标签：ade error listen failed head max 应用 业务 memset
tcp是一种基于流的应用层协议，其“可靠的数据传输”实现的原理就是，“拥塞控制”的滑动窗口机制，该机制包含的算法主要有“慢启动”，“拥塞避免”，“快速重传”。
linux环境下，应用层TCP消息体定义如下：
typedef struct TcpMsg_s { TcpMsgHeader head; void* msg; }TcpMsg;
其中，head表示自定义的TCP消息头，它的定义如下：
//TCP消息类型，根据业务需求定义
typedef enum MSGTYPE _e { EP_REG_REQ = 0, EP_REQ_RSP = 1, }MSGTYPE;
//TCP消息头定义的通用框架 typedef struct TcpMsgHead_s { int len;//消息长度（用作TCP粘包处理) MSGTYPE type;//消息类型（用作接收端消息的解析） }TcpMsgHead;
TCP客户端和服务端都采用linux提供的epoll机制(epoll_create(),epoll_wait(),epoll_ctl())对socket实现监听（可读，可写事件等）。
开源事件驱动库lievent对socket事件的监听也是通过对epoll事件的封装实现的。
基本原理：利用linux网络通信API(scoket(),bind(),listen())来创建服务器端socket；
代码如下：输入参数：localip，本地ip；port：服务端本地的监听端口号；输出：返回-1，表示失败；返回>0的fd，表示socket建立成功；
1 int TcpServer(uint32_t lcoalip, int port) 2 { 3 int fd; 4 struct sockaddr_in addr; 5 6 //socket建立 7 if ((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) 8 { 9 printf("IN TcpServer() scoket created failed,errno is %d, strerror is %s\n", errno, strerror(errno)); 10 return -1; 11 } 12 13 //设置socket为非阻塞模式 14 int flags = fcntl(fd, F_GETFL, 0); 15 fcntl(fd, F_SETFL, flags | O_NONBLOCK); 16 17 memset(&addr, 0 , sizeof(addr)); 18 addr.sin_family = AF_INET; 19 addr.sin_addr.s_addr = localip; 20 addr.sin_port = port; 21 22 //绑定本地端口和IP 23 if (bind(fd, (struct sockaddr_in)&addr, sizeof(addr) < 0)) 24 { 25 printf("IN TcpServer() bind failed,fd is%d, errno is %d, strerror is %s\n", fd, errno, strerror(errno)); 26 return -1; 27 } 28 29 if (listen(fd, 20< 0)) 30 { 31 printf("IN TcpServer() listen failed,fd is%d, errno is %d, strerror is %s\n", fd, errno, strerror(errno)); 32 return -1; 33 } 34 35 //add the socket to epoll event 36 if (SubscribeFd(fd, SOCKET_EV) != 0)
{
return -1;
} 37 return fd; 38 }
实现如下：
输入参数：fd，待监听的fd；type，枚举型变量，表明TCP类型，是客户端还是服务端；port：服务端的监听端口号；输出：返回-1，表示监听失败；返回0，表示将该socket成功添加到维护在全局变量g_epoll（TCP_EPOLL类型结构体）中的监听事件中；其中TCP_TYPE枚举变量和TCP_EPOLL结构体的定义如下：
typedef enum { CLIENT = 0, SERVER = 1, }TCP_TYPE; #define MAX_NUM_EPOLL 1000//最多可监听的socket数目 typedef struct TCP_EPOLL_s { struct epoll_event* p_event; int nb_evnet;
int nb_client;//for tcp server int epoll_fd; int sock_listen;//for tcp server int sock[MAX_NUM_EPOLL]; TCP_NL_MSG* p_tcp_nl_msg;//TCP粘包处理数据结构 }TCP_EPOLL;
int SubscribeFd (int fd, TCP_TYPE type) { struct epoll_event event; if (CLIENT == type) { event.events = EPOLLOUT | EPOLLET;//监听类型为可写事件 } else if (SERVER == type) { event.events = EPOLLIN | EPOLLET;//监听类型为可读事件 } event.date.u64 = 0; evnet.data.fd = fd; g_epoll.nb_event++; g_epoll.p_event = realloc(g_epoll.p_event, g_epoll.nb_event * sizeof(struct epoll_event)); //add epoll control event if (epoll_ctl(g_epoll.epoll_fd, EPOLL_CTL_ADD, fd, &event) != 0) { printf("epoll_ctl failed for fd %d, errno is %d, strerror is %s\n", fd, errno, strerror(errno)); return -1; } printf("successfully subscribe fd %d\n", fd); return 0; }
