SO_REUSEADDR, SO_RCVBUF, SO_SNDBUF 简单用法

tcpserver.c

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <string.h>#include <errno.h>#include <sys/socket.h>#include <arpa/inet.h>#include <assert.h>#define BUFFER_SIZE 1204int main(int argc, char **argv){    if (argc <= 3)    {        printf("Usage:%s ip port recv_size\n", argv[0]);        return -1;    }    const char *ip = argv[1];    int port = atoi(argv[2]);    struct sockaddr_in address;    bzero(&address, sizeof(address));    address.sin_family = AF_INET;    address.sin_port = htons(port);    inet_pton(AF_INET, ip, &address.sin_addr);    int sock = socket(PF_INET, SOCK_STREAM, 0);    assert(sock >= 0);    int reuse = 1;    setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));    int recvbuf = atoi(argv[3]);    int len = sizeof(recvbuf);    setsockopt(sock, SOL_SOCKET, SO_RCVBUF, &recvbuf, sizeof(recvbuf));    getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &recvbuf, (socklen_t *)&len);    printf("get socketopt recvbuf:%d\n", recvbuf);    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[BUFFER_SIZE];        while(1)        {            memset(buffer, '\0', BUFFER_SIZE);            if(recv(connfd, buffer, BUFFER_SIZE-1, 0) > 0)            {                printf("recv:%s\n", buffer);            }            else            {                break;            }        }        close(connfd);    }    close(sock);    return 0;}

tcpclient.c

#include <stdio.h>#include <stdlib.h>#include <sys/socket.h>#include <arpa/inet.h>#include <assert.h>#include <unistd.h>#include <string.h>#define BUFFER_SIZE 1024int main(int argc, char **argv){    if (argc <= 3)    {        printf("Usage:%s ip port send_size\n", argv[0]);        return -1;    }    const char *ip = argv[1];    int port = atoi(argv[2]);    struct sockaddr_in server_address;    bzero(&server_address, sizeof(server_address));    server_address.sin_family = AF_INET;    server_address.sin_port = htons(port);    inet_pton(AF_INET, ip, &server_address.sin_addr);    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("get sockopt tcp bufffer size:%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);    }    else    {        printf("connect %s failed\n", ip);    }    close(sock);        return 0;}

编译：
gcc tcpserver.c -o tcpserver
gcc tcpclient.c -o tcpclient

运行： ./tcpserver 127.0.0.1 55555 2000

get socketopt recvbuf:4000
recv:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
recv:aaaaaaaaaaaaaaaaaaaaaaaa

运行client：./tcpclient 127.0.0.1 55555 5000
get sockopt tcp bufffer size:10000