Example Servers Pt 1

1
Example Servers Pt 1

• Objective
• To discuss key aspects of various server
  implementations

2
Server Example Outline

• Support Functions
• passiveUDP ( )
• passivesock ( )
• Iterative - Connectionless (UDPTimed.cpp)
• Iterative - Connection-Oriented (TCPdtd.cpp)
• Concurrent Connection-Oriented (TCPEchod.cpp)
• Single Process Concurrent (TCPMechod.cpp)

3
Iterative Connectionless Servers (UDP)

• / passUDP.cpp - passiveUDP /
• include ltwinsock.hgt
• SOCKET passivesock(const char , const char ,
  int)
• /------------------------------------------------
  --
• Create a passive socket for use in a UDP server
  
• ------------------------------------------------
  /
• SOCKET passiveUDP(const char service)
• return passivesock(service, "udp", 0)

4
passivesock (service, protocol, qlen)

• / passsock.cpp - passivesock /
• include ltstdlib.hgt
• include ltstring.hgt
• include ltwinsock.hgt
• void errexit(const char , ...)
• u_short portbase 0 / For test servers /
• /-----------------------------------------------
• passivesock - allocate bind a server socket
  using TCP or UDP
• ----------------------------------------------/

5
passivesock (service, protocol, qlen)

• SOCKET passivesock(const char service,
• const char transport, int qlen)
• struct servent pse // Service info entry
• struct protoent ppe // Protocol info entry
• struct sockaddr_in sin // Internet 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

6
passivesock (service, protocol, qlen)

• SOCKET passivesock(const char service,
• const char transport, int qlen)
• struct servent pse // Service info entry
• struct protoent ppe // Protocol info entry
• struct sockaddr_in sin // Internet 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

7
passivesock (service, protocol, qlen)

• / Map service name to port number /
• if ( pse getservbyname(service, transport)
  ) sin.sin_port htons(ntohs((u_short)pse-gts_port
  ) portbase)
• else if
• ((sin.sin_port htons((u_short)atoi(service)))
  0) errexit("can't get \"s\" service \n",
  service)
• / Map protocol name to protocol number /
• if ( (ppe getprotobyname(transport))
  0) errexit("can't get \"s\" protocol \n",
  transport)
• / Use protocol to choose a socket type /
• if (strcmp(transport, "udp") 0)
• type SOCK_DGRAM
• else
• type SOCK_STREAM

8
passivesock (service, protocol, qlen)

• / Allocate a socket /
• s socket(PF_INET, type, ppe-gtp_proto)
• if (s INVALID_SOCKET)
• errexit(Socket Error d\n", GetLastError())
  
• / Bind the socket /
• if (bind(s, (struct sockaddr )sin, sizeof(sin))
  SOCKET_ERROR)
• errexit(Bind Error s port d\n", service,
• GetLastError())
• if (typeSOCK_STREAM listen(s, qlen)
  SOCKET_ERROR)
• errexit(cant listen on s port d\n",
  service, GetLastError())
• return s

9
passivesock (service, protocol, qlen)

• / Allocate a socket /
• s socket(PF_INET, type, ppe-gtp_proto)
• if (s INVALID_SOCKET)
• errexit(Socket Error d\n", GetLastError())
  
• / Bind the socket /
• if (bind(s, (struct sockaddr )sin, sizeof(sin))
  SOCKET_ERROR)
• errexit(Bind Error s port d\n", service,
• GetLastError())
• if (typeSOCK_STREAM listen(s, qlen)
  SOCKET_ERROR)
• errexit(cant listen on s port d\n",
  service, GetLastError())
• return s

10
Iterative Connectionless ServersTIME Server

• / UDPtimed.cpp - main /
• include lttime.hgt
• include ltwinsock.hgt
• SOCKET passiveUDP(const char )
• void errexit(const char , ...)
• define WINEPOCH 2208988800 // Windows epoch
• define WSVERS MAKEWORD(2, 0)
• /------------------------------------------------
  --
• main - Iterative UDP server for TIME service
• ------------------------------------------------
  /

11
Iterative Connectionless ServersTIME Server

• int main(int argc, char argv)
• struct sockaddr_in fsin // From address of
  client
• char service "time"// service name or port
• char buf2048//"input" buffer any size gt1
  packet
• SOCKET sock // server socket
• time_t now // current time
• int alen // from-address length
• WSADATA wsadata

