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#undef _GNU_SOURCE |
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#define _GNU_SOURCE |
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|
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#include <limits.h> |
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#include <sys/types.h> |
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#include <sys/stat.h> |
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#include <sys/wait.h> |
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#include <dlfcn.h> |
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#include <errno.h> |
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#include <unistd.h> |
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#include <sys/socket.h> |
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#include <sys/socket.h> |
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#include <stdio.h> |
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#include <string.h> |
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#include <arpa/inet.h> |
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|
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#include <unordered_map> |
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#include <mutex> |
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|
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#define PATHBUFSIZE 4097 |
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#define NAMEMAX 255 |
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#define DEFAULT_SHORTENER "/root/enametoolong/shortener-prod" |
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|
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static std::mutex shorten_mutex; |
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|
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static int shortener_fd = -1; |
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static pid_t shortener_pid; |
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|
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static void |
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die (const char *msg) |
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{ |
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perror ("socketpair"); |
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exit (EXIT_FAILURE); |
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} |
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|
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static bool |
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xread (int fd, void *buf, size_t count) |
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{ |
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while (count > 0) |
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{ |
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ssize_t bytesRead = read (fd, buf, count); |
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|
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if (bytesRead < 0) |
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{ |
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if (errno == EINTR) |
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continue; |
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|
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return false; |
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} |
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else if (bytesRead == 0) |
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return false; |
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|
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buf = (char *)buf + bytesRead; |
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count -= bytesRead; |
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} |
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|
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return true; |
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} |
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|
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static bool |
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xwrite(int fd, const void *buf, size_t count) |
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{ |
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while (count > 0) |
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{ |
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ssize_t bytesWritten = send (fd, buf, count, MSG_NOSIGNAL); |
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|
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if (bytesWritten < 0) |
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{ |
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if (errno == EINTR) |
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continue; |
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|
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return false; |
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} |
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|
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buf = (char *)buf + bytesWritten; |
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count -= bytesWritten; |
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} |
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|
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return true; |
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} |
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|
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static void |
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shortener_open (void) |
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{ |
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int sp[2]; |
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|
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if (socketpair (AF_UNIX, SOCK_STREAM, 0, sp) < 0) |
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die ("socketpair"); |
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|
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shortener_pid = vfork (); |
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|
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if (shortener_pid < 0) |
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die ("vfork"); |
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|
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if (shortener_pid == 0) |
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{ |
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dup2 (sp[1], 0); |
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dup2 (sp[1], 1); |
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close (sp[0]); |
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|
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static const char *const argv[2] = { "-", 0 }; |
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const char *shortener_path = secure_getenv ("ENAMETOOLONG_SHORTENER"); |
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execve (shortener_path ? shortener_path : DEFAULT_SHORTENER, const_cast<char *const *>(argv), 0); |
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_exit (126); |
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} |
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|
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close (sp[1]); |
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|
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shortener_fd = sp[0]; |
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} |
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|
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static void |
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shortener_close (void) |
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{ |
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if (shortener_fd < 0) |
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return; |
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|
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close (shortener_fd); |
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shortener_fd = -1; |
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|
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if (shortener_pid > 0) |
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{ |
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int wstatus; |
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waitpid (shortener_pid, &wstatus, 0); |
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shortener_pid = -1; |
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} |
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|
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sleep (1); // rate limit retries |
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} |
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|
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static std::unordered_map<std::string, std::string> cache; |
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|
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__attribute__ ((__cold__, __noinline__)) |
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static const char * |
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shorten (const char *path) |
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{ |
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std::lock_guard<std::mutex> guard (shorten_mutex); |
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|
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std::string &shorter = cache[path]; |
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|
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if (shorter.size ()) |
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return shorter.c_str (); |
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|
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for (;;) |
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{ |
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if (shortener_fd < 0) |
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shortener_open (); |
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|
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uint32_t slen = strlen (path); |
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uint32_t nlen = htonl (slen); |
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xwrite (shortener_fd, &nlen, sizeof nlen); |
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xwrite (shortener_fd, path, slen); |
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|
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if (xread (shortener_fd, &nlen, sizeof nlen)) |
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{ |
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nlen = ntohl (nlen); |
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|
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if (nlen < PATHBUFSIZE) |
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{ |
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shorter.resize (nlen); |
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|
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if (xread (shortener_fd, shorter.data (), nlen)) |
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return shorter.c_str (); |
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} |
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} |
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|
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shortener_close (); |
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} |
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} |
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|
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static bool |
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toolong (const char *path) |
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{ |
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size_t clen = 0; |
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|
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for (;;) |
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{ |
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if (*path == '/') |
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clen = 0; |
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else if (!*path) |
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return false; |
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else if (++clen > NAMEMAX) |
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return true; |
| 184 |
|
| 185 |
++path; |
| 186 |
} |
| 187 |
} |
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|
| 189 |
#include "wrap.C" |
