kkumar-fk

server.sin_family  = AF_INET;
server.sin_port    = htons(SERVER_PORT);
bcopy(server_ent->h_addr, &server.sin_addr.s_addr, server_ent->h_length);

/* Connect to server, and set the socket's destination IP address and port#
 * based on above parameters. Also, request the kernel to automatically set
 * the Source IP and port# if the application did not call bind() prior to connect().
 */
connect(fd, (struct sockaddr *)&server, sizeof server);

kkumar-fk

struct sock *inet_csk_accept(struct sock *sk)
{
    struct sock *newsk = NULL;   /* client socket */

    /* Make sure that this socket is listening, and that it has something pending. */
    lock_sock(sk);
    if (sk->sk_state == TCP_LISTEN)
        if ("there are completed connections waiting to be accepted")
            newsk = get_first_connection(sk);
    release_sock(sk);

kkumar-fk

$ ss -tlnpe | grep :45000
LISTEN     0     128    *:45000                *:*  users:(("my_server",pid=1975,fd=3)) ino:3854935788 sk:37d59c
LISTEN     0     128    *:45000                *:*  users:(("my_server",pid=1974,fd=3)) ino:3854935786 sk:37d59d

kkumar-fk

$ ss -tlnpe | grep :45000
LISTEN     0     128    *:45000   *:* users:(("my_server",pid=3020,fd=3),("my_server",pid=3019,fd=3)) ino:3854904087 sk:37d5a0

kkumar-fk

unsigned int index = reciprocal_scale(phash, num_socks);

return reuse->socks[index];

kkumar-fk

static int inet_reuseport_add_sock(struct sock *new_sk)
{
    /* First check if another identical LISTEN socket, prev_sk,
     * exists. ... Then do the following:
     */
    if (prev_sk) {
        /*
         * Not the first listener - do the following:
         *	- Grow prev_sk->sk_reuseport_cb structure if required.
         *	- Save new_sk socket pointer in prev_sk's socks[].

kkumar-fk

struct sock_reuseport {
    u16		max_socks; /* Allocated size of socks[] array */
    u16		num_socks; /* #Elements in socks[] */
    struct sock	*socks[0]; /* All sockets added to this group */
};

kkumar-fk

struct sock *reuseport_select_sock(struct sock *sk, unsigned int phash)
{
    /* Get control block of sockets in this SO_REUSEPORT group */
    struct sock_reuseport *reuse = sk->sk_reuseport_cb;

    /* Get count of sockets in the group */
    int num_socks = reuse->num_socks;

    /* Calculate value between 0 and 'num_socks-1' (both inclusive) */
    unsigned int index = reciprocal_scale(phash, num_socks);

kkumar-fk

struct sock *__inet_lookup_listener(tcp_hashinfo, skb, src_addr, src_port, dst_addr, dst_port)
{
	/*
	 * Use the destination port# to calculate a hash table slot# of the listen socket.
	 * inet_lhashfn() returns a number between 0 and INET_LHTABLE_SIZE-1 (both
	 * inclusive).
	 */
	unsigned int hash = inet_lhashfn(dst_port);

	/* Use this hash slot# to index the global LISTEN hash table */

kkumar-fk

struct sock *__inet_lookup(tcp_hashinfo, skb, src_addr, src_port, dst_addr, dst_port)
{
    /* Convert dest_port# from network to host byte order */
    u16 hnum = ntohs(dst_port);

    /* First look for an established socket ... */
    sk = __inet_lookup_established(tcp_hashinfo, src_addr, src_port, dst_addr, hnum);
    if (sk)
        return sk;