- TCP/IP Illustrated, Volume 2
- Addison-Wesley Professional Computing Series
- Preface
- Acknowledgments
- Structure Definitions
- Function and Macro Definitions
- 1. Introduction
- 1.1. Introduction
- 1.1. Introduction
- 1.2. Source Code Presentation
- 1.3. History
- 1.4. Application Programming Interfaces
- 1.5. Example Program
- 1.6. System Calls and Library Functions
- 1.7. Network Implementation Overview
- 1.8. Descriptors
- 1.9. Mbufs (Memory Buffers) and Output Processing
- 1.10. Input Processing
- 1.11. Network Implementation Overview Revisited
- 1.12. Interrupt Levels and Concurrency
- 1.13. Source Code Organization
- 1.14. Test Network
- 1.15. Summary
- 1.1. Introduction
- 2. Mbufs: Memory Buffers
- 2.1. Introduction
- 2.1. Introduction
- 2.2. Code Introduction
- 2.3. Mbuf Definitions
- 2.4. mbuf Structure
- 2.5. Simple Mbuf Macros and Functions
- 2.6. m_devget and m_pullup Functions
- 2.7. Summary of Mbuf Macros and Functions
- 2.8. Summary of Net/3 Networking Data Structures
- 2.9. m_copy and Cluster Reference Counts
- 2.10. Alternatives
- 2.11. Summary
- 2.1. Introduction
- 3. Interface Layer
- 3.1. Introduction
- 3.1. Introduction
- 3.2. Code Introduction
- 3.3. ifnet Structure
- 3.4. ifaddr Structure
- 3.5. sockaddr Structure
- 3.6. ifnet and ifaddr Specialization
- 3.7. Network Initialization Overview
- 3.8. Ethernet Initialization
- 3.9. SLIP Initialization
- 3.10. Loopback Initialization
- 3.11. if_attach Function
- 3.12. ifinit Function
- 3.13. Summary
- 3.1. Introduction
- 4. Interfaces: Ethernet
- 4.1. Introduction
- 4.1. Introduction
- 4.2. Code Introduction
- 4.3. Ethernet Interface
- leintr Function
- leread Function
- ether_input Function
- Broadcast and multicast recognition
- Link-level demultiplexing
- Queue the packet
- ether_output Function
- Host route
- Gateway route
- Avoid ARP flooding
- IP output
- Explicit Ethernet output
- Unrecognized address families
- Ethernet header
- lestart Function
- Interface must be initialized
- Dequeue frame from output queue
- Transmit frame and pass to BPF
- Repeat if device is ready for more frames
- Mark device as busy
- 4.4. ioctl System Call
- 4.5. Summary
- 4.1. Introduction
- 5. Interfaces: SLIP and Loopback
- 6. IP Addressing
- 6.1. Introduction
- 6.1. Introduction
- 6.2. Code Introduction
- 6.3. Interface and Address Summary
- 6.4. sockaddr_in Structure
- 6.5. in_ifaddr Structure
- 6.6. Address Assignment
- ifioctl Function
- in_control Function
- Preconditions: SIOCSIFADDR, SIOCSIFNETMASK, and SIOCSIFDSTADDR
- Superuser only
- Allocate structure
- Initialize structure
- Address Assignment: SIOCSIFADDR
- in_ifinit Function
- Assign address and notify hardware
- Ethernet configuration
- Discard previous routes
- Construct network mask and default subnetmask
- Construct network and subnetwork numbers
- Establish route for host or network
- Join all-hosts group
- Network Mask Assignment: SIOCSIFNETMASK
- Destination Address Assignment: SIOCSIFDSTADDR
- Retrieving Interface Information
- Multiple IP Addresses per Interface
- Additional IP Addresses: SIOCAIFADDR
- Deleting IP Addresses: SIOCDIFADDR