基本原理：利用linux网络通信API(scoket(),connect())来创建客户端socket；
代码如下：输入参数：peerip，服务端IP；localip，本地ip；port：服务端的监听端口号；输出：返回-1，表示失败；返回>0的fd，表示socket建立成功；
1 int TCPClient(uint32_t peerip,uint32_t localip,uint16_t port) 2 { 3 int fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); 4 if (fd < 0) 5 { 6 printf("TCPClient() socket failed"); 7 return -1; 8 } 9 10 struct sockaddr_in localaddr = {0}; 11 localaddr.sin_family = AF_INET; 12 localaddr.sin_addr.s_addr = localip; 13 //localaddr.sin_port = htons(port); 14 15 int ret = bind(fd, (struct sockaddr *)&localaddr, sizeof(localaddr)); 16 if (ret < 0) 17 { 18 printf("TCPClient() bind failed localip %u", localip); 19 return -1; 20 } 21 22 int flags = fcntl(fd, F_GETFL, 0); 23 fcntl(fd, F_SETFL, flags | O_NONBLOCK); 24 25 struct sockaddr_in servaddr = {0}; 26 servaddr.sin_family = AF_INET; 27 servaddr.sin_addr.s_addr = peerip; 28 servaddr.sin_port = htons(port); 29 30 ret = connect(fd, (sockaddr *)&servaddr, sizeof(servaddr)); 31 if(ret < 0) 32 { 33 if (errno != EINPROGRESS) 34 { 35 printf("TCPClient() connect failed, peerip %u, port %u", peerip, port); 36 return -1; 37 } 38 } 39 40 printf("TCPClient() connect success, fd = %u,peerip %u, port %u",fd, peerip, port); 41 42 return fd; 43 }
TCP服务端监听到监听socket有EPOLLIN事件到来时，调用int accept_fd = accept();接收此连接请求，然后服务端要利用epoll_create()为accept_fd创建新的监听事件；
1 void tcp_thread()
2 {
3 CreateEpoll();
4 CreateSocketFdEpoll(g_tcp_type);
5
6 while (1)
7 {
8 //wait for a message
9 EpollRecvMsg();
10 }
11 }
1 TCP_EPOLL g_epoll;//全局Epoll变量
2
3 //EPOLL事件的建立
4 void CreateEpoll()
5 {
6 g_epoll.epoll_fd = epoll_create1(0);
7 g_epoll.nb_event = 0;
8 }
1 int CreateSocketFdEpoll(TCO_TYPE type)
2 {
3 uint32_t server_ip = inet_addr(SERVER_IP);
4 uint32_t local_ip = inet_addr(LOCAL_IP);
5
6 int fd;
7 if (CLIENT == type)
8 {
9 fd = TcpClient(server_ip, SERVER_PORT, local_ip);
10 g_epoll.sock = fd;
11 }
12 else if (SERVER == type)
13 {
14 fd = TcpServer(local_ip, LOCAL_PORT);
15 g_epoll.sock_listen = fd;
16 }
17
18 g_epoll.p_tcpNLMsg = (TCP_NL_MSG)malloc(sizeof(TCP_NL_MSG));
19
20 InitTcpNLMsg(g_epoll.p_tcpNLMsg);
21 }
1 void InitTcpNLMsg(TCP_NL_MSG* pTcpNLMsg)
2 {
3 pTcpNLMsg->g_recv_len = 0;
4 pTcpNLMsg->flag_in_NL_proc = FALSE;
5 memset(pTcpNLMsg->g_recv_buff, 0, MAX_MSG_LEN);
6 }
1 void EpollRecvMsg()
