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cpn_server.cpp
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cpn_server.cpp
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/*
** server.c -- a stream socket server demo
*/
#include <stdio.h>
#include <iostream>
#include <sstream>
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#define BACKLOG 20 // how many pending connections queue will hold
#define MAXBUFLEN 100
#include "aotp_lib.h"
//global variables
string received_request;
string message;
char operation;
vector<double> operands;
int port_number = 5004;
int numbytes; int numbytes1, numbytes2, numbytes3;
char buf1[MAXBUFLEN];
int sockfd, new_fd; // listen on sock_fd, new connection on new_fd
struct addrinfo hints, *servinfo, *p;
char buf[MAXBUFLEN];
struct sockaddr_storage their_addr; // connector's address information
socklen_t sin_size;
struct sigaction sa;
int yes=1;
char s[INET6_ADDRSTRLEN];
int rv;
string port_number_str;
string result_string;
//error function
void error(string& s, int socket_int)
{
cout<<"ERROR:" + s <<endl;
s = "ERROR " + s + "\r";
if ((send(socket_int, s.c_str(), s.size(), 0)) == -1) //send the error to the client.
{
perror("Server Error: Send in the error function");
}
cout<<"the server is still listening on:"<<port_number_str<<endl;
}
// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
if (sa->sa_family == AF_INET) {
return &(((struct sockaddr_in*)sa)->sin_addr);
}
return &(((struct sockaddr_in6*)sa)->sin6_addr);
}
int main(int argc, char *argv[])
{
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC; //we can use either ipv6 or ipv4
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE; // use my IP
if (argc != 3) {
fprintf(stderr,"usage: server hostname\n");
exit(1);
}
//fill in the struct addrinfo with all the info about the server side
if ((rv = getaddrinfo(NULL, argv[2], &hints, &servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return 1;
}
// loop through all the results and bind to the first we can
for(p = servinfo; p != NULL; p = p->ai_next)
{
if ((sockfd = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("server: socket");
continue;
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
sizeof(int)) == -1) {
perror("setsockopt");
exit(1);
}
if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
close(sockfd);
perror("server: bind");
continue;
}
break;
}
freeaddrinfo(servinfo);
if (p == NULL)
{
fprintf(stderr, "server: failed to bind\n");
return 2;
}
else
printf("server: binded the socket succesfully\n");
printf("server: waiting for connections... \n");
while(1) // main accept() loop
{
if (listen(sockfd, BACKLOG) == -1)
{
perror("listen");
exit(1);
}
sin_size = sizeof their_addr;
new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
if (new_fd == -1)
{
perror("accept");
continue;
}
inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr),
s, sizeof s);
printf("server: client at %s is now connected\n", s);
if (!fork())
{ // this is the child process
//receive the data form client into a buffer
//printf("Server: waiting to receive data from the client side....\n");
if ((numbytes = recv(new_fd, buf, MAXBUFLEN-1 , 0)) == -1)
{
perror("recv");
exit(1);
}
//print the adress of the client
printf("server: Received packet from client at %s\n",
inet_ntop(their_addr.ss_family,
get_in_addr((struct sockaddr *)&their_addr),
s, sizeof s));
//print the number of bytes received and print the bytes.
printf("server: packet is %d bytes long\n", numbytes);
buf[numbytes] = '\0';
printf("server: packet contains %s \n", buf);
//reading the message from the client.
received_request.clear();
received_request = buf;
message.clear();
message = get_message(received_request);
//cout<<"Message after parsing the received request is:"<<message<<endl;
void error(string&, int);
void check_the_message(string&, int);
check_the_message(message, new_fd);
}//fork
}//while
close(sockfd);
return 0;
}//main
void check_the_message(string& message, int new_fd)
{
void change_the_port(string&);
if(!check_message(message))
{
string s = "bad request";
error(s, new_fd);
}
else
{
operation = get_operation(received_request);
if(!check_operation(operation))
{
string s = "invalid operation";
error(s, new_fd);
}
else
{
operands.clear();
operands = get_operands(received_request);
if(!check_operands(operands))
{
string s = "bad operands";
error(s, new_fd);
}
else
{
string result_str = do_operation(operation, operands);
//cout<<"the result received from the aotp_lib is:"<<result_str<<endl;
result_string = "ACR " + result_str + "\r";
port_number_str = to_string(port_number);
string change_port_msg = "CPN " + port_number_str + "\r";
if ((numbytes1 = send(new_fd, change_port_msg.c_str(), change_port_msg.size(), 0)) == -1)
{perror("Server: error while sending the CPN message");
exit(1);}
cout<<"Server: Sent CPN message to the client\n";
//receive the change port acknowledgement on the old port(new_fd)
if ((numbytes2 = recv(new_fd, buf1, MAXBUFLEN-1 , 0)) == -1)
{
printf("error while receiving the CPN_ack");
exit(1);
}
buf1[numbytes2] = '\0';
string buffer = buf1;
message = get_message(buffer);
if(message == "CPN_ACK")
{
cout<<"Sever: Received the acknowledgement for 'CPN' message:"<<message<<endl;
change_the_port(port_number_str);
}
else if(message != "CPN_ACK")
{
string s = "Server: Received NO acknowledgement for CPN";
error(s, new_fd);
}
close(new_fd);
port_number++;
}//else
}//else
}//esle
}
void change_the_port(string& port_number_str)
{
//change of port number to notified port number??
//1.create structs using get_addrinfo() system call??
cout<<"Server: changing to the new port number "<<port_number_str<<endl;
if ((rv = getaddrinfo(NULL, port_number_str.c_str(), &hints, &servinfo)) != 0)
{
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
//return 1;
}
//2.create new socket with new port num using those structs??
for(p = servinfo; p != NULL; p = p->ai_next)
{
if ((sockfd = socket(p->ai_family, p->ai_socktype, //same sock_fd as before but it got new fd
p->ai_protocol)) == -1) {
perror("server: socket");
continue;
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
sizeof(int)) == -1) {
perror("setsockopt");
exit(1);
}
//3.bind the socket to new port number
if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
close(sockfd);
perror("server: bind");
continue;
}
break;
}
//listen for new conns
freeaddrinfo(servinfo);
if (p == NULL)
{
fprintf(stderr, "server: failed to bind\n");
//return 2;
}
else
cout<<"Server: succesfully binded to the port on:"<<port_number<<endl;
if (listen(sockfd, BACKLOG) == -1)
{
perror("listen");
exit(1);
}
sin_size = sizeof their_addr;
new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size); //new_fd got over written
if (new_fd == -1)
{
perror("accept");
}
else
{
inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr),
s, sizeof s);
printf("server: client at %s is now connected", s);
cout<<"on the new port number:"<<port_number_str<<endl;
////////////////////////////
if (!fork())
{ // this is the child process
//close(sockfd); // child doesn't need the listener
if ((numbytes1 = send(new_fd, result_string.c_str(), result_string.size(), 0)) == -1)
perror("server: Error while sending the result");
else
printf("Server: sent result to the client at %s\n\n", inet_ntop(their_addr.ss_family,
get_in_addr((struct sockaddr *)&their_addr),
s, sizeof s) );
}
cout<<"Server: The server is now listening on port number:"<<port_number<<endl;
}
//return 1;
}