- 6.7. Interface ioctl Processing
- 6.8. Internet Utility Functions
- 6.9. ifnet Utility Functions
- 6.10. Summary
- 6.1. Introduction
- 7. Domains and Protocols
- 8. IP: Internet Protocol
- 8.1. Introduction
- 8.10. Summary
- 9. IP Option Processing
- 10. IP Fragmentation and Reassembly
- 11. ICMP: Internet Control Message Protocol
- 11.1. Introduction
- 11.1. Introduction
- 11.2. Code Introduction
- 11.3. icmp Structure
- 11.4. ICMP protosw Structure
- 11.5. Input Processing: icmp_input Function
- 11.6. Error Processing
- 11.7. Request Processing
- Echo Query: ICMP_ECHO and ICMP_ECHOREPLY
- Timestamp Query: ICMP_TSTAMP and ICMP_TSTAMPREPLY
- Address Mask Query: ICMP_MASKREQ and ICMP_MASKREPLY
- Select subnet mask
- Convert to reply
- Select destination address
- Information Query: ICMP_IREQ and ICMP_IREQREPLY
- Router Discovery: icmp_routeradvert and icmp_routersolicit
- 11.8. Redirect Processing
- 11.9. Reply Processing
- 11.10. Output Processing
- 11.11. icmp_error Function
- 11.12. icmp_reflect Function
- 11.13. icmp_send Function
- 11.14. icmp_sysctl Function
- 11.15. Summary
- 11.1. Introduction
- 12. IP Multicasting
- 12.1. Introduction
- 12.1. Introduction
- 12.2. Code Introduction
- 12.3. Ethernet Multicast Addresses
- 12.4. ether_multi Structure
- 12.5. Ethernet Multicast Reception
- 12.6. in_multi Structure
- 12.7. ip_moptions Structure
- 12.8. Multicast Socket Options
- 12.9. Multicast TTL Values
- 12.10. ip_setmoptions Function
- Construct the defaults
- Process options
- Discard structure if defaults are OK
- Selecting an Explicit Multicast Interface: IP_MULTICAST_IF
- Validation
- Select the default interface
- Selecting an Explicit Multicast TTL: IP_MULTICAST_TTL
- Validate and select the default TTL
- Selecting Multicast Loopbacks: IP_MULTICAST_LOOP
- Validate and select the loopback policy
- 12.11. Joining an IP Multicast Group
- Validation
- Locate the interface
- Already a member?
- Join the group
- in_addmulti Function
- Already a member
- Update the in_multi list
- Update the interface and announce the change
- slioctl and loioctl Functions: SIOCADDMULTI and SIOCDELMULTI
- leioctl Function: SIOCADDMULTI and SIOCDELMULTI
- ether_addmulti Function
- Initialize address range
- Already receiving
- Update ether_multi list
- 12.12. Leaving an IP Multicast Group
- 12.13. ip_getmoptions Function
- 12.14. Multicast Input Processing: ipintr Function
- 12.15. Multicast Output Processing: ip_output Function
- 12.16. Performance Considerations
- 12.17. Summary
- 12.1. Introduction
- 13. IGMP: Internet Group Management Protocol
- 14. IP Multicast Routing
- 14.1. Introduction
- 14.1. Introduction
- 14.2. Code Introduction
- 14.3. Multicast Output Processing Revisited
- 14.4. mrouted Daemon
- 14.5. Virtual Interfaces
- 14.6. IGMP Revisited
- 14.7. Multicast Routing
- 14.8. Multicast Forwarding: ip_mforward Function
- Arrival on physical interface
- Arrival on a tunnel
- Delete tunnel options
- Expired TTL or local multicast
- No route available
- Arrived on unexpected interface
- phyint_send Function
- tunnel_send Function
- Will the tunnel options fit?
