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web-server.c
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web-server.c
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/* nbdkit
* Copyright Red Hat
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Red Hat nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* See web-server.h */
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <inttypes.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <pthread.h>
#include "web-server.h"
#ifndef SOCK_CLOEXEC
/* For this file, we don't care if fds are marked cloexec; leaking is okay. */
#define SOCK_CLOEXEC 0
#endif
enum method { HEAD, GET };
static char tmpdir[] = "/tmp/wsXXXXXX";
static char sockpath[] = "............./sock";
static int listen_sock = -1;
static int fd = -1;
static struct stat statbuf;
static char request[16384];
static check_request_t check_request;
static void *start_web_server (void *arg);
static void handle_requests (int s);
static void handle_file_request (int s, enum method method);
static void handle_mirror_redirect_request (int s);
static void handle_mirror_data_request (int s, enum method method, char byte);
static void send_404_not_found (int s);
static void send_405_method_not_allowed (int s);
static void send_500_internal_server_error (int s);
static void xwrite (int s, const char *buf, size_t len);
static void xpread (char *buf, size_t count, off_t offset);
static void
cleanup (void)
{
if (fd >= 0)
close (fd);
if (listen_sock >= 0)
close (listen_sock);
listen_sock = -1;
unlink (sockpath);
rmdir (tmpdir);
}
const char *
web_server (const char *filename, check_request_t _check_request)
{
struct sockaddr_un addr;
pthread_t thread;
int err;
check_request = _check_request;
/* Open the file. */
fd = open (filename, O_RDONLY|O_CLOEXEC);
if (fd == -1) {
perror (filename);
return NULL;
}
if (fstat (fd, &statbuf) == -1) {
perror ("stat");
goto err1;
}
/* Create the temporary directory for the socket. */
if (mkdtemp (tmpdir) == NULL) {
perror ("mkdtemp");
goto err1;
}
/* Create the listening socket for the web server. */
memcpy (sockpath, tmpdir, strlen (tmpdir));
listen_sock = socket (AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
if (listen_sock == -1) {
perror ("socket");
goto err2;
}
addr.sun_family = AF_UNIX;
memcpy (addr.sun_path, sockpath, strlen (sockpath) + 1);
if (bind (listen_sock, (struct sockaddr *) &addr, sizeof addr) == -1) {
perror (sockpath);
goto err3;
}
if (listen (listen_sock, SOMAXCONN) == -1) {
perror ("listen");
goto err4;
}
/* Run the web server in a separate thread. */
err = pthread_create (&thread, NULL, start_web_server, NULL);
if (err) {
errno = err;
perror ("pthread_create");
goto err4;
}
err = pthread_detach (thread);
if (err) {
errno = err;
perror ("pthread_detach");
goto err4;
}
atexit (cleanup);
return sockpath;
err4:
unlink (sockpath);
err3:
close (listen_sock);
err2:
rmdir (tmpdir);
err1:
close (fd);
return NULL;
}
static void *
start_web_server (void *arg)
{
fprintf (stderr, "web server: listening on %s\n", sockpath);
for (;;) {
int s = accept (listen_sock, NULL, NULL);
if (s == -1) {
/* This is not an error: The server has closed the socket in
* cleanup() because it is exiting, resulting in accept(2) above
* returning EBADF, so just exit the thread.
