c - getting bad input from dirty buffer -

essentially have simulating tcp connection sockets , sending information between client , server between sockets. want use single buffer each file, unfortunately when writing, overwrites buffer getting bad/dirty string in line (b) buffer containing noexistshed, hed part, being remnant of established previous message written. @ first client prints connection status: established fine, later on, because of dirty buffer, printf in line (c), prints 1, since "noexistshed" , "noexist" different.

all buffers declared char buffer[1024];. user , pass defined char user[80] , char pass[80], (although seeking make these 2 single buffer).

this problematic section of client:

read(clientsocket, buffer, 1024);    /*---- print received message ----*/   printf("connection status: %s\n", buffer);       printf("please enter username:\n");   scanf ("%s", user);    write(clientsocket, user, strlen(user)+1);    read(clientsocket, buffer, 80); // error happens here -- (b)    printf("%s comparison result %d", buffer, strcmp(buffer, "noexists")); // --- (c)    if(strcmp(buffer, "noexists") == 0)   {   printf("user doesn't exist\n");     exit(1);   } 

this problematic section of server:

  strcpy(buffer,"established.");   write(sendersocket,buffer,13,0);    memset(buffer,0,sizeof(buffer)); // ---- (a)    read(sendersocket, buffer, 80, 0);    int x;   for(x=0; x < 7 && strcmp(ul[0][0], buffer) != 0; x++);    printf("%d", x);    if(x == 7)   {     strcpy(buffer,"noexists");   } else {     strcpy(buffer,"exists");   }    write(sendersocket, buffer, strlen(buffer), 0);    read(sendersocket, buffer, 80, 0);   

line (a) presume might solution problems have read in other questions/sites, not working. have tried replacing buffer[0] = '\0'; , buffer[n] = '\0'; (with n being assigned value of read/write) no luck. i've tried putting after/before writes , reads, there many permutations can done, don't think can solve on own. appreciate help.