/*
* WebServer.c
*
* Created on: Nov 3, 2012
* Author: pavithra
*
* A web server in C language using only the standard libraries.
* The port number is passed as an argument.
*
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <errno.h>
#define EOL "\r\n"
#define EOL_SIZE 2
typedef struct {
char *ext;
char *mediatype;
} extn;
//Possible media types
extn extensions[] ={
{"gif", "image/gif" },
{"txt", "text/plain" },
{"jpg", "image/jpg" },
{"jpeg","image/jpeg"},
{"png", "image/png" },
{"ico", "image/ico" },
{"zip", "image/zip" },
{"gz", "image/gz" },
{"tar", "image/tar" },
{"htm", "text/html" },
{"html","text/html" },
{"php", "text/html" },
{"pdf","application/pdf"},
{"zip","application/octet-stream"},
{"rar","application/octet-stream"},
{0,0} };
/*
A helper function
*/
void error(const char *msg) {
perror(msg);
exit(1);
}
/*
A helper function
*/
int get_file_size(int fd) {
struct stat stat_struct;
if (fstat(fd, &stat_struct) == -1)
return (1);
return (int) stat_struct.st_size;
}
/*
A helper function
*/
void send_new(int fd, char *msg) {
int len = strlen(msg);
if (send(fd, msg, len, 0) == -1) {
printf("Error in send\n");
}
}
/*
This function recieves the buffer
until an "End of line(EOL)" byte is recieved
*/
int recv_new(int fd, char *buffer) {
char *p = buffer; // Use of a pointer to the buffer rather than dealing with the buffer directly
int eol_matched = 0; // Use to check whether the recieved byte is matched with the buffer byte or not
while (recv(fd, p, 1, 0) != 0) // Start receiving 1 byte at a time
{
if (*p == EOL[eol_matched]) // if the byte matches with the first eol byte that is '\r'
{
++eol_matched;
if (eol_matched == EOL_SIZE) // if both the bytes matches with the EOL
{
*(p + 1 - EOL_SIZE) = '\0'; // End the string
return (strlen(buffer)); // Return the bytes recieved
}
} else {
eol_matched = 0;
}
p++; // Increment the pointer to receive next byte
}
return (0);
}
/*
A helper function: Returns the
web root location.
*/
char* webroot() {
// open the file "conf" for reading
FILE *in = fopen("conf", "rt");
// read the first line from the file
char buff[1000];
fgets(buff, 1000, in);
// close the stream
fclose(in);
char* nl_ptr = strrchr(buff, '\n');
if (nl_ptr != NULL)
*nl_ptr = '\0';
return strdup(buff);
}
/*
Handles php requests
*/
void php_cgi(char* script_path, int fd) {
send_new(fd, "HTTP/1.1 200 OK\n Server: Web Server in C\n Connection: close\n");
dup2(fd, STDOUT_FILENO);
char script[500];
strcpy(script, "SCRIPT_FILENAME=");
strcat(script, script_path);
putenv("GATEWAY_INTERFACE=CGI/1.1");
putenv(script);
putenv("QUERY_STRING=");
putenv("REQUEST_METHOD=GET");
putenv("REDIRECT_STATUS=true");
putenv("SERVER_PROTOCOL=HTTP/1.1");
putenv("REMOTE_HOST=127.0.0.1");
execl("/usr/bin/php-cgi", "php-cgi", NULL);
}
/*
This function parses the HTTP requests,
arrange resource locations,
check for supported media types,
serves files in a web root,
sends the HTTP error codes.
*/
int connection(int fd) {
char request[500], resource[500], *ptr;
int fd1, length;
if (recv_new(fd, request) == 0) {
printf("Recieve Failed\n");
}
printf("%s\n", request);
// Check for a valid browser request
ptr = strstr(request, " HTTP/");
if (ptr == NULL) {
printf("NOT HTTP !\n");
} else {
*ptr = 0;
ptr = NULL;
if (strncmp(request, "GET ", 4) == 0) {
ptr = request + 4;
}
if (ptr == NULL) {
printf("Unknown Request ! \n");
} else {
if (ptr[strlen(ptr) - 1] == '/') {
strcat(ptr, "index.html");
}
strcpy(resource, webroot());
strcat(resource, ptr);
char* s = strchr(ptr, '.');
int i;
for (i = 0; extensions[i].ext != NULL; i++) {
if (strcmp(s + 1, extensions[i].ext) == 0) {
fd1 = open(resource, O_RDONLY, 0);
printf("Opening \"%s\"\n", resource);
if (fd1 == -1) {
printf("404 File not found Error\n");
send_new(fd, "HTTP/1.1 404 Not Found\r\n");
send_new(fd, "Server : Web Server in C\r\n\r\n");
send_new(fd, "<html><head><title>404 Not Found</head></title>");
send_new(fd, "<body><p>404 Not Found: The requested resource could not be found!</p></body></html>");
//Handling php requests
} else if (strcmp(extensions[i].ext, "php") == 0) {
php_cgi(resource, fd);
sleep(1);
close(fd);
exit(1);
} else {
printf("200 OK, Content-Type: %s\n\n",
extensions[i].mediatype);
send_new(fd, "HTTP/1.1 200 OK\r\n");
send_new(fd, "Server : Web Server in C\r\n\r\n");
if (ptr == request + 4) // if it is a GET request
{
if ((length = get_file_size(fd1)) == -1)
printf("Error in getting size !\n");
size_t total_bytes_sent = 0;
ssize_t bytes_sent;
while (total_bytes_sent < length) {
//Zero copy optimization
if ((bytes_sent = sendfile(fd, fd1, 0,
length - total_bytes_sent)) <= 0) {
if (errno == EINTR || errno == EAGAIN) {
continue;
}
perror("sendfile");
return -1;
}
total_bytes_sent += bytes_sent;
}
}
}
break;
}
int size = sizeof(extensions) / sizeof(extensions[0]);
if (i == size - 2) {
printf("415 Unsupported Media Type\n");
send_new(fd, "HTTP/1.1 415 Unsupported Media Type\r\n");
send_new(fd, "Server : Web Server in C\r\n\r\n");
send_new(fd, "<html><head><title>415 Unsupported Media Type</head></title>");
send_new(fd, "<body><p>415 Unsupported Media Type!</p></body></html>");
}
}
close(fd);
}
}
shutdown(fd, SHUT_RDWR);
}
int main(int argc, char *argv[]) {
int sockfd, newsockfd, portno, pid;
socklen_t clilen;
struct sockaddr_in serv_addr, cli_addr;
if (argc < 2) {
fprintf(stderr, "ERROR, no port provided\n");
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
bzero((char *) &serv_addr, 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);
/*
Server runs forever, forking off a separate
process for each connection.
*/
while (1) {
newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
if (newsockfd < 0)
error("ERROR on accept");
pid = fork();
if (pid < 0)
error("ERROR on fork");
if (pid == 0) {
close(sockfd);
connection(newsockfd);
exit(0);
} else
close(newsockfd);
} /* end of while */
close(sockfd);
return 0; /* we never get here */
}
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