Problem - Kevin Tafuro

different ways. On FreeBSD systems, for example, the information must be explicitly
sent, and the receiver must be able to handle receiving it. On Linux systems, the
information is automatically sent if the receiver asks for it.
A third problem is that not all implementations pass the same information. Linux
passes the process ID, user ID, and group ID of the sending process. FreeBSD
includes all groups that the process is a member of, but it does not include the process
ID. At a minimum, you can expect to get the process’s user and group IDs and
nothing more.
#include
#include
#include
#include
#include
#include
#include
#if !defined(linux) && !defined(__NetBSD__)
#include
#endif
#ifndef SCM_CREDS
#define SCM_CREDS SCM_CREDENTIALS
#endif
#ifndef linux
# ifndef __NetBSD__
# define SPC_PEER_UID(c) ((c)->cr_uid)
# define SPC_PEER_GID(c) ((c)->cr_groups[0])
# else
# define SPC_PEER_UID(c) ((c)->sc_uid)
# define SPC_PEER_GID(c) ((c)->sc_gid)
# endif
#else
# define SPC_PEER_UID(c) ((c)->uid)
# define SPC_PEER_GID(c) ((c)->gid)
#endif
#ifdef __NetBSD__
typedef struct sockcred spc_credentials;
#else
typedef struct ucred spc_credentials;
#endif
spc_credentials *spc_get_credentials(int sd) {
int nb, sync;
char ctrl[CMSG_SPACE(sizeof(struct ucred))];
size_t size;
struct iovec iov[1] = { { 0, 0 } };
struct msghdr msg = { 0, 0, iov, 1, ctrl, sizeof(ctrl), 0 };
struct cmsghdr *cmptr;
spc_credentials *credentials;
Performing Authentication with Unix Domain Sockets | 483
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