Thread: recv() and recvfrom()

I did post some code, but if you really believe that the full code will help, there you go:

Code:

#define DNS_LNT 500


int DnsLookup(char *dns_server, char *host_name, char dns_id, char dns_type, char *msg)
 {
    int sockfd, numbytes, addr_lnt, tot_lnt;
    struct sockaddr_in ina;

    tot_lnt = DnsSetMsg(msg, host_name, dns_id, dns_type);  
/* this only sets a DNS message and returns the length */
    if ((sockfd=socket(AF_INET, SOCK_DGRAM, 0))==-1)
       return(0);

    ina.sin_family = AF_INET;
    ina.sin_port = htons(DNSPORT);   // port 53
    ina.sin_addr.s_addr = inet_addr(dns_server);
    memset(ina.sin_zero, '\0', 8);

    if ((numbytes=sendto(sockfd, msg, tot_lnt, 0, (struct sockaddr *)&ina, sizeof(struct sockaddr)))==-1)
       return(0);

    memset(msg, '\0', DNS_LNT);
    addr_lnt = sizeof(struct sockaddr);
    if ((numbytes=recvfrom(sockfd, msg, DNS_LNT-1, 0, (struct sockaddr *)&ina, &addr_lnt))==-1)
       return(0);

    closesocket(sockfd);
    if (msg[1]!=dns_id)
       return(0);
    return(1);
 }

You're asking all the wrong questions, the only important thing that's missing is the declaration of msg:
char msg[DNS_LNT]={0};

All of the problems where in recvfrom(), nothing else matters, when (if) the program died, it died on recvfrom().

note: at the end of DnsLookup() the msg contains the entire dns response, with all the answers, so it's pretty big.