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Listen and accept function


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This PPT is about TCP Listen and accept function and it is explaining three way handshaking also

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Listen and accept function

  1. 1. What is a socket ?It is an interface betweenapplication layer and transportlayer within a host. CNP Seminar by Jithin P 2
  2. 2. Application Layer Transport Layer Socket CNP Seminar by Jithin P 3
  3. 3. Why socket ?Kannadasan YamunaFor Identification ? CNP Seminar by Jithin P 4
  4. 4. Why socket ?Hostel Name + Room No IP address + Port number Socket CNP Seminar by Jithin P 5
  5. 5. listen() accept() CNP Seminar by Jithin P 6
  6. 6. listen() Called only by TCP server Performs two actions  Convert the socket in to passive socket  Specify the maximum number of connections the kernel should queue CNP Seminar by Jithin P 8
  7. 7.  For a listening socket the kernel maintains two queues  An incomplete connection queue  Waiting for 3-way handshake  A complete connection queue  Completed 3-way handshake CNP Seminar by Jithin P 9
  8. 8. 3-way handshaking client server Connect called Create entry on incomplete queueConnect returns Entry moved from incomplete queue to complete queue CNP Seminar by Jithin P 10
  9. 9. int listen(int sockfd, int backlog) CNP Seminar by Jithin P 11
  10. 10. Questions ? What is the default size of backlog ? Which queue is longest one (complete/incomplete) ? What will happen when queue is full ? CNP Seminar by Jithin P 12
  11. 11. accept() Completed connection queue Incomplete connection queue Arriving SYNCNP Seminar by Jithin P 13
  12. 12. accept()int accept(int sockfd, socket addr, socket addrlen) If success return a brand new descriptor ie descriptor of connected socket. CNP Seminar by Jithin P 14
  13. 13. References Unix Network Programming  W.Richard Stevens Computer Networking a top down approach  James F Kurose Wikipedia CNP Seminar by Jithin P 15
  14. 14. QuestionsCNP Seminar by Jithin P 16