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Copyright 2024 Oxide Computer Company
Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved.
Copyright 2008 AT&T
The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
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When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
#include <sys/socket.h>
#include <netinet/in.h>
s = socket(AF_INET, SOCK_RAW, proto);
t = t_open ("/dev/rawip", O_RDWR);
Packets sent to or from this system may be subject to IPsec policy. See ipsec(4P) for more information.
Raw IP sockets are connectionless and are normally used with the sendto() and recvfrom() calls (see send(3SOCKET) and recv(3SOCKET)), although the connect(3SOCKET) call may also be used to fix the destination for future datagram. In this case, the read(2) or recv(3SOCKET) and write(2) or send(3SOCKET) calls may be used. If proto is IPPROTO_RAW or IPPROTO_IGMP, the application is expected to include a complete IP header when sending. Otherwise, that protocol number will be set in outgoing datagrams and used to filter incoming datagrams and an IP header will be generated and prepended to each outgoing datagram. In either case, received datagrams are returned with the IP header and options intact.
If an application uses IP_HDRINCL and provides the IP header contents, the IP stack does not modify the following supplied fields under any conditions: Type of Service, DF Flag, Protocol, and Destination Address. The IP Options and IHL fields are set by use of IP_OPTIONS, and Total Length is updated to include any options. Version is set to the default. Identification is chosen by the normal IP ID selection logic. The source address is updated if none was specified and the TTL is changed if the packet has a broadcast destination address. Since an application cannot send down fragments (as IP assigns the IP ID), Fragment Offset is always 0. The IP Checksum field is computed by IP. None of the data beyond the IP header are changed, including the application-provided transport header.
The socket options supported at the IP level are: IP_OPTIONS
IP options for outgoing datagrams. This socket option may be used to set IP options to be included in each outgoing datagram. IP options to be sent are set with setsockopt() (see getsockopt(3SOCKET)). The getsockopt(3SOCKET) call returns the IP options set in the last setsockopt() call. IP options on received datagrams are visible to user programs only using raw IP sockets. The format of IP options given in setsockopt() matches those defined in the IP specification with one exception: the list of addresses for the source routing options must include the first-hop gateway at the beginning of the list of gateways. The first-hop gateway address will be extracted from the option list and the size adjusted accordingly before use. IP options may be used with any socket type in the Internet family.
Enable or obtain IPsec security settings for this socket. For more details on the protection services of IPsec, see ipsec(4P).
Join a multicast group.
Leave a multicast group.
Limit reception and transmission of packets to this interface. Takes an integer as an argument. The integer is the selected interface index.
Time to live for packets. This option takes an unsigned integer that must be betweeen 1 and 255 and sets that as the default time to live in the IP Header.
Controls the minimum TTL that is required in an IP packet before accepting it. If the value is set to 100, then only IP packets with a TTL of 100 or higher are accepted. Packets with a TTL less than the minimum are dropped. This option takes an integer as an argument and must be in the range of 0 to 255. A value of 0 indicates that all packets should be accepted.
The following option takes in_pktinfo_t as the parameter: IP_PKTINFO
Set the source address and/or transmit interface of the packet(s). Note that the IP_BOUND_IF socket option takes precedence over the interface index passed in IP_PKTINFO.
struct in_pktinfo {
unsigned int ipi_ifindex;/* send/recv interface index */
struct in_addr ipi_spec_dst;/* matched source addr. */
struct in_addr ipi_addr;/* src/dst addr. in IP hdr */
} in_pktinfo_t;
When passed in (on transmit) via ancillary data with IP_PKTINFO, ipi_spec_dst
is used as the source address and ipi_ifindex is used as the interface index to
send the packet out.
The following options are boolean switches controlling the reception of ancillary data. The option value is type int; a non-zero value enables the option whilst a zero value disables it. IP_DONTFRAG
This option controls the behavior of IP-level fragmentation. When this option is enabled (non-zero), then the IP Don't Fragment (DF) flag is always set in the IP header. At the same time, Path MTU discovery is disabled for the given socket. When this option is disabled, then the networking stack will determine when to insert the DF flag in the IP header based on the current state of Path MTU discovery. The system default is to treat this option as disabled, that is that Path MTU discovery is in effect.
