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recur.c
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1997-01-27
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/* Handling of recursive HTTP retrieving.
Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif /* HAVE_UNISTD_H */
#include <errno.h>
#include <assert.h>
#include <ctype.h>
#include <sys/types.h>
#include "wget.h"
#include "options.h"
#include "url.h"
#include "recur.h"
#include "utils.h"
#include "retr.h"
#include "http.h"
#include "ftp.h"
#include "mtch.h"
#include "host.h"
extern struct options opt;
extern char *version_string;
/* A slist of downloaded URL-s */
urlpos *urls_downloaded;
slist *urls_html;
/* The core of recursive retrieving. Endless recursion is avoided by
having all URL-s stored to a linked list of URL-s, which is checked
before loading any URL. That way no URL can get loaded twice.
The function also supports specification of maximum recursion depth
and a load of goodies. */
uerr_t
recursive_retrieve(const char *file, const char *this_url,
int flags)
{
static slist *ulist; /* List of undesirable-to-load
URL-s. */
static char **forbidden = NULL; /* List of forbidden locations */
static int depth; /* Recursion depth */
static char *base_dir; /* Base direcory we're recursing from
(used by no_parent). */
static char *robots_host; /* The host name for which we last
checked robots. */
char *constr, *filename, *newloc;
char *canon_this_url = NULL;
int dt, inl;
int this_url_ftp; /* See below the explanation */
uerr_t err;
urlinfo *rurl;
urlpos *url_list, *cur_url;
char *rfile; /* For robots */
urlinfo *u;
if (flags & RCLEANUP)
{
free_slist(ulist);
ulist = NULL;
free_vec(forbidden);
forbidden = NULL;
free_slist(urls_html);
urls_html = NULL;
free_urlpos(urls_downloaded);
urls_downloaded = NULL;
if (base_dir)
free(base_dir);
if (robots_host)
free(robots_host);
return RETROK;
}
assert(this_url != NULL);
assert(file != NULL);
/* If quota was exceeded earlier, bail out. */
if (opt.quota && (opt.downloaded > opt.quota))
return QUOTEXC;
/* Cache the current URL in the list. */
if (flags & RFIRST_TIME)
{
ulist = add_slist(ulist, this_url, 0);
urls_downloaded = NULL;
urls_html = NULL;
/* Enter this_url to the slist, in original and "enhanced"
form. */
u = newurl();
err = parseurl(this_url, u, 0);
if (err == URLOK)
{
ulist = add_slist(ulist, u->url, 0);
urls_downloaded = add_url(urls_downloaded, u->url, file);
urls_html = add_slist(urls_html, file, NOSORT);
if (opt.no_parent)
base_dir = nstrdup(u->dir); /* Set the base dir. */
/* Set the canonical this_url to be sent as referer. This
problem exists only when running the first time. */
canon_this_url = nstrdup(u->url);
}
else
{
DEBUGP("Double yuck! The *base* URL is broken.\n");
base_dir = NULL;
}
freeurl(u, 1);
depth = 1;
robots_host = NULL;
forbidden = NULL;
}
else
++depth;
/* Bail out if opt.maxreclevel is exceeded. */
if ((opt.maxreclevel != 0) && (depth > opt.maxreclevel))
{
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile, "Recursion depth %d exceeded max. depth %d.\n",
depth, opt.maxreclevel);
#endif
--depth;
return RECLEVELEXC;
}
/* Determine whether this_url is an FTP URL. If it is, it means
that the retrieval is done through proxy. In that case, FTP
links will be followed by default and recursion will not be
turned off when following them. */
this_url_ftp = (urlproto(this_url) == URLFTP);
/* Get the URL-s from an HTML file: */
url_list = get_urls_html(file,
canon_this_url ? canon_this_url : this_url, 0);
/* Decide what to do with each of the URLs. A URL will be loaded if
it meets several requirements, discussed later. */
for (cur_url = url_list; cur_url; cur_url = cur_url->next)
{
/* If quota was exceeded earlier, bail out. */
if (opt.quota && (opt.downloaded > opt.quota))
break;
/* Parse the URL for convenient use in other functions, as well
as to get the optimized form. It also checks URL
integrity. */
u = newurl();
if (parseurl(cur_url->url, u, 0) != URLOK)
{
DEBUGP("Yuck! A bad URL.\n");
freeurl(u, 1);
continue;
}
if (u->proto == URLFILE)
{
DEBUGP("Nothing to do with file:// around here.\n");
freeurl(u, 1);
continue;
}
assert(u->url != NULL);
constr = nstrdup(u->url);
/* Several checkings whether a file is acceptable to load:
1. check if URL is ftp, and we don't load it
2. check for relative links (if relative_only is set)
3. check for domain
4. check for no-parent
5. check for excludes && includes
6. check for suffix
7. check for same host (if spanhost is unset), with possible
gethostbyname baggage
8. check for robots.txt
Addendum: If the URL is FTP, and it is to be loaded, only the
domain and suffix settings are "stronger".
