#include <sys/socket.h> //成功0,失败-1 int getsockopt(int sock, int level, int optname, void *optval, socklen_t *optlen); //成功0,失败-1 int setsockopt(int sock, int level, int optname, const void *optval, socklen_t *optlen);
sock_type.c
#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/socket.h> void error_handling(char *message); int main(int argc, char *argv[]) { int tcp_sock; int udp_sock; int sock_type; socklen_t optlen; int state; optlen = sizeof(sock_type); tcp_sock = socket(PF_INET, SOCK_STREAM, 0); udp_sock = socket(PF_INET, SOCK_DGRAM, 0); printf("SOCK_STREAM: %d\n", SOCK_STREAM); printf("SOCK_DGRAM: %d\n", SOCK_DGRAM); state = getsockopt(tcp_sock, SOL_SOCKET, SO_TYPE, (void*)sock_type, &optLen); if(state) error_handling("getsockopt() error"); printf("Socket type one: %d\n", sock_type); state = getsockopt(udp_sock, SOL_SOCKET, SO_TYPE, (void*)sock_type, &optLen); if(state) error_handling("getsockopt() error"); printf("Socket type two: %d\n", sock_type); return 0; } void error_handling(char *message) { fputs(message, stderr); fputc('\n', stderr); exit(1); }
gcc sock_type.c -o socktype ./socktype
get_buf.c
#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/socket.h> void error_handling(char *message); int main(int argc, char *argv[]) { int sock; int snd_buf; int rcv_buf; int state; socklen_t len; sock = socket(PF_INET, SOCK_STREAM, 0); len = sizeof(snd_buf); //输出缓冲大小 state = getsockopt(sock, SOL_SOCKET, SO_SNDBUF, (void*)snd_buf, &len); if(state) error_handling("getsockopt() error"); printf("Input buffer size: %d\n", rcv_buf); //输入缓冲大小 state = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, (void*)rcv_buf, &len); if(state) error_handling("getsockopt() error"); printf("Output buffer size: %d\n", snd_buf); return 0; } void error_handling(char *message) { fputs(message, stderr); fputc('\n', stderr); exit(1); }
gcc get_buf.c -o getbuf ./getbuf
set_buf.c
#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/socket.h> void error_handling(char *message); int main(int argc, char *argv[]) { int sock; int snd_buf=1024*3; int rcv_buf=104*3; int state; socklen_t len; sock = socket(PF_INET, SOCK_STREAM, 0); state = setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (void*)snd_buf, sizeof(snd_buf)); if(state) error_handling("setsockopt() error"); state = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (void*)rcv_buf, sizeof(rcv_buf)); if(state) error_handling("setsockopt() error"); len = sizeof(snd_buf); //输出缓冲大小 state = getsockopt(sock, SOL_SOCKET, SO_SNDBUF, (void*)snd_buf, &len); if(state) error_handling("getsockopt() error"); printf("Input buffer size: %d\n", rcv_buf); //输入缓冲大小 state = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, (void*)rcv_buf, &len); if(state) error_handling("getsockopt() error"); printf("Output buffer size: %d\n", snd_buf); return 0; } void error_handling(char *message) { fputs(message, stderr); fputc('\n', stderr); exit(1); }
gcc set_buf.c -o setbuf ./setbuf
先断开连接(先发送FIN消息)的主机经历Time-wait状态(套接字延迟释放,确保对方收到最后的ACK消息),此时相应端口是正在使用状态。
reuseaddr_eserver.c
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <arpa/inet.h> #include <sys/socket.h> #define TRUE 1 #define FALSE 0 void error_handling(char *message); int main(int argc, char *argv[]) { int serv_sock; int clnt_sock; char message[30]; int option; int opt_len; int str_len; struct sockaddr_in serv_addr; struct sockaddr_in clnt_addr; socklen_t addr_size; if(argc!=2) { printf("Usage : %s <port>\n", argv[0]); exit(1); } serv_sock = socket(PF_INET, SOCK_STREAM, 0); if(serv_sock==-1) error_handling("socket() error"); opt_len = sizeof(option); optiont = TRUE; setsockopt(serv_sock, SOL_SOCKET, SO_REUSEADDR, (void *)&option, opt_len); addr_size = sizeof(struct sockaddr_in); memset(&serv_addr, 0, addr_size); serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); serv_addr.sin_port = htons(atoi(argv[1])); if(bind(serv_sock, (struct sockaddr*)&serv_addr, addr_size)==-1) error_handling("bind() error"); if(listen(serv_sock, 5)==-1) error_handling("listen() error"); for(i=0; i<5; i++) { clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_addr, &addr_size ); if(clnt_sock==-1) error_handling("accept() error"); else printf("Connected client %d\n", i+1); while((str_len=read(clnt_sock, message, BUF_SIZE))!=0) write(clnt_sock, message, str_len); close(clnt_sock); } close(serv_sock); return 0; } void error_handling(char *message) { fputs(message, stderr); fputc('\n', stderr); exit(1); }
gcc reuseaddr_eserver.c -o reserver ./reserver 9190 //Connected client 1 //Connected client 2 //Connected client 3
TCP套接字默认使用Nagle算法交换数据,最大限度地进行缓冲,直到收到ACK,防止数据包过多发生网络过载(影响传输),提高网络传输效率。
“大文件数据”应禁用Nagle算法,可以提高传输速度,类似于并行传输,不用等上一个数据包收到ACK后再发送下一个数据包,可以同时发送多个数据包。
int opt_val=1; setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&opt_val, sizeof(opt_val));
int opt_val; socklen_t opt_len=sizeof(opt_val); getsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&opt_val, &opt_val);
#include <winsock2.h> //成功0,失败SOCKET_ERROR int getsockopt(SOCKET sock, int level, int optname, char *optval, int *optlen); //成功0,失败-1 int setsockopt(SOCKET sock, int level, int optname, const char *optval, int optlen);
buf_win.c
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <winsock2.h> void ErrorHanding(char *message); int main(int argc, char *argv[]) { WSADATA wsaData; SPCKET sock; int snd_buf=1024*3; int rcv_buf=104*3; int state; if(WSAStartup(MAKEWORD(2, 2), &wsaData)!=0) ErrorHanding("WSAStartup() error!"); sock = socket(PF_INET, SOCK_STREAM, 0); ShorSocketBufSize(sock); state = setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char*)&snd_buf, sizeof(snd_buf)); if(state==SOCKET_ERROR) error_handling("setsockopt() error"); state = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char*)&rcv_buf, sizeof(rcv_buf)); if(state==SOCKET_ERROR) error_handling("setsockopt() error"); ShorSocketBufSize(sock); closesocket(sock); WSACleanup(); return 0; } void ShorSocketBufSize(SOCKET sock) { int snd_buf; int rcv_buf; int state; int len; len=sizeof(snd_buf); state = getsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char*)&snd_buf, &len); if(state==SOCKET_ERROR) error_handling("getsockopt() error"); printf("Output buffer size: %d\n", snd_buf); len=sizeof(rcv_buf); state = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char*)&rcv_buf, &len); if(state==SOCKET_ERROR) error_handling("getsockopt() error"); printf("Input buffer size: %d\n", rcv_buf); } void ErrorHanding(char *message) { fputs(message, stderr); fputc('\n', stderr); exit(1); }
gcc buf_win.c -o buf_win ./buf_win