未使用C从TCP套接字正确接收数据
我正在使用Ubuntu 12.04 32位版本我编写了一个程序来从TCP客户端接收XML文件。 同一个程序也是通过unix域套接字从另一个进程接收数据。 为此，我正在使用poll（）系统调用。
我的问题是，有些时候我没有正确地获取XML数据，或者有些时候它缺少了。 但是由于我使用的是TCP，如果有客户端会知道数据丢失。 但客户端不显示任何错误。 任何人都可以告诉我为什么会发生这种情况？
我可以提供一些代码：
int config_server_tcp(int port)
{
int sockfd = -1;
struct sockaddr_in my_addr; // my address information
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
perror("socket() failed.");
}
else
{
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(port);
my_addr.sin_addr.s_addr = htonl(INADDR_ANY); // automatically fill with my IP
memset(&(my_addr.sin_zero), 0, 8); // zero the rest of the struct
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1)
{
perror("bind() failed.");
}
else
{
if (listen (sockfd, 8) == -1)
{
perror("listen() failed.");
}
}
}
return sockfd;
}
int send_to_tcp_server(unsigned char * message, int size, char * server_ip, int port)
{
int sockfd;
struct sockaddr_in their_addr;
int numbytes = -1;
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
perror("socket() failed.");
}
else
{
their_addr.sin_family = AF_INET;
their_addr.sin_port = htons(port);
their_addr.sin_addr.s_addr=inet_addr(server_ip);
memset(&(their_addr.sin_zero), ' ', 8); // zero the rest of the struct
if (connect(sockfd, (struct sockaddr *)&their_addr, sizeof (their_addr)) == -1)
{
perror("connect() failed.");
}
else
{
if ((numbytes=send(sockfd , message, size, 0)) == -1)
{
printf ("Sending failed.n");
}
}
close (sockfd);
}
return numbytes;
}
void process_tcp (int sock)
{
struct sockaddr_in their_addr; // talker's address information
int received;
socklen_t addr_len;
char buffer[BUFF_SIZE];
addr_len = sizeof (their_addr);
int clientfd = accept (sock, (struct sockaddr *)&their_addr, &addr_len);
if (clientfd == -1)
{
perror("accept() failed.");
}
else
{
do
{
received = recv(clientfd, buffer, BUFF_SIZE, 0);
if (received == -1)
{
perror("recv() failed.");
break;
}
else
{
//do something
}
}
while (received != 0);
close (clientfd);
}
}
进程TCP功能在循环中被调用
这个错误几乎肯定存在于你未显示的代码中，这些代码根据XML-over-TCP协议来组装应用程序级消息。 以下是一种方法：
void process_tcp (int sock)
{
struct sockaddr_in their_addr;
int received, total_received;
socklen_t addr_len;
char buffer[BUFF_SIZE];
addr_len = sizeof (their_addr);
int clientfd = accept (sock, (struct sockaddr *)&their_addr, &addr_len);
if (clientfd == -1)
{
perror("accept() failed.");
}
else
{
total_received = 0;
do
{
received = recv(clientfd, buffer + total_received,
BUFF_SIZE - total_received, 0);
if (received == -1)
{
perror("recv() failed.");
break;
}
if (received > 0)
total_received += received;
}
while (received != 0);
buffer[total_received] = 0;
// here we can do something with 'buffer'
close (clientfd);
}
}
请注意，缺少很多错误检查。
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