12
Iterative Connectionless ServersTIME Server

• switch (argc)
• case 1
• break
• case 2
• service argv1
• break
• default
• errexit("usage UDPtimed port\n")
• if (WSAStartup(WSVERS, wsadata)) errexit("WSASta
  rtup failed\n")
• sock passiveUDP(service)

13
Iterative Connectionless ServersTIME Server

• while (1)
• alen sizeof(fsin)
• if (recvfrom(sock, buf, sizeof(buf), 0,
• (struct sockaddr )fsin, alen)
  SOCKET_ERROR)
• errexit("recvfrom error d\n",GetLastError()
  ) (void) time(now)
• now htonl((u_long)(now WINEPOCH))
• (void) sendto(sock, (char )now,
  sizeof(now), 0, (struct sockaddr )fsin,
  sizeof(fsin))
• return 1 / not reached /

14
Iterative Connectionless ServersTIME Server

• while (1)
• alen sizeof(fsin)
• if (recvfrom(sock, buf, sizeof(buf), 0,
• (struct sockaddr )fsin, alen)
  SOCKET_ERROR)
• errexit("recvfrom error d\n",GetLastError()
  ) (void) time(now)
• now htonl((u_long)(now WINEPOCH))
• (void) sendto(sock, (char )now,
  sizeof(now), 0, (struct sockaddr )fsin,
  sizeof(fsin))
• return 1 / not reached /

15
Iterative Connection OrientedTCPdaytimed

• / TCPdtd.cpp - main, TCPdaytimed /
• include ltstdlib.hgt
• include ltwinsock.hgt
• include lttime.hgt
• void errexit(const char , ...)
• void TCPdaytimed(SOCKET)
• SOCKET passiveTCP(const char , int)
• define QLEN 5
• define WSVERS MAKEWORD(2, 0)
• /------------------------------------------------
  -
• main - Iterative TCP server for DAYTIME service
  
• ------------------------------------------------
  /

16
Iterative Connection OrientedTCPdaytimed

• void main(int argc, char argv)
• struct sockaddr_in fsin //From address of
  client
• char service "daytime" //Service or port
• SOCKET msock, ssock // master slave sockets
• int alen // from-address length
• WSADATA wsadata
• switch (argc)
• case 1 break
• case 2 service argv1
• break
• default errexit("usage TCPdaytimed
  port\n")

17
Iterative Connection OrientedTCPdaytimed

• if (WSAStartup(WSVERS, wsadata) ! 0)
• errexit("WSAStartup failed\n")
• msock passiveTCP(service, QLEN)
• while (1)
• alen sizeof(struct sockaddr)
• ssock accept(msock,(struct sockaddr)fsin,
• alen)
• if (ssock INVALID_SOCKET)
• errexit("accept failed d\n",
  GetLastError())
• TCPdaytimed(ssock)
• (void) closesocket(ssock)

18
Iterative Connection OrientedTCPdaytimed

• void TCPdaytimed(SOCKET fd)
• char pts // pointer to time string
• time_t now // current time
• (void) time(now)
• pts ctime(now)
• (void) send(fd, pts, strlen(pts), 0)

19
Concurrent Connection-OrientedTCPechod.c

• / TCPechod.cpp - main, TCPechod /
• include ltstdio.hgt, ltwinsock.hgt, ltprocess.hgt
• define QLEN 5 // max connection queue length
• define STKSIZE 16536
• define BUFSIZE 4096
• define WSVERS MAKEWORD(2, 0)
• SOCKET msock, ssock // master slave sockets
• int TCPechod(SOCKET)
• void errexit(const char , ...)
• SOCKET passiveTCP(const char , int)

20
Concurrent Connection-OrientedTCPechod.c

• int main(int argc, char argv)
• char service "echo"// service name, port
• struct sockaddr_in fsin // address of a client
• int alen // length of client's address
• WSADATA wsadata
• switch (argc)
• case 1 break
• case 2 service argv1
• break
• default errexit("usage TCPechod
  port\n")
• if (WSAStartup(WSVERS, wsadata) ! 0)
• errexit("WSAStartup failed\n")

