Socket

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Description

The socket function creates a socket that is bound to a specific transport service provider.

Info.png
Note
The analyzed malware could be a sniffer.

Syntax

SOCKET WSAAPI socket(
  _In_ int af,
  _In_ int type,
  _In_ int protocol
);

Parameters

af [in]
The address family specification. Possible values for the address family are defined in the Winsock2.h header file.
On the Windows SDK released for Windows Vista and later, the organization of header files has changed and the possible values for the address family are defined in the Ws2def.h header file. Note that the Ws2def.h header file is automatically included in Winsock2.h, and should never be used directly.
The values currently supported are AF_INET or AF_INET6, which are the Internet address family formats for IPv4 and IPv6. Other options for address family (AF_NETBIOS for use with NetBIOS, for example) are supported if a Windows Sockets service provider for the address family is installed. Note that the values for the AF_ address family and PF_ protocol family constants are identical (for example, AF_INET and PF_INET), so either constant can be used.
The table below lists common values for address family although many other values are possible.
Af Meaning
AF_UNSPEC
0
The address family is unspecified.
AF_INET
2
The Internet Protocol version 4 (IPv4) address family.
AF_IPX
6
The IPX/SPX address family. This address family is only supported if the NWLink IPX/SPX NetBIOS Compatible Transport protocol is installed.

This address family is not supported on Windows Vista and later.

AF_APPLETALK
16
The AppleTalk address family. This address family is only supported if the AppleTalk protocol is installed.

This address family is not supported on Windows Vista and later.

AF_NETBIOS
17
The NetBIOS address family. This address family is only supported if the Windows Sockets provider for NetBIOS is installed.

The Windows Sockets provider for NetBIOS is supported on 32-bit versions of Windows. This provider is installed by default on 32-bit versions of Windows.

The Windows Sockets provider for NetBIOS is not supported on 64-bit versions of windows including Windows 7, Windows Server 2008, Windows Vista, Windows Server 2003, or Windows XP.

The Windows Sockets provider for NetBIOS only supports sockets where the type parameter is set to SOCK_DGRAM.

The Windows Sockets provider for NetBIOS is not directly related to the NetBIOS programming interface. The NetBIOS programming interface is not supported on Windows Vista, Windows Server 2008, and later.

AF_INET6
23
The Internet Protocol version 6 (IPv6) address family.
AF_IRDA
26
The Infrared Data Association (IrDA) address family.

This address family is only supported if the computer has an infrared port and driver installed.

AF_BTH
32
The Bluetooth address family.

This address family is supported on Windows XP with SP2 or later if the computer has a Bluetooth adapter and driver installed.

type [in]
The type specification for the new socket. Possible values for the socket type are defined in the Winsock2.h header file.
The following table lists the possible values for the type parameter supported for Windows Sockets 2:
Type Meaning
SOCK_STREAM
1
A socket type that provides sequenced, reliable, two-way, connection-based byte streams with an OOB data transmission mechanism. This socket type uses the Transmission Control Protocol (TCP) for the Internet address family (AF_INET or AF_INET6).
SOCK_DGRAM
2
A socket type that supports datagrams, which are connectionless, unreliable buffers of a fixed (typically small) maximum length. This socket type uses the User Datagram Protocol (UDP) for the Internet address family (AF_INET or AF_INET6).
SOCK_RAW
3
A socket type that provides a raw socket that allows an application to manipulate the next upper-layer protocol header. To manipulate the IPv4 header, the IP_HDRINCL socket option must be set on the socket. To manipulate the IPv6 header, the IPV6_HDRINCL socket option must be set on the socket.
SOCK_RDM
4
A socket type that provides a reliable message datagram. An example of this type is the Pragmatic General Multicast (PGM) multicast protocol implementation in Windows, often referred to as reliable multicast programming.

This type value is only supported if the Reliable Multicast Protocol is installed.

