Chapter 4: Server Software Design Creating a Passive Socket Chapter gae a Algorithm and issues Use procedures to hide the details a Iterative servers Two high-level procedures a Concurrent connection-oriented passrveUDP servers a Singly-threaded, concurrent The low-level procedure: passivesock servers Multiprotocol servers Multiservice servers Uniform, efficient management of server concurrency Iterative Connectionless Servers passiveUDP A connectionless server calls function passiveUDPto passUDP. cpp-passiveUDP*/ create a socke CossivelDP calls passivesock to create a #include <winsock. hp connectionless socket SOCKET passivesock(const char*, const char * int): To maks it keaeyototst c bent and s rver software c passiveUDP-create a passive socket for use in a UDP The importance soffware cannot be tested while the production passiveUDP(const char * service continues to execute Using portbase makes it possible to test multiple turn passivesock(service, "udp", o versions passivesock passiveUDP void errexit(const char*,: soler sockaddr_n sinc /. an Internet endpoint address entry u_short portbase =0:/ port base, for test servers type: /socket type(SOCK-STREAM, SOCK_DGRAM)- passivesock-allocate bind a server socket using ToP or UDP nsin port hons(ntohs((u.)pse-s_port portbase: else if ((sin, inport Name of a service errexitccan't get \7s\"service entry\n, service):4 哈工大计算机学院 李全龙 Network Application Development Server Software Design 19 Chapter 4: Server Software Design Chapter goal: „ Algorithm and issues „ Iterative servers „ Concurrent, connection-oriented servers „ Singly-threaded, concurrent servers „ Multiprotocol servers „ Multiservice servers „ Uniform, efficient management of server concurrency 哈工大计算机学院 李全龙 Network Application Development Server Software Design 20 Creating a Passive Socket „ Use procedures to hide the details „ Two high-level procedures: „ passiveUDP „ passiveTCP „ The low-level procedure: passivesock 哈工大计算机学院 李全龙 Network Application Development Server Software Design 21 Iterative Connectionless Servers „ A connectionless server calls function passiveUDP to create a socket „ passiveUDP calls passivesock to create a connectionless socket „ To make it easy to test client and server software, passivesock relocates all port values by adding the contents of global integer portbase „ The importance: „ If a new version of a client-server application uses the same protocol port numbers as an existing, production version, the new software cannot be tested while the production version continues to execute. „ Using portbase makes it possible to test multiple versions 哈工大计算机学院 李全龙 Network Application Development Server Software Design 22 passiveUDP /* passUDP.cpp - passiveUDP */ #include <winsock.h> SOCKET passivesock(const char *, const char *, int); /*------------------------------------------------------------------------ * passiveUDP - create a passive socket for use in a UDP server *------------------------------------------------------------------------ */ SOCKET passiveUDP(const char *service) { return passivesock(service, "udp", 0); } 哈工大计算机学院 李全龙 Network Application Development Server Software Design 23 passivesock /* passsock.cpp - passivesock */ #include <stdlib.h> #include <string.h> #include <winsock.h> void errexit(const char *, ...); u_short portbase = 0; /* port base, for test servers */ /*----------------------------------------------------------------------- * passivesock - allocate & bind a server socket using TCP or UDP *------------------------------------------------------------------------ */ SOCKET passivesock(const char *service, const char *transport, int qlen) Name of a service Name of protocol Length of the connection request queue (only for TCP) 哈工大计算机学院 李全龙 Network Application Development Server Software Design 24 passiveUDP { struct servent *pse; /* pointer to service information entry */ struct protoent *ppe; /* pointer to protocol information entry */ struct sockaddr_in sin;/* an Internet endpoint address */ SOCKET s; /* socket descriptor */ int type; /* socket type (SOCK_STREAM, SOCK_DGRAM)*/ memset(&sin, 0, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_addr.s_addr = INADDR_ANY; /* Map service name to port number */ if ( pse = getservbyname(service, transport) ) sin.sin_port = htons(ntohs((u_short)pse->s_port) + portbase); else if ( (sin.sin_port = htons((u_short)atoi(service))) == 0 ) errexit("can't get \"%s\" service entry\n", service);