push notification in FCM using http post - c++

Question

I'd like to send http post to my fcm clients.
I made android client app using FCM, and server is executed on Window environment.
I was finding how to push notification that fcm offer, finally
I found that using http, I can make it easily.
fire base said that I can use this.
https://fcm.googleapis.com/fcm/send
Content-Type:application/json
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA
{
"to": "/topics/foo-bar",
"data": {
"message": "This is a Firebase Cloud Messaging Topic Message!",
}
}
but I don't know how to apply this to my code.
because I didn't learn how to use http.
to match host, I used 'gethostbyname' function.
However this function return 'nullptr'!
what I want to know is what hname should be? my local ip? or what?
I really confused.
this is my code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>
#include <windows.h>
#pragma comment(lib, "ws2_32.lib")
#define MAXLINE 4096
#define MAXSUB 400
SSIZE_T process_http(int sockfd, char *page, char *poststr,char *auKey,char *topic)
{
char sendline[MAXLINE + 1], recvline[MAXLINE + 1];
SSIZE_T n;
snprintf(sendline, MAXSUB,
"https:%s\r\n"
"Content-type: application/json\r\n"
"Authorization:key=%s\r\n"
"{\r\n"
"\"to\":\"\\topics\\%s\",\r\n"
"\"data\" : {\r\n"
"\"message\" : \"%s\",\r\n"
"}\r\n"
"}\r\n"
, page, auKey, topic, poststr);
printf("send data : %s\n\n", sendline);
send(sockfd, sendline, strlen(sendline), 0);
while ((n = recv(sockfd, recvline, MAXLINE, 0)) > 0)
{
recvline[n] = '\0';
printf("%s\n\n", recvline);
}
return n;
}
int main()
{
WSADATA wsaData;
SOCKET hSocket;
int strlen;
hostent *Host;
SOCKADDR_IN servAddr;
//********** You can change. Put any values here *******
char *hname = "https://fcm.googleapis.com/fcm/send";
char *page_0 = "//fcm.googleapis.com/fcm/send";
char *auKey = "AAAAXTiYFNU:APA91bGcH-Ee7JDVC9ZvDA4n09VR3W6x3AEcVrWQjrhbCeQQ_L5pF-7mNRgeMg0xW8g78uLVkjygJ93Za3NL7BXxDvetpZYTSHfiitZwPpiD9iQhgslNuy5Mlz4iuhAHILUpXhAK_o1W";
char *poststr_0 = "1#";// using camera Number
char *topic = "news"; // input topic name
//*******************************************************
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
printf("WSAStartup failed.\n");
exit(1);
}
while (1)
{
hSocket = socket(PF_INET, SOCK_STREAM, 0);
if (hSocket == INVALID_SOCKET)
{
printf("Socket failed.\n");
exit(1);
}
//Host = gethostbyname(hname);
memset(&servAddr, 0, sizeof(servAddr));
servAddr.sin_family = AF_INET;
servAddr.sin_addr.s_addr = inet_addr(hname);
servAddr.sin_port = htons(80);
if (connect(hSocket, (SOCKADDR*)&servAddr, sizeof(servAddr)) == SOCKET_ERROR)
{
printf("Connect failed.\n");
exit(1);
}
printf("Connected\n\n");
process_http(hSocket, page_0, poststr_0, auKey, topic);
closesocket(hSocket);
Sleep(10000);
}
WSACleanup;
return 0;
}

Answer 1

I made it based on your source. This source used "C". Thank you.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>
#include <windows.h>
#pragma comment(lib, "ws2_32.lib")
#define MAXLINE 4096
#define MAXSUB 400
SSIZE_T process_http(int sockfd, char *page, char *hname, char *data,char *auKey)
{
char sendline[MAXLINE + 1], recvline[MAXLINE + 1];
SSIZE_T n;
sprintf(sendline,
// Header
"POST %s HTTP/1.1\r\n"
"Host: %s\r\n"
"Content-Type: application/json;charset=utf-8;\r\n"
"Authorization:key=%s\r\n"
"Content-Length: %d\r\n\r\n"
// Data
"%s", page, hname, auKey, strlen(data), data);
printf("send data : %s\n\n", sendline);
send(sockfd, sendline, strlen(sendline), 0);
while ((n = recv(sockfd, recvline, MAXLINE, 0)) > 0)
{
recvline[n] = '\0';
printf("recv : %s\n\n", recvline);
}
return n;
}
int main()
{
WSADATA wsaData;
SOCKET hSocket;
int strlen;
struct hostent *Host;
SOCKADDR_IN servAddr;
char *hname = "fcm.googleapis.com";
char *page_0 = "/fcm/send";
char *auKey = "(Input your authorization key)";
char *data = "";
data =
"{\"to\":\"/topics/(Input your topic)\","
"\"data\":{"
"\"title\":\"TEST TITLE\","
"\"message\":\"TEST_Message\""
"}"
"}\"\r\n";
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
printf("WSAStartup failed.\n");
exit(1);
}
if ((Host = gethostbyname(hname)) == NULL) {
fprintf(stderr, " gethostbyname error for host: %s:",hname);
exit(1);
}
hSocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (hSocket == INVALID_SOCKET)
{
printf("Socket failed.\n");
exit(1);
}
memset(&servAddr, 0, sizeof(servAddr));
servAddr.sin_family = AF_INET; // IP v4
servAddr.sin_addr.s_addr = inet_addr(inet_ntoa(*(struct in_addr*)*Host->h_addr_list));
servAddr.sin_port = htons(80);
if (connect(hSocket, (SOCKADDR*)&servAddr, sizeof(servAddr)) == SOCKET_ERROR)
{
printf("Connect failed.\n");
exit(1);
}
printf("Connected\n\n");
process_http(hSocket, page_0, hname, data, auKey);
closesocket(hSocket);
WSACleanup;
return 0;
}