2 {
3 int epoll_ret = 0;
4 int epoll_timeout = -1;
5
6 do
7 {
8 epoll_ret = epoll_wait(g_epoll.epoll_fd, g_epoll.p_event, g_epoll.nb_event, epoll_timeout);
9 }while(epoll_ret < 0 && errno == EINTR);
10
11 if (epoll_ret < 0)
12 {
13 printf("epoll_wait failed: %s\n", strerror(errno));
14 return;
15 }
16
17 //遍历处理每一个当前监听到的事件
18 for (int i=0;i<epoll_ret;++i)
19 {
20 int fd = g_epoll.p_event[i].data.fd;
21
22 if (CLIENT == g_tcp_type)
23 {
24 if (g_epoll.p_event[i].events & EPOLLOUT) //the socket is writable，socket可写，表明服务端已accept该客户端的connect请求
25 {
26 if (JudgeIfConnSucc(fd) == 0)//判断TCP连接是否建立成功
27 {
28 struct epoll_event* p_ev = &(g_epoll.p_event[i]);
29 p_ev ->events = EPOLLIN | EPOLLET;
30
31 epoll_ctl(g_epoll.epoll_fd, EPOLL_CTL_MOD,fd, p_ev );//对TCP客户端socket修改其监听类型，由可写改为可读
32
33 printf("tcp_fd_client %d can be written\n", fd);
34 }
35 }
36 else if(g_epoll.p_event[i].events & EPOLLIN) //the socket is readable
37 {
38 RecvTcpMsg(fd);
39 }
40 }
41 else if (SERVER== g_tcp_type)
42 { if (g_epoll.p_event[i].events & EPOLLIN) //the socket is readable,服务端socket可读
43 {
44 if (fd == g_epoll.sock_listen)//服务端接收到一个TCP连接请求
45 {
46 struct sockaddr s_addr;
47 socklen_t length = sizeof(struct sockaddr);
48
49 int conn_fd = accept(fd, &s_addr, &length);//服务端接收来自客户端的连接请求
50
51 int flags = fcntl(conn_fd, F_GETFL, 0);
52 fcmt(conn_fd, F_SETFL, flags | O_NONBLOCK);
53
54 g_epoll.sock[g_epoll.nb_client++] = conn_fd;
55
56 SubscribeFd(conn_fd, SERVER);//服务端将新建立的TCP连接建立新的epoll监听事件，并维护在全局变量中
57
58 printf("Receive a tcp conn request, conn_fd is %d\n", fd);
59 }
60 else //support multi tcp client
61 {
62 RecvTcpMsg(fd);//接收TCP消息（先进行粘包处理，然后根据消息类型进入不同的处理分支）
63 }
64 }
65 }
66 }
67 }
函数实现如下：
输入：fd，发送socket；type，业务定义的tcp消息类型；msg指针：指向待发送的消息地址；length，待发送的msg的字节数；
输出：成功，返回发送的字节数；失败，返回-1；
#define MAX_LEN_BUFF 65535
int SendTcpMsg(int fd, MSGTYPE type, void* msg, int length) { uint8_t buf[MAX_LEN_BUFF]; memset(buf,0,MAX_LEN_BUFF); uint32_t bsize = 0; TcpMsgHead* head = (TcpMsgHead*)buf; bsize += sizeof(TcpMsgHead);
//将待发送消息内容拷贝到待发送缓存中 memcpy(buf+bsize, msg, length); bsize += length;
//封装TCP消息头，指明消息类型（用作接收端消息的解析）和消息长度（用作TCP粘包处理） head->type = type; head->msglen = bsize; int ret = send(fd,(const void*)buf,bsize,0); if(ret != bsize) { printf("Failed to send tcp msg,errno=%u,ret=%d, strerror is %s\n", errno, ret, strerror(errno)); return -1; } printf("Success to send tcp msg, msg type is %d\n", type); return ret; }
linux epoll机制对TCP 客户端和服务端的监听C代码通用框架实现
标签：ade error listen failed head max 应用 业务 memset
原文地址：http://www.cnblogs.com/studyofadeerlet/p/7265616.html
