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vger/main.c

295 lines
6.9 KiB
C

#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <pwd.h>
#include <stdarg.h>
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#include <stdio.h>
#include <stdlib.h>
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#include <string.h>
#include <syslog.h>
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#include <unistd.h>
#include "mimes.h"
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#define GEMINI_PART 9
#define DEFAULT_LANG "en"
#define DEFAULT_CHROOT "/var/gemini"
#define GEMINI_REQUEST_MAX 1024 /* see https://gemini.circumlunar.space/docs/specification.html */
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void display_file(const char *, const char *);
void status (const int, const char *, const char *);
void drop_privileges(const char *, const char *);
void eunveil(const char *path, const char *permissions);
size_t estrlcpy(char *dst, const char *src, size_t dstsize);
void
eunveil(const char *path, const char *permissions)
{
if (unveil(path, permissions) == -1) {
syslog(LOG_DAEMON, "unveil on %s failed", path);
err(1, "unveil");
}
}
size_t
estrlcpy(char *dst, const char *src, size_t dstsize)
{
size_t n = 0;
n = strlcpy(dst, src, dstsize);
if (n >= dstsize) {
err(1, "estrlcpy failed");
}
return n;
}
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void
drop_privileges(const char *user, const char *path)
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{
struct passwd *pw;
int chrooted = 0;
/*
* use chroot() if an user is specified requires root user to be
* running the program to run chroot() and then drop privileges
*/
if (strlen(user) > 0) {
/* is root? */
if (getuid() != 0) {
syslog(LOG_DAEMON, "chroot requires program to be run as root");
errx(1, "chroot requires root user");
}
/* search user uid from name */
if ((pw = getpwnam(user)) == NULL) {
syslog(LOG_DAEMON, "the user %s can't be found on the system", user);
err(1, "finding user");
}
/* chroot worked? */
if (chroot(path) != 0) {
syslog(LOG_DAEMON, "the chroot_dir %s can't be used for chroot", path);
err(1, "chroot");
}
chrooted = 1;
if (chdir("/") == -1) {
syslog(LOG_DAEMON, "failed to chdir(\"/\")");
err(1, "chdir");
}
/* drop privileges */
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid)) {
syslog(LOG_DAEMON, "dropping privileges to user %s (uid=%i) failed",
user, pw->pw_uid);
err(1, "Can't drop privileges");
}
}
#ifdef __OpenBSD__
/*
* prevent access to files other than the one in path
*/
if (chrooted) {
eunveil("/", "r");
} else {
eunveil(path, "r");
}
/*
* prevent system calls other parsing queryfor fread file and
* write to stdio
*/
if (pledge("stdio rpath", NULL) == -1) {
syslog(LOG_DAEMON, "pledge call failed");
err(1, "pledge");
}
#endif
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}
void
status(const int code, const char *file_mime, const char *lang)
{
printf("%i %s; lang=%s\r\n",
code, file_mime, lang);
}
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void
display_file(const char *path, const char *lang)
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{
FILE *fd;
struct stat sb;
ssize_t nread;
char *buffer[BUFSIZ];
const char *file_mime;
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/* this is to check if path is a directory */
if (stat(path, &sb) == -1)
goto err;
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/* open the file requested */
if ((fd = fopen(path, "r")) == NULL)
goto err;
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/* check if directory */
if (S_ISDIR(sb.st_mode) == 1)
goto err;
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file_mime = get_file_mime(path);
status(20, file_mime, lang);
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/* read the file and write it to stdout */
while ((nread = fread(buffer, sizeof(char), sizeof(buffer), fd)) != 0)
fwrite(buffer, sizeof(char), nread, stdout);
fclose(fd);
syslog(LOG_DAEMON, "path served %s", path);
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return;
err:
/* return an error code and no content */
status(40, "text/gemini", lang);
syslog(LOG_DAEMON, "path invalid %s", path);
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}
int
main(int argc, char **argv)
{
char request [GEMINI_REQUEST_MAX] = {'\0'};
char hostname [GEMINI_REQUEST_MAX] = {'\0'};
char file [GEMINI_REQUEST_MAX] = {'\0'};
char path [GEMINI_REQUEST_MAX] = DEFAULT_CHROOT;
char lang [3] = DEFAULT_LANG;
char user [_SC_LOGIN_NAME_MAX] = "";
int virtualhost = 0;
int option = 0;
int chroot = 0;
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int start_with_gemini = 0;
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char *pos = NULL;
while ((option = getopt(argc, argv, ":d:l:u:v")) != -1) {
switch (option) {
case 'd':
estrlcpy(path, optarg, sizeof(path));
break;
case 'v':
virtualhost = 1;
break;
case 'l':
estrlcpy(lang, optarg, sizeof(lang));
break;
case 'u':
estrlcpy(user, optarg, sizeof(user));
chroot = 1;
break;
}
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}
/*
* do chroot if an user is supplied run pledge/unveil if OpenBSD
*/
drop_privileges(user, path);
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/* change basedir to / to build the filepath if we use chroot */
if (chroot == 1)
estrlcpy(path, "/", sizeof(path));
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/*
* read 1024 chars from stdin
* to get the request
*/
if (fgets(request, GEMINI_REQUEST_MAX, stdin) == NULL){
/*TODO : add error code 5x */
syslog(LOG_DAEMON, "request is too long (1024 max): %s", request);
exit(1);
}
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/* remove \r\n at the end of string */
pos = strchr(request, '\r');
if (pos != NULL)
*pos = '\0';
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/*
* check if the beginning of the request starts with
* gemini://
*/
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start_with_gemini = strncmp(request, "gemini://", GEMINI_PART);
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/* the request must start with gemini:// */
if (start_with_gemini != 0) {
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/* error code url malformed */
syslog(LOG_DAEMON, "request «%s» doesn't match gemini:// at index %i",
request, start_with_gemini);
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exit(1);
}
syslog(LOG_DAEMON, "request %s", request);
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/* remove the gemini:// part */
memmove(request, request + GEMINI_PART, sizeof(request) - GEMINI_PART);
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/*
* look for the first / after the hostname
* in order to split hostname and uri
*/
pos = strchr(request, '/');
if (pos != NULL) {
/* if there is a / found */
int position = -1;
for (size_t i = 0; i < sizeof(request); i++) {
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if (*pos == request[i]) {
position = i;
break;
}
}
/* separate hostname and uri */
if (position != -1) {
/*estrlcpy(hostname, request - position + 1, sizeof(request - position + 1));*/
estrlcpy(file, request+position+1, sizeof(request+position+1));
request[position +1] = '\0'; /* this is faster than strlcpy above*/
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/*
* use a default file if no file are requested this
* can happen in two cases gemini://hostname/
* gemini://hostname/directory/
*/
if (strlen(file) == 0)
estrlcpy(file, "/index.gmi", 11);
if (file[strlen(file) - 1] == '/')
strlcat(file, "index.gmi", sizeof(file));
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} else {
syslog(LOG_DAEMON, "unknown situation after parsing query");
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exit(2);
}
} else {
/*
* there are no slash / in the request
* -2 to remove \r\n
*/
estrlcpy(hostname, request, sizeof(hostname));
estrlcpy(file, "/index.gmi", 11);
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}
/*
* if virtualhost feature is actived looking under the default path +
* hostname directory gemini://foobar/hello will look for
* path/foobar/hello
*/
if (virtualhost) {
strlcat(path, hostname, sizeof(path));
strlcat(path, "/", sizeof(path));
}
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/* add the base dir to the file requested */
strlcat(path, file, sizeof(path));
/* open file and send it to stdout */
display_file(path, lang);
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return (0);
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}