getpeername(2)

getpeername2

Get name of connected peer

Usage

#include <sys/types.h>

#include <sys/socket.h>

int

getpeername(int s, struct sockaddr * restrict name, socklen_t * restrict namelen);

Library

Standard C Library (libc, -lc)

Overview

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

Return values

The getpeername() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

Errors

The call succeeds unless:

[EBADF]

The argument s is not a valid descriptor.

[ECONNRESET]

The connection has been reset by the peer.

[EINVAL]

The value of the namelen argument is not valid.

[ENOTSOCK]

The argument s is a file, not a socket.

[ENOTCONN]

The socket is not connected.

[ENOBUFS]

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

[EFAULT]

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

Releases

87 releases since FreeBSD 2.0.5-RELEASE; the text changed 43 times.

  1. 2.0.5–2.1.7.1
  2. 2.2.2–3.4
  3. 3.5–3.5.1
  4. 4.0
  5. 4.1
  6. 4.1.1–4.3
  7. 4.4
  8. 4.5–4.11
  9. 5.0
  10. 5.1–5.2.1
  11. 5.3–6.3
  12. 6.4
  13. 7.0
  14. 7.1
  15. 7.2
  16. 7.3
  17. 7.4
  18. 8.0
  19. 8.1
  20. 8.2
  21. 8.3
  22. 8.4
  23. 9.0
  24. 9.1
  25. 9.2
  26. 9.3
  27. 10.0
  28. 10.1
  29. 10.2
  30. 10.3
  31. 10.4
  32. 11.0
  33. 11.1
  34. 11.2
  35. 11.3
  36. 11.4
  37. 12.0
  38. 12.1
  39. 12.2
  40. 12.3
  41. 12.4
  42. 13.0–13.2
  43. 13.3–14.5
  44. 15.0–16.0

History

The getpeername() system call appeared in 4.2BSD.

From base 16.0-CURRENT-20261027-61c70dc16a79 in FreeBSD 16.0-CURRENT (2026-10-27). Parsed by carta from the page's mdoc source.