SOCK_SEQPACKET
5
A socket type that provides a pseudo-stream packet based on datagrams.
In Windows Sockets 2, new socket types were introduced. An application can dynamically discover the attributes of each available transport protocol through the WSAEnumProtocols function. So an application can determine the possible socket type and protocol options for an address family and use this information when specifying this parameter. Socket type definitions in the Winsock2.h and Ws2def.h header files will be periodically updated as new socket types, address families, and protocols are defined.
In Windows Sockets 1.1, the only possible socket types are SOCK_DGRAM and SOCK_STREAM.
protocol [in]
The protocol to be used. The possible options for the protocol parameter are specific to the address family and socket type specified. Possible values for the protocol are defined in the Winsock2.h and Wsrm.h header files.
On the Windows SDK released for Windows Vista and later, the organization of header files has changed and this parameter can be one of the values from the IPPROTO enumeration type defined in the Ws2def.h header file. Note that the Ws2def.h header file is automatically included in Winsock2.h, and should never be used directly.
If a value of 0 is specified, the caller does not wish to specify a protocol and the service provider will choose the protocol to use.
When the af parameter is AF_INET or AF_INET6 and the type is SOCK_RAW, the value specified for the protocol is set in the protocol field of the IPv6 or IPv4 packet header.
The table below lists common values for the protocol although many other values are possible.
protocol Meaning
IPPROTO_IP
0
dummy for IP
IPPROTO_ICMP
1
The Internet Control Message Protocol (ICMP). This is a possible value when the af parameter is AF_UNSPEC, AF_INET, or AF_INET6 and the type parameter is SOCK_RAW or unspecified.

This protocol value is supported on Windows XP and later.

IPPROTO_IGMP
2
The Internet Group Management Protocol (IGMP). This is a possible value when the af parameter is AF_UNSPEC, AF_INET, or AF_INET6 and the type parameter is SOCK_RAW or unspecified.

This protocol value is supported on Windows XP and later.

BTHPROTO_RFCOMM
3
The Bluetooth Radio Frequency Communications (Bluetooth RFCOMM) protocol. This is a possible value when the af parameter is AF_BTH and the type parameter is SOCK_STREAM.

This protocol value is supported on Windows XP with SP2 or later.

IPPROTO_TCP
6
The Transmission Control Protocol (TCP). This is a possible value when the af parameter is AF_INET or AF_INET6 and the type parameter is SOCK_STREAM.
IPPROTO_UDP
17
The User Datagram Protocol (UDP). This is a possible value when the af parameter is AF_INET or AF_INET6 and the type parameter is SOCK_DGRAM.
IPPROTO_ICMPV6
58
The Internet Control Message Protocol Version 6 (ICMPv6). This is a possible value when the af parameter is AF_UNSPEC, AF_INET, or AF_INET6 and the type parameter is SOCK_RAW or unspecified.

This protocol value is supported on Windows XP and later.

IPPROTO_RM
113
The PGM protocol for reliable multicast. This is a possible value when the af parameter is AF_INET and the type parameter is SOCK_RDM. On the Windows SDK released for Windows Vista and later, this protocol is also called IPPROTO_PGM.

This protocol value is only supported if the Reliable Multicast Protocol is installed.

IPPROTO_RAW
255
raw IP packet

Return value

If no error occurs, socket returns a descriptor referencing the new socket. Otherwise, a value of INVALID_SOCKET is returned, and a specific error code can be retrieved by calling WSAGetLastError.

Error code Meaning
WSANOTINITIALISED A successful WSAStartup call must occur before using this function.
WSAENETDOWN The network subsystem or the associated service provider has failed.
WSAEAFNOSUPPORT The specified address family is not supported. For example, an application tried to create a socket for the AF_IRDA address family but an infrared adapter and device driver is not installed on the local computer.
WSAEINPROGRESS A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.
WSAEMFILE No more socket descriptors are available.
WSAEINVAL An invalid argument was supplied. This error is returned if the af parameter is set to AF_UNSPEC and the type and protocol parameter are unspecified.
WSAEINVALIDPROVIDER The service provider returned a version other than 2.2.
WSAEINVALIDPROCTABLE The service provider returned an invalid or incomplete procedure table to the WSPStartup.
WSAENOBUFS No buffer space is available. The socket cannot be created.
WSAEPROTONOSUPPORT The specified protocol is not supported.
WSAEPROTOTYPE The specified protocol is the wrong type for this socket.
WSAEPROVIDERFAILEDINIT The service provider failed to initialize. This error is returned if a layered service provider (LSP) or namespace provider was improperly installed or the provider fails to operate correctly.
WSAESOCKTNOSUPPORT The specified socket type is not supported in this address family.