- Duplicate the datagram and allocate mbuf for new header and tunnel options
- Modify IP header
- Construct tunnel options
- Send the tunneled datagram
- 14.9. Cleanup: ip_mrouter_done Function
- 14.10. Summary
- 14.1. Introduction
- 15. Socket Layer
- 15.1. Introduction
- 15.1. Introduction
- 15.2. Code Introduction
- 15.3. socket Structure
- 15.4. System Calls
- 15.5. Processes, Descriptors, and Sockets
- 15.6. socket System Call
- 15.7. getsock and sockargs Functions
- 15.8. bind System Call
- 15.9. listen System Call
- 15.10. tsleep and wakeup Functions
- 15.11. accept System Call
- 15.12. sonewconn and soisconnected Functions
- 15.13. connect System call
- 15.14. shutdown System Call
- 15.15. close System Call
- 15.16. Summary
- 15.1. Introduction
- 16. Socket I/O
- 16.1. Introduction
- 16.1. Introduction
- 16.2. Code Introduction
- 16.3. Socket Buffers
- 16.4. write, writev, sendto, and sendmsg System Calls
- 16.5. sendmsg System Call
- 16.6. sendit Function
- 16.7. sosend Function
- Reliable Protocol Buffering
- Unreliable Protocol Buffering
- sosend Code
- Lock send buffer
- Check for space
- Use data from top
- Copy data from process
- Pass data to the protocol
- Cleanup
- Compute transfer size and semantics
- If requested, disable routing
- Compute available space
- Enforce message size limit
- Wait for more space?
- Wait for space
- Allocate packet header or standard mbuf
- If possible, use a cluster
- Prepare the mbuf
- Get data from the process
- Fill another buffer?
- sosend Summary
- Performance Considerations
- 16.8. read, readv, recvfrom, and recvmsg System Calls
- 16.9. recvmsg System Call
- 16.10. recvit Function
- 16.11. soreceive Function
- 16.12. soreceive Code
- If necessary, wait for data
- Process address and control information
- Setup data transfer
- Mbuf data transfer loop
- Cleanup
- Receive OOB data
- Connection confirmation
- Can the call be satisfied now?
- Wait for more data?
- Yes, wait for more data
- dontblock
- Return address information
- Return control information
- Prepare to transfer data
- Check for transition between OOB and regular data
- Update OOB mark
- Finished with mbuf?
- More data to process
- Update OOB mark
- End of logical record
- MSG_WAITALL
- Error or no more data will arrive
- Wait for data to arrive
- Synchronize m and nextrecord with receive buffer
- Process next mbuf
- Truncated message
- End of record processing
- Nothing transferred
- Analysis
- 16.13. select System Call
- Validation and setup
- Copy file descriptor sets from process
- Setup timeout value
- Scan file descriptors
- Error or some descriptors are ready
- Timeout expired?
- Status changed during selscan
- Wait for buffer changes
- Ready to return
- selscan Function
- Locate descriptors to be monitored
- Poll descriptor
- Descriptor is ready
- soo_select Function
- Is socket readable?
- Is socket writeable?
- Are there any exceptional conditions pending?
- selrecord Function
- Already selecting on this descriptor
- Select collision with another process?
