not an error.
107 {
108 printf("error occured while receiving the message from the kernel.\n");
109 printf("error code %d \n ", pError->error);
110 printf("\n****** %s ********\n",strerror( -1 * pError->error));
111 printf("msg->nlmsg_len %d\n", pError->msg.nlmsg_len);
112 printf("msg->nlmsg_type %x\n", pError->msg.nlmsg_type);
113 printf("msg->nlmsg_flags %x\n",pError->msg.nlmsg_flags);
114 printf("msg->nlmsg_seq: %d\n", pError->msg.nlmsg_seq);
115 printf("msg->nlmsg_pid: %d\n", pError->msg.nlmsg_pid);
116 return 0;
117 }
118 }
119 else
120 {
121
122 printf("Message from kernel:\n ");
123 printf("Packet ID: %d\n",packet->packet_id);
124 printf("Payload size:%d\n", packet->data_len);
125 for(i = 0; i < packet->data_len; ++i )
126 {
127 printf("%c ", packet->payload[ i ]);
128 }
129 printf("\n");
130
131 }
132 printf("\n dumping packets over \n");
133 netlinkHeader=(struct nlmsghdr *)buf1;
134 packet=NLMSG_DATA(netlinkHeader);
135 /*for the example just forward all packets*/
136 //netlinkHeader = (struct nlmsghdr*)buf2;
137 netlinkHeader->nlmsg_type=IPQM_VERDICT;
138 netlinkHeader->nlmsg_len=NLMSG_LENGTH(sizeof(struct ipq_verdict_msg));
139 netlinkHeader->nlmsg_flags=(NLM_F_REQUEST);/*this is a request, don’t ask for an answer*/
140 netlinkHeader->nlmsg_pid=getpid();
141 netlinkHeader->nlmsg_seq=seq++;/*arbitrary unique value to allow response correlation*/
142 ver_data=(struct ipq_verdict_msg *)NLMSG_DATA(netlinkHeader);
143
144 //ver_data->value=NF_ACCEPT;
145 //ver_data->value=NF_QUEUE;
146 ver_data->id=packet->packet_id;
147 if(sendto(nl_sock_fd,(void *)netlinkHeader,netlinkHeader->nlmsg_len,0,
148 (struct sockaddr *)&nl_addr,sizeof(struct sockaddr_nl)) < 0)
149 {
150 perror("unable to send mode message");
151 exit(0);
152 }
153
154
155 }
156
157 return 0;
158 }
输出就像
socket fd =3
portion of data sent to netlink
18 0 0 0 11 0 1 0 0 0 0
0 38 30 0 0 2 0 0 0 0
0 0 0
socket is up and waiting for messages....
iam at recvfrom
NLMSG_LENGTH = 88
message received with pid=0
error occured while receiving the message from the kernel.
error code -22
****** Invalid argument ********
msg->nlmsg_len 24
msg->nlmsg_type 11
msg->nlmsg_flags 1
msg->nlmsg_seq: 0
msg->nlmsg_pid: 12344
请帮帮我 并提供一些有助于学习原始插座的最佳书籍