*/
if (errno == EBADF)
return NULL;
perror ("web server: accept");
exit (EXIT_FAILURE);
}
handle_requests (s);
}
}
static void
handle_requests (int s)
{
bool eof = false;
fprintf (stderr, "web server: accepted connection\n");
while (!eof) {
size_t r, n, sz;
enum method method;
char path[128];
/* Read request until we see "\r\n\r\n" (end of headers) or EOF. */
n = 0;
for (;;) {
if (n >= sizeof request - 1 /* allow one byte for \0 */) {
fprintf (stderr, "web server: request too long\n");
exit (EXIT_FAILURE);
}
sz = sizeof request - n - 1;
r = read (s, &request[n], sz);
if (r == -1) {
perror ("read");
exit (EXIT_FAILURE);
}
if (r == 0) {
eof = true;
break;
}
n += r;
request[n] = '\0';
if (strstr (request, "\r\n\r\n"))
break;
}
if (n == 0)
continue;
fprintf (stderr, "web server: request:\n%s", request);
/* Call the optional user function to check the request. */
if (check_request) check_request (request);
/* Get the method and path fields from the first line. */
if (strncmp (request, "HEAD ", 5) == 0) {
method = HEAD;
n = strcspn (&request[5], " \n\t");
if (n >= sizeof path) {
send_500_internal_server_error (s);
eof = true;
break;
}
memcpy (path, &request[5], n);
path[n] = '\0';
}
else if (strncmp (request, "GET ", 4) == 0) {
method = GET;
n = strcspn (&request[4], " \n\t");
if (n >= sizeof path) {
send_500_internal_server_error (s);
eof = true;
break;
}
memcpy (path, &request[4], n);
path[n] = '\0';
}
else {
send_405_method_not_allowed (s);
eof = true;
break;
}
fprintf (stderr, "web server: requested path: %s\n", path);
/* For testing retry-request + curl:
* /mirror redirects round-robin to /mirror1, /mirror2, /mirror3
* /mirror1 returns a file of \x01 bytes
* /mirror2 returns a file of \x02 bytes
* /mirror3 returns 404 errors
* Anything else returns a 500 error
*/
if (strcmp (path, "/mirror") == 0)
handle_mirror_redirect_request (s);
else if (strcmp (path, "/mirror1") == 0)
handle_mirror_data_request (s, method, 1);
else if (strcmp (path, "/mirror2") == 0)
handle_mirror_data_request (s, method, 2);
else if (strcmp (path, "/mirror3") == 0) {
send_404_not_found (s);
eof = true;
}
else if (strncmp (path, "/mirror", 7) == 0) {
send_500_internal_server_error (s);
eof = true;
}
/* Otherwise it's a regular file request. 'path' is ignored, we
* only serve a single file passed to web_server().
*/
else
handle_file_request (s, method);
fprintf (stderr, "web server: completed request\n");
}
fprintf (stderr, "web server: closing socket\n");
close (s);
}
static void
handle_file_request (int s, enum method method)
{
const bool headers_only = method == HEAD;
uint64_t offset, length, end;
const char *p;
const char response1_ok[] = "HTTP/1.1 200 OK\r\n";
const char response1_partial[] = "HTTP/1.1 206 Partial Content\r\n";
const char response2[] =
"Accept-rANGES: bytes\r\n" /* See RHBZ#1837337 */
"Connection: close\r\n"
"Content-Type: application/octet-stream\r\n";
char response3[64];
const char response4[] = "\r\n";
char *data;
/* If there's no Range request header then send the full size as the
* content-length.
*/
p = strcasestr (request, "\r\nRange: bytes=");
if (p == NULL) {
offset = 0;
length = statbuf.st_size;
xwrite (s, response1_ok, strlen (response1_ok));
}
else {
p += 15;
if (sscanf (p, "%" SCNu64 "-%" SCNu64, &offset, &end) != 2) {
fprintf (stderr, "web server: could not parse "
"range request from curl client\n");
exit (EXIT_FAILURE);
}
/* Unclear but "Range: bytes=0-4" means bytes 0-3. '4' is the
* byte beyond the end of the range.
