Programming with TCP/IP

1
Socket system calls for connection-oriented proto
col
2
Not necessary in UDP!!
3
Socket system call

• int sockfd socket (int family, int type, int
  protocol
• Family AF_UNIX, AF_INET Type SOCK_STREAM,
  SOCK_DGRAM, SOCK_RAW
• struct sockaddr
• unsigned short sa_family
  //specifies the address type
• char sa_data14
  //specifies the address value
• struct sockaddr_in
• short sin_family
• unsigned short sin_port 16 bit
• struct in_addr sin_addr 32 bit unsigned long
  s_addr
• char sin_zero8

4
Network Byte Order Functions

• Example
• struct sockaddr_in sin
• sin.sin_family AF_INET
• sin.sin_port htons(9999)
• sin.sin_addr.s_addr inet_addr(130.233.224.13)
  
• inet_aton(130.233.224.13, sin.sin_addr)
• unsigned short htons(unsigned short)
• unsigned short ntohs(unsigned short)
• unsigned long htonl(unsigned long)
• unsigned long ntohl(unsigned long)

5
Server system calls

• int bind(int sockfd, struct sockaddr myaddr, int
  addrlen)
• int listen(int socket, int qlength)
• !newsockfd accept(int sockfd, void peer, int
  addrlen)
• int getpeername(int sockfd, struct sockaddr
  addr, int addrlen)
• struct hostent gethostbyaddr(const char
  peer_addr, int len, int type)
• ! (char) socaddr_in.sin_addr, name in
  hostent-gth_name

6
Client system calls

• int connect(int sockfd, struct sockaddr
  servaddr, int addrlen)
• struct hostent gethostbyname(const char name)
• ! addr.sin_addr ((struct in_addr )
  hostent-gth_addr)
• write or read(fd, buff_ptr, num_bytes)
• int send(int s, const char msg, int len, int
  flags)
• int recv(int s, char buf, int len, int flags)
• flags MSG_PEEK, MSG_OOB etc.
• close(int socket), shutdown(int socket, int how)