Processes not terminating - c

Question

There are some strange things happening in my client-server application. Please, look at these simple fork client/server:
CLIENT:
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <arpa/inet.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/wait.h>
#define IP_SERVER "192.168.1.89"
#define PORT_SERVER 65000
#define BUFFERSIZE 1024
#define NUMFILES 3
double timeElapsed(struct timeval* before, struct timeval* after) {
return after->tv_sec - before->tv_sec + (double) (after->tv_usec - before->tv_usec)/1000000;
}
void getFile(char *request, struct sockaddr_in server) {
char buffer[1024];
int sockProc, res;
int file;
int sizeServ = sizeof(server);
int writeFile;
sockProc = socket(AF_INET, SOCK_STREAM, 0);
if (sockProc < 0) {
printf("Error on creating socket client\n");
perror("");
exit(1);
}
file = open(request, O_CREAT | O_WRONLY, S_IRWXU);
res = connect(sockProc, (struct sockaddr*)&server, (socklen_t)sizeServ);
if (res < 0) {
printf("Error on connecting to server!\n");
perror("");
exit(1);
}
res = send(sockProc, (void*)request, strlen(request), 0);
memset(buffer, 0, sizeof(buffer));
while((res = recv(sockProc, (void*)buffer, sizeof(buffer), 0)) > 0) {
write(file, (void*)buffer, strlen(buffer));
memset(buffer, 0, sizeof(buffer));
}
close(sockProc);
close(file);
return;
}
int main(int argc, char** argv) {
int sockCli, res, i;
struct sockaddr_in server;
int sizeServ = sizeof(server);
memset(&server, 0, sizeof(server));
server.sin_family = AF_INET;
inet_pton(AF_INET, IP_SERVER, &server.sin_addr);
server.sin_port = htons(PORT_SERVER);
char files[NUMFILES][32];
char nameFile[32];
char command[32] = "rm *.txt";
system(command);
struct timeval begin;
struct timeval end;
pid_t processes[NUMFILES];
for(i = 0; i<NUMFILES; i++) {
memset(nameFile, 0, sizeof(nameFile));
printf("Inserisci nome file (con estensione) da ricevere:\n");
scanf("%s", nameFile);
strcpy(files[i], nameFile);
}
gettimeofday(&begin, NULL);
for(i=0; i<NUMFILES; i++) {
pid_t child = fork();
if(child == 0) {
getFile(files[i], server);
exit(0);
}
else {
processes[i] = child;
continue;
}
}
/*for(i=0; i<NUMFILES; i++) {
waitpid(processes[i], NULL, 0);
}*/
wait(NULL);
gettimeofday(&end, NULL);
printf("Time elapsed on TCP is %f seconds\n", timeElapsed(&begin, &end));
return 0;
}
and the SERVER:
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <arpa/inet.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#define IP_SERVER "192.168.1.89"
#define PORT_SERVER 65000
#define BUFFERSIZE 1024
void execRequest(int* sockCli, struct sockaddr_in* client) {
char buffer[BUFFERSIZE];
char request[BUFFERSIZE];
int res;
memset(request, 0, sizeof(request));
res = recv(*sockCli, (void*)request, sizeof(request), 0);
if(res < 0) {
printf("Error on recv()\n");
perror("");
exit(1);
}
printf("Requested file %s\n", request);
char resource[32] = "files/";
strcat(resource, request);
int file = open(resource, O_RDONLY);
if (file < 0) {
printf("File %s does not exist\n", request);
exit(1);
}
memset(buffer, 0, sizeof(buffer));
while((res = read(file, (void*)buffer, sizeof(buffer))) > 0) {
send(*sockCli, (void*)buffer, strlen(buffer), 0);
memset(buffer, 0, sizeof(buffer));
}
close((*sockCli));
close(file);
free(sockCli);
free(client);
return;
}
int main(int argc, char** argv) {
int sockServ, i, res;
int *sockCli;
struct sockaddr_in server;
struct sockaddr_in* client;
sockServ = socket(AF_INET, SOCK_STREAM, 0);
if(sockServ < 0) {
printf("Error in creating socket\n");
perror("");
exit(1);
}
memset(&server, 0, sizeof(server));
server.sin_addr.s_addr = inet_addr(IP_SERVER);
server.sin_port = htons(PORT_SERVER);
server.sin_family = AF_INET;
int reuse = 1;
res = setsockopt(sockServ, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(int));
if (res < 0) {
printf("setsockopt() REUSEADDR failed\n");
perror("");
exit(1);
}
res = bind(sockServ, (struct sockaddr*)&server, sizeof(server));
if (res < 0) {
printf("Error on bindind TCP server!\n");
perror("");
exit(1);
}
res = listen(sockServ, 5);
if (res < 0) {
printf("Error on listening TCP server!\n");
perror("");
exit(1);
}
while(1) {
sockCli = (int*)malloc(sizeof(int));
client = (struct sockaddr_in*)malloc(sizeof(struct sockaddr_in));
int sizeClient = sizeof(struct sockaddr_in);
*sockCli = accept(sockServ, (struct sockaddr*)client, &sizeClient);
if ((*sockCli) < 0) {
printf("accept() failed\n");
perror("");
continue;
}
printf("Connected to %s:%d\n", inet_ntoa(client->sin_addr), client->sin_port);
if( !fork() ) {
execRequest(sockCli, client);
exit(0);
}
else
continue;
}
return 0;
}
This is very strange. The processes created by the client don't terminate even if the server closes the sockets and so recv() should return 0 and let client processes exit from the loop. Moreover there's something strange about reading files:
the server simply reads files.txt but in doing this it includes the string ".txt" in the read characters and sends all this mixture to the client...why?
they are simple file mono character like
aaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaa
but the server reads and and sends:
aaaaaaaaaaaaaaaaaa.txt
aaaaaaaaaaaaaaaaaa
can I solve all this?

Answer 1

You can't use strlen(buffer), just because you're loading characters from a text file doesn't mean that buffer will be a valid string unless you take steps to ensure it is. And you don't; there's no termination since you can fill all of buffer with data from the file.

Answer 2

How many times must we play the broken record here on Stack Overflow? Don't cast malloc!
I chalk this error to failure to read the manual(s), to find out what header to include, what a string is (and hence what strlen/strcat/str*{anything}* expects of its input, what printf expects of arguments that correspond to a %s format specifier, etc.) and what read/recv produces.
res = recv(*sockCli, (void*)request, sizeof(request), 0);
if(res < 0) {
printf("Error on recv()\n");
perror("");
exit(1);
}
printf("Requested file %.*s\n", res, request); // NOTE the field width provided by 'res'
By the manual, examples such as res = read(file, (void*)buffer, sizeof(buffer)) supposedly store either an error or a length. The condition ensures that the send code will only execute when it's a length value, so why not use it as one? send(*sockCli, (void*)buffer, res, 0);?
The presense of these problems seems to indicate that your method of learning isn't working. Which book are you reading? Learning C without a book is a bit like learning which berries are poisonous without communication.