我有一个只有TCP连接的功能服务器代码。现在我希望服务器从UDP连接接收。我使用端口2000用于TCP＆amp;端口2001用于UDP。这是我的代码片段
struct timeval timeout; // timeout for select(), 1ms
timeout.tv_sec = 0;
timeout.tv_usec = 1000;
fd_set master; // master file descriptor list
fd_set read_fds; // temp file descriptor list for select()
int fdmax; // maximum file descriptor number
FD_ZERO(&master); // clear the master and temp sets
FD_ZERO(&read_fds);
// TCP port setup
int sockfd; // listening socket descriptor
int newsockfd; // newly accept()ed socket descriptor
struct sockaddr_storage remoteaddr; // client address
socklen_t addrlen;
char buf_tcp[256]; // buffer for client data
char buf_copy_tcp[256];
int recv_bytes;
char remoteIP[INET6_ADDRSTRLEN];
int yes=1; // for setsockopt() SO_REUSEADDR
int i, k, rv_getaddrinfo, rv_setsockopt, rv_bind, rv_listen, rv_select;
struct addrinfo hints, *servinfo, *ptr;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;
rv_getaddrinfo = getaddrinfo(NULL, "2000", &hints, &servinfo);
for(ptr=servinfo; ptr!=NULL; ptr=ptr->ai_next)
{
sockfd = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
rv_setsockopt = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));
rv_bind = bind(sockfd, ptr->ai_addr, ptr->ai_addrlen);
break;
}
if (ptr == NULL)
{
fprintf(stderr, "CLI Server error: failed to bind\n\r");
exit(2);
}
freeaddrinfo(servinfo); // all done with this
rv_listen = listen(sockfd, 10);
////////////////////////////////////////////////////////////////////////////////////////////////
// UDP port setup
int sockfd_udp; // listening socket descriptor
struct sockaddr_storage remoteaddr_udp; // client address
socklen_t addrlen_udp;
char buf_udp[256]; // buffer for client data
char buf_copy_udp[256];
int recv_bytes_udp;
char remoteIP_udp[INET6_ADDRSTRLEN];
int yes_udp=1; // for setsockopt() SO_REUSEADDR
int j, rv_getaddrinfo_udp, rv_setsockopt_udp, rv_bind_udp;
struct addrinfo hints_udp, *servinfo_udp, *ptr_udp;
memset(&hints_udp, 0, sizeof(hints_udp));
hints_udp.ai_family = AF_UNSPEC;
hints_udp.ai_socktype = SOCK_DGRAM;
hints_udp.ai_flags = AI_PASSIVE;
rv_getaddrinfo_udp = getaddrinfo(NULL, "2001", &hints_udp, &servinfo_udp);
for(ptr_udp=servinfo_udp; ptr_udp!=NULL; ptr_udp=ptr_udp->ai_next)
{
sockfd_udp = socket(ptr_udp->ai_family, ptr_udp->ai_socktype, ptr_udp->ai_protocol);
rv_setsockopt_udp = setsockopt(sockfd_udp, SOL_SOCKET, SO_REUSEADDR, &yes_udp, sizeof(int));
rv_bind_udp = bind(sockfd_udp, ptr_udp->ai_addr, ptr_udp->ai_addrlen);
break;
}
if (ptr_udp == NULL)
{
fprintf(stderr, "CLI UDP Server error: failed to bind\n\r");
exit(2);
}
freeaddrinfo(servinfo_udp); // all done with this
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// add the listener to the master set
FD_SET(sockfd, &master);
FD_SET(sockfd_udp, &master);
// keep track of the biggest file descriptor
if(sockfd > sockfd_udp)
fdmax = sockfd; // so far, it's this one
else
fdmax = sockfd_udp; // so far, it's this one
do
{
read_fds = master; // copy it
rv_select = select(fdmax+1, &read_fds, NULL, NULL, &timeout);
// run through the existing connections looking for data to read
for(i=0; i<=fdmax; i++)
{
if (FD_ISSET(i, &read_fds))
{ // we got one!!
if (i == sockfd)
{
// handle new connections
addrlen = sizeof(remoteaddr);
newsockfd = accept(sockfd, (struct sockaddr *)&remoteaddr, &addrlen);
FD_SET(newsockfd, &master); // add to master set
if (newsockfd > fdmax) // keep track of the max
fdmax = newsockfd;
inet_ntop(remoteaddr.ss_family, get_in_addr((struct sockaddr*)&remoteaddr), remoteIP, INET6_ADDRSTRLEN);
fprintf(stdout, "CLI Server: new connection from %s on socket %d\n\r", remoteIP, newsockfd);
}
else if (i == sockfd_udp)
{
// handle new udp connections
addrlen_udp = sizeof(remoteaddr_udp);
recv_bytes_udp = recvfrom(i, buf_udp, sizeof(buf_udp), 0, (struct sockaddr *)&remoteaddr_udp, &addrlen_udp);
inet_ntop(remoteaddr_udp.ss_family, get_in_addr((struct sockaddr*)&remoteaddr_udp), remoteIP_udp, INET6_ADDRSTRLEN);
for(j=0; j<=recv_bytes_udp; j++)
{
if( (buf_udp[k] == '\r') | (buf_udp[k] == '\n') )
buf_udp[k] = '\0';
}
fprintf(stdout, "CLI UDP Server: received %s from connection %s\n\r", buf_udp, remoteIP_udp);
}
else
{ // handle data from a client
if ((recv_bytes = recv(i, buf_tcp, sizeof(buf_tcp), 0)) <= 0)
{ // got error or connection closed by client
if (recv_bytes == 0) // connection closed
{
fprintf(stdout, "CLI Server: socket %d hung up\n\r", i);
}
else
{
perror("CLI Server error: recv");
exit(6);
}
close(i); // bye!
FD_CLR(i, &master); // remove from master set
}
else
{
for(k=0; k<=recv_bytes; k++)
{
if( (buf_tcp[k] == '\r') | (buf_tcp[k] == '\n') )
buf_tcp[k] = '\0';
}
fprintf(stdout, "CLI Server: received %s from socket %d\n\r", buf_tcp, i);
}
} // END handle data from client
} // END got new incoming connection
} // END looping through file descriptors
} while(QUIT);
我正在每个阶段进行错误检查，但没有将其包含在代码段中。当我编译＆amp;运行这个，我可以连接到端口2000但不能连接到2001，我的Tera术语终端关闭连接被拒绝消息。为什么客户端无法连接到端口2001（UDP套接字），而是连接到端口2000（TCP套接字）。服务器只响应客户端消息，直到客户端进入QUIT。
我已经从Beej的网络编程指南selectserver.c代码中建模了这段代码。
答案 0 :(得分：0)
我上面写的程序是正确的，但我对套接字编程的理解不是。这是一个侥幸，我设法编写正确的代码，但感谢@EJP在评论中进行了扩展讨论，以澄清我的疑问。
我的错误是使用Teraterm的TCP客户端连接到UDP服务器。两种通信都是相互排斥的。因此无法相互沟通。所以我不得不使用UDP客户端。 Netcat使用netcat -u <ip address> <port>提供UDP客户端选项。然后我的UDP服务器能够从UDP客户端接收消息。
另一个错误是在DATAGRAM套接字中将bind（）与connect（）混淆。连接的DGRAM就是当我在服务器和服务器上使用连接时。客户。
我认为问题出在select（）上，因为我错误地认为UDP＆amp; TCP套接字不能在select（）中同时使用。但上面的代码是你为多个客户端编写UDP / TCP服务器的方法。
再次感谢Beej＆amp; @EJP