- No collision
- selwakeup Function
- Wake all processes during a collision
- 16.14. Summary
- 16.1. Introduction
- 17. Socket Options
- 18. Radix Tree Routing Tables
- 18.1. Introduction
- 18.1. Introduction
- 18.2. Routing Table Structure
- 18.3. Routing Sockets
- 18.4. Code Introduction
- 18.5. Radix Node Data Structures
- 18.6. Routing Structures
- 18.7. Initialization: route_init and rtable_init Functions
- 18.8. Initialization: rn_init and rn_inithead Functions
- 18.9. Duplicate Keys and Mask Lists
- 18.10. rn_match Function
- 18.11. rn_search Function
- 18.12. Summary
- 18.1. Introduction
- 19. Routing Requests and Routing Messages
- 19.1. Introduction
- 19.1. Introduction
- 19.2. rtalloc and rtalloc1 Functions
- 19.3. RTFREE Macro and rtfree Function
- 19.4. rtrequest Function
- Delete from routing tree
- Remove reference to gateway routing table entry
- Call interface request function
- Return pointer or release reference
- Locate corresponding interface
- Allocate memory for routing table entry
- Allocate and copy gateway address
- Copy destination address
- Add entry to routing tree
- Store interface pointers
- Copy metrics for newly cloned route
- Call interface request function
- Return pointer and increment reference count
- Example: Cloned Routes with Network Masks
- 19.5. rt_setgate Function
- 19.6. rtinit Function
- 19.7. rtredirect Function
- 19.8. Routing Message Structures
- 19.9. rt_missmsg Function
- 19.10. rt_ifmsg Function
- 19.11. rt_newaddrmsg Function
- 19.12. rt_msg1 Function
- 19.13. rt_msg2 Function
- 19.14. sysctl_rtable Function
- 19.15. sysctl_dumpentry Function
- 19.16. sysctl_iflist Function
- 19.17. Summary
- 19.1. Introduction
- 20. Routing Sockets
- 20.1. Introduction
- 20.1. Introduction
- 20.2. routedomain and protosw Structures
- 20.3. Routing Control Blocks
- 20.4. raw_init Function
- 20.5. route_output Function
- Check mbuf for validity
- Allocate buffer
- Check version number
- Destination address required
- Handle optional genmask
- Locate existing entry
- Do not allow network match
- Use network mask to find correct entry
- Return destination, gateway, and masks
- Return interface information
- Construct reply
- Change gateway
- Locate new interface
- Check if interface changed
- Update metrics
- Call interface request function
- Store clone generation mask
- Update bitmask of locked metrics
- Return error or OK
- Release held route
- No process to receive message
- Other listeners but no loopback copy
- Convert buffer into mbuf chain
- Avoid loopback copy
- Set address family of routing message
- 20.6. rt_xaddrs Function
- 20.7. rt_setmetrics Function
- 20.8. raw_input Function
- 20.9. route_usrreq Function
- 20.10. raw_usrreq Function
- 20.11. raw_attach, raw_detach, and raw_disconnect Functions
- 20.12. Summary
- 20.1. Introduction
- 21. ARP: Address Resolution Protocol
- 21.1. Introduction
- 21.1. Introduction
- 21.2. ARP and the Routing Table
- 21.3. Code Introduction
- 21.4. ARP Structures
- 21.5. arpwhohas Function
- 21.6. arprequest Function
- 21.7. arpintr Function
- 21.8. in_arpinput Function
- Look for matching interface and IP address
- Validate sender’s hardware address
- Check sender’s IP address
- Search routing table for match with sender’s IP address
- Update existing entry or fill in new entry
- Check if sender’s hardware addresses changed
- Record sender’s hardware address
- Update newly resolved ARP entry
- Finished with ARP reply packets
- This host is the target
- Check if this host is a proxy server for target
- Form proxy reply
- Complete construction of ARP reply packet
- Fill in sockaddr with Ethernet header
- 21.9. ARP Timer Functions
- 21.10. arpresolve Function
- 21.11. arplookup Function
- 21.12. Proxy ARP
- 21.13. arp_rtrequest Function
- Initialize ARP timeout function
- Ignore indirect routes