Note that .html and (yuck) .htm will get loaded
regardless of suffix rules (but that is remedied later with
unlink).
More time- and memory- consuming tests should be put later on
the list. */
/* inl is set if the URL we are working on (constr) is stored in
ulist. Its usage is crucial to avoid the constant calls to
in_slist, which is quite slow. */
inl = in_slist(ulist, constr);
/* If it is FTP, and FTP is not followed, chuck it out. */
if (!inl)
if (u->proto == URLFTP && !opt.follow_ftp && !this_url_ftp)
{
DEBUGP("Uh, it is FTP but i'm not in the mood to follow FTP.\n");
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
/* If it is absolute link and they are not followed, chuck it
out. */
if (!inl && u->proto != URLFTP)
if (opt.relative_only && !(cur_url->flags & URELATIVE))
{
DEBUGP("It doesn't really look like a relative link.\n");
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
/* If its domain is not to be accepted/looked-up, chuck it
out. */
if (!inl)
if (!accept_domain(u))
{
DEBUGP("I don't like the smell of that domain.\n");
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
/* Check for parent directory. */
if (!inl && opt.no_parent)
{
/* Check for base_dir first. */
if (!(base_dir && frontcmp(base_dir, u->dir)))
{
/* Failing that, check for parent dir. */
urlinfo *ut = newurl();
if (parseurl(this_url, ut, 0) != URLOK)
DEBUGP("Double yuck! The *base* URL is broken.\n");
else if (!frontcmp(ut->dir, u->dir))
{
/* Failing that too, kill the URL. */
DEBUGP("Trying to escape parental guidance with no_parent on.\n");
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
freeurl(ut, 1);
}
}
/* If the file does not match the acceptance list, or is on the
rejection list, chuck it out. The same goes for the
directory exclude- and include- lists. */
if (!inl && (opt.includes || opt.excludes))
{
if (!accdir(u->dir, ALLABS))
{
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile, "%s (%s) is excluded/not-included.\n",
constr, u->dir);
#endif
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
}
if (!inl)
{
char *suf = NULL;
/* We check for acceptance/rejection rules only for non-HTML
documents. Since we don't know whether they really are
HTML, it will be deduced from (an OR-ed list):
1) u->file is "" (meaning it is a directory)
2) suffix exists, AND:
a) it is "html", OR
b) it is "htm"
If the file *is* supposed to be HTML, it will *not* be
subject to acc/rej rules. That's why the `!'. */
if (!
(!*u->file
|| (((suf = suffix(constr)) != NULL)
&& (!strcmp(suf, "html") || !strcmp(suf, "htm")))))
{
if (!acceptable(u->file))
{
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile,
"%s (%s) does not match acc/rej rules.\n",
constr, u->file);
#endif
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
}
if (suf)
free(suf);
}
/* Optimize the URL (which includes possible DNS lookup) only
after all other possibilities have been exhausted. */
if (!inl)
{
if (!opt.simple_check)
opt_url(u);
free(constr);
constr = nstrdup(u->url);
inl = in_slist(ulist, constr);
if (!inl && !((u->proto == URLFTP) && !this_url_ftp))
if (!opt.spanhost && this_url && !same_host(this_url, constr))
{
DEBUGP("This is not the same hostname as the parent's.\n");
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
}
/* What about robots.txt? */
if (!inl && opt.use_robots && u->proto == URLHTTP)
{
/* Since Wget knows about only one set of robot rules at a
time, /robots.txt must be reloaded whenever a new host is
accessed.
