utun2/tests/test_etcp_link_simple.c

// test_etcp_link_simple.c - Simple test with two ETCP_LINKs via UDP sockets
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <errno.h>
#include <time.h>

#define TEST_PORT 22345

typedef struct {
    int fd;
    struct sockaddr_in addr;
} socket_t;

// Create UDP socket
static socket_t* create_socket(int port) {
    socket_t* sock = calloc(1, sizeof(socket_t));
    if (!sock) return NULL;
    
    sock->fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sock->fd < 0) {
        free(sock);
        return NULL;
    }
    
    int flags = fcntl(sock->fd, F_GETFL, 0);
    fcntl(sock->fd, F_SETFL, flags | O_NONBLOCK);
    
    memset(&sock->addr, 0, sizeof(sock->addr));
    sock->addr.sin_family = AF_INET;
    sock->addr.sin_addr.s_addr = INADDR_ANY;
    sock->addr.sin_port = htons(port);
    
    if (bind(sock->fd, (struct sockaddr*)&sock->addr, sizeof(sock->addr)) < 0) {
        perror("bind");
        close(sock->fd);
        free(sock);
        return NULL;
    }
    
    printf("Socket created on port %d (fd=%d)\n", port, sock->fd);
    return sock;
}

// Send data
static int send_data(socket_t* sock, const char* data, size_t len, int dst_port) {
    struct sockaddr_in dst;
    memset(&dst, 0, sizeof(dst));
    dst.sin_family = AF_INET;
    dst.sin_addr.s_addr = inet_addr("127.0.0.1");
    dst.sin_port = htons(dst_port);
    
    ssize_t sent = sendto(sock->fd, data, len, 0, (struct sockaddr*)&dst, sizeof(dst));
    printf("[SEND] Sent %zd/%zu bytes to port %d\n", sent, len, dst_port);
    return (sent == len) ? 0 : -1;
}

// Receive data
static int recv_data(socket_t* sock, char* buffer, size_t max_len) {
    struct sockaddr_in from;
    socklen_t from_len = sizeof(from);
    
    ssize_t received = recvfrom(sock->fd, buffer, max_len, 0, (struct sockaddr*)&from, &from_len);
    if (received < 0) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            printf("[RECV] No data available\n");
        } else {
            perror("[RECV] recvfrom");
        }
        return -1;
    }
    
    printf("[RECV] Received %zd bytes from port %d\n", received, ntohs(from.sin_port));
    return received;
}

int main(void) {
    printf("=== Simple Socket Test ===\n");
    
    // Create sockets
    socket_t* server = create_socket(TEST_PORT);
    socket_t* client = create_socket(TEST_PORT + 1);
    
    if (!server || !client) {
        fprintf(stderr, "Failed to create sockets\n");
        return 1;
    }
    
    float start_time = (float)clock() / CLOCKS_PER_SEC;
    
    // Send from client to server
    const char* test_data = "Hello, world!";
    printf("\n[SEND] Client sending: '%s'\n", test_data);
    if (send_data(client, test_data, strlen(test_data), TEST_PORT) < 0) {
        fprintf(stderr, "Send failed\n");
        return 1;
    }
    
    // Receive on server
    usleep(50000);
    char buffer[2048];
    int received = recv_data(server, buffer, sizeof(buffer));
    if (received > 0) {
        buffer[received] = '\0';
        printf("[RECV] Server got: '%s'\n", buffer);
        
        if (strcmp(buffer, test_data) == 0) {
            printf("✅ SUCCESS: Data matches!\n");
        } else {
            printf("❌ FAIL: Data mismatch\n");
        }
    }
    
    // Send response from server to client
    const char* reply = "Reply from server";
    printf("\n[SEND] Server sending reply: '%s'\n", reply);
    if (send_data(server, reply, strlen(reply), TEST_PORT + 1) < 0) {
        fprintf(stderr, "Send failed\n");
        return 1;
    }
    
    // Receive on client
    usleep(50000);
    received = recv_data(client, buffer, sizeof(buffer));
    if (received > 0) {
        buffer[received] = '\0';
        printf("[RECV] Client got: '%s'\n", buffer);
    }
    
    float end_time = (float)clock() / CLOCKS_PER_SEC;
    printf("\nTiming: %.3f ms\n", (end_time - start_time) * 1000);
    
    // Cleanup
    close(server->fd);
    close(client->fd);
    free(server);
    free(client);
    
    printf("\n=== Test completed ===\n");
    return 0;
}