hss_add_entry

Source: hss-ports.h:28

Inserts a port into a sorted array, skipping duplicates.

Signature

static void hss_add_entry(struct hss_port_entry *e, int *n, int port, const char *name);

Parameter	Description
`e`	Array of `struct hss_port_entry`
`n`	Pointer to current count (updated in-place)
`port`	Port number to insert
`name`	Service name, or `NULL` to use the port number as the name

Deduplication

for (int i = 0; i < *n; i++)
    if (e[i].port == port) return;

Before inserting, scan the existing array. If the port already exists, return immediately — no duplicate entries.

Capacity guard

if (*n >= MAX_PORTS) return;

MAX_PORTS is 256 (hss-ports.h:8). If the array is full, silently skip. This prevents buffer overflow when /etc/services plus the modern-port list plus user config produce more than 256 candidates.

Sorted insertion

int i = (*n)++;
while (i > 0 && e[i - 1].port > port) { e[i] = e[i - 1]; i--; }
e[i].port = port;

Rather than appending and sorting later, the port is inserted in sorted order in a single pass. The while loop shifts larger entries rightward to make room, then writes the new entry at the correct position.

This means the array is always sorted — no separate sort pass needed. The sorted order is visible in hss.c where the probe loop iterates ports[] in ascending port-number order, so output appears sorted by port.

Service name handling

if (name)
    snprintf(e[i].service_name, sizeof(e[i].service_name), "%.20s", name);
else
    snprintf(e[i].service_name, sizeof(e[i].service_name), "%d", port);

If name is provided (from /etc/services), store it, truncated to 20 characters.
If name is NULL (from the built-in modern-port list or user config), use the decimal port number as the name.

Why sorted + deduplicated

The final port list is probed in order (hss.c:80), so sorted insertion means:

Output appears in ascending port order (matches ss behavior).
No port is probed twice (dedup keeps the scan fast).
The array is ready to use immediately — no post-processing.

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