A Very Simple HTTP Server writen in C

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This is a part of the semester assignment. I felt like sharing it because I couldnt find any simple code like this on internet. This is in no way a complete web server and is just a simple one day hack to build something that can talk to a web browser.

  • 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 client. I know it's not a very efficient way of doing it but this code is just to demonstrate a very simple use-case and it's okay to be sloppy and miss details.

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



#define CONNMAX 1000
#define BYTES 1024

char *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=10000
	char PORT[6];
	ROOT = getenv("PWD");

	int slot=0;

	//Parsing the command line arguments
	while ((c = getopt (argc, argv, "p:r:")) != -1)
		switch (c)
			case 'r':
				ROOT = malloc(strlen(optarg));
			case 'p':
			case '?':
				fprintf(stderr,"Wrong arguments given!!!\n");
	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 connected
	int i;
	for (i=0; i<CONNMAX; i++)

	// ACCEPT connections
	while (1)
		addrlen = sizeof(clientaddr);
		clients[slot] = accept (listenfd, (struct sockaddr *) &clientaddr, &addrlen);

		if (clients[slot]<0)
			error ("accept() error");
			if ( fork()==0 )

		while (clients[slot]!=-1) slot = (slot+1)%CONNMAX;

	return 0;

//start server
void 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");
	// socket and bind
	for (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()");


	// listen for incoming connections
	if ( listen (listenfd, 1000000) != 0 )
		perror("listen() error");

//client connection
void 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"));
	else if (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);
				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...