21
Concurrent Connection-OrientedTCPechod.c

• msock passiveTCP(service, QLEN)
• while (1)
• alen sizeof(fsin)
• ssock accept(msock, (struct sockaddr
  )fsin,
• alen)
• if (ssock INVALID_SOCKET)
• errexit("accept error d\n",
  GetLastError()) if (_beginthread((void ()(void
  ))TCPechod,
• STKSIZE, (void )ssock) lt 0)
• errexit("_beginthread s\n",
  strerror(errno))
• return 1 / not reached /

22
Concurrent Connection-OrientedTCPechod.c

• int TCPechod(SOCKET fd)
• char bufBUFSIZE
• int cc
• cc recv(fd, buf, sizeof buf, 0)
• while (cc ! SOCKET_ERROR cc gt 0)
• if (send(fd, buf, cc, 0) SOCKET_ERROR)
  printf("send error d\n", GetLastError())
• break
• cc recv(fd, buf, sizeof buf, 0)
• if (cc SOCKET_ERROR)
• printf("recv error d\n", GetLastError()) clo
  sesocket(fd)
• return 0

23
Managing multiple sockets
Start
Create Master Socket
24
Managing multiple sockets
First Client Connection
Second Client Connection
25
Single-Process ConcurrentTCPmechod.c

• void main(int argc, char argv)
• char service "echo"// service name/port
• struct sockaddr_in fsin // From address of
  client
• SOCKET msock // master server socket
• fd_set rfds // read file descriptor
  set fd_set afds // active file descriptor
  set int alen // from-address
  length WSADATA wsdata
• unsigned int fdndx
• switch (argc)
• case 1 break
• case 2 service argv1
• break
• default errexit("usage TCPmechod port\n")

26
Single-Process ConcurrentTCPmechod.c

• if (WSAStartup(WSVERS, wsdata) ! 0)
• errexit("WSAStartup failed\n")
• msock passiveTCP(service, QLEN)
• FD_ZERO(afds)
• FD_SET(msock, afds)
• while (1)
• memcpy(rfds, afds, sizeof(rfds))
• if(select(FD_SETSIZE,rfds,(fd_set)0,(fd_set)
  0,
• (struct timeval )0) SOCKET_ERROR) er
  rexit("select error d\n", GetLastError())

27
Single-Process ConcurrentTCPmechod.c

• if (WSAStartup(WSVERS, wsdata) ! 0)
• errexit("WSAStartup failed\n")
• msock passiveTCP(service, QLEN)
• FD_ZERO(afds)
• FD_SET(msock, afds)
• while (1)
• memcpy(rfds, afds, sizeof(rfds))
• if(select(FD_SETSIZE,rfds,(fd_set)0,(fd_set)
  0,
• (struct timeval )0) SOCKET_ERROR) er
  rexit("select error d\n", GetLastError())

28
Single-Process ConcurrentTCPmechod.c

• if (WSAStartup(WSVERS, wsdata) ! 0)
• errexit("WSAStartup failed\n")
• msock passiveTCP(service, QLEN)
• FD_ZERO(afds)
• FD_SET(msock, afds)
• while (1)
• memcpy(rfds, afds, sizeof(rfds))
• if(select(FD_SETSIZE,rfds,(fd_set)0,(fd_set)
  0,
• (struct timeval )0) SOCKET_ERROR) er
  rexit("select error d\n", GetLastError())

29
Single-Process ConcurrentTCPmechod.c

• if (FD_ISSET(msock, rfds))
• SOCKET ssock
• alen sizeof(fsin)
• ssock accept(msock,(struct sockaddr
  )fsin,alen) if (ssock INVALID_SOCKET)
• errexit("accept error d\n", GetLastError())
  FD_SET(ssock, afds)
• for (fdndx0 fdndxltrfds.fd_count fdndx)
• SOCKET fd rfds.fd_arrayfdndx
• if (fd ! msock FD_ISSET(fd, rfds))
• if (echo(fd) 0)
• (void) closesocket(fd)
• FD_CLR(fd, afds)

30
Single-Process ConcurrentTCPmechod.c

• // echo - echo one buffer of data, returning byte
  count
• int echo(SOCKET fd)
• char bufBUFSIZE
• int cc
• cc recv(fd, buf, sizeof buf, 0)
• if (cc SOCKET_ERROR)
• errexit("echo recv error d\n",
  GetLastError())
• if (cc send(fd, buf, cc, 0)
  SOCKET_ERROR) errexit("echo send error d\n",
  GetLastError())
• return cc