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#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <sys/stat.h>
#include <openssl/sha.h>
#include "talk.h"
#include "util.h"
#define PORT 231
#define USERSDIR "./users/"
#define PASSWORDFILE "./passwd"
static int initsocket(struct sockaddr_in address, socklen_t len){
int s;
if ((s = socket(AF_INET, SOCK_STREAM, 0)) == -1){
perror("socket");
return -1;
}
if ((bind(s, (struct sockaddr *)&address, len)) != 0) {
perror("bind");
return -1;
}
listen(s, 10);
return s;
}
static bool checkpasswd(char *username, char *password) {
char *passwdline, *tok;
unsigned char hash[SHA_DIGEST_LENGTH];
FILE *f = fopen(PASSWORDFILE, "r");
while ((passwdline = readupto(f, ':')) != NULL){
tok = readnchars(f, 20);
if (strcmp(passwdline, username) == 0){
SHA1((unsigned char *)password, 30, hash);
if (memcmp((char *)hash, tok, 20) == 0){
free(tok);
free(passwdline);
return true;
} else {
free(tok);
free(passwdline);
return false;
}
}
free(tok);
free(passwdline);
}
return false;
}
int main(){
struct sockaddr_in address;
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons(PORT);
socklen_t len = sizeof(address);
int s;
if ((s = initsocket(address, len)) < 0) return s;
int client;
for (;;) {
if ((client = accept(s, (struct sockaddr *)&address, &len)) == -1){
perror("accept");
return 1;
}
int size = sizeof(packet);
packet *buf = malloc(size);
recv(client, buf, size, 0);
char *userdir, *tok, *passwdline, *msg;
unsigned char hash1[SHA_DIGEST_LENGTH], hash2[SHA_DIGEST_LENGTH];
FILE *f, *fmsg;
int len;
switch (buf->type){
case MSG:
buf->msg = calloc(1, buf->msglen);
recv(client, buf->msg, buf->msglen, 0);
if (checkpasswd(buf->username, buf->password) == true){
if (buf->msg == NULL || strlen(buf->msg) == 0) {
buf->msg = "(null)";
goto end;
}
userdir = malloc(80);
snprintf(userdir, 80, "%s%s/%s", USERSDIR, buf->recipient, buf->username);
fmsg = fopen(userdir, "a+");
if (fmsg == NULL) goto nosuchuser;
fprintf(fmsg, "%s\n", buf->msg);
fclose(fmsg);
free(userdir);
goto end;
} else {
buf->type = PASSAUTHFAIL;
goto end;
}
nosuchuser:
buf->type = NOSUCHUSER;
end:
send(client, buf, size, 0);
break;
case GET:
if (checkpasswd(buf->username, buf->password) == true){
len = 128;
userdir = calloc(1, len);
snprintf(userdir, len, "%s%s/%s", USERSDIR, buf->username, buf->recipient);
f = fopen(userdir, "r");
if (f == NULL) {
buf->type = NEVERMSGED;
send(client, buf, size, 0);
break;
}
msg = readupto(f, EOF);
buf->msg = msg;
buf->msglen = strlen(msg);
send(client, buf, size, 0);
send(client, buf->msg, buf->msglen, 0);
remove(userdir);
free(userdir);
userdir = NULL;
} else {
buf->type = PASSAUTHFAIL;
}
send(client, buf, size, 0);
break;
case NEWUSER:
userdir = calloc(1, strlen(USERSDIR) + strlen(buf->username));
strcat(userdir, USERSDIR);
strcat(userdir, buf->username);
if (mkdir(userdir, 0777) == -1) {
buf->type = USERMAKEERROR;
} else {
buf->type = NEWUSER;
SHA1((unsigned char *)buf->password, 30, hash1);
f = fopen(PASSWORDFILE, "a+");
if (f == NULL) exit(1);
fprintf(f, "%s:%s\n", buf->username, hash1);
fclose(f);
free(userdir);
userdir = NULL;
}
send(client, buf, size, 0);
break;
default:
buf->type = UNKNOWNCMD;
send(client, buf, size, 0);
break;
}
free(buf->msg);
free(buf);
close(client);
}
close(s);
return 0;
}
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