A new C-based register.cgi

src/Makefile

@@ -1,3 +1,6 @@
-all: in.tokend
+all: in.tokend register.cgi
+
+in.tokend: in.tokend.o xxtea.o
+
+register.cgi: register.cgi.o cgi.o
 
-in.tokend: in.tokend.c xxtea.c

src/cgi.c

@@ -0,0 +1,90 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include "cgi.h"
+
+static size_t inlen = 0;
+
+int
+cgi_init()
+{
+  char *rm = getenv("REQUEST_METHOD");
+
+  if (! (rm && (0 == strcmp(rm, "POST")))) {
+    printf("405 Method not allowed\n"
+           "Allow: POST\n"
+           "Content-type: text/html\n"
+           "\n"
+           "<h1>Method not allowed</h1>\n"
+           "<p>I only speak POST.  Sorry.</p>\n");
+    return -1;
+  }
+
+  inlen = atoi(getenv("CONTENT_LENGTH"));
+
+  return 0;
+}
+
+static int
+read_char()
+{
+  if (inlen) {
+    inlen -= 1;
+    return getchar();
+  }
+  return EOF;
+}
+
+static char
+tonum(int c)
+{
+  if ((c >= '0') && (c <= '9')) {
+    return c - '0';
+  }
+  if ((c >= 'a') && (c <= 'f')) {
+    return 10 + c - 'a';
+  }
+  if ((c >= 'A') && (c <= 'F')) {
+    return 10 + c - 'A';
+  }
+  return 0;
+}
+
+static char
+read_hex()
+{
+  int a = read_char();
+  int b = read_char();
+
+  return tonum(a)*16 + tonum(b);
+}
+
+/* Read a key or a value.  Since & and = aren't supposed to appear
+   outside of boundaries, we can use the same function for both.
+*/
+size_t
+read_item(char *str, size_t maxlen)
+{
+  int    c;
+  size_t pos = 0;
+
+  while (1) {
+    c = read_char();
+    switch (c) {
+      case EOF:
+      case '=':
+      case '&':
+        str[pos] = '\0';
+        return pos;
+      case '%':
+        c = read_hex();
+        break;
+      case '+':
+        c = ' ';
+        break;
+    }
+    if (pos < maxlen - 1) {
+      str[pos] = c;
+      pos += 1;
+    }
+  }
+}

src/cgi.h

@@ -0,0 +1,9 @@
+#ifndef __CGI_H__
+#define __CGI_H__
+
+#include <stddef.h>
+
+int cgi_init();
+size_t read_item(char *str, size_t maxlen);
+
+#endif

src/register.cgi.c

@@ -0,0 +1,113 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <ctype.h>
+#include "cgi.h"
+
+char *BASE_PATH = "/var/lib/ctf/teams";
+
+
+unsigned int
+djbhash(char const *buf, size_t buflen)
+{
+  unsigned int h = 5381;
+
+  while (buflen--) {
+    h = ((h << 5) + h) ^ *(buf++);
+  }
+  return h;
+}
+
+void
+page(char *title, char *fmt, ...)
+{
+  FILE    *p;
+  va_list  ap;
+
+  printf("Content-type: text/html\r\n\r\n");
+  fflush(stdout);
+  p = popen("./template", "w");
+  if (NULL == p) {
+    printf("<h1>%s</h1>\n", title);
+    p = stdout;
+  } else {
+    fprintf(p, "Title: %s\n", title);
+  }
+  va_start(ap, fmt);
+  vfprintf(p, fmt, ap);
+  va_end(ap);
+  fclose(p);
+}
+
+int
+main(int argc, char *argv[])
+{
+  char   team[80];
+  size_t teamlen;
+  char   hash[9];
+
+  if (-1 == cgi_init()) {
+    return 0;
+  }
+
+  /* Read in team name, the only thing we care about */
+  while (1) {
+    size_t len;
+    char   key[20];
+
+    len = read_item(key, sizeof(key));
+    if (0 == len) break;
+    if ((1 == len) && ('t' == key[0])) {
+      teamlen = read_item(team, sizeof(team));
+    }
+  }
+
+  /* Compute the hash */
+  sprintf(hash, "%08x", djbhash(team, teamlen));
+
+  /* Write team name into file */
+  {
+    char filename[100];
+    int  fd;
+    int  ret;
+
+    ret = snprintf(filename, sizeof(filename),
+                   "%s/%s",
+                   BASE_PATH, hash);
+    if (sizeof(filename) == ret) {
+      printf(("500 Server screwed up\n"
+              "Content-type: text/plain\n"
+              "\n"
+              "The full path to the team hash file is too long.\n"));
+      return 0;
+    }
+    fd = creat(filename, 0444);
+    if (-1 == fd) {
+      page("Bad team name",
+           ("<p>Either that team name is already in use, or you "
+            "found a hash collision (way to go). "
+            "In any case, you're going to "
+            "have to pick something else.</p>"
+            "<p>If you're just trying to find your team hash again,"
+            "it's <samp>%s</samp>.</p>"),
+           hash);
+      return 0;
+    }
+    write(fd, team, teamlen);
+    close(fd);
+  }
+
+  /* Let them know what their hash is. */
+  page("Team registered",
+       ("<p>Team hash: <samp>%s</samp></p>"
+        "<p><b>Save your team hash somewhere!</b>.  You will need it "
+        "to claim points.</b></p>"),
+       hash);
+
+  return 0;
+}