#include <sys/socket.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

#define BUFFER_SIZE 512

int main(int argc, char* argv[])
{
    if (argc <= 3)
    {
        printf("usage: %s ip_address port_number send_bufer_size\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    struct sockaddr_in server_address = {0};
    server_address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &server_address.sin_addr);
    server_address.sin_port = htons(port);

    int sock = socket(PF_INET, SOCK_STREAM, 0);
    assert(sock >= 0);

    int sendbuf = atoi(argv[3]);
    int len = sizeof(sendbuf);
    setsockopt(sock, SOL_SOCKET, SO_SNDBUF, &sendbuf, sizeof(sendbuf));
    getsockopt(sock, SOL_SOCKET, SO_SNDBUF, &sendbuf, (socklen_t*)&len);
    printf("the tcp send buffer size after setting is %d\n", sendbuf);

    if (connect(sock, (struct sockaddr*)&server_address, sizeof(server_address)) != -1)
    {
        char buffer[BUFFER_SIZE];
        memset(buffer, 'a', BUFFER_SIZE);
        send(sock, buffer, BUFFER_SIZE, 0);
    }

    close(sock);
    return 0;
}

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

int main(int argc, char* argv[])
{
    if (argc <= 2)
    {
        printf("usage: %s ip_address port_number\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    struct sockaddr_in server_address = {0};
    server_address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &server_address.sin_addr);
    server_address.sin_port = htons(port);

    int sockfd = socket(PF_INET, SOCK_STREAM, 0);
    assert(sockfd >= 0);
    if (connect(sockfd, (struct sockaddr*)&server_address, sizeof(server_address)) < 0)
    {
        printf("connection failed\n");
    }
    else
    {
        printf("send oob data out\n");
        const char* oob_data = "abc";
        const char* normal_data = "123";
        send(sockfd, normal_data, strlen(normal_data), 0);
        send(sockfd, oob_data, strlen(oob_data), MSG_OOB);
        send(sockfd, normal_data, strlen(normal_data), 0);
    }

    close(sockfd);
    return 0;
}

#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

int main(int argc, char* argv[])
{
    if (argc <= 2)
    {
        printf("usage: %s ip_address port_number\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    struct sockaddr_in address = {0};
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);
    int sock = socket(PF_INET, SOCK_STREAM, 0);
    assert(sock >= 0);

    int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));
    assert(ret != -1);

    ret = listen(sock, 5);
    assert(ret != -1);

    struct sockaddr_in client;
    socklen_t client_addrlength = sizeof(client);
    int connfd = accept(sock, (struct sockaddr*)&client, &client_addrlength);
    if (connfd < 0)
    {
        printf("errno is: %d\n", errno);
    }
    else
    {
        char remote[INET_ADDRSTRLEN];
        printf("connected with ip: %s and port: %d\n", inet_ntop(AF_INET, &client.sin_addr, remote, INET_ADDRSTRLEN), ntohs(client.sin_port));
        close(connfd);
    }

    close(sock);
    return 0;
}

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

#define BUF_SIZE 1024

int main(int argc, char* argv[])
{
    if (argc <= 2)
    {
        printf("usage: %s ip_address port_number\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    struct sockaddr_in address = {0};
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);

    int sock = socket(PF_INET, SOCK_STREAM, 0);
    assert(sock >= 0);

    int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));
    assert(ret != -1);

    ret = listen(sock, 5);
    assert(ret != -1);

    struct sockaddr_in client;
    socklen_t client_addrlength = sizeof(client);
    int connfd = accept(sock, (struct sockaddr*)&client, &client_addrlength);
    if (connfd < 0)
    {
        printf("errno is: %d\n", errno);
    }
    else
    {
        char buffer[BUF_SIZE];

        memset(buffer, '\0', BUF_SIZE);
        ret = recv(connfd, buffer, BUF_SIZE - 1, 0);
        printf("got %d bytes of normal data '%s'\n", ret, buffer);

        memset(buffer, '\0', BUF_SIZE);
        ret = recv(connfd, buffer, BUF_SIZE - 1, MSG_OOB);
        printf("got %d bytes of oob data '%s'\n", ret, buffer);

        memset(buffer, '\0', BUF_SIZE);
        ret = recv(connfd, buffer, BUF_SIZE - 1, 0);
        printf("got %d bytes of normal data '%s'\n", ret, buffer);

        close(connfd);
    }

    close(sock);
    return 0;
}