When enabled on a SOCK_DGRAM socket, enables receipt of the destination IP address of the incoming packet. Returns inaddr_t as ancillary data.
When enabled on a SOCK_DGRAM socket, enables receipt of the IP options from the incoming packet. Returns variable-length IP options, up to 40 bytes, as ancillary data.
Enable/disable receipt of the index of the interface the packet arrived on, the local address that was matched for reception, and the inbound packet's actual destination address. Takes boolean as the parameter. Returns in_pktinfo_t as ancillary data.
When enabled on a SOCK_DGRAM socket, enables receipt of the source link-layer address for the incoming packet. Returns struct sockaddr_dl as ancillary data.
When enabled on a SOCK_DGRAM socket, the IP TTL (time to live) field for an incoming datagram is returned as uint8_t in ancillary data.
When enabled, the IP TOS (type of service) field is returned as uint8_t in ancillary data. For SOCK_DGRAM sockets, the ancillary data item is included for every call to recvmsg(). For SOCK_STREAM sockets, where there is no direct mapping between received TCP segments and receive operations, the ancillary data item will only be present when this option is first enabled, and subsequently only if the value changes.
The following options take a struct ip_mreq as the parameter. The structure contains a multicast address which must be set to the CLASS-D IP multicast address and an interface address. Normally the interface address is set to INADDR_ANY which causes the kernel to choose the interface on which to join. IP_BLOCK_SOURCE
Block multicast packets whose source address matches the given source address. The specified group must be joined previously using IP_ADD_MEMBERSHIP or MCAST_JOIN_GROUP.
Unblock (begin receiving) multicast packets which were previously blocked using IP_BLOCK_SOURCE.
Begin receiving packets for the given multicast group whose source address matches the specified address.
Stop receiving packets for the given multicast group whose source address matches the specified address.
The following options take a struct ip_mreq_source as the parameter. The structure contains a multicast address (which must be set to the CLASS-D IP multicast address), an interface address, and a source address. MCAST_JOIN_GROUP
Join a multicast group. Functionally equivalent to IP_ADD_MEMBERSHIP.
Block multicast packets whose source address matches the given source address. The specified group must be joined previously using IP_ADD_MEMBERSHIP or MCAST_JOIN_GROUP.
Unblock (begin receiving) multicast packets which were previously blocked using MCAST_BLOCK_SOURCE.
Leave a multicast group. Functionally equivalent to IP_DROP_MEMBERSHIP.
Begin receiving packets for the given multicast group whose source address matches the specified address.
Stop receiving packets for the given multicast group whose source address matches the specified address.
The following options take a struct group_req or struct group_source_req as the parameter. The `group_req structure contains an interface index and a multicast address which must be set to the CLASS-D multicast address. The group_source_req structure is used for those options which include a source address. It contains an interface index, multicast address, and source address. IP_MULTICAST_IF
The outgoing interface for multicast packets. This option takes a struct in_addr as an argument, and it selects that interface for outgoing IP multicast packets. If the address specified is INADDR_ANY, it uses the unicast routing table to select the outgoing interface (which is the default behavior).
Time to live for multicast datagrams. This option takes an unsigned character as an argument. Its value is the TTL that IP uses on outgoing multicast datagrams. The default is 1.
Loopback for multicast datagrams. Normally multicast datagrams are delivered to members on the sending host (or sending zone). Setting the unsigned character argument to 0 causes the opposite behavior, meaning that when multiple zones are present, the datagrams are delivered to all zones except the sending zone.
This option takes an integer argument as its input value. The least significant 8 bits of the value are used to set the Type Of Service field in the IP header of the outgoing packets.
