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server.cpp
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server.cpp
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#include <iostream>
#include <string>
#include <vector>
#include <memory>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <netinet/tcp.h>
#include <netdb.h>
#define DEFAULT_PORT "32345"
#define TFO_QLEN 128
#define LISTEN_QLEN 128
#define BUFFER_SIZE 4096
#define MAX_EVENTS 32
#include "common.h"
int open_socket(const std::string &port)
{
struct addrinfo hint, *res;
std::memset(&hint, 0, sizeof(hint));
hint.ai_family = AF_UNSPEC;
hint.ai_socktype = SOCK_STREAM;
hint.ai_flags = AI_PASSIVE | AI_NUMERICSERV;
int e = getaddrinfo(nullptr, port.c_str(), &hint, &res);
if( e != 0 )
{
std::cerr << "getaddrinfo: " << gai_strerror(e) << std::endl;
std::exit(EXIT_FAILURE);
}
int sock;
struct addrinfo *rp;
for( rp = res; rp != nullptr; rp = rp->ai_next )
{
sock = socket(rp->ai_family, rp->ai_socktype | SOCK_NONBLOCK, rp->ai_protocol);
if( sock == -1 ) continue;
if( bind(sock, rp->ai_addr, rp->ai_addrlen) == 0 ) break;
close(sock);
}
if( rp == nullptr )
{
std::cerr << "Couldn't bind." << std::endl;
std::exit(EXIT_FAILURE);
}
int protocol = rp->ai_protocol;
freeaddrinfo(res);
const int qlen = TFO_QLEN;
e = setsockopt(sock, protocol, TCP_FASTOPEN, &qlen, sizeof(qlen));
if( e == -1 )
{
close(sock);
cerror("setsockopt");
std::exit(EXIT_FAILURE);
}
if( listen(sock, LISTEN_QLEN) == -1 )
{
close(sock);
cerror("listen");
std::exit(EXIT_FAILURE);
}
return sock;
}
int accept_and_register(int sfd, int epollfd)
{
// Accept a new connection
struct sockaddr addr;
socklen_t addrlen = sizeof(addr);
int s;
do
{
s = accept4(sfd, &addr, &addrlen, SOCK_NONBLOCK);
} while( s == -1 && errno == EINTR );
if( s == -1 )
{
cerror("accept");
std::exit(EXIT_FAILURE);
}
struct epoll_event ev;
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = s;
if( epoll_ctl(epollfd, EPOLL_CTL_ADD, s, &ev) == -1 )
{
perror("epoll_ctl: EPOLL_CTL_ADD");
std::exit(EXIT_FAILURE);
}
return s;
}
void process_client_socket(int s, int epollfd)
{
static std::vector<char> buf(BUFFER_SIZE);
ssize_t rs;
while( (rs = recv(s, &buf[0], buf.size(), 0)) != 0 )
{
if( rs == -1 )
{
if( errno == EINTR ) continue;
if( errno == EAGAIN || errno == EWOULDBLOCK ) return;
cerror("recv");
break;
}
ssize_t sent;
// EAGAIN or EWOULDBLOCK is retuned when the socket buffer is full
// We should try with another socket for maximum performance, however,
// we just wait until the buffer becomes available as we don't have
// enough buffer for that.
do {
sent = send(s, &buf[0], rs, 0);
} while( sent == -1 &&
(errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) );
if( sent == -1 )
{
cerror("send");
break;
}
}
if( epoll_ctl(epollfd, EPOLL_CTL_DEL, s, nullptr) == -1 )
cerror("epoll_ctl: EPOLL_CTL_DEL");
close(s);
}
void server(const std::string &port)
{
FD sfd(open_socket(port));
struct epoll_event ev, events[MAX_EVENTS];
FD epollfd(epoll_create1(0));
if( epollfd == -1 )
{
cerror("epoll_create1");
std::exit(EXIT_FAILURE);
}
ev.events = EPOLLIN;
ev.data.fd = sfd;
if( epoll_ctl(epollfd, EPOLL_CTL_ADD, sfd, &ev) == -1 )
{
perror("epoll_ctl: EPOLL_CTL_ADD");
std::exit(EXIT_FAILURE);
}
while( 1 )
{
const int nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);
if( nfds == -1 )
{
if( errno == EINTR ) continue;
cerror("epoll_wait");
std::exit(EXIT_FAILURE);
}
for( int i = 0; i < nfds; ++i )
{
if( events[i].data.fd == sfd )
accept_and_register(sfd, epollfd);
else
process_client_socket(events[i].data.fd, epollfd);
}
}
}
int main(int argc, char *argv[])
{
std::string port;
if( argc <= 1 )
{
port = DEFAULT_PORT;
} else {
port = argv[1];
}
server(port);
}