- RTM_ADD command
- Backward compatibility
- Initialize entry for network route to interface
- Send gratuitous ARP request
- Verify sockaddr_dl Structure
- Handle route changes
- Initialize llinfo_arp structure
- Handle local host specially
- Make entry permanent and set Ethernet address
- Set interface pointer to loopback interface
- Verify la pointer
- Delete llinfo_arp structure
- 21.14. ARP and Multicasting
- 21.15. Summary
- 21.1. Introduction
- 22. Protocol Control Blocks
- 22.1. Introduction
- 22.1. Introduction
- 22.2. Code Introduction
- 22.3. inpcb Structure
- 22.4. in_pcballoc and in_pcbdetach Functions
- 22.5. Binding, Connecting, and Demultiplexing
- 22.6. in_pcblookup Function
- 22.7. in_pcbbind Function
- 22.8. in_pcbconnect Function
- Validate argument
- Handle connection to 0.0.0.0 and 255.255.255.255 specially
- Release route if no longer valid
- Acquire route
- Determine outgoing interface
- Verify that socket pair is unique
- Implicit bind and assignment of ephemeral port
- Store foreign address and foreign port in PCB
- IP Source Address Versus Outgoing Interface Address
- 22.9. in_pcbdisconnect Function
- 22.10. in_setsockaddr and in_setpeeraddr Functions
- 22.11. in_pcbnotify, in_rtchange, and in_losing Functions
- 22.12. Implementation Refinements
- 22.13. Summary
- 22.1. Introduction
- 23. UDP: User Datagram Protocol
- 23.1. Introduction
- 23.1. Introduction
- 23.2. Code Introduction
- 23.3. UDP protosw Structure
- 23.4. UDP Header
- 23.5. udp_init Function
- 23.6. udp_output Function
- Discard optional control information
- Temporarily connect an unconnected socket
- Prepend IP and UDP headers
- Prepending IP/UDP Headers and Mbuf Clusters
- UDP Checksum Calculation and Pseudo-Header
- Prepare pseudo-header for checksum computation
- Calculate checksum
- Fill in UDP length, TTL, and TOS
- Send datagram
- Disconnect temporarily connected socket
- 23.7. udp_input Function
- General Validation of Received UDP Datagram
- Discard IP options
- Verify UDP length
- Save copy of IP header and verify UDP checksum
- Demultiplexing Unicast Datagrams
- Check one-behind cache
- Search all UDP PCBs
- Generate ICMP port unreachable error
- Return source IP address and source port
- IP_RECVDSTADDR socket option
- Unimplemented socket options
- Append data to socket’s receive queue
- Error return
- Demultiplexing Multicast and Broadcast Datagrams
- Connected UDP Sockets and Multihomed Hosts
- 23.8. udp_saveopt Function
- 23.9. udp_ctlinput Function
- 23.10. udp_usrreq Function
- 23.11. udp_sysctl Function
- 23.12. Implementation Refinements
- 23.13. Summary
- 23.1. Introduction
- 24. TCP: Transmission Control Protocol
- 25. TCP Timers
- 25.1. Introduction
- 25.1. Introduction
- 25.2. Code Introduction
- 25.3. tcp_canceltimers Function
- 25.4. tcp_fasttimo Function
- 25.5. tcp_slowtimo Function
- 25.6. tcp_timers Function
- FIN_WAIT_2 and 2MSL Timers
- 2MSL timer
- FIN_WAIT_2 timer
- Persist Timer
- Force window probe segment
- Connection Establishment and Keepalive Timers
- Connection-establishment timer expires after 75 seconds
- Keepalive timer expires after 2 hours of idle time
- Drop connection when no response
- Send a keepalive probe
- Reset keepalive timer
- 25.7. Retransmission Timer Calculations
- 25.8. tcp_newtcpcb Function
- 25.9. tcp_setpersist Function
- 25.10. tcp_xmit_timer Function
- 25.11. Retransmission Timeout: tcp_timers Function
- 25.12. An RTT Example
- 25.13. Summary
- 25.1. Introduction
- 26. TCP Output
- 26.1. Introduction
- 26.1. Introduction
- 26.2. tcp_output Overview
- 26.3. Determine if a Segment Should be Sent
- 26.4. TCP Options
- 26.5. Window Scale Option
- 26.6. Timestamp Option
- 26.7. Send a Segment
- Build MSS option
- Should window scale option be sent?
- Build window scale option
- Should timestamp option be sent?
