#include #include #include #include #include #include #include #include #include #include #include #include "common.h" #ifdef NODUMP # define DUMPf(fmt, args...) #else # define DUMPf(fmt, args...) fprintf(stderr, "%s:%s:%d " fmt "\n", __FILE__, __FUNCTION__, __LINE__, ##args) #endif #define DUMP() DUMPf("") #define DUMP_d(v) DUMPf("%s = %d", #v, v) #define DUMP_x(v) DUMPf("%s = 0x%x", #v, v) #define DUMP_s(v) DUMPf("%s = %s", #v, v) #define DUMP_c(v) DUMPf("%s = '%c' (0x%02x)", #v, v, v) #define DUMP_p(v) DUMPf("%s = %p", #v, v) #define POST_MAX 1024 /* * CGI */ static int is_cgi = 0; static char **argv = NULL; static int read_char_argv() { static int arg = 0; static char *p; if (NULL == argv) { return EOF; } if (0 == arg) { arg = 1; p = argv[1]; } if (! p) { return EOF; } else if (! *p) { arg += 1; p = argv[arg]; return '&'; } return *(p++); } static int read_char_stdin() { static int inlen = -1; if (-1 == inlen) { char *p = getenv("CONTENT_LENGTH"); if (p) { inlen = atoi(p); if (inlen > POST_MAX) { inlen = POST_MAX; } if (inlen < 0) { inlen = 0; } } else { inlen = 0; } } if (inlen) { inlen -= 1; return getchar(); } return EOF; } static int read_char_query_string() { static char *p = (char *)-1; if ((char *)-1 == p) { p = getenv("QUERY_STRING"); } if (! p) { return EOF; } else if (! *p) { return EOF; } else { return *(p++); } } static int (* read_char)() = read_char_argv; int cgi_init(char *global_argv[]) { char *rm = getenv("REQUEST_METHOD"); if (! rm) { read_char = read_char_argv; argv = global_argv; } else if (0 == strcmp(rm, "POST")) { read_char = read_char_stdin; is_cgi = 1; } else if (0 == strcmp(rm, "GET")) { read_char = read_char_query_string; is_cgi = 1; } else { printf(("405 Method not allowed\r\n" "Allow: GET, POST\r\n" "Content-type: text/plain\r\n" "\r\n" "%s is not allowed.\n"), rm); return -1; } return 0; } 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 cgi_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; } } } void cgi_head(char *title) { if (is_cgi) { printf("Content-type: text/html\r\n\r\n"); } printf(("\n" "\n" " \n" " %s\n" " \n" " \n" " \n" "

%s

\n"), title, title); } void cgi_foot() { printf("\n" " \n" "\n"); } void cgi_result(int code, char *desc, char *fmt, ...) { va_list ap; if (is_cgi) { printf("%d %s\r\n", code, desc); } cgi_head(desc); va_start(ap, fmt); vprintf(fmt, ap); va_end(ap); cgi_foot(); exit(0); } void cgi_fail(int err) { switch (err) { case ERR_GENERAL: cgi_result(500, "Points not awarded", "

The server is unable to award your points at this time.

"); case ERR_NOTEAM: cgi_result(409, "No such team", "

There is no team with that hash.

"); case ERR_CLAIMED: cgi_result(409, "Already claimed", "

That is the correct answer, but your team has already claimed these points.

"); default: cgi_result(409, "Failure", "

Failure code: %d

", err); } } void cgi_page(char *title, char *fmt, ...) { va_list ap; cgi_head(title); va_start(ap, fmt); vprintf(fmt, ap); va_end(ap); cgi_foot(); exit(0); } void cgi_error(char *text) { cgi_result(500, "Internal error", "

