[英]Unable to send the message again using C socket
我创建了一个 ClientSocket 和一个 ServerSocket 类来简化功能。 在发送数据时,首先我发送一个 16 字节的标头,其中包含消息长度,然后是消息。 但是我在第二次将数据从客户端发送到服务器时遇到了问题。 起初它正确发送标头和消息,但之后我在从客户端读取标头时从ServerSocket::get_message
read()
获得 0 字节输出。 请帮帮我。
Server.cpp中的发送和接收部分
string ServerSocket::get_message(int client_socket_fd) {
//char *header = client_buffers[client_socket_fd].read_header;
char *read_buffer = client_buffers[client_socket_fd].read_buffer;
char header[16];
memset(header, 0, sizeof(header));
int read_result = -1;
read_result = read(client_socket_fd, header, 16);
cout << read_result << endl;
if (read_result > 0){
int read_size = stoi(string(header));
cout << read_size << endl;
memset(read_buffer, 0, sizeof(read_buffer));
read_result = read(client_socket_fd, read_buffer,read_size);
if (read_result > 0) return string(read_buffer);
}
cerr << "Unable to recieve message from client socket " << client_socket_fd << endl;
return "";
}
int ServerSocket::_send(int client_socket_fd, string message) {
//char *header = client_buffers[client_socket_fd].write_header;
char *write_buffer = client_buffers[client_socket_fd].write_buffer;
char header[16];
memset(header, 0, sizeof(header));
string write_size = to_string(message.length());
copy(write_size.begin(), write_size.end(), header);
int write_result = write(client_socket_fd, header, 16); // sending size of message
if (write_result > 0) {
write_result = write(client_socket_fd, message.c_str(), message.length());
}
if (write_result <= 0)
cerr << "Unable to send to client socket fd : " << client_socket_fd << endl;
return write_result;
}
Client.cpp中的发送和接收部分
string ClientSocket::_recieve(){
char read_header[16];
memset(read_header, 0, sizeof(read_header));
int read_result = read(socket_fd, read_header, 16);
if (read_result >0) {
int read_size = stoi(string(read_header));
memset(recieve_buffer, 0, sizeof(recieve_buffer));
read_result = read(socket_fd, recieve_buffer, read_size);
}
if ( read_result > 0) return string(recieve_buffer);
cerr << "Unable to read from server." << endl;
return "";
}
int ClientSocket::_send(string message) {
char write_header[16];
memset(write_header, 0, sizeof(write_header));
cout << message.length() << endl;
string s = to_string(message.length());
copy(s.begin(),s.end(), write_header);
int write_result = write(socket_fd, write_header, 16);
if (write_result > 0)
write_result = write(socket_fd, message.c_str(), message.length());
if (write_result <=0) cerr << "Unable to send message : "<< message << endl;
return write_result;
}
该代码在使用套接字时表现出两个最常见的错误:
send
/ write
和recv
/ read
可能无法发送/接收请求的字节数。 代码必须处理部分读/写才能正常工作。std::string
(此处为std::string
和stoi
)的函数之前,您需要对其进行零终止。 当recv
填满整个缓冲区时, memset
没有帮助,您需要为recv
不会覆盖的空终止符保留一个额外的字节。
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