// Copyright (c) Microsoft Corporation. All rights reserved.

// Licensed under the MIT License.

//! @brief Implements GetFullyQualifiedName on Linux

#include "getcomputername.h"

#include "getfullyqualifiedname.h"

#include <errno.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netdb.h>

//! @brief GetFullyQualifiedName retrieves the fully qualified dns name of the host

//!

//! @retval username as UTF-8 string, or null if unsuccessful

char *GetFullyQualifiedName()

{

errno = 0;

char *computerName = GetComputerName();

if (computerName == NULL)

{

return NULL;

}

struct addrinfo hints, *info;

memset(&hints, 0, sizeof hints);

hints.ai_family = AF_UNSPEC; /*either IPV4 or IPV6*/

hints.ai_socktype = SOCK_STREAM;

hints.ai_flags = AI_CANONNAME;

/* There are several ways to get the domain name:

* uname(2), gethostbyname(3), resolver(3), getdomainname(2),

* and getaddrinfo(3). Some of these are not portable, some aren't

* POSIX compliant, and some are being deprecated. getaddrinfo seems

* to be the best choice.

*/

char *fullName = NULL;

if (getaddrinfo(computerName, "http", &hints, &info) != 0)

{

goto exit;

}

// return the first canonical name in the list

fullName = strndup(info->ai_canonname, strnlen(info->ai_canonname, NI_MAXHOST));

// only free info if getaddrinfo was successful

freeaddrinfo(info);

exit:

free(computerName);

return fullName;

}