Recv總是收到1個字節

Question

我對此非常厭煩 - 我試圖修復它大約5個小時，我仍然不能找到問題，也許你們可以。

我的問題是，當我從服務器發送IP時，recv在客戶端總是recv少一個字節。而服務器始終發送數據和右數據，並在客戶端IP地址的正確ammount的總是悄無1號，它總是第一個這樣的服務器發送：

192.168.0.101

客戶接受：

92.168.0.101

還有一點很重要的是客戶的名字總是沒有任何問題地被接收到 - 它只發生在IP地址上。

在那仔細看看：

服務器端發送數據[2串 - 首先是客戶端的名稱，第二個是他的IP地址]：

j是列表的迭代循環thourght所有客戶端和客戶端變量是被要求的所有客戶端的數據

std::cout << j->client_name << " "; 
int lenght = j->client_name.length()+1 ; //+1 for '\0' byte at the client buffer 
std::cout << "Lenght (+1): " << lenght << " "; 
lenght = htonl(lenght); //change byte order to network 
send(client->client_socket,(char*)&lenght,sizeof(int),0); 
std::cout << "I have sent: " << send(client->client_socket,j->client_name.c_str(),j->client_name.length(),0) << std::endl; 
std::cout << inet_ntoa(j->client_connection.sin_addr) << " "; //showing IP adress 
unsigned lenght2 = strlen(inet_ntoa(j->client_connection.sin_addr))+1; //+1 for '\0' byte at the client buffer 
std::cout << "Lenght (+1): " << lenght2 << " "; 
unsigned realistic_lenght = lenght2; 
lenght2 = htonl(lenght2); 
send(client->client_socket,(char*)&lenght,sizeof(unsigned),0); 
std::cout << "I have sent: " << send(client->client_socket,inet_ntoa(j->client_connection.sin_addr),realistic_lenght,0) << std::endl; 

正如我在服務器端的一切說似乎是好的，這裏的代碼，即可獲得在客戶端的數據之一：

char* data_buffor; 
int lenght = 0; 
recv(data.client_socket,(char*)&lenght,sizeof(int),0); 
lenght = ntohl(lenght); 
std::cout << "I have received: " << lenght << std::endl; 
data_buffor = new char[lenght]; 
if (data_buffor != NULL) std::cout << "ALLOCATION WAS SUCCESFULL" << std::endl; 
std::cout << "I have received: " << recv(data.client_socket,data_buffor,lenght,0) << std::endl; 
data_buffor[lenght-1] = '\0'; 
temp.client_name = data_buffor; // everything is fine here 
delete data_buffor; 
data_buffor = NULL; 
unsigned lenght2 = 0; 
recv(data.client_socket,(char*)&lenght2,sizeof(unsigned),0); 
lenght2 = ntohl(lenght2); 
std::cout << "I have received: " << lenght2 << std::endl; // I DONT KNOW WHY BUT HERE I GET CRAZY NUMBERS LIKE 3203 and I should get 14 with IP: 192.168.0.101 + one byte for '\0' I think that may be causing all problems but I have no idea how to fix it. 
data_buffor = new char[lenght2]; 
if (data_buffor != NULL) std::cout << "ALLOCATION WAS SUCCESFULL" << std::endl; 
std::cout << "I have received " << recv(data.client_socket,data_buffor,lenght2,0) << std::endl; 
temp.client_ip_adress = data_buffor; 
all_clients.push_back(temp); 
delete data_buffor 
data_buffor = NULL; 

任何幫助將不勝感激。

Answer 1

當服務器發送客戶端名稱時，它發送length作爲字符串+ 1的長度以包含終止NULL字符。但是，由std::string::length()返回的值確實是而不是包含終止空值，因此服務器實際上並未將終止空值發送給客戶端。當客戶端讀取名稱時，它會讀取IP地址的第一個字符作爲名稱的終止NULL，但您永遠不會注意到，因爲客戶端將使用'\0'覆蓋data_buffor中的該字節，而不是依靠服務器發送'\0' 。