A LinuxJunky Blog: A Very Simple HTTP Server writen in C

This is a part of the semester assignment. I felt like sharing it because I couldnt find any simple code like this on internet..

I have just edited the code to meet my requirements, originally it was made by my friend.. This code simply creates a web server with root in the current working directory and default port as 10000..

Can handle a maximum of 1000 clients.. fork() is used to handle each clients. Not a very efficient way if the number of clients increase but its a basic example to how you how to implement a simple HTTP Server.

/*
AUTHOR: Abhijeet Rastogi (http://www.google.com/profiles/abhijeet.1989)
This is a very simple HTTP server. Default port is 10000 and ROOT for the server is your current working directory..
You can provide command line arguments like:- $./a.aout -p [port] -r [path]
for ex.
$./a.out -p 50000 -r /home/
to start a server at port 50000 with root directory as "/home"
$./a.out -r /home/shadyabhi
starts the server at port 10000 with ROOT as /home/shadyabhi
*/#include<stdio.h>#include<string.h>#include<stdlib.h>#include<unistd.h>#include<sys/types.h>#include<sys/stat.h>#include<sys/socket.h>#include<arpa/inet.h>#include<netdb.h>#include<signal.h>#include<fcntl.h>#define CONNMAX 1000#define BYTES 1024char*ROOT;int listenfd, clients[CONNMAX];void error(char*);void startServer(char*);void respond(int);int main(int argc,char* argv[]){struct sockaddr_in clientaddr;socklen_t addrlen;char c;

 //Default Values PATH = ~/ and PORT=10000char PORT[6];
 ROOT = getenv("PWD");
 strcpy(PORT,"10000");int slot=0;//Parsing the command line argumentswhile((c = getopt (argc, argv,"p:r:"))!=-1)
  switch(c)
  {
   case'r':
    ROOT = malloc(strlen(optarg));
    strcpy(ROOT,optarg);
    break;
   case'p':
    strcpy(PORT,optarg);
    break;
   case'?':
    fprintf(stderr,"Wrong arguments given!!!\n");
    exit(1);
   default:
    exit(1);
  }

 printf("Server started at port no. %s%s%s with root directory as %s%s%s\n","\033[92m",PORT,"\033[0m","\033[92m",ROOT,"\033[0m");// Setting all elements to -1: signifies there is no client connectedint i;for(i=0; i<CONNMAX; i++)
  clients[i]=-1;
 startServer(PORT);// ACCEPT connectionswhile(1){
  addrlen =sizeof(clientaddr);
  clients[slot]= accept (listenfd,(struct sockaddr *)&clientaddr,&addrlen);
  if(clients[slot]<0)
   error ("accept() error");
  else
  {
   if( fork()==0)
   {
    respond(slot);
    exit(0);
   }
  }
  while(clients[slot]!=-1) slot =(slot+1)%CONNMAX;}return0;}//start servervoid startServer(char*port){struct addrinfo hints,*res,*p;// getaddrinfo for host
 memset (&hints,0,sizeof(hints));
 hints.ai_family = AF_INET;
 hints.ai_socktype = SOCK_STREAM;
 hints.ai_flags = AI_PASSIVE;if(getaddrinfo( NULL, port,&hints,&res)!=0){
  perror ("getaddrinfo() error");
  exit(1);}// socket and bindfor(p = res; p!=NULL; p=p->ai_next){
  listenfd = socket (p->ai_family, p->ai_socktype,0);
  if(listenfd ==-1)continue;
  if(bind(listenfd, p->ai_addr, p->ai_addrlen)==0)break;}if(p==NULL){
  perror ("socket() or bind()");
  exit(1);}
 freeaddrinfo(res);// listen for incoming connectionsif( listen (listenfd,1000000)!=0){
  perror("listen() error");
  exit(1);}}//client connectionvoid respond(int n){char mesg[99999],*reqline[3], data_to_send[BYTES], path[99999];int rcvd, fd, bytes_read;
 memset((void*)mesg,(int)'\0',99999);
 rcvd=recv(clients[n], mesg,99999,0);if(rcvd<0)// receive error
  fprintf(stderr,("recv() error\n"));elseif(rcvd==0)// receive socket closed
  fprintf(stderr,"Client disconnected upexpectedly.\n");else// message received{
  printf("%s", mesg);
  reqline[0]= strtok (mesg," \t\n");
  if( strncmp(reqline[0],"GET\0",4)==0)
  {
   reqline[1]= strtok (NULL," \t");
   reqline[2]= strtok (NULL," \t\n");
   if( strncmp( reqline[2],"HTTP/1.0",8)!=0&& strncmp( reqline[2],"HTTP/1.1",8)!=0)
   {
    write(clients[n],"HTTP/1.0 400 Bad Request\n",25);
   }
   else
   {
    if( strncmp(reqline[1],"/\0",2)==0)
     reqline[1]="/index.html";  //Because if no file is specified, index.html will be opened by default (like it happens in APACHE...
    strcpy(path, ROOT);
    strcpy(&path[strlen(ROOT)], reqline[1]);
    printf("file: %s\n", path);
    if((fd=open(path, O_RDONLY))!=-1)//FILE FOUND
    {
     send(clients[n],"HTTP/1.0 200 OK\n\n",17,0);
     while((bytes_read=read(fd, data_to_send, BYTES))>0)
      write (clients[n], data_to_send, bytes_read);
    }
    else write(clients[n],"HTTP/1.0 404 Not Found\n",23);//FILE NOT FOUND
   }
  }}//Closing SOCKET
 shutdown (clients[n], SHUT_RDWR);   //All further send and recieve operations are DISABLED...
 close(clients[n]);
 clients[n]=-1;}