Simple TCP Socket Server and Client in C

err_check.h

#ifndef INCLUDE_ERR_CHECK_H
#define INCLUDE_ERR_CHECK_H

#define ERR_CHECK(x, y) do { \
    int retval = (x); \
    if (retval == -1) { \
        perror((y)); \
        exit(1); \
    } \
} while(0)

#define ERR_CHECK_RET(x, y, z) do { \
    int retval = (x); \
    if (retval == -1) { \
        perror((z)); \
        exit(1); \
    } else { \
        *(y) = retval; \
    } \
} while(0)

#endif

sockconn.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#include <sys/types.h>
#include <sys/socket.h>

#include <netdb.h>
#include <arpa/inet.h>
#include <netinet/in.h>

#include "err_check.h"

#define CHUNK_LEN 256

int main(int argc, char *argv[]) 
{
    struct addrinfo hints, *res;
    int sockfd, status;

    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    if ((status = getaddrinfo(argv[1], argv[2], &hints, &res)) != 0) {
        fprintf(stderr, "getaddrinfo error: %s\n", gai_strerror(status));
        exit(1);
    }

    ERR_CHECK_RET(socket(res->ai_family, res->ai_socktype, res->ai_protocol), &sockfd, "socket");

    ERR_CHECK(connect(sockfd, res->ai_addr, res->ai_addrlen), "connect");

    char buf[CHUNK_LEN];
    int bytes_read;

    memset(buf, 0, CHUNK_LEN);
    ERR_CHECK_RET(recv(sockfd, buf, CHUNK_LEN, 0), &bytes_read, "recv");

    printf("%d bytes read\n", bytes_read);
    printf("%s", buf);

    return 0;
}

socklisten.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#include <sys/types.h>
#include <sys/socket.h>

#include <netdb.h>
#include <arpa/inet.h>
#include <netinet/in.h>

#include "err_check.h"

#define DEFAULT_PORT "3490"
#define LISTEN_QUEUE_CAPACITY 5

int main(int argc, char *argv[]) 
{
    struct sockaddr_storage client_addr;
    socklen_t client_addr_size;
    struct addrinfo hints, *res;
    int sockfd, client_sockfd, status;

    bool using_custom_host = argc == 3;

    char* hostname = using_custom_host ? argv[1] : NULL;
    char* port = using_custom_host ? argv[2] : DEFAULT_PORT;

    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    if (!using_custom_host) hints.ai_flags = AI_PASSIVE;

    if ((status = getaddrinfo(hostname, port, &hints, &res)) != 0) {
        fprintf(stderr, "getaddrinfo error: %s\n", gai_strerror(status));
        exit(1);
    };

    ERR_CHECK_RET(socket(res->ai_family, res->ai_socktype, res->ai_protocol), &sockfd, "socket");

    int yes = 1;
    ERR_CHECK(setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes), "setsockopt");
    ERR_CHECK(bind(sockfd, res->ai_addr, res->ai_addrlen), "bind");

    ERR_CHECK(listen(sockfd, LISTEN_QUEUE_CAPACITY), "listen");

    client_addr_size = sizeof client_addr_size;
    ERR_CHECK_RET(accept(sockfd, (struct sockaddr *)&client_addr, &client_addr_size), &client_sockfd, "accept");

    char *msg = "Santa was here!\n";
    int len, bytes_sent;

    len = strlen(msg);
    ERR_CHECK_RET(send(client_sockfd, msg, len, 0), &bytes_sent, "send");

    printf("%d bytes sent\n", bytes_sent);

    return 0;
}