- Build timestamp option
- Check if options have overflowed segment
- Update statistics
- Allocate an mbuf for IP and TCP headers
- Copy data into mbuf
- Set PSH flag
- Update statistics
- Get mbuf for IP and TCP headers
- Copy IP and TCP header templates into mbuf
- Decrement snd_nxt if FIN is being retransmitted
- Set sequence number field of segment
- Set acknowledgment field of segment
- Set header length if options present
- Don’t advertise less than one full-sized segment
- Observe upper limit for advertised window on this connection
- Do not shrink window
- Set urgent offset
- Remember starting sequence number
- Increment snd_nxt
- Update snd_max
- Set retransmission timer
- Persist state
- Add trace record for socket debugging
- Set IP length, TTL, and TOS
- Pass datagram to IP
- Update rcv_adv and last_ack_sent
- More data to send?
- 26.8. tcp_template Function
- 26.9. tcp_respond Function
- 26.10. Summary
- 26.1. Introduction
- 27. TCP Functions
- 27.1. Introduction
- 27.1. Introduction
- 27.2. tcp_drain Function
- 27.3. tcp_drop Function
- 27.4. tcp_close Function
- 27.5. tcp_mss Function
- Acquire a route if necessary
- Initialize smoothed RTT estimator
- Initialize smoothed mean deviation estimator
- Calculate initial RTO
- Use MSS from routing table MTU
- Round MSS down to multiple of MCLBYTES
- Check if destination local or nonlocal
- Other end’s MSS is upper bound
- Round buffer sizes to multiple of MSS
- Initialize congestion window and slow start threshold
- Example
- 27.6. tcp_ctlinput Function
- 27.7. tcp_notify Function
- 27.8. tcp_quench Function
- 27.9. TCP_REASS Macro and tcp_reass Function
- 27.10. tcp_trace Function
- 27.11. Summary
- 27.1. Introduction
- 28. TCP Input
- 28.1. Introduction
- 28.1. Introduction
- 28.2. Preliminary Processing
- Get IP and TCP headers in first mbuf
- Verify TCP checksum
- Verify TCP offset field
- Get headers plus option into first mbuf
- Process timestamp option quickly
- Save input flags and convert fields to host byte order
- Locate Internet PCB
- Drop segment and generate RST
- Silently drop segment
- Unscale advertised window
- Save connection state and IP/TCP headers if socket debug option enabled
- Create new socket if segment arrives for listening socket
- Compute window scale factor
- Reset idle time and keepalive timer
- Process TCP options if not in LISTEN state
- 28.3. tcp_dooptions Function
- 28.4. Header Prediction
- Check if segment is the next expected
- Update ts_recent from received timestamp
- Test for pure ACK
- Update RTT estimators
- Delete acknowledged bytes from send buffer
- Stop retransmit timer
- Awaken waiting processes
- Generate more output
- Test for next in-sequence data segment
- Complete processing of received data
- Statistics
- 28.5. TCP Input: Slow Path Processing
- 28.6. Initiation of Passive Open, Completion of Active Open
- Initiation of Passive Open
- Drop if RST, ACK, or no SYN
- Drop if broadcast or multicast
- Get mbuf for client’s IP address and port
- Set local address in PCB
- Connect PCB to peer
- Allocate and initialize IP and TCP header template
- Process any TCP options
- Initialize ISS
- Initialize sequence number variables in control block
- ACK the SYN and change state
- Completion of Active Open
- Verify received ACK
- Process and drop RST segment
- Verify SYN flag set
- Process ACK
- Turn off retransmission timer
- Initialize receive sequence numbers
- Connection is established
- Check for window scale option
- Pass any queued data to process
- Update RTT estimators
