micro_httpd.c

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <ctype.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>

#define SERVER_NAME "micro_httpd"
#define SERVER_URL "https://github.com/gasp/micro_httpd"
#define PROTOCOL "HTTP/1.0"
#define RFC1123FMT "%a, %d %b %Y %H:%M:%S GMT"

// Forwards
static void file_details(char* dir, char* name);
static void send_error(int status, char* title, char* extra_header, char* text);
static void send_headers(int status, char* title, char* extra_header, char* mime_type, off_t length, time_t mod);
static char* get_mime_type(char* name);
static void strdecode(char* to, char* from);
static int hexit(char c);
static void strencode(char* to, size_t tosize, const char* from);

int
main(int argc, char** argv) {
  char line[10000], method[10000], path[10000], protocol[10000], idx[20000], location[20000];
  char* file;
  size_t len;
  int ich;
  struct stat sb;
  FILE* fp;
  struct dirent **dl;
  int i, n;

  if (argc != 2)
    send_error(500, "Internal Error", (char*) 0, "Config error - no dir specified.");
  if (chdir(argv[1]) < 0)
    send_error(500, "Internal Error", (char*) 0, "Config error - couldn't chdir().");
  if (fgets(line, sizeof(line), stdin) == (char*) 0)
    send_error(400, "Bad Request", (char*) 0, "No request found.");
  if (sscanf(line, "%[^ ] %[^ ] %[^ ]", method, path, protocol) != 3)
    send_error(400, "Bad Request", (char*) 0, "Can't parse request.");
  while (fgets(line, sizeof(line), stdin) != (char*) 0) {
    if (strcmp(line, "\n") == 0 || strcmp(line, "\r\n") == 0)
      break;
  }
  if (strcasecmp(method, "get") != 0)
    send_error(501, "Not Implemented", (char*) 0, "That method is not implemented.");
  if (path[0] != '/')
    send_error(400, "Bad Request", (char*) 0, "Bad filename.");
  file = &(path[1]);
  strdecode(file, file);
  if (file[0] == '\0')
    file = "./";
    len = strlen(file);
  if (file[0] == '/' || strcmp(file, "..") == 0 || strncmp(file, "../", 3) == 0 || strstr(file, "/../") != (char*) 0 || strcmp(&(file[len-3]), "/..") == 0)
    send_error(400, "Bad Request", (char*) 0, "Illegal filename.");
  if (stat(file, &sb) < 0)
    send_error(404, "Not Found", (char*) 0, "File not found.");
  if (S_ISDIR(sb.st_mode)) {
  if (file[len-1] != '/') {
    (void) snprintf(location, sizeof(location), "Location: %s/", path);
    send_error(302, "Found", location, "Directories must end with a slash.");
  }
  (void) snprintf(idx, sizeof(idx), "%sindex.html", file);
  if (stat(idx, &sb) >= 0) {
    file = idx;
    goto do_file;
  }
  send_headers(200, "Ok", (char*) 0, "text/html", -1, sb.st_mtime);
  (void) printf("\
<!DOCTYPE html>\n\
<html>\n\
  <head>\n\
    <meta charset=\"utf-8\">\n\
    <title>Index of %s</title>\n\
  </head>\n\
  <body bgcolor=\"#ecffec\">\n\
    <h4>Index of %s</h4>\n\
    <pre>\n", file, file);
    n = scandir(file, &dl, NULL, alphasort);
    if (n < 0)
      perror("scandir");
    else
      for (i = 0; i < n; ++i)
        file_details(file, dl[i]->d_name);
    (void) printf("\
    </pre>\n\
    <hr>\n\
    <address><a href=\"%s\">%s</a></address>\n\
  </body>\n\
</html>\n", SERVER_URL, SERVER_NAME);
  } else {
    do_file:
    fp = fopen(file, "r");
    if (fp == (FILE*) 0)
      send_error(403, "Forbidden", (char*) 0, "File is protected.");
    send_headers(200, "Ok", (char*) 0, get_mime_type(file), sb.st_size, sb.st_mtime);
    while ((ich = getc(fp)) != EOF)
      putchar(ich);
  }

