Server instantly skips pin search - c

Question

I am trying to create two programs that send messages to each other using sockets following the server-client model.
The client is supposed to put a pin (in this case "1234") but the server for some reason skips the function search4pin(). I tried using atoi() to read the variable buffer and storing it to pin but it changed nothing. Using gdb I saw that the variable does not take a value. Thanks for your time.
Server:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#define MAX_PINS 1
void error(const char *msg){
perror(msg);
exit(1);
}
int search4pin(int pin,int pins[]){
for(int i=0;i<MAX_PINS;i++){
if(pin==pins[i])
return 0;
}
return 1;
}
int main(int argc, char *argv[]){
int sockfd, newsockfd, portno, pid;
socklen_t clilen;
char buffer[256];
char* comm[20],*cbuff;
struct sockaddr_in serv_addr, cli_addr;
int n,i,done=0,pin,correct=0,pins[MAX_PINS]={1234};
char str[INET_ADDRSTRLEN];
char* args;
if (argc < 2)
{
fprintf(stderr, "No port provided\n");
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
memset((char *) &serv_addr, 0, sizeof(serv_addr));
portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
if (bind(sockfd,(struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
error("ERROR on binding");
listen(sockfd, 5);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
if (newsockfd < 0)
error("ERROR on accept");
if (inet_ntop(AF_INET, &cli_addr.sin_addr, str, INET_ADDRSTRLEN) == NULL) {
fprintf(stderr, "Could not convert byte to address\n");
exit(1);
}
fprintf(stdout, "The client address is :%s\n", str);
bzero(buffer,256);
n = read(newsockfd,buffer,255);
if (n < 0) error("ERROR reading from socket");
sscanf(buffer,"%d",&pin);
while(!search4pin(pin,pins)){
n = write(newsockfd, "Wrong pin!\n", 12);
if (n < 0) error("ERROR writing to socket");
}
/*Some other
code*/
close(newsockfd);
close(sockfd);
return 0;
}
Client:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
void error(const char *msg){
perror(msg);
exit(0);
}
int main(int argc, char *argv[]){
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[256];
if (argc < 3){
fprintf(stderr, "usage %s hostname port\n", argv[0]);
exit(0);
}
portno = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
server = gethostbyname(argv[1]);
if (server == NULL){
fprintf(stderr, "ERROR, no such host\n");
exit(0);
}
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,server->h_length);
serv_addr.sin_port = htons(portno);
if (connect(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
printf("What is the password?\n");
n = write(sockfd, stdin, sizeof(int));
if (n < 0)
error("ERROR writing to socket");
return 0;
}