Receiving a malloc error when running a simple client program - c

Question

I am trying to test a client program to make sure that it correctly sends and receives messages from a server. When I run the program I get this weird error from malloc. Any help would be great. I've been looking at this code for way too long. Thanks in advance.
Here is the error:
// The first test runs okay
TEST 1 :
Connected to server
-> Socket open success
-> Request sent success
-> Response received success
Testing print:
Response received: <replyLoadAvg>0.228027:0.250000:0.280273</replyLoadAvg>
LoadAvg for 1min :: 0.228027
LoadAvg for 5min :: 0.250000
LoadAvg for 15min :: 0.280273
Real response -> <replyLoadAvg>0.228027:0.250000:0.280273</replyLoadAvg>
// Then I get this error for some reason
clientc(17781) malloc: ********* error for object 0x7fd048404318: incorrect checksum for
freed object - object was probably modified after being freed.
********* set a breakpoint in malloc_error_break to debug
Abort trap: 6
here is the client code:
// prototype
char* verifyString(char*);
void printLoadAvg(char*);
int receiveResponse(int, char **);
int main(int argc, char *argv[])
{
int sockfd;
char *name;
char *port;
struct sockaddr_in * dest;
if(argc != 3)
{
printf("Not enough arguments -- Exiting program\n");
return 0;
}
name = argv[1];
port = argv[2];
char * received;
char send[256];
char testMessages[5][256] = {"<loadavg/>", "<echo>Hello World!</echo>", "<echo> </echo>", "", "<echo>Bye Bye World...<echo>"};
char expectedResponses[5][256] = {"", "<reply>Hello World!</reply>", "<reply></reply>","<error>unknown format</error>", "<error>unknown format</error>"};
int i;
srand(time(NULL));
for(i = 0; i < 5; i++)
{
printf("\nTEST %i", i+1);
printf(((rand() % 2) ? ":\n" : " :\n"));
sprintf(send, "%s", testMessages[i]);
sockfd = createSocket(name, atoi(port), &dest);
if(sockfd < 0){
printf(" xx Open socket failed\n");
}
else{
printf(" -> Socket open success\n");
if(sendRequest(sockfd, send, dest) < 0){
printf(" xx Send failed\n");
}
else{
printf(" -> Request sent success\n");
if(receiveResponse(sockfd, &received) < 0){
printf(" xx Receive failed\n");
}
else{
printf(" -> Response received success\n");
if(i!=0 && strcmp(received, expectedResponses[i]) != 0){
printf("Incorrect message\n");
printf("Expected: %s\n", expectedResponses[i]);
printf("Received: %s\n", received);
}
else if(i!=0){
printf("Test %i. passed successfully!\n", i+1);
}
else{
printf("Testing print:\n");
printResponse(received);
fprintf(stdout, "Real response -> %s\n", received);
}
}
}
}
free(received);
free(dest);
if(closeSocket(sockfd)==0){
printf(" -> Socket closed success\n");
}
else{
printf(" XX Close failed\n");
}
}
return 0;
}
int createSocket( char* hostname, int port, struct sockaddr_in** dest)
{
// fill in the socket address struct
(*dest) = (struct sockaddr_in *)malloc(sizeof(struct sockaddr_in));
struct hostent *hostptr;
hostptr = gethostbyname(hostname);
int socketfd;
memset((void *) (*dest), 0, (size_t)sizeof(struct sockaddr_in));
(*dest)->sin_family = (short)(AF_INET);
memcpy((void*)& (*dest)->sin_addr, (void *) hostptr->h_addr, hostptr->h_length);
(*dest)->sin_port = htons((u_short)port);
// now get the file descriptor for the socket
if((socketfd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
return -1;
}
// connect to the server at the location displayed by TCPserver.c
if(connect(socketfd, (struct sockaddr*)(*dest), sizeof(struct sockaddr)) < 0) {
perror("Error: call to connect()\n");
return -1;
}
printf("Connected to server\n");
return socketfd;
}
int sendRequest(int sock, char* request, struct sockaddr_in* dest)
{
// send a request through the socket to the server.
if(write(sock, request, BUFFERSIZE) < 0)
{
return -1;
}
return 0;
}
int receiveResponse(int sock, char ** response)
{
// dynamically allocate memory to be used in this function
(*response) = malloc(sizeof(char));
// wait for a response from the server
if(read(sock, (*response), BUFFERSIZE) < 0)
{
return -1;
}
return 0;
}
int closeSocket(int sock)
{
int error = 0;
if(close(sock))
{
perror("Error: Failed to close socket\n");
error = -1;
}
return error;
}
void printResponse(char* response)
{
char* buffer = "<replyloadavg>";
int i, isLoadAvg = 0;
// verify the string is in the correct format by calling the verifty string function
// then print the string to the screen.
printf("Response received: %s\n", verifyString(response));
for(i = 0; i < 14; i++)
{
if(response[i] == buffer[i])
isLoadAvg = 0;
else
{
isLoadAvg = 1;
i = 15;
}
}
if (isLoadAvg)
{
printLoadAvg(response);
}
}
char* verifyString(char* string)
{
int i, count = 0;
// step through the array until you come to the last '>' (the end of the string)
// then insert the NULL terminator at the end of the string.
for(i = 0; i < BUFFERSIZE; i++)
{
if(string[i] == '>')
count++;
if(count == 2)
{
string[i + 1] = '\0';
i = BUFFERSIZE;
}
}
return string;
}
void printLoadAvg(char* string)
{
int i = 0, j;
// these three arrays hold the newly formated strings, the ones that are easier to read.
char s1[BUFFERSIZE], s2[BUFFERSIZE], s3[BUFFERSIZE];
// step through the string until you reach the end of the string
while(string[i] != '>')
{
i++;
}
i++;
// now insert a colon and then save the contents of the string to the appropriate s array.
for(j = 0; string[i] != ':'; j++, i++)
{
s1[j] = string[i];
}
// be sure to set the null terminator at the end.
s1[j] = '\0';
i++;
for(j = 0; string[i] != ':'; j++, i++)
{
s2[j] = string[i];
}
// be sure to set the null terminator at the end.
s2[j] = '\0';
i++;
// now move to the beginning of the end of the string array
for(j = 0; string[i] != '<'; j++, i++)
{
s3[j] = string[i];
}
// now insert one more null terminator for the final s array.
s3[j] = '\0';
// now print out the newly fomrated strings.
printf("\nLoadAvg for 1min :: %s\n", s1);
printf("LoadAvg for 5min :: %s\n", s2);
printf("LoadAvg for 15min :: %s\n", s3);
}

Answer 1

(*response) = malloc(sizeof(char));
// wait for a response from the server
if(read(sock, (*response), BUFFERSIZE) < 0)
What size is BUFFERSIZE. Is it bigger than 1? If so, you will overflow your buffer...