  (void) fflush(stdout);
  exit(0);
}

static void
file_details(char* dir, char* name) {
  static char encoded_name[1000];
  static char path[2000];
  struct stat sb;
  char timestr[16];

  strencode(encoded_name, sizeof(encoded_name), name);
  (void) snprintf(path, sizeof(path), "%s/%s", dir, name);
  if (lstat(path, &sb) < 0)
    (void) printf("<a href=\"%s\">%-32.32s</a>    ???\n", encoded_name, name);
  else {
    (void) strftime(timestr, sizeof(timestr), "%Y-%m-%d %H:%m", localtime(&sb.st_mtime));
    (void) printf("<a href=\"%s\">%-32.32s</a>    %15s %14lld\n", encoded_name, name, timestr, (long long) sb.st_size);
  }
}

static void
send_error(int status, char* title, char* extra_header, char* text) {
  send_headers(status, title, extra_header, "text/html", -1, -1);
  (void) printf("\
<!DOCTYPE html>\n\
<html>\n\
  <head>\n\
    <meta charset=\"utf-8\">\n\
    <title>%d %s</title>\n\
  </head>\n\
  <body bgcolor=\"#cc9999\">\n\
    <h1>%d %s</h1>\n", status, title, status, title);
    (void) printf("%s\n", text);
    (void) printf("\
    <hr>\n\
    <address><a href=\"%s\">%s</a></address>\n\
  </body>\n\
</html>\n", SERVER_URL, SERVER_NAME);
  (void) fflush(stdout);
  exit(1);
}

static void
send_headers(int status, char* title, char* extra_header, char* mime_type, off_t length, time_t mod) {
  time_t now;
  char timebuf[100];

  (void) printf("%s %d %s\015\012", PROTOCOL, status, title);
  (void) printf("Server: %s\015\012", SERVER_NAME);
  now = time((time_t*) 0);
  (void) strftime(timebuf, sizeof(timebuf), RFC1123FMT, gmtime(&now));
  (void) printf("Date: %s\015\012", timebuf);
  if (extra_header != (char*) 0)
    (void) printf("%s\015\012", extra_header);
  if (mime_type != (char*) 0)
    (void) printf("Content-Type: %s\015\012", mime_type);
  if (length >= 0)
    (void) printf("Content-Length: %lld\015\012", (long long) length);
  if (mod != (time_t) -1) {
    (void) strftime(timebuf, sizeof(timebuf), RFC1123FMT, gmtime(&mod));
    (void) printf("Last-Modified: %s\015\012", timebuf);
  }
  (void) printf("Connection: close\015\012");
  (void) printf("\015\012");
}

static char*
get_mime_type(char* name) {
  char* dot;
  dot = strrchr(name, '.');
  if (dot == (char*) 0) return "text/plain; charset=UTF-8";
  if (strcmp(dot, ".html") == 0 || strcmp(dot, ".htm") == 0)
    return "text/html; charset=UTF-8";
  if (strcmp(dot, ".jpg") == 0 || strcmp(dot, ".jpeg") == 0)
    return "image/jpeg";
  if (strcmp(dot, ".gif") == 0)
    return "image/gif";
  if (strcmp(dot, ".png") == 0)
    return "image/png";
  if (strcmp(dot, ".css") == 0)
    return "text/css";
  if (strcmp(dot, ".wav") == 0)
    return "audio/wav";
  if (strcmp(dot, ".avi") == 0)
    return "video/x-msvideo";
  if (strcmp(dot, ".mov") == 0 || strcmp(dot, ".qt") == 0)
    return "video/quicktime";
  if (strcmp(dot, ".mpeg") == 0 || strcmp(dot, ".mpe") == 0 || strcmp (dot, ".mpg") == 0)
    return "video/mpeg";
  if (strcmp(dot, ".mkv") == 0)
    return "video/mkv";
  if (strcmp(dot, ".mp3") == 0)
    return "audio/mpeg";
  if (strcmp(dot, ".ogg") == 0)
    return "application/ogg";
  return "text/plain; charset=UTF-8";
}

static void
strdecode(char* to, char* from) {
  for (; *from != '\0'; ++to, ++from) {
    if (from[0] == '%' && isxdigit(from[1]) && isxdigit(from[2])) {
      *to = hexit(from[1]) * 16 + hexit(from[2]);
      from += 2;
    }
    else *to = *from;
  }
  *to = '\0';
}

static int
hexit(char c) {
  if (c >= '0' && c <= '9')
    return c - '0';
  if (c >= 'a' && c <= 'f')
    return c - 'a' + 10;
  if (c >= 'A' && c <= 'F')
    return c - 'A' + 10;
  return 0;        /* shouldn't happen, we're guarded by isxdigit() */
}

static void
strencode(char* to, size_t tosize, const char* from) {
  int tolen;

  for (tolen = 0; *from != '\0' && tolen + 4 < tosize; ++from) {
    if (isalnum(*from) || strchr("/_.-~", *from) != (char*) 0) {
      *to = *from;
      ++to;
      ++tolen;
    } else {
      (void) sprintf(to, "%%%02x", (int) *from & 0xff);
      to += 3;
      tolen += 3;
    }
  }
  *to = '\0';
}