[완료] dereferencing pointer to incomplete type 에러 잡기

cc -Wall -O3 -g -I../include  -c -o net.o net.c
net.c: In function ‘send_icmp’:
net.c:92: error: dereferencing pointer to incomplete type
net.c:105: error: dereferencing pointer to incomplete type
net.c:108: error: dereferencing pointer to incomplete type
net.c:109: error: dereferencing pointer to incomplete type
net.c:92: warning: unused variable ‘cbuf’
make[1]: *** [net.o] Error 1

 88 send_icmp(struct sbuff *b, struct sockaddr_in6 *sin, int ifidx)
 89 {
 90     struct iovec iov = { b->head, b->len };
 91     struct in6_pktinfo *ipi;
 92     uint8_t cbuf[CMSG_SPACE(sizeof (*ipi))];
 93     struct cmsghdr *cmsg = (struct cmsghdr *)cbuf;
 94     struct msghdr msg = {
 95         .msg_name = sin,
 96         .msg_namelen = sizeof (*sin),
 97         .msg_iov = &iov,
 98         .msg_iovlen = 1,
 99         .msg_control = cbuf,
100         .msg_controllen = sizeof (cbuf),
101     };
102 
103     cmsg->cmsg_level = IPPROTO_IPV6;
104     cmsg->cmsg_type = IPV6_PKTINFO;
105     cmsg->cmsg_len = CMSG_LEN(sizeof (*ipi));
106 
107     ipi = (struct in6_pktinfo *)CMSG_DATA(cmsg);
108     memset(ipi, 0, sizeof (*ipi));
109     ipi->ipi6_ifindex = ifidx;
110 
111     DBG(&dbg, "sending %d bytes to %s (%d)", b->len,
112         inet_ntop(AF_INET6, &sin->sin6_addr, abuf, sizeof (abuf)),
113         ifidx);
114 
115     if (sendmsg(icmp6sock, &msg, 0) < 0) {
116         DBG(&dbg_snd, "sendmsg: %s", strerror(errno));
117         return (-1);
118     }
119     return (0);
120 }

 33 #include <sys/param.h>
 34 #include <sys/types.h>
 35 #include <sys/socket.h>
 36 
 37 #include <arpa/inet.h>
 38 
 39 #include <net/if.h>
 40 #include <net/route.h>
 41 
 42 #include <netinet/in.h>
 43 
 44 #include <errno.h>
 45 #include <stdio.h>
 46 #include <string.h>
 47 #include <unistd.h>