Large File transfer error in Socket in C -

i m building code transferring file server.c client.c program . during run time not working . m sending file in chunks of 512 bytes . source file 784 kb has 88000 names in it.

this program works correctly on 127.0.0.1 not working when connect 2 computers on lan/wifi .

i m not including complete file function m going transfer/recieve file

help me find error in code.

if u test between 2 computers .

if u guys have better code file sending , recieving please post ,see need control out of function after transfer done . appreciate .

i m using linux following purpose & gcc compiltion

server.c function

void filesender(char fs_name[],int ncfd) { char sdbuf[length]; file *fs=fopen(fs_name,"r"); if(fs==null) {     perror("\n[server] file not found on server directory");     exit(1); }  bzero(sdbuf, length);  int fs_block_sz;   while((fs_block_sz = fread(sdbuf, sizeof(char), length, fs))>0) {     if(send(ncfd, sdbuf, fs_block_sz, 0) < 0)     {         puts("\n[server] error: sending file failed");         exit(1);     }     bzero(sdbuf, length); } puts("\n[server] file sended successfull"); } 

client.c

void filereciever(int id,int ncfd) { char revbuf[length]; //buffer variable hold recieved data char *fr_name; char fid=id; asprintf(&fr_name,"result%c.txt",fid);  file *fr = fopen(fr_name, "a"); if(fr == null) {     printf("[server] file %s cannot opened.\n", fr_name); } else {     bzero(revbuf, length);      int fr_block_sz = 0;     while((fr_block_sz = recv(ncfd, revbuf, length, 0)) > 0)     {         int write_sz = fwrite(revbuf, sizeof(char), fr_block_sz, fr);         if(write_sz < fr_block_sz)         {             puts("\n[server] file write failed");         }         bzero(revbuf, length);         if (fr_block_sz == 0 || fr_block_sz != 512)          {             break;         }     }     if(fr_block_sz < 0)     {         if (errno == eagain)         {             puts("\n[server] error: recv() timed out");         }         else         {             printf("\n[server] error: recv() failed due errno = %d", errno);         }     }     printf("[server] file received server!\n");     fclose(fr); }} 

you should check result of send()

for tcp socket, send() put data os's internal queue, may sometime fill part of requested size. supposed handle such incomplete send , retry later.

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edit: op disclosed more information in comments, seems problem not (yet) related network, seems there bug choosing file send, , need post relevant code further diagnose.