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Proxy & Networking 15-213: Introduction to Computer Systems – Recitation H April 11, 2011

Carnegie Mellon. Proxy & Networking 15-213: Introduction to Computer Systems – Recitation H April 11, 2011. Carnegie Mellon. Today. News Proxy Networking. Carnegie Mellon. News. Proxylab out last Thursday Exam in two weeks. Carnegie Mellon. Proxy. Carnegie Mellon. What is a Proxy?.

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Proxy & Networking 15-213: Introduction to Computer Systems – Recitation H April 11, 2011

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  1. Carnegie Mellon Proxy & Networking15-213: Introduction to Computer Systems – Recitation HApril 11, 2011

  2. Carnegie Mellon Today • News • Proxy • Networking

  3. Carnegie Mellon News • Proxylab out last Thursday • Exam in two weeks

  4. Carnegie Mellon Proxy

  5. Carnegie Mellon What is a Proxy? • Intermediary between client and server

  6. Carnegie Mellon Your Proxy • Threaded • Client requests must use different threads • Caching • Content is cached locally and served from there • IPv4 • Only 32-bit addresses: 192.168.99.211 • HTTP • Only serve HTTP/1.0 GET requests

  7. Carnegie Mellon Your Proxy • Both client and server

  8. Carnegie Mellon Recommended Progress • Implement a sequential proxy • Upgrade to a threaded proxy • Make into a caching proxy • Worry about race conditions and proper locking of data structures! (next recitation)

  9. Carnegie Mellon Testing • No autograder • Test simple pages at the beginning and more complicated ones as your proxy improves • Not all pages will work! • Useful: netcat • Client: nc <host> <port> • Server nc –l <port>

  10. Carnegie Mellon Networking

  11. Carnegie Mellon Server • Berkeley Sockets Interface • For making a server: • socket • bind • listen • accept • close

  12. Carnegie Mellon socket(domain, type, protool) intsock_fd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP); • Through which all communication goes through • Domain: Protocol family to use • PF_INET is IPv4 • Type: Type of protocol to use • SOCK_STREAM stream with in-order delivery • Protocol: Specific protocol to use • IPPROTO_TCP means TCP

  13. Carnegie Mellon bind(sock_fd, my_addr, addrlen) structsockaddr_insockaddr; memset(&sockaddr, 0, sizeof(sockaddr); sockaddr.sin_family = AF_INET; sockaddr.sin_addr.s_addr = INADDR_ANY; sockaddr.sin_port = htons(listenPort) err = bind(sock_fd, (structsockaddr *) sockaddr, sizeof(sockaddr)); • sock_fd: file descriptor of socket • my_addr: address to bind to (where we are registering this server) • Information about what the socket will be used for: internet, listening any address, port • addrlen: size of addrstruct

  14. Carnegie Mellon listen(sock_fd, backlog) err = listen(sock_fd, MAX_WAITING_CONNECTIONS); • sock_fd: Socket to listen on • backlog: maximum number of waiting connections

  15. Carnegie Mellon accept(sock_fd, addr, addrlen) structsockaddr_inclient_addr; socklen_tmy_addr_len = sizeof(client_addr); client_fd = accept(listener_fd, &client_addr, &my_addr_len); • sock_fd: Socket to listen on • addr: pointer to sockaddrstruct to hold clisnt information • Find out who connected to you • addrlen: length of the addrstruct • Return: File descriptor!

  16. Carnegie Mellon Client • For connecting to a server: • socket • connect • close

  17. Carnegie Mellon connect(sock_fd, addr, addrlen) structsockaddr_inremote_addr; /* initialize remote_addr */ err = connect(listener_fd, &remote_addr, sizeof(remote_addr)); • sock_fd: Socket to connect with • addr: pointer to sockaddrstruct that holds information about who to connect to • addrlen: length of the addrstruct

  18. Carnegie Mellon close(sock_fd) err = close(sock_fd); • sock_fd: Socket to close

  19. Carnegie Mellon Sending/Receiving Data • send/recv • write/read • func(fd, buffer, buffer_len) • fd: File to write to • buffer: What to write • buffer_len: How many bytes to write • send/recv have extra flags parameter

  20. Carnegie Mellon Questions?

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