getpeername

Implemented in Antinomie 0.7.0 · Syscall list

Synopsis

long getpeername(int fd, struct sockaddr *usockaddr, int *usockaddr_len);

Number (x86-64)	52
ABI	common
Kernel entry point	sys_getpeername

This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.

Description

Returns the address of the peer a socket is connected to.

Arguments

Name	Type	Meaning
fd (arg0)	int	File descriptor to operate on.
usockaddr (arg1)	struct sockaddr *	Pointer to a socket address.
usockaddr_len (arg2)	int *	Pointer to the size of the socket address.

Return value

On success: 0.

In an Antinomie trace the Return column and the ret filter field show the raw kernel return value. On failure that is the negative errno, for example -2 for ENOENT, not the -1 plus errno that the libc wrapper gives. syscall.errno holds the positive errno and syscall.success is false.

Common errors

Raw return	Name	Meaning
-9	EBADF	A file descriptor is not valid for this operation.
-107	ENOTCONN	The socket is not connected.

Man page

getpeername(2) on man7.org

Captured by Antinomie

Coverage mark: Implemented. Every pointer argument has a capture rule in the pinned kernel patch and none of them records a “no decoder”, “address only” or “not observed” gap on any code path. Individual values can still be incomplete on a particular call; see the capture statuses.

Every call is recorded as an Entry record (the six argument words and the pointees copied at entry) and an Exit record (the return value and the pointees copied at exit).

Arguments

Argument	When	How	Recorded field key	Condition
fd (arg0)	Entry	raw scalar word	args.0, args.fd
usockaddr (arg1)	Entry	the pointer itself, as a raw word	args.1, args.raw[1]
↳ pointee	Exit	socket address (sockaddr layout), length min(written length, capacity)	arg1.sockaddr	result is 0 or greater and the address pointer is not NULL
usockaddr_len (arg2)	Entry	the pointer itself, as a raw word	args.2, args.raw[2]
↳ pointee	Entry	socklen_t value the program provides	arg2.socklen.capacity	the address pointer is not NULL
↳ pointee	Exit	socklen_t value the kernel wrote	arg2.socklen.output	result is 0 or greater and the address pointer is not NULL

Filter fields

• Result: ret, syscall.errno, syscall.success, syscall.duration_ns.
• Argument words: args.fd (arg0), args.usockaddr (arg1), args.usockaddr_len (arg2); args.0 to args.5 by position.
• Structure sockaddr behind usockaddr (arg1): args.usockaddr.<member> for sa_family.
• Structure wait_status behind usockaddr_len (arg2): args.usockaddr_len.<member> for value.

See Syscall Trace filter for the full syntax.

For what the capture statuses mean, see Capture statuses. For what is never recorded, see Known gaps.