*/
length = end - offset;
xwrite (s, response1_partial, strlen (response1_partial));
}
xwrite (s, response2, strlen (response2));
snprintf (response3, sizeof response3,
"Content-Length: %" PRIu64 "\r\n", length);
xwrite (s, response3, strlen (response3));
xwrite (s, response4, strlen (response4));
if (headers_only)
return;
/* Send the file content. */
data = malloc (length);
if (data == NULL) {
perror ("malloc");
exit (EXIT_FAILURE);
}
xpread (data, length, offset);
xwrite (s, data, length);
free (data);
}
/* Request for /mirror */
static void
handle_mirror_redirect_request (int s)
{
static char rr = '1'; /* round robin '1', '2', '3' */
/* Note we send 302 (temporary redirect), same as Fedora's mirrorservice. */
const char found[] = "HTTP/1.1 302 Found\r\nContent-Length: 0\r\n";
char location[] = "Location: /mirrorX\r\n";
char close_[] = "Connection: close\r\n";
const char eol[] = "\r\n";
location[17] = rr;
rr++;
if (rr == '4')
rr = '1';
xwrite (s, found, strlen (found));
xwrite (s, location, strlen (location));
xwrite (s, close_, strlen (close_));
xwrite (s, eol, strlen (eol));
}
static void
handle_mirror_data_request (int s, enum method method, char byte)
{
const bool headers_only = method == HEAD;
uint64_t offset, length, end;
const char *p;
const char response1_ok[] = "HTTP/1.1 200 OK\r\n";
const char response1_partial[] = "HTTP/1.1 206 Partial Content\r\n";
const char response2[] =
"Accept-rANGES: bytes\r\n" /* See RHBZ#1837337 */
"Connection: close\r\n"
"Content-Type: application/octet-stream\r\n";
char response3[64];
const char response4[] = "\r\n";
char *data;
/* If there's no Range request header then send the full size as the
* content-length.
*/
p = strcasestr (request, "\r\nRange: bytes=");
if (p == NULL) {
offset = 0;
length = statbuf.st_size;
xwrite (s, response1_ok, strlen (response1_ok));
}
else {
p += 15;
if (sscanf (p, "%" SCNu64 "-%" SCNu64, &offset, &end) != 2) {
fprintf (stderr, "web server: could not parse "
"range request from curl client\n");
exit (EXIT_FAILURE);
}
/* Unclear but "Range: bytes=0-4" means bytes 0-3. '4' is the
* byte beyond the end of the range.
*/
length = end - offset;
xwrite (s, response1_partial, strlen (response1_partial));
}
xwrite (s, response2, strlen (response2));
snprintf (response3, sizeof response3,
"Content-Length: %" PRIu64 "\r\n", length);
xwrite (s, response3, strlen (response3));
xwrite (s, response4, strlen (response4));
if (headers_only)
return;
/* Send the file content. */
data = malloc (length);
if (data == NULL) {
perror ("malloc");
exit (EXIT_FAILURE);
}
memset (data, byte, length);
xwrite (s, data, length);
free (data);
}
static void
send_404_not_found (int s)
{
const char response[] =
"HTTP/1.1 404 Not Found\r\n"
"Content-Length: 0\r\n"
"Connection: close\r\n"
"\r\n";
xwrite (s, response, strlen (response));
}
static void
send_405_method_not_allowed (int s)
{
const char response[] =
"HTTP/1.1 405 Method Not Allowed\r\n"
"Content-Length: 0\r\n"
"Connection: close\r\n"
"\r\n";
xwrite (s, response, strlen (response));
}
static void
send_500_internal_server_error (int s)
{
const char response[] =
"HTTP/1.1 500 Internal Server Error\r\n"
"Content-Length: 0\r\n"
"Connection: close\r\n"
"\r\n";
xwrite (s, response, strlen (response));
}
static void
xwrite (int s, const char *buf, size_t len)
{
ssize_t r;
while (len > 0) {
r = write (s, buf, len);
if (r == -1) {
perror ("write");
exit (EXIT_FAILURE);
}
buf += r;
len -= r;
}
}
static void
xpread (char *buf, size_t count, off_t offset)
{
ssize_t r;
while (count > 0) {
r = pread (fd, buf, count, offset);
if (r == -1) {
perror ("read");
exit (EXIT_FAILURE);
}
if (r == 0) {
fprintf (stderr, "pread: unexpected end of file\n");
exit (EXIT_FAILURE);
}
buf += r;
count -= r;
offset += r;
}
}