Error with sendto() function: Invalid Argument Error - sockets

Question

I am working on writing a ping CLI program for linux and I have been getting errno 22: invalid argument in the sendto() function. I don't understand why, all the arguments seem to be correct.
Here is where I call the function:
// send echo request
bytesSent = sendto(socketFD, // socket file descriptor
(char*)&packet, PacketSize, // packet and size
0, // flags
(sockaddr*)DestinationAddr, (socklen_t)sizeof(DestinationAddr)); // destination address and size
'packet' looks like this:
(I call initializePacket() in the function where I call sendto())
struct PacketData {
icmphdr header;
char message[PacketSize - sizeof(header)]; // want total size to be 64 bytes
};
PacketData initializePacket(int &transmitted) {
PacketData packet = {};
packet.header.type = ICMP_ECHO; // set ICMP type to Echo
packet.header.un.echo.id = getpid() & 0xFFFF; // set id (ICMP field is 16 bits)
packet.header.checksum = 0; // fixed checksum because data is unchanging
packet.header.un.echo.sequence = transmitted++;
// fill up message
memset(&packet.message, '0', sizeof(packet.message));
packet.message[PacketSize - sizeof(packet.header) - 1] = '\0';
return packet;
}
'DestinationAddr' is this:
// variables needed to store IP Address
addrinfo* result;
sockaddr_in* DestinationAddr;
char ipString[INET_ADDRSTRLEN];
// get IP Address and store in result (passed by reference)
if (getIPAddress(argv[1], result) != 0) {
std::cout << "Invalid IP Address. Terminating ...\n";
exit(EXIT_FAILURE);
}
else {
DestinationAddr = (sockaddr_in*)result->ai_addr; // get struct from resulting linked list
void* address;
address = &DestinationAddr->sin_addr; // store IP Address
inet_ntop(result->ai_family, address, ipString, sizeof(ipString)); // convert binary IP to string
std::cout << "IP: " << ipString << std::endl;
}
And the getIPAddress() function is:
int getIPAddress(char* hostName, addrinfo* &result) {
addrinfo tempStruct = {0};
tempStruct.ai_family = AF_INET; // want IPv4
tempStruct.ai_socktype = SOCK_DGRAM; // set socket type to datagram
tempStruct.ai_flags = AI_PASSIVE; // fill in IP automatically
// get and validate IP address
return (getaddrinfo(hostName, &PortNo, &tempStruct, &result));
}
PortNo is defined as: const char PortNo = '0';

Answer 1

According to documentation icmp:
A user protocol may receive ICMP packets for all local sockets by opening a raw socket with the protocol IPPROTO_ICMP.
So, try creating your socket like that:
socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)
And, if you encounter EPERM error, then run your program as root.