Error: Bad address when using sendto() in raw sockets - c

Question

I'm writing a simple network application and I need to craft a UDP packet and send it to a specific host.
int main(void){
// Message to be sent.
char message[] = "This is something";
int sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
if(sockfd < 0){
perror("Error creating socket");
exit(1);
}
struct sockaddr_in this, other;
this.sin_family = AF_INET;
other.sin_family = AF_INET;
this.sin_port = htons(8080);
other.sin_port = htons(8000);
this.sin_addr.s_addr = INADDR_ANY;
other.sin_addr.s_addr = inet_addr("10.11.4.99");
if(bind(sockfd, (struct sockaddr *)&this, sizeof(this)) < 0){
printf("Bind failed\n");
exit(1);
}
char packet[64] = {0};
struct udphdr *udph = (struct udphdr *) packet;
strcpy(packet + sizeof(struct udphdr), message);
udph->uh_sport = htons(8080);
udph->uh_dport = htons(8000);
udph->uh_ulen = htons(sizeof(struct udphdr) + sizeof(message));
udph->uh_sum = 0;
if(sendto(sockfd, packet, udph->uh_ulen, 0, (struct sockaddr *) &other, sizeof(other)) < 0)
perror("Error");
else
printf("Packet sent successfully\n");
close(sockfd);
return 0;
}
Everything is working fine till the call to sendto(). The sendto() is giving "Bad address". can anyone point me where I'm going wrong? Is there any problem with binding a port to a raw socket?

Answer 1

The code transform the length of the messag (udph->uh_len) to network byte order (htons). This is not needed, as the parameter type of size_t. Only port number (in sockaddr structures) need the htons conversion.
udph->uh_ulen = sizeof(struct udphdr) + sizeof(message);
Current code produce large number (>8000) in uh_ulen, causing the send to fail.