This option specifies the address of the onlink nexthop for traffic originating from that socket. It causes the routing table to be bypassed and outgoing traffic is sent directly to the specified nexthop. This option takes an ipaddr_t argument representing the IPv4 address of the nexthop as the input value. The IP_NEXTHOP option takes precedence over IPOPT_LSRR. IP_BOUND_IF and SO_DONTROUTE take precedence over IP_NEXTHOP. This option has no meaning for broadcast and multicast packets. The application must ensure that the specified nexthop is alive. An application may want to specify the IP_NEXTHOP option on a TCP listener socket only for incoming requests to a particular IP address. In this case, it must avoid binding the socket to INADDR_ANY and instead must bind the listener socket to the specific IP address. In addition, typically the application may want the incoming and outgoing interface to be the same. In this case, the application must select a suitable nexthop that is onlink and reachable via the desired interface and do a setsockopt (IP_NEXTHOP) on it. Then it must bind to the IP address of the desired interface. Setting the IP_NEXTHOP option requires the PRIV_SYS_NET_CONFIG privilege.
The multicast socket options (IP_MULTICAST_IF, IP_MULTICAST_TTL, IP_MULTICAST_LOOP and IP_RECVIF) can be used with any datagram socket type in the Internet family.
At the socket level, the socket option SO_DONTROUTE may be applied. This option forces datagrams being sent to bypass routing and forwarding by forcing the IP Time To Live field to 1, meaning that the packet will not be forwarded by routers.
Raw IP datagrams can also be sent and received using the TLI connectionless primitives.
Datagrams flow through the IP layer in two directions: from the network up to user processes and from user processes down to the network. Using this orientation, IP is layered above the network interface drivers and below the transport protocols such as UDP and TCP. The Internet Control Message Protocol (ICMP) is logically a part of IP. See icmp(4P).
IP provides for a checksum of the header part, but not the data part, of the datagram. The checksum value is computed and set in the process of sending datagrams and checked when receiving datagrams.
IP options in received datagrams are processed in the IP layer according to the protocol specification. Currently recognized IP options include: security, loose source and record route (LSRR), strict source and record route (SSRR), record route, and internet timestamp.
By default, the IP layer will not forward IPv4 packets that are not addressed to it. This behavior can be overridden by using routeadm(8) to enable the ipv4-forwarding option. IPv4 forwarding is configured at boot time based on the setting of routeadm(8)'s ipv4-forwarding option.
For backwards compatibility, IPv4 forwarding can be enabled or disabled using ndd(8)'s ip_forwarding variable. It is set to 1 if IPv4 forwarding is enabled, or 0 if it is disabled.
Additionally, finer-grained forwarding can be configured in IP. Each interface can be configured to forward IP packets by setting the IFF_ROUTER interface flag. This flag can be set and cleared using ifconfig(8)'s router and router options. If an interface's IFF_ROUTER flag is set, packets can be forwarded to or from the interface. If it is clear, packets will neither be forwarded from this interface to others, nor forwarded to this interface. Setting the ip_forwarding variable sets all of the IPv4 interfaces' IFF_ROUTER flags.
For backwards compatibility, each interface creates an <ifname>:ip_forwarding /dev/ip variable that can be modified using ndd(8). An interface's :ip_forwarding ndd variable is a boolean variable that mirrors the status of its IFF_ROUTER interface flag. It is set to 1 if the flag is set, or 0 if it is clear. This interface specific <ifname> :ip_forwarding ndd variable is obsolete and may be removed in a future release of Solaris. The ifconfig(8) router and -router interfaces are preferred.
The IP layer sends an ICMP message back to the source host in many cases when it receives a datagram that can not be handled. A "time exceeded" ICMP message is sent if the "time to live" field in the IP header drops to zero in the process of forwarding a datagram. A "destination unreachable" message is sent if a datagram can not be forwarded because there is no route to the final destination, or if it can not be fragmented. If the datagram is addressed to the local host but is destined for a protocol that is not supported or a port that is not in use, a destination unreachable message is also sent. The IP layer may send an ICMP "source quench" message if it is receiving datagrams too quickly. ICMP messages are only sent for the first fragment of a fragmented datagram and are never returned in response to errors in other ICMP messages.
The IP layer supports fragmentation and reassembly. Datagrams are fragmented on output if the datagram is larger than the maximum transmission unit (MTU) of the network interface. Fragments of received datagrams are dropped from the reassembly queues if the complete datagram is not reconstructed within a short time period.
