SIMPLE SOLUTIONS

GETPEERNAME(2) - man page online | system calls

Get name of connected peer socket.

Chapter
2015-12-28
GETPEERNAME(2)                      Linux Programmer's Manual                      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 buf‐ fer 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 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 The third argument of getpeername() is in reality an int * (and this is what 4.x BSD and libc4 and libc5 have). Some POSIX confusion resulted in the present socklen_t, also used by glibc. See also accept(2). For stream sockets, once a connect(2) has been performed, either socket can call getpeer‐ name() 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 get‐ peername() 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 4.04 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 http://www.kernel.org/doc/man-pages/.
Linux 2015-12-28 GETPEERNAME(2)
This manual Reference Other manuals
getpeername(2) referred by accept(2freebsd) | accept4(2freebsd) | connect(2freebsd) | explain(1) | explain(3) | explain_getpeername(3) | explain_getpeername_or_die(3) | getnameinfo(3) | getpeereid(3) | getpeername(2freebsd) | getsockname(1) | getsockname(2freebsd) | milter(3bobcat) | msocket(2viewos) | ng_ksocket(4freebsd) | rights(4freebsd) | sa(3) | socket(2) | socket(2freebsd) | socket(7)
refer to accept(2) | bind(2) | connect(2) | getsockname(2) | ip(7) | recv(2) | socket(7) | unix(7) | write(2)