Example Servers Pt 2Example Servers Pt 2

Objective:

To discuss key aspects of various server implementations

Server Example OutlineServer Example Outline

Multi-Protocol Server – (Daytimed.cpp)

Multi-Service Server – (Superd.c)

3

Multiprotocol ServerMultiprotocol Server daytimed.c daytimed.c

/* daytimed.cpp - main, daytime */

#include <stdio.h>

#include <time.h>

#include <winsock.h>

void daytime(char buf[]);

void errexit(const char *, ...);

SOCKET passiveTCP(const char *, int);

SOCKET passiveUDP(const char *);

#define WSVERSMAKEWORD(2, 0)

#define QLEN 5

#define LINELEN 128

4

Multiprotocol ServerMultiprotocol Server daytimed.c daytimed.c

void main(int argc, char *argv[])

{

char *service = "daytime";// service name

char buf[LINELEN+1]; // line buffer

struct sockaddr_in fsin; // Request from address

int alen; // from-address length

SOCKET tsock; // TCP master socket

SOCKET usock; // UDP socket

fd_set rfds; // readable file descriptors

int rv; WSADATA wsadata;

5

Multiprotocol ServerMultiprotocol Server daytimed.c daytimed.c

switch (argc) {

case 1: break;

case 2: service = argv[1];

break;

default:

errexit("usage: daytimed [port]\n");

}

if (WSAStartup(WSVERS, &wsadata) != 0)

errexit("WSAStartup failed\n");

tsock = passiveTCP(service, QLEN);

usock = passiveUDP(service);

FD_ZERO(&rfds);

6

Multiprotocol ServerMultiprotocol Server daytimed.c daytimed.c

while (1) {FD_SET(tsock, &rfds);FD_SET(usock, &rfds);if(select(FD_SETSIZE,&rfds,(fd_set*)0,(fd_set*)0,

(struct timeval *)0) == SOCKET_ERROR)errexit("select error: %d\n", GetLastError());if (FD_ISSET(tsock, &rfds)) {SOCKET ssock; /* TCP slave socket */alen = sizeof(fsin);ssock = accept(tsock, (struct sockaddr

*)&fsin, &alen);if (ssock == INVALID_SOCKET)errexit("accept failed: %d\n",GetLastError());

7

Multiprotocol ServerMultiprotocol Server daytimed.c daytimed.c

daytime(buf);(void) send(ssock, buf, strlen(buf), 0);(void) closesocket(ssock);

} if (FD_ISSET(usock, &rfds)) {

alen = sizeof(fsin);rv = recvfrom(usock, buf, sizeof(buf), 0, (struct sockaddr *)&fsin, &alen);if (rv == SOCKET_ERROR)

errexit("recvfrom: error %d\n",GetLastError());daytime(buf);(void) sendto(usock, buf, strlen(buf), 0,

(struct sockaddr *)&fsin, sizeof(fsin));}

}}

8

Multiprotocol ServerMultiprotocol Server daytimed.c daytimed.c

/*----------------------------------------------------- * daytime - fill the given buffer with the time of day *-----------------------------------------------------*/

void daytime(char buf[]){

time_t now;(void) time(&now);sprintf(buf, "%s", ctime(&now));

}

9

Multi-service Server - Multi-service Server - superd.csuperd.c/* superd.cpp - main, doTCP */#include <process.h>#include <winsock.h>#define UDP_SERV 0#define TCP_SERV 1struct service{

char *sv_name;char sv_useTCP;SOCKET sv_sock;void (*sv_func)(SOCKET);

};void TCPechod(SOCKET), TCPchargend(SOCKET),

TCPdaytimed(SOCKET), TCPtimed(SOCKET);

10

Multi-service Server - Multi-service Server - superd.csuperd.cSOCKET passiveTCP(const char *, int);SOCKET passiveUDP(const char *);void errexit(const char *, ...);void doTCP(struct service *);struct service svent[] = {

{ "echo", TCP_SERV, INVALID_SOCKET, TCPechod },{ "chargen", TCP_SERV, INVALID_SOCKET, TCPchargend },{ "daytime", TCP_SERV, INVALID_SOCKET, TCPdaytimed },{ "time", TCP_SERV, INVALID_SOCKET, TCPtimed },{ 0, 0, 0, 0 },

};#define WSVERS MAKEWORD(2, 0)#define QLEN 5#define LINELEN 128extern u_short portbase; /* from passivesock() */

11

Multi-service Server - Multi-service Server - superd.csuperd.c

void main(int argc, char *argv[]){

struct service *psv; // service table pointerfd_set afds, rfds; /* file descriptorsWSADATA wsdata;switch (argc) {

case 1: break;case 2: portbase = (u_short) atoi(argv[1]);

break;default: errexit("usage: superd [portbase]\n");

}if (WSAStartup(WSVERS, &wsdata))

errexit("WSAStartup failed\n");FD_ZERO(&afds);

12

Multi-service Server - Multi-service Server - superd.csuperd.c

for (psv = &svent[0];psv->sv_name; ++psv){

if (psv->sv_useTCP)psv->sv_sock = passiveTCP(psv->sv_name, QLEN);

elsepsv->sv_sock = passiveUDP(psv->sv_name);

FD_SET(psv->sv_sock, &afds);}

Multi-service Server - Multi-service Server - superd.csuperd.cwhile (1) {

memcpy(&rfds, &afds, sizeof(rfds));if (select(FD_SETSIZE, &rfds, (fd_set *)0, (fd_set *)0,(struct timeval *)0) == SOCKET_ERROR)

errexit("select error: %d\n", GetLastError());for (psv=&svent[0]; psv->sv_name; ++psv) {

if (FD_ISSET(psv->sv_sock, &rfds)) {if (psv->sv_useTCP)

doTCP(psv); else

psv->sv_func(psv->sv_sock);}

}}

14

Multi-service ServerMulti-service Server superd.csuperd.c

/*---------------------------------------------------- * doTCP - handle a TCP service connection request *--------------------------------------------------*/

void doTCP(struct service *psv){struct sockaddr_in fsin; // Request from addressint alen; /* from-address length */SOCKET ssock;alen = sizeof(fsin);ssock = accept(psv->sv_sock,(struct sockaddr*)&fsin,&alen);if (ssock == INVALID_SOCKET)

errexit("accept: %d\n", GetLastError());if (_beginthread((void (*)(void *))psv->sv_func, 0,

(void *)ssock) == (unsigned long) -1)errexit("_beginthread: %s\n", strerror(errno));

}

SummarySummary

Servers can use different concurrency techniques to support multiple services at the same time.

Multiprotocol servers support a single server, but through multiple protocols

Multiservice servers share a common infrastructure (process context, etc.) across a number of small, low utilization servers to improve the efficiency of service support.