Advanced UNIX programming

1
Advanced UNIX programming

• Fall 2002
• Instructor Ashok Srinivasan
• Lecture 17

Acknowledgements The syllabus and power point
presentations are modified versions of those by
T. Baker and X. Yuan
2
Announcements

• Reading assignment
• Chapters 3 and 4 of UNP
• Collect midterm from me
• ... during my office hours
• T 215-315 pm or W 215-315 pm
• If you have questions on HW2 results, meet the
  grader

3
Week 7 Topics

• Basic TCP sockets
• Socket address structure
• Byte ordering and manipulation functions
• socket, connect, bind, listen, accept
• Client-Server design
• Concurrent server

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Basic TCP sockets

• Socket address structure
• Byte ordering and manipulation functions
• socket, connect, bind, listen, accept

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Socket address structure

• struct in_addr
• in_addr_t s_addr
• struct sockaddr_in
• uint8_t sin_len
• sa_family_t sin_family
• in_port_t sin_port
• struct in_addr sin_addr
• char sin_zero8
• Always use sockaddr_in type for manipulation and
  convert it to sockaddr
• See example1.c and example2.c

struct sockaddr uint8_t sa_len
sa_family_t sa_family char sa_data14
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Network byte order

• What happen when we run example2.c as server on
  program and example1.c as client on linprog?
• sin_port and sin_addr must be in network byte
  order
• Check example3.c
• What is the difference between program and
  linprog?

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Byte ordering functions

• include ltarpa/inet.hgt
• uint16_t htons(uint16_t host16bitvalue)
• uint32_t htonl(uint32_t host32bitvalue)
• uint16_t ntohs(uint16_t net16bitvalue)
• uint32_t ntohl(uint32_t net32bitvalue)
• See example3.c

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Byte manipulation functions

• include ltstring.hgt
• void memset(void dst, int c, size_t len)
• void memcpy(void dst, void src, size_t
  nbytes)
• void memcmp(const void ptr1, const void ptr2,
  size_t nbytes)

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Address conversion functions

• include ltarpa/inet.hgt
• in_addr_t inet_addr(const char cp)
• char inet_ntoa(struct in_addr in)
• The ones below should be preferred
• inet_ntop(address family, source, destination,
  size)
• inet_pton(address family, source, destination)