net_sockif.c: add ip level s|getsockopt support in SOCK_CTRL

[zhhyu7]

Summary

fix the issue where acquiring the lock gets stuck due to the sconn lock not being initialized.
provides support for s|getsockopt(IPPROTO_IP|IPPROTO_IPV6) through the SOCK_CTRL socket.

Impact

Update this section, where applicable, on how change affects users,
build process, hardware, documentation, security, compatibility, etc.

Testing

sim:matter with test code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(void) {
    int sock_fd;
    int ret;
    int tos_value_to_set;
    int tos_value_read;
    socklen_t optlen;

    // 1. Create a CTRL socket (SOCK_CTRL)
    sock_fd = socket(AF_INET, SOCK_CTRL, 0);
    if (sock_fd < 0) {
        perror("socket() failed");
        return EXIT_FAILURE;
    }
    printf("CTRL socket created successfully. FD: %d\n", sock_fd);

    // 2. Define the IP_TOS value we want to set
    // IP_TOS is a byte (0-255). Common values:
    // Low Delay (0x10): 16 decimal - for interactive traffic
    // High Throughput (0x08): 8 decimal - for bulk data
    // High Reliability (0x04): 4 decimal
    // We'll set it to "Low Delay" (0x10 = 16 decimal)
    tos_value_to_set = 0x10; // Low Delay
    printf("Attempting to set IP_TOS to: 0x%02x (%d decimal)\n", 
           tos_value_to_set, tos_value_to_set);

    // 3. Set the IP_TOS socket option using setsockopt()
    ret = setsockopt(sock_fd,            // socket file descriptor
                     IPPROTO_IP,         // level: IP protocol level
                     IP_TOS,             // option name: Type of Service
                     &tos_value_to_set,  // pointer to the option value
                     sizeof(tos_value_to_set)); // size of the option value

    if (ret < 0) {
        perror("setsockopt(IP_TOS) failed");
        close(sock_fd);
        return EXIT_FAILURE;
    }
    printf("Successfully set IP_TOS option.\n");

    // 4. Prepare to read back the IP_TOS value
    tos_value_read = 0;
    optlen = sizeof(tos_value_read);

    // 5. Read the IP_TOS socket option using getsockopt()
    ret = getsockopt(sock_fd,    // socket file descriptor
                     IPPROTO_IP, // level: IP protocol level
                     IP_TOS,     // option name: Type of Service
                     &tos_value_read, // buffer to store the retrieved value
                     &optlen);   // size of the buffer (in/out parameter)

    if (ret < 0) {
        perror("getsockopt(IP_TOS) failed");
        close(sock_fd);
        return EXIT_FAILURE;
    }

    // Note: The kernel may modify/round the TOS value you set.
    // It typically only uses the 6 most significant bits (DSCP field).
    printf("Successfully read back IP_TOS option.\n");
    printf("Read value: 0x%02x (%d decimal)\n", 
           tos_value_read, tos_value_read);

    // 6. Clean up: close the socket
    close(sock_fd);
    printf("\nSocket closed. Program finished.\n");

    return EXIT_SUCCESS;
}

NuttX log:

Starting program: /home/zhhyu/source/upstream/nuttx/nuttx 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

NuttShell (NSH) NuttX-12.12.0-RC0
MOTD: username=admin password=Administrator
nsh> hello
CTRL socket created successfully. FD: 3
Attempting to set IP_TOS to: 0x10 (16 decimal)
Successfully set IP_TOS option.
Successfully read back IP_TOS option.
Read value: 0x10 (16 decimal)

Socket closed. Program finished.
nsh>