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#include <fcgi_stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/select.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#define FCGI_BUF_SIZE 4096
static int write_all(int fd, char *buf, size_t size)
{
size_t nleft = size;
while (nleft > 0) {
ssize_t nwritten = write(fd, buf, nleft);
if (nwritten < 0)
return nleft - size; /* zero or negative to indicate error */
buf += nwritten;
nleft -= nwritten;
}
return size;
}
static void fcgi_pass(int fd_stdin, int fd_stdout, int fd_stderr)
{
char buf[FCGI_BUF_SIZE];
size_t nread;
fd_set rset;
int maxfd = (fd_stdout > fd_stderr) ? fd_stdout : fd_stderr;
int nready;
/* slurp the whole input and pass it to CGI */
while ((nread = fread(buf, 1, sizeof(buf), stdin))) {
if (write_all(fd_stdin, buf, nread) <= 0) return;
}
close(fd_stdin);
/* now wait for CGI replies on stdout and stderr */
while (fd_stdout >= 0 && fd_stderr >= 0) {
FD_ZERO(&rset);
if (fd_stdout >= 0) FD_SET(fd_stdout, &rset);
if (fd_stderr >= 0) FD_SET(fd_stderr, &rset);
nready = select(maxfd, &rset, NULL, NULL, NULL);
if (nready < 0) {
if (errno == EAGAIN) continue;
return; /* better error checking needed */
}
if (fd_stdout >= 0 && FD_ISSET(fd_stdout, &rset)) {
nread = read(fd_stdout, buf, sizeof(buf));
if (nread <= 0) {
close(fd_stdout);
fd_stdout = -1;
}
fwrite(buf, 1, nread, stdout);
}
if (fd_stderr >= 0 && FD_ISSET(fd_stderr, &rset)) {
nread = read(fd_stderr, buf, sizeof(buf));
if (nread <= 0) {
close(fd_stderr);
fd_stderr = -1;
}
fwrite(buf, 1, nread, stderr);
}
}
}
int check_file_perms(const char *path)
{
struct stat ls;
struct stat fs;
if (lstat(path, &ls) < 0) {
return -ENOENT;
} else if (S_ISREG(ls.st_mode)) {
if (ls.st_mode & S_IXUSR) {
return 0;
} else {
return -EACCES;
}
} else if (!S_ISLNK(ls.st_mode)) {
return -EACCES;
}
if (stat(path, &fs) < 0) {
return -ENOENT;
} else if (S_ISREG(fs.st_mode)) {
if (fs.st_mode & S_IXUSR) {
return 0;
} else {
return -EACCES;
}
} else {
return -EACCES;
}
}
char *get_cgi_filename()
{
int buflen = 1, docrootlen;
char *buf;
char *docroot, *scriptname, *p;
if ((p = getenv("DOCUMENT_ROOT"))) {
docroot = p;
buflen += docrootlen = strlen(p);
} else {
return NULL;
}
if ((p = getenv("SCRIPT_NAME"))) {
buflen += strlen(p);
scriptname = p;
} else {
return NULL;
}
buf = malloc(buflen);
if (!buf) return NULL;
strcpy(buf, docroot);
strcpy(buf + docrootlen, scriptname);
while(1) {
switch(check_file_perms(buf)) {
case -EACCES: return NULL;
case 0: return buf;
default:
p = strrchr(buf, '/');
if (!p) return NULL;
*p = 0;
}
}
return NULL;
}
static void handle_fcgi_request()
{
int pipe_in[2];
int pipe_out[2];
int pipe_err[2];
char *filename;
/* XXX error handling */
pipe(pipe_in);
pipe(pipe_out);
pipe(pipe_err);
switch(fork()) {
case -1:
return;
case 0: /* child */
filename = get_cgi_filename();
if (!filename) {
puts("Status: 403 Forbidden\nContent-type: text/plain\n\n403");
exit(99);
}
close(pipe_in[1]);
close(pipe_out[0]);
close(pipe_err[0]);
dup2(pipe_in[0], 0);
dup2(pipe_out[1], 1);
dup2(pipe_err[1], 2);
execl(filename, filename, NULL);
/* we _do_ want a 502 here probably */
exit(99);
default: /* parent */
close(pipe_in[0]);
close(pipe_out[1]);
close(pipe_err[1]);
fcgi_pass(pipe_in[1], pipe_out[0], pipe_err[0]);
}
}
int main(int argc, char **argv)
{
signal(SIGCHLD, SIG_IGN);
signal(SIGPIPE, SIG_IGN);
while (FCGI_Accept() >= 0) {
handle_fcgi_request();
}
return 0;
}
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