Пример POST запроса

//------------------------------------------------------------------------------
#include <winsock>
#include <stdio.h>
//------------------------------------------------------------------------------
int get_addr(char *host_name)
{
    int res = -1;
 
    HOSTENT *phe = gethostbyname(host_name);
    if (phe)
        for (int i = 0; i < 4; i++)
            ((BYTE *)&res)[i] = phe->h_addr_list[0][i];
 
    return res;
}
//------------------------------------------------------------------------------
int main(int argc, char* argv[])
{
    WSADATA wsa_data;
    if (WSAStartup(0x101, &wsa_data))
    {
        printf("WSAStartup error (%i)\n", WSAGetLastError());
        system("pause");
        return -1;
    }
 
    if (wsa_data.wVersion != 0x101)
    {
        printf("Bad WSA version (%i)\n", wsa_data.wVersion);
        system("pause");
        return -1;
    }
 
    SOCKET s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (s == INVALID_SOCKET)
    {
        printf("socket error (%i)\n", WSAGetLastError());
        system("pause");
        return -1;
    }
 
    int use_host_name;
    char host_name[256];
    char host_ip[256];
    int host_port;
    char doc[256];
 
    printf("use_host_name (0 for host_ip or 1 for host_name): ");
    scanf("%i", &use_host_name);
 
    if (use_host_name)
    {
        printf("host_name: ");
        scanf("%s", host_name);
    }
    else
    {
        printf("host_ip: ");
        scanf("%s", host_ip);
    }
 
    printf("host_port: ");
    scanf("%i", &host_port);
 
    printf("doc (for example /index.htm or /): ");
    scanf("%s", doc);
 
    SOCKADDR_IN sa;
    sa.sin_family = AF_INET;
    sa.sin_port = htons(host_port);
    sa.sin_addr.S_un.S_addr = use_host_name? get_addr(host_name) : inet_addr(host_ip);
 
    printf("wait for server...\n");
 
    while (true)
    {
        int connect_res = connect(s, (SOCKADDR *)&sa, sizeof(sa));
        if (!connect_res) break;
 
        Sleep(250);
    }
 
    printf("connected\n");
 
    char message[256];
 
    int message_size = sprintf
    (
        message,
        "GET [url]http://%s:%i%s[/url] HTTP/1.1\r\n"
        "Host: %s:%i\r\n"
        "Connection: Close\r\n"
        "\r\n",
        (use_host_name? host_name : host_ip),
        host_port,
        doc,
        (use_host_name? host_name : host_ip),
        host_port
    );
 
    if (send(s, message, message_size, 0) == SOCKET_ERROR)
    {
        printf("send error (%i)\n", WSAGetLastError());
        system("pause");
        return -1;
    }
 
    char buffer[100000];
    int buffer_size = sizeof(buffer);
    buffer_size = recv(s, buffer, buffer_size, 0);
    if (buffer_size == SOCKET_ERROR)
    {
        printf("recv error (%i)\n", WSAGetLastError());
        system("pause");
        return -1;
    }
    buffer[buffer_size] = '\0';
    printf("from_server: %s\n", buffer);
 
    closesocket(s);
 
    WSACleanup();
 
    system("pause");
    return 0;
}

char buffer[123];

char *buffer = new char[123];

char *buffer = (char *)malloc(123);