Linux内核3.7 TCP Fast Open验证实例

Linux内核在3.6和3.7合入了TCP Fast Open特性，在3.7.3版本上验证了一下，I did it!

以下是C语言实例（LWN介绍）：

server端代码：

#include <string.h>         #include <sys/types.h> /* See NOTES */#include <sys/socket.h>#include <netinet/in.h>int main(){    int portno = 5060;    socklen_t clilen;    char buffer[256];    struct sockaddr_in serv_addr, cli_addr;    int cfd;    int sfd = socket(AF_INET, SOCK_STREAM, 0);   // Create socket        bzero((char *) &serv_addr, sizeof(serv_addr));    serv_addr.sin_family = AF_INET;    serv_addr.sin_addr.s_addr = INADDR_ANY;    serv_addr.sin_port = htons(portno);    bind(sfd, &serv_addr,sizeof(serv_addr));      // Bind to well known address        int qlen = 5;                 // Value to be chosen by application    int err = setsockopt(sfd, IPPROTO_TCP/*SOL_TCP*/, 23/*TCP_FASTOPEN*/, &qlen, sizeof(qlen));        listen(sfd,1);                // Mark socket to receive connections    cfd = accept(sfd, NULL, 0);   // Accept connection on new socket    while(1){        int len = read(cfd,buffer,256);        if(len)             printf("tcp fast open: %s\\n",buffer);        else             break;        // read and write data on connected socket cfd    }        close(cfd);}

client端代码：

#include <sys/socket.h>#include <netinet/in.h>#include <netdb.h> #include <errno.h>int main(){    struct sockaddr_in serv_addr;    struct hostent *server;    char *data = "Hello, tcp fast open";    int data_len = strlen(data);            int sfd = socket(AF_INET, SOCK_STREAM, 0);    server = gethostbyname("localhost");        bzero((char *) &serv_addr, sizeof(serv_addr));    serv_addr.sin_family = AF_INET;    bcopy((char *)server->h_addr,          (char *)&serv_addr.sin_addr.s_addr,         server->h_length);    serv_addr.sin_port = htons(5060);    int len = sendto(sfd, data, data_len, 0x20000000/*MSG_FASTOPEN*/,                 (struct sockaddr *) &serv_addr, sizeof(serv_addr));    printf("error: %s\\n",strerror(errno));    close(sfd);    sleep(5);    }

执行结果：

# ./server        

tcp fast open: Hello, tcp fast open

# ./client        

error: Success 

环境：Fedora 18升级内核到3.7.3；glibc 2.17；gcc 4.7.2 

记得要执行：

echo 1 > /proc/sys/net/ipv4/tcp_fastopen