Ifaddrs

Ifaddrs is a C library function used in Unix-like operating systems to retrieve information about network interfaces and their associated addresses. The function is defined in the ifaddrs.h header file and is part of the POSIX standard. It provides a way to obtain a linked list of network interfaces, each with its own set of addresses, including IPv4 and IPv6 addresses, as well as hardware addresses.

The ifaddrs function takes a pointer to a pointer to an ifaddrs structure as its argument. This structure contains information about a single network interface, including its name, address family, and address. The function returns zero on success and a non-zero value on failure.

To use ifaddrs, a program must first declare a pointer to an ifaddrs structure and then call the ifaddrs function, passing the address of this pointer. The function will then allocate memory for the linked list of ifaddrs structures and populate it with information about the network interfaces. The program can then traverse the linked list to access the information it needs.

Once the program is finished with the linked list, it should call the freeifaddrs function to free the allocated memory. This function takes a pointer to an ifaddrs structure as its argument and frees the memory for the entire linked list.

Ifaddrs is a powerful tool for network programming, allowing developers to easily retrieve information about network interfaces and their associated addresses. However, it is important to use it carefully, as it can be used to gather sensitive information about a system's network configuration.