#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <sys/timeb.h>
#include <unistd.h>
#include <signal.h>

long int thout = 0;
int setTime = 0;
int requestNum = 0;

void overRun_handler(int signo)
{
if(signo == SIGALRM)
{
printf("\n<<--Response %d terminate by order-->>n",requestNum);
printf(">>%ld bytes has been transmitted\n>>",thout);
exit(1);
}
else printf("Catch a wrong signal.\n");

void proxyProcess(int,int,int);

int main(int argc,char **argv)
{
if(signal(SIGALRM,overRun_handler)==SIG_ERR)
{
perror("Can't regist signal handler");
exit(1);
}
if(argc!=3)
{
printf("Arguments are needed: %s <port number><connection time>\n",argv[0]);
exit(0);
}
if(atoi(argv[1])<=0)
{
printf("Invalid port number.\n");
exit(0);
}
if(atoi(argv[2])<0)
{
printf("Invalid connection time.\nNo time set.\n");
}
else setTime = atoi(argv[2]);

struct sockaddr_in sin;
struct sockaddr_in cin;
short port = atoi(argv[1]);
int sd, csd, mode;
int len = sizeof(sin);
int fd =open("static.txt", O_WRONLY|O_CREAT|O_TRUNC);

if(fd < 0)
{
perror("Fail to initial static file.");
exit(1);
}
else
{
write(fd, "0",1);
close(fd);
}

if(port>8000) mode=1;
else mode =0;

memset(&sin,0, sizeof(sin));
memset(&cin,0, sizeof(cin));
sin.sin_family =AF_INET;
sin.sin_addr.s_addr =INADDR_ANY;
sin.sin_port =htons(port);

sd = socket(AF_INET,SOCK_STREAM,0);
if(sd<0)
{
perror("Fail to socket(sd)");
exit(1);
}
if((bind(sd, (struct sockaddr *)(&sin), sizeof(sin)))<0)
{
perror("Fail to bind");
exit(1);
}
if((bind(sd, (struct sockaddr *)(&sin), sizeof(sin)))<0)
{
perror("Fail to bind");
exit(1);
}
if ((listen(sd, 10))<0)
{
perror("Fail to listen");
exit(1);
}
while(1)
{
csd = accept(sd, (struct sockaddr *)(&cin), &len);
requestNum++;
if ((fork() == 0) && (csd>0))
{
if((close(sd))<0)
{
perror("Fail to close (sd)");
}
printf("\n<--Begin of %d -->\n", requestNum);
printf("--%d-->Client IP:%s\n--%d-->Port: %d\n", requestNum, 
inet_ntoa(cin.sin_addr), requestNum, ntohs(cin.sin_port));
proxyProcess(csd,requestNum, mode);
if((close(csd))<0)
{
perror("Fail to close (csd)");
}
exit(0);
}
else if(csd < 0)
{
perror("Fail to accept");
exit(0);
}
else close(csd);
}
close(sd);
return 0;
}

void proxyProcess(int csd, int requestNum, int mode)
{
struct sockaddr_in web;
char * request, *begin, *end, *c, *ip;
char url1[512];
char url2[512];
char buf[2048];
int n, i, wsd;
int iport = 80;
int count = 0;
struct timeb time1, time2;

memset(buf, 0, sizeof(buf));
memset(url1, 0, sizeof(url1));
memset(url2, 0, sizeof(url2));

n = read (csd, buf, 2048);

if((strstr(buf,"Proxy-Authorization: Basic U2NodW1hY2hlcjpkYXZpZDg40TI5"))==0)
{
printf("There is no authorization\n");
char *msg = "HTTP/1.1 407 Proxy Authentication Required\r\nContent-Type: text/html\r\nProxy-Authenticate: Basic realm=\n";
write(csd, msg, strlen(msg));
close(csd);
exit(0);
}

begin = strstr(buf, "Accept Encoding: ");
if(begin!=NULL)
{
end = strstr(begin, "\r\n");
end +=2;
request = calloc(sizeof(char), strlen(buf)-(end-begin));
memcopy(request, buf, begin-buf);
strcat(request, end);
}

c = strstr(buf, "Host:\n ");
for (c+=5, i=0; *c!='\r'; c++, i++)
{
if(*c == ':')
{
c++;
int j = 0;
char port[5];
memset(port, 0, sizeof(port));
for(j = 0; *c!= ' '; c++, j++)
{
port[j] = *c;

if(j>5)
break;
}
iport = atoi(port);
break;
}
else
url1[i] = *c;
}

printf("--%d-->To:%s(port:%d)\n", requestNum, url1, iport);

