linux c radius

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <radius/radius.h>

int main(int argc, char *argv[]) {
    if (argc != 5) {
        fprintf(stderr, "Usage: %s <server> <port> <secret> <username>\n", argv[0]);
        return 1;
    }

    const char *server = argv[1];
    int port = atoi(argv[2]);
    const char *secret = argv[3];
    const char *username = argv[4];

    RADIUS_CTX *ctx = radius_ctx_new();
    if (!ctx) {
        perror("radius_ctx_new");
        return 1;
    }

    if (radius_ctx_init(ctx, server, port, secret) != 0) {
        perror("radius_ctx_init");
        radius_ctx_free(ctx);
        return 1;
    }

    RADIUS_PACKET *pkt = radius_packet_new(RADIUS_ACCESS_REQUEST, NULL);
    if (!pkt) {
        perror("radius_packet_new");
        radius_ctx_free(ctx);
        return 1;
    }

    radius_packet_set_attr(pkt, RADIUS_USER_NAME, username, strlen(username));
    radius_packet_set_attr(pkt, RADIUS_USER_PASSWORD, "password", strlen("password"));

    if (radius_sendrecv(ctx, pkt) != 0) {
        perror("radius_sendrecv");
        radius_packet_free(pkt);
        radius_ctx_free(ctx);
        return 1;
    }

    if (radius_packet_get_code(pkt) == RADIUS_ACCESS_ACCEPT) {
        printf("Authentication successful!\n");
    } else {
        printf("Authentication failed!\n");
    }

    radius_packet_free(pkt);
    radius_ctx_free(ctx);
    return 0;
}