Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

getpeername(2)


NAME

   getpeername - get name of connected peer socket

SYNOPSIS

   #include <sys/socket.h>

   int getpeername(int sockfd, struct sockaddr *addr, socklen_t *addrlen);

DESCRIPTION

   getpeername()  returns  the address of the peer connected to the socket
   sockfd, in the buffer pointed to by addr.  The addrlen argument  should
   be  initialized to indicate the amount of space pointed to by addr.  On
   return it contains the actual size of the  name  returned  (in  bytes).
   The name is truncated if the buffer provided is too small.

   The  returned address is truncated if the buffer provided is too small;
   in this case, addrlen will return a value greater than was supplied  to
   the call.

RETURN VALUE

   On  success,  zero is returned.  On error, -1 is returned, and errno is
   set appropriately.

ERRORS

   EBADF  The argument sockfd is not a valid file descriptor.

   EFAULT The addr argument points to memory not in a valid  part  of  the
          process address space.

   EINVAL addrlen is invalid (e.g., is negative).

   ENOBUFS
          Insufficient  resources  were available in the system to perform
          the operation.

   ENOTCONN
          The socket is not connected.

   ENOTSOCK
          The file descriptor sockfd does not refer to a socket.

CONFORMING TO

   POSIX.1-2001, POSIX.1-2008, SVr4, 4.4BSD (getpeername() first  appeared
   in 4.2BSD).

NOTES

   For background on the socklen_t type, see accept(2).

   For stream sockets, once a connect(2) has been performed, either socket
   can call getpeername() to obtain the address of the  peer  socket.   On
   the   other   hand,   datagram  sockets  are  connectionless.   Calling
   connect(2) on a datagram  socket  merely  sets  the  peer  address  for
   outgoing  datagrams  sent  with  write(2)  or  recv(2).   The caller of
   connect(2) can use getpeername() to obtain the  peer  address  that  it
   earlier  set  for  the  socket.  However, the peer socket is unaware of
   this information, and calling getpeername() on  the  peer  socket  will
   return  no  useful  information  (unless  a  connect(2)  call  was also
   executed on the peer).  Note also that the receiver of a  datagram  can
   obtain the address of the sender when using recvfrom(2).

SEE ALSO

   accept(2), bind(2), getsockname(2), ip(7), socket(7), unix(7)

COLOPHON

   This  page  is  part of release 4.09 of the Linux man-pages project.  A
   description of the project, information about reporting bugs,  and  the
   latest     version     of     this    page,    can    be    found    at
   https://www.kernel.org/doc/man-pages/.



Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.



Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.



Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.



Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.


birds banner