", text); } /* * Common routines */ /* cut -d$ANCHOR -f2- | grep -Fx "$NEEDLE" */ int anchored_search(char const *filename, char const *needle, char const anchor) { FILE *f = fopen(filename, "r"); size_t nlen = strlen(needle); char line[1024]; int ret = 0; while (f) { char *p; if (NULL == fgets(line, sizeof line, f)) { break; } /* Find anchor */ if (anchor) { p = strchr(line, anchor); if (! p) { continue; } p += 1; } else { p = line; } /* Don't bother with strcmp if string lengths differ. If this string is shorter than the previous, it's okay. This is just a performance hack. */ if ((p[nlen] != '\n') && (p[nlen] != '\0')) { continue; } p[nlen] = 0; /* Okay, now we can compare! */ if (0 == strcmp(p, needle)) { ret = 1; break; } } if (f) { fclose(f); } return ret; } void urandom(char *buf, size_t buflen) { static int fd = -2; if (-2 == fd) { srandom(time(NULL) * getpid()); fd = open("/dev/urandom", O_RDONLY); } if (-1 != fd) { int len; len = read(fd, buf, buflen); if (len == buflen) { return; } } /* Fall back to libc's crappy thing */ { int i; for (i = 0; i < buflen; i += 1) { buf[i] = (char)random(); } } } int my_snprintf(char *buf, size_t buflen, char *fmt, ...) { int len; va_list ap; va_start(ap, fmt); len = vsnprintf(buf, buflen - 1, fmt, ap); va_end(ap); buf[buflen - 1] = '\0'; if (len >= buflen) { return buflen - 1; } else { return len; } } void ctf_chdir() { static int initialized = 0; int i; if (initialized) { return; } initialized = 1; /* chdir to $CTF_BASE */ { char const *ctf_base = getenv("CTF_BASE"); if (ctf_base) { chdir(ctf_base); } } /* Keep going up one directory until there's a packages directory */ for (i = 0; i < 5; i += 1) { struct stat st; if ((0 == stat("packages", &st)) && S_ISDIR(st.st_mode)) { return; } chdir(".."); } fprintf(stderr, "Can not determine CTF_BASE directory: exiting.\n"); exit(66); } static char * mkpath(char const *type, char const *fmt, va_list ap) { char relpath[PATH_MAX]; static char path[PATH_MAX]; ctf_chdir(); vsnprintf(relpath, sizeof(relpath) - 1, fmt, ap); relpath[sizeof(relpath) - 1] = '\0'; /* $CTF_BASE/type/relpath */ my_snprintf(path, sizeof(path), "%s/%s", type, relpath); return path; } char * state_path(char const *fmt, ...) { va_list ap; char *ret; va_start(ap, fmt); ret = mkpath("state", fmt, ap); va_end(ap); return ret; } char * package_path(char const *fmt, ...) { va_list ap; char *ret; va_start(ap, fmt); ret = mkpath("packages", fmt, ap); va_end(ap); return ret; } int team_exists(char const *teamhash) { struct stat buf; int ret; int i; if ((! teamhash) || (! *teamhash)) { return 0; } /* Check for invalid characters. */ for (i = 0; teamhash[i]; i += 1) { if (! isalnum(teamhash[i])) { return 0; } } /* stat seems to be the preferred way to check for existence. */ ret = stat(state_path("teams/names/%s", teamhash), &buf); if (-1 == ret) { return 0; } return 1; } /* Return values: -1: general error -2: no such team -3: points already awarded */ int award_points(char const *teamhash, char const *category, const long points, char const *uid) { char line[100]; int linelen; char *filename; FILE *f; time_t now = time(NULL); if (! team_exists(teamhash)) { return ERR_NOTEAM; } linelen = snprintf(line, sizeof(line), "%s %s %ld %s", teamhash, category, points, uid); if (sizeof(line) <= linelen) { return ERR_GENERAL; } if (anchored_search(state_path("points.log"), line, ' ')) { return ERR_CLAIMED; } /* At one time I had this writing to a single log file, using lockf. This works, as long as nobody ever tries to edit the log file. Editing the log file would require locking it, which would block everything trying to score, effectively taking down the entire contest. If you can't lock it first--and nothing in busybox lets you do this--you have to bring down pretty much everything manually anyway. By putting new scores into new files and periodically appending those files to the main log file, it is possible to stop the thing that appends, edit the file at leisure, and then start the appender back up, all without affecting things trying to score: they're still able to record their score and move on. */ filename = state_path("points.tmp/%lu.%d.%s.%s.%ld", (unsigned long)now, getpid(), teamhash, category, points); f = fopen(filename, "w"); if (! f) { return ERR_GENERAL; } if (EOF == fprintf(f, "%lu %s\n", (unsigned long)now, line)) { return ERR_GENERAL; } fclose(f); /* Rename into points.new */ { char ofn[PATH_MAX]; strncpy(ofn, filename, sizeof(ofn)); filename = state_path("points.new/%lu.%d.%s.%s.%ld", (unsigned long)now, getpid(), teamhash, category, points); rename(ofn, filename); } return 0; }