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Old 05-01-2006, 05:34 AM   #1
LQ Newbie
Registered: Oct 2005
Posts: 28

Rep: Reputation: 15
Error: dereferencing pointer to incomplete type

hi ,

this is the error which i got when compiling a C pgm:

con1.c:471: dereferencing pointer to incomplete type
con1.c:473: dereferencing pointer to incomplete type

this is the code lines which produced the error

int main(int argc, char **argv)

char *dev = NULL;
char errbuf[PCAP_ERRBUF_SIZE];
char *fname;
int n;
struct sockaddr_in serv_addr;
struct hostent *server;
pcap_t *handle;
bpf_u_int32 mask;
bpf_u_int32 net;
struct pcap_pkthdr *h;
const u_char *sp;
struct pcap_pkthdr hdr;
pcap_dumper_t *dumpfile;
int num_packets = 5;

// Establishing a connection to the server

if (argc < 3) {
fprintf(stderr,"usage %s hostname port\n", argv[0]);
portno = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
server = gethostbyname(argv[1]);
if (server == NULL) {
fprintf(stderr,"ERROR, no such host\n");
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
// here is the error
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length); //
serv_addr.sin_port = htons(portno);
if (connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");

Any idea.
thanks and regards
cynthia thomas
Old 05-01-2006, 09:10 AM   #2
Senior Member
Registered: Nov 2005
Location: Hanoi
Distribution: Fedora 13, Ubuntu 10.04
Posts: 2,379

Rep: Reputation: 148Reputation: 148
Originally Posted by cynthia_thomas
// here is the error
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length); //
h_addr is a character array whilst s_addr is of type unsigned long.

The copy that you are attempting will not give you the result that you are hoping for, being a conversion from a character representation of the IP address to a numerical representation.

Check out the function inet_aton()



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