FILE * fp = fopen("list.txt", "r");
while(feof(fp) == 0)
{
fgets(url2, 512, fp);
url2[strlen(url2)-1] = '\0';

if(strcmp(url2, url1) == 0)
{
printf("\n<--!Websites in blacklist!-->\n");
memset(url1, 0, sizeof(url1));
i = open("html.html", O_RDONLY);
while(1)
{
n = read(i, url1, 512);
write(csd, url1, 512);
memset(url1, 0, sizeof(url1));

if(n!=512)
break;
}
close(i);
printf("\n<--End of Process %d-->\n", requestNum);
break;
exit(0);
}
else
memset(url2, 0, sizeof(url2));
}
fclose(fp);

struct hostent * host;
host = gethostbyname(url1);
ip = inet_ntoa(*((struct in_addr *)host -> h_addr));
printf("--%d-->To:%s\n", requestNum, ip);
web.sin_family = AF_INET;
web.sin_port = htons(iport);
web.sin_addr.s_addr = inet_addr(ip);
if((wsd = socket(PF_INET, SOCK_STREAM, 0))<0)
{
perror("Fail to connect (wsd)");
exit(1);
}
printf("\n<--Request %d-->\n%s\n", requestNum, request);
write(wsd, request, strlen(request));
free(request);
memset(buf, 0, sizeof(buf));
count = 0;
ftime(&time1);
while((n = read(wsd, buf, 2048))>0)
{
char * response = calloc(sizeof(char), n);

if(count == 0)
{
ftime(&time2);
printf("<<Response time of request %d --<%lmds\n", requestNum,(time2.time-time1.time)*1000+(time2.millitm-time1.millitm));
if(setTime != 0)
alarm(setTime);
count ++;
}
if(strstr(buf, "<html>") !=0)
printf("A website has been opened\n");

fp = fopen("static.txt","r");
fscanf(fp, "%ld", &thout);
fclose(fp);
thout +=n;
fp = fopen("static.txt", "w");
fprintf(fp, "%ld", thout);
fclose(fp);

if(mode == 1)
{
if((begin = strstr(buf, "<titlt>"))|| (begin=
strstr(buf, "<title>")))
{
char warn[] = "Proxy:";
begin +=7;
if((c = strstr(buf, "Content-Length"))!=0)
{
char * str = strstr(c, "\r\n");
str +=2;
memcpy(response, buf, c-buf);
strncat(response, str, begin - str);
}
else
memcpy(response, buf, begin-buf);

strncat(response, warn, strlen(warn));
strncat(response, begin, strlen(begin));
write(csd, response, strlen(response));
}
else
write(csd, buf, n);
}
else write(csd, buf, n);

if((c = strstr(buf, "\r\n\r\n"))&&(count == 1))
{
count++;
printf("\n<--Response %d-->\n", requestNum);
for(i=0; i<=c-buf; i++)
printf("%c", buf[1]);
printf("\n");
}
memset(buf, 0, sizeof(buf));
}
printf(">>%ld Bytes have been transmitted.\n", thout);
printf("\n<--End of Process %d-->\n", requestNum);
}

jocelyn@jocelyn-VirtualBox:~$ gcc -Wall -o proxy proxy.c
proxy.c: In function ‘overRun_handler’:
proxy.c:28:5: warning: ‘main’ is normally a non-static function [-Wmain]
proxy.c: In function ‘main’:
proxy.c:101:28: warning: pointer targets in passing argument 3 of ‘accept’ differ in signedness [-Wpointer-sign]
/usr/include/i386-linux-gnu/sys/socket.h:214:12: note: expected ‘socklen_t * __restrict__’ but argument is of type ‘int *’
proxy.c: In function ‘overRun_handler’:
proxy.c:130:6: error: static declaration of ‘proxyProcess’ follows non-static declaration
proxy.c:26:6: note: previous declaration of ‘proxyProcess’ was here
proxy.c: In function ‘proxyProcess’:
proxy.c:163:2: warning: implicit declaration of function ‘memcopy’ [-Wimplicit-function-declaration]
proxy.c:247:2: warning: use of ‘l’ length modifier with ‘m’ type character [-Wformat]
proxy.c:132:21: warning: variable ‘web’ set but not used [-Wunused-but-set-variable]
proxy.c: In function ‘overRun_handler’:
proxy.c:301:1: error: expected declaration or statement at end of input

void proxyProcess(int,int,int);

void proxyProcess(int csd, int requestNum, int mode)