Errors in sending discovered at the network interface driver layer are passed by IP back up to the user process.
Multi-Data Transmit allows more than one packet to be sent from the IP module to another in a given call, thereby reducing the per-packet processing costs. The behavior of Multi-Data Transmit can be overridden by using ndd(8) to set the /dev/ip variable, ip_multidata_outbound to 0. Note, the IP module will only initiate Multi-Data Transmit if the network interface driver supports it.
Packets received on a network interface from an external source.
Packets to be sent out a network interface.
Packets being forwarded through this host to another network.
Packets that have been sent by a local application to another.
Packets about to be received by a local application from another.
Currently, only a single function may be registered for each event. As a result, if the slot for an event is already occupied by someone else, a second attempt to register a callback fails.
To receive packet events in a kernel module, it is first necessary to obtain a handle for either IPv4 or IPv6 traffic. This is achieved by passing NHF_INET or NHF_INET6 through to a net_protocol_lookup() call. The value returned from this call must then be passed into a call to net_register_hook(), along with a description of the hook to add. For a description of the structure passed through to the callback, please see hook_pkt_event(9S). For IP packets, this structure is filled out as follows: hpe_ifp
Identifier indicating the inbound interface for packets received with the "physical in" event.
Identifier indicating the outbound interface for packets received with the "physical out" event.
Pointer to the start of the IP header (not the ethernet header).
Pointer to the start of the mblk_t chain containing the IP packet.
Pointer to the mblk_t with the IP header in it.
A new network interface has been instantiated.
A network interface is no longer associated with this protocol.
At least one logical interface is now ready to receive packets.
There are no logical interfaces expecting to receive packets.
An address has changed on a logical interface.
Braden, R., RFC 1122, Requirements for Internet Hosts - Communication Layers, Information Sciences Institute, University of Southern California, October 1989.
Postel, J., RFC 791, Internet Protocol - DARPA Internet Program Protocol Specification, Information Sciences Institute, University of Southern California, September 1981.
A bind() operation was attempted with a "reserved" port number and the effective user ID of the process was not the privileged user. Setting the IP_NEXTHOP was attempted by a process lacking the PRIV_SYS_NET_CONFIG privilege.
A bind() operation was attempted on a socket with a network address/port pair that has already been bound to another socket.
A bind() operation was attempted for an address that is not configured on this machine.
A sendmsg() operation with a non-NULL msg_accrights was attempted.
A getsockopt() or setsockopt() operation with an unknown socket option name was given.
A getsockopt() or setsockopt() operation was attempted with the IP option field improperly formed; an option field was shorter than the minimum value or longer than the option buffer provided.
A connect() operation was attempted on a socket on which a connect() operation had already been performed, and the socket could not be successfully disconnected before making the new connection.
A sendto() or sendmsg() operation specifying an address to which the message should be sent was attempted on a socket on which a connect() operation had already been performed.
A send(), sendto(), or sendmsg() operation was attempted to send a datagram that was too large for an interface, but was not allowed to be fragmented (such as broadcasts).
An attempt was made to establish a connection by means of connect(), or to send a datagram by means of sendto() or sendmsg(), where there was no matching entry in the routing table; or if an ICMP "destination unreachable" message was received.
A send() or write() operation, or a sendto() or sendmsg() operation not specifying an address to which the message should be sent, was attempted on a socket on which a connect() operation had not already been performed.
The system ran out of memory for fragmentation buffers or other internal data structures.
SO_SNDBUF or SO_RCVBUF exceeds a system limit.
Invalid length for IP_OPTIONS.
Invalid address for IP_MULTICAST_IF. Invalid (offlink) nexthop address for IP_NEXTHOP.
Not a multicast address for IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP.
Bad interface address for IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP.
Address already joined for IP_ADD_MEMBERSHIP.
Address not joined for IP_DROP_MEMBERSHIP.
Invalid socket type.
No permissions.
Users of higher-level protocols such as TCP and UDP should be able to see received IP options.