5-10-setsendbuffer.c

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

#define BUFFER_SIZE  1024

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

    struct sockaddr_in server_address;
    bzero(&server_address, sizeof(server_address));
    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 len = sizeof(sendbuf);
    /*先设置TCP发送缓冲区的大小， 然后释放即读取之*/
    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;
}