- Simultaneous open
- Drop any received data that follows receive window
- Force update of window variables
- 28.7. PAWS: Protection Against Wrapped Sequence Numbers
- 28.8. Trim Segment so Data is Within Window
- Check if any duplicate data at front of segment
- Remove duplicate SYN
- Check for entire duplicate packet
- Check for duplicate FIN
- Generate duplicate ACK
- Handle simultaneous open or self-connect
- Update statistics for partial duplicate segments
- Remove duplicate data and update urgent offset
- Calculate number of bytes beyond right edge of window
- Check for new incarnation of a connection in the TIME_WAIT state
- Check for probe of closed window
- Drop other segments that are completely outside window
- Handle segments that contain some valid data
- When to Drop an ACK
- 28.9. Self-Connects and Simultaneous Opens
- 28.10. Record Timestamp
- 28.11. RST Processing
- 28.12. Summary
- 28.1. Introduction
- 29. TCP Input
- 29.1. Introduction
- 29.1. Introduction
- 29.2. ACK Processing Overview
- 29.3. Completion of Passive Opens and Simultaneous Opens
- 29.4. Fast Retransmit and Fast Recovery Algorithms
- 29.5. ACK Processing
- Adjust congestion window
- Check for out-of-range ACK
- Calculate number of bytes acknowledged
- Update RTT estimators
- Check if all outstanding data has been acknowledged
- Unacknowledged data outstanding
- Karn’s Algorithm and Timestamps
- Update congestion window
- Remove acknowledged bytes from the send buffer
- Wakeup processes waiting on send buffer
- Receipt of ACK in FIN_WAIT_1 state
- Set FIN_WAIT_2 timer
- Receipt of ACK in CLOSING state
- Receipt of ACK in LAST_ACK state
- Receipt of ACK in TIME WAIT state
- 29.6. Update Window Information
- 29.7. Urgent Mode Processing
- 29.8. tcp_pulloutofband Function
- 29.9. Processing of Received Data
- 29.10. FIN Processing
- 29.11. Final Processing
- 29.12. Implementation Refinements
- 29.13. Header Compression
- 29.14. Summary
- 29.1. Introduction
- 30. TCP User Requests
- 30.1. Introduction
- 30.1. Introduction
- 30.2. tcp_usrreq Function
- in_control processes ioctl requests
- Control information is invalid
- PRU_ATTACH request
- PRU_DETACH request
- Assign ephemeral port
- Connect PCB
- Initialize IP and TCP headers
- Calculate window scale factor
- Set socket and connection state
- Initialize sequence numbers
- Send initial SYN
- PRU_SHUTDOWN request
- PRU_RCVD request
- PRU_SEND request
- PRU_ABORT request
- PRU_SENSE request
- Verify that reading out-of-band data is appropriate
- Check that out-of-band byte has arrived
- Return out-of-band byte
- Flip flags
- Check for room and append to send buffer
- Calculate urgent pointer
- Force TCP output
- 30.3. tcp_attach Function
- 30.4. tcp_disconnect Function
- 30.5. tcp_usrclosed Function
- 30.6. tcp_ctloutput Function
- 30.7. Summary
- 30.1. Introduction
- 31. BPF: BSD Packet Filter
- 32. Raw IP
- Epilogue
- A. Solutions to Selected Exercises
- Chapter 1
- Chapter 1
- Chapter 2
- Chapter 3
- Chapter 4
- Chapter 5
- Chapter 6
- Chapter 7
- Chapter 8
- Chapter 9
- Chapter 10
- Chapter 11
- Chapter 12
- Chapter 13
- Chapter 14
- Chapter 15
- Chapter 16
- Chapter 17
- Chapter 18
- Chapter 19
- Chapter 20
- Chapter 21
- Chapter 22
- Chapter 23
- Chapter 24
- Chapter 25
- Chapter 26
- Chapter 27
- Chapter 28
- Chapter 29
- Chapter 30
- Chapter 31
- Chapter 32
- Chapter 1
- B. Source Code Availability
- C. RFC 1122 Compliance
- C.1. Link-Layer Requirements
- Bibliography
-
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