vger/main.c

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6.0 KiB
C
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#include <sys/stat.h>
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#include <err.h>
#include <errno.h>
#include <pwd.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <syslog.h>
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#include <unistd.h>
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#include "mimes.h"
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#define BUFF_LEN_1 1000
#define BUFF_LEN_2 1025
#define BUFF_LEN_3 1024
#define GEMINI_PART 9
#define DEFAULT_LANG "en"
#define DEFAULT_CHROOT "/var/gemini/"
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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 *);
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void
drop_privileges(const char *user, const char *path)
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{
struct passwd *pw;
/*
* 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");
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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 path %s can't be used for chroot", path);
err(1, "chroot");
}
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if (chdir("/") == -1) {
syslog(LOG_DAEMON, "failed to chdir(\"/\")");
err(1, "chdir");
}
/* drop privileges */
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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 (unveil(path, "r") == -1) {
syslog(LOG_DAEMON, "unveil on %s failed", path);
err(1, "unveil");
}
/*
* 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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}
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void
status(const int code, const char *file_mime, const char *lang)
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{
printf("%i %s; lang=%s\r\n",
code, file_mime, lang);
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}
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void
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display_file(const char *path, const char *lang)
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{
size_t buflen = BUFF_LEN_1;
char *buffer[BUFF_LEN_1];
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char extension[10];
char file_mime[50];
ssize_t nread;
struct stat sb;
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FILE *fd;
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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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get_file_mime(path, file_mime, sizeof(file_mime));
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status(20, file_mime, lang);
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/* read the file and write it to stdout */
while ((nread = fread(buffer, sizeof(char), buflen, 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 buffer [BUFF_LEN_2];
char request [BUFF_LEN_2];
char hostname [BUFF_LEN_2];
char file [BUFF_LEN_2];
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char path [BUFF_LEN_2] = DEFAULT_CHROOT;
char lang [3] = DEFAULT_LANG;
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char user [_SC_LOGIN_NAME_MAX];
int virtualhost = 0;
int option;
int start_with_gemini;
char *pos;
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while ((option = getopt(argc, argv, ":d:l:u:v")) != -1) {
switch (option) {
case 'd':
strlcpy(path, optarg, sizeof(path));
break;
case 'v':
virtualhost = 1;
break;
case 'l':
strlcpy(lang, optarg, sizeof(lang));
break;
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case 'u':
strlcpy(user, optarg, sizeof(user));
break;
}
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}
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/*
* do chroot if an user is supplied run pledge/unveil if OpenBSD
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*/
drop_privileges(user, path);
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/*
* read 1024 chars from stdin
* to get the request
*/
fgets(request, BUFF_LEN_3, stdin);
/* remove \r\n at the end of string */
pos = strchr(request, '\r');
if (pos != NULL)
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*pos = '\0';
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/*
* check if the beginning of the request starts with
* gemini://
*/
start_with_gemini = strncmp(request, "gemini://", 9);
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/* the request must start with gemini:// */
if (start_with_gemini != 0) {
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/* error code url malformed */
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syslog(LOG_DAEMON, "request «%s» doesn't match gemini:// at index %i",
request, start_with_gemini);
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exit(1);
}
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syslog(LOG_DAEMON, "request %s", request);
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/* remove the gemini:// part */
strlcpy(buffer, request + GEMINI_PART, sizeof(buffer) - GEMINI_PART);
strlcpy(request, buffer, sizeof(request));
/*
* 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;
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for (int i = 0; i < sizeof(request); i++) {
if (*pos == request[i]) {
position = i;
break;
}
}
/* separate hostname and uri */
if (position != -1) {
strlcpy(hostname, request, position + 1);
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strlcpy(file, request + position + 1, sizeof(request));
/*
* use a default file if no file are requested this
* can happen in two cases gemini://hostname/
* gemini://hostname/directory/
*/
if (strlen(file) == 0)
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strlcpy(file, "/index.gmi", 11);
if (file[strlen(file) - 1] == '/')
strlcat(file, "index.gmi", sizeof(file));
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} else {
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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
*/
strlcpy(hostname, request, sizeof(hostname));
strlcpy(file, "/index.gmi", 11);
}
/*
* 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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}