sockets - C linux server blocking -

server:

#include<stdio.h> #include<string.h>    //strlen #include<sys/socket.h> #include<arpa/inet.h> //inet_addr #include<unistd.h>    //write #include<stdlib.h> #include<sys/types.h> #include<sys/socket.h> #include<sys/stat.h> #include<netinet/in.h> #include<fcntl.h> #include <netdb.h> #include <dirent.h> #include <stdbool.h> #include <string.h> #include "shared.h"  char **serverfoldertree; int serverfoldersnumber;  files *fls; int serverfilesnumber;  void getfolders() {     = 0;     serverfoldertree = allocatefoldertree();     serverfoldersnumber = getfoldertree(serverfoldertree, "", server_root); }  void getfiles() {     i=0;     fls = getfilelist(fls, "", server_root);         serverfilesnumber = i; }  int main() {     int socket_desc , client_sock , c , read_size;     struct sockaddr_in server , client;     char client_message[2000], tmp[2000];      //create socket     socket_desc = socket(af_inet , sock_stream , 0);     if (socket_desc == -1)     {         printf("could not create socket");     }      //prepare sockaddr_in structure     server.sin_family = af_inet;     server.sin_addr.s_addr = inaddr_any;     server.sin_port = htons( 8888 );      //bind     if( bind(socket_desc,(struct sockaddr *)&server , sizeof(server)) < 0)     {         //print error message         perror("bind failed. error");         return 1;     }      //listen     listen(socket_desc , 3);      acceptnew:      //accept , incoming connection     printf("\nwaiting incoming connections...\n");     c = sizeof(struct sockaddr_in);      //accept connection incoming client     client_sock = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c);     if (client_sock < 0)     {         perror("accept failed");         return 1;     }     printf("connection accepted\n");      //receive message client     while( (read_size = recv(client_sock , client_message , 2000 , 0)) > 0 )     {     if(!strcmp(client_message, folder_tree_req))//folder tree requested     {         printf("recieved: folder tree req\n");         getfolders();          //send folder tree nr         sprintf(tmp,"%d",serverfoldersnumber);         write(client_sock , tmp , strlen(tmp)+1);          //send folder tree elements         int i;         for(i=0;i<serverfoldersnumber;i++)         {         //strcpy(tmp, serverfoldertree[i]);          sprintf(tmp,"%s",serverfoldertree[i]);         printf("%s\n", tmp);         write(client_sock , tmp , 1000);         }     }     }      if(read_size == 0)     {         printf("client disconnected\n");         fflush(stdout);     //goto acceptnew;//listen connection     }     else if(read_size == -1)     {         perror("recv failed");     }      return 0; } 

client:

#include<stdio.h> //printf #include<string.h>    //strlen #include<sys/socket.h>    //socket #include<arpa/inet.h> //inet_addr #include<stdlib.h> #include<sys/types.h> #include<sys/socket.h> #include<sys/stat.h> #include<netinet/in.h> #include<fcntl.h> #include <netdb.h> #include <dirent.h> #include <stdbool.h> #include <string.h> #include "shared.h"  char **clientfoldertree, **serverfoldertree; int clientfoldersnumber, serverfoldersnumber;  files *fls; int clientfilesnumber;  void getfolders() {     = 0;     clientfoldertree = allocatefoldertree();     serverfoldertree = allocatefoldertree();     clientfoldersnumber = getfoldertree(clientfoldertree, "", client_root); }  void getfiles() {     i=0;     fls = getfilelist(fls, "", client_root);         clientfilesnumber = i; }  int main() {     int sock;     struct sockaddr_in server;     char message[1000] , server_reply[2000];     bool k=true;       //create socket     sock = socket(af_inet , sock_stream , 0);     if (sock == -1)     {         printf("could not create socket");     }      server.sin_addr.s_addr = inet_addr("127.0.0.1");     server.sin_family = af_inet;     server.sin_port = htons( 8888 );      //connect remote server     if (connect(sock , (struct sockaddr *)&server , sizeof(server)) < 0)     {         perror("connect failed. error");         return 1;     }      printf("connected\n");      //req folder tree     getfolders();      strcpy(message, folder_tree_req);     if( send(sock , message , strlen(message) , 0) < 0)     {          puts("send failed");          return 1;     }      //receive folder tree number     recv(sock , server_reply , 2000 , 0);     serverfoldersnumber = atoi(server_reply);      printf("server fld nr: %d\n", serverfoldersnumber);     //recieve folder tree     for(i=0;i<serverfoldersnumber;i++)     {     if(recv(sock , server_reply , 2000 , 0) < 0)     {       puts("recv failed");       break;     }      printf("got: %s\n", server_reply);     }      close(sock);     return 0; } 

the server says sent list (and prints correctly) on client side recieves foldernumber (printed , works it's 10) when reciving tree prints "got: " less 3 times.

what problem here?

you assuming call recv() load single, complete folder string server_reply buffer, ie. need call recv() many times there folder strings.

that not work.

tcp not know, or care, null-terminated c-strings. transfers octet/byte streams only. if, say, have 50 folder names take 8000 bytes, possible, (though unlikely), may have call recv() 8000 times data, each call returning 1 byte.

edit:

sending folders not problem - send how many strings, strings.

sending request server problem:

if( send(sock , message , strlen(message) , 0)

will not send null-terminator. works first-time side-effect of server buffer array being initialized 0.

receiving request @ server problem:

read_size = recv(client_sock , client_message , 2000 , 0)

may read of folder_tree_req, or 1 char of it, or in between.

receiving size @ client problem:

recv(sock , server_reply , 2000 , 0);

may return entire ascii number, or first character of it, or in between, or entire ascii number plus part/s of folder string/s.

write(client_sock , tmp , 1000);

will try send entire 1000 bytes, null-terminated folder name @ start , uninitialized/leftover bytes @ end.

..and on.

you should fix code makes no assumptions messages longer 1 byte.

you should fix code not depend upon complete, null-terminated strings being transferred.

you should fix code not matter if data sent x send() calls received in 1 recv() call, x recv() calls or >x recv() calls.

sorry if seems messy, that's life tcp. if don't lock cannot go wrong, screw up, on else's installation, if seem work ok in testing.