NAME

       nng_tcp - TCP/IP transport

SYNOPSIS

           #include <nng/transport/tcp/tcp.h>

           int nng_tcp_register(void);

DESCRIPTION

       The tcp transport provides communication support between sockets across a TCP/IP network. Both IPv4 and
       IPv6 are supported when the underlying platform also supports it.

   Registration
       This transport is generally built-in to the core of NNG, so no extra steps to use it should be necessary.

   URI Format
       This transport uses URIs using the scheme tcp://, followed by an IP address or hostname, followed by a
       colon and finally a TCP port number. For example, to contact port 80 on the localhost either of the
       following URIs could be used: tcp://127.0.0.1:80 or tcp://localhost:80.

       A URI may be restricted to IPv6 using the scheme tcp6://, and may be restricted to IPv4 using the scheme
       tcp4://.

           Note

           Specifying tcp6:// may not prevent IPv4 hosts from being used with IPv4-in-IPv6 addresses,
           particularly when using a wildcard hostname with listeners. The details of this varies across
           operating systems.

           Note

           Both tcp6:// and tcp4:// are specific to NNG, and might not be understood by other implementations.

           Tip

           We recommend using either numeric IP addresses, or names that are specific to either IPv4 or IPv6 to
           prevent confusion and surprises.

       When specifying IPv6 addresses, the address must be enclosed in square brackets ([]) to avoid confusion
       with the final colon separating the port.

       For example, the same port 80 on the IPv6 loopback address (::1) would be specified as tcp://[::1]:80.

       The special value of 0 (INADDR_ANY) can be used for a listener to indicate that it should listen on all
       interfaces on the host. A short-hand for this form is to either omit the address, or specify the asterisk
       (*) character. For example, the following three URIs are all equivalent, and could be used to listen to
       port 9999 on the host:

        1. tcp://0.0.0.0:9999

        2. tcp://*:9999

        3. tcp://:9999

       The entire URI must be less than NNG_MAXADDRLEN bytes long.

   Socket Address
       When using an nng_sockaddr structure, the actual structure is either of type nng_sockaddr_in (for IPv4)
       or nng_sockaddr_in6 (for IPv6).

   Transport Options
       The following transport options are supported by this transport, where supported by the underlying
       platform.

       •   NNG_OPT_LOCADDR

       •   NNG_OPT_REMADDR

       •   NNG_OPT_TCP_KEEPALIVE

       •   NNG_OPT_TCP_NODELAY

       •   NNG_OPT_URL

SEE ALSO

       nng_options(5), nng_sockaddr(5), nng_sockaddr_in(5), nng_sockaddr_in6(5), nng_tcp_options(5), nng(7)

                                                   2025-02-02                                         NNG_TCP(7)