robots_host holds the host the current `forbid' variable
is assigned to. */
if (!robots_host || !same_host(robots_host, u->host))
{
if (robots_host)
free(robots_host);
/* Now make robots_host the new host, no matter what the
result will be. So if there is no /robots.txt on the
site, Wget will not retry getting robots all the
time. */
robots_host = nstrdup(u->host);
free_vec(forbidden);
forbidden = NULL;
err = retrieve_robots(constr, ROBOTS_FILENAME);
if (err == ROBOTSOK)
{
rurl = robots_url(constr, ROBOTS_FILENAME);
rfile = url_filename(rurl);
forbidden = parse_robots(rfile);
freeurl(rurl, 1);
free(rfile);
}
}
/* Now that we have (or don't have) robots, we can check for
them. */
if (!robots_match(u, forbidden))
{
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile, "Stuffing %s because %s forbids it.\n",
this_url, ROBOTS_FILENAME);
#endif
ulist = add_slist(ulist, constr, 0);
inl = 1;
}
}
filename = NULL;
/* If it wasn't chucked out, do something with it. */
if (!inl)
{
DEBUGP("I've decided to load it -> ");
/* Add it to the list of already-loaded URL-s. */
ulist = add_slist(ulist, constr, 0);
/* Automatically followed FTPs will *not* be downloaded
recursively. */
if (u->proto == URLFTP)
{
/* Don't you adore side-effects? */
opt.recursive = 0;
}
/* Reset its type. */
dt = 0;
/* Retrieve it. */
retrieve_url(constr, &filename, &newloc,
canon_this_url ? canon_this_url : this_url, &dt);
if (u->proto == URLFTP)
{
/* Restore... */
opt.recursive = 1;
}
if (newloc)
{
free(constr);
constr = newloc;
}
/* In case of convert_links: If there was no error, add it to
the list of downloaded URLs. We might need it for
conversion. */
if (opt.convert_links && filename)
{
if (dt & RETROKF)
{
urls_downloaded = add_url(urls_downloaded, constr, filename);
/* If the URL is HTML, note it. */
if (dt & TEXTHTML)
urls_html = add_slist(urls_html, filename, NOSORT);
}
}
/* If it is not an error, and it is of type text/html, parse
it recursively. */
if ((dt & TEXTHTML) && (dt & RETROKF))
recursive_retrieve(filename, constr, 0);
#ifdef DEBUG
else if (opt.debug)
fprintf(opt.lfile, "%s is not text/html so we don't chase.\n",
filename ? filename: "(null)");
#endif
/* If an suffix-rejected file was loaded only because it was HTML,
undo the error now */
if (opt.delete_after || (filename && !acceptable(filename)))
{
if (opt.verbose)
fprintf(opt.lfile, "Removing %s%s\n", filename,
opt.delete_after ? "." :
" since it should be rejected.");
if (unlink(filename) && !opt.quiet)
fprintf(opt.lfile, "unlink: %s\n", mystrerror(errno));
dt &= ~RETROKF;
}
/* If everything was OK, and links are to be converted, let's
store the local filename. */
if (opt.convert_links && (dt & RETROKF) && (filename != NULL))
{
cur_url->flags |= UABS2REL;
cur_url->local_name = nstrdup(filename);
}
}
#ifdef DEBUG
else if (opt.debug)
fprintf(opt.lfile, "%s already in list, so we don't load.\n", constr);
#endif
/* Free filename and constr. */
if (filename)
free(filename);
if (constr)
free(constr);
freeurl(u, 1);
/* Increment the pbuf for the appropriate size. */
}
if (opt.convert_links)
convert_links(file, url_list);
/* Free the linked list of URL-s. */
free_urlpos(url_list);
/* Free the canonical this_url. */
if (canon_this_url)
free(canon_this_url);
/* Decrement the recursion depth. */
--depth;
if (opt.quota && (opt.downloaded > opt.quota))
return QUOTEXC;
else
return RETROK;
}
/* Simple calls to convert_links will often fail because only the
downloaded files are converted, and Wget cannot know which files
will be converted in the future. So, if we have file fileone.html
with:
<a href=/c/something.gif>
and /c/something.gif was not downloaded because it exceeded the
recursion depth, the reference will *not* be changed.
However, later we can encounter /c/something.gif from an "upper"
level HTML (let's call it filetwo.html), and it gets downloaded.
But now we have a problem because /c/something.gif will be
correctly transformed in filetwo.html, but not in fileone.html,
since Wget could not have known that /c/something.gif will be
downloaded in the future.
This is why Wget must, after the whole retrieval, call
convert_all_links to go once more through the entire list of
retrieved HTML-s, and re-convert them.
All the downloaded HTMLs are kept in urls_html, and downloaded URLs
in urls_downloaded. From these two lists information is
extracted. */
void
convert_all_links(void)
{
uerr_t res;
urlpos *l1, *l2, *urls;
urlinfo *u;
slist *html;
urlpos *urlhtml;
for (html = urls_html; html; html = html->next)
{
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile, "Rescanning %s\n", html->string);
#endif
/* Determine the URL of the HTML file. get_urls_html will need
it. */
for (urlhtml = urls_downloaded; urlhtml; urlhtml = urlhtml->next)
if (!strcmp(urlhtml->local_name, html->string))
break;
#ifdef DEBUG
if (opt.debug)
{
if (urlhtml)
fprintf(opt.lfile, "It should correspond to %s.\n", urlhtml->url);
else
fprintf(opt.lfile, "I cannot find the corresponding URL.\n");
}
#endif
/* Parse the HTML file... */
urls = get_urls_html(html->string, urlhtml ? urlhtml->url : NULL, 1);
if (!urls)
continue;
for (l1 = urls; l1; l1 = l1->next)
{
/* The URL must be in canonical form to be compared. */
u = newurl();
res = parseurl(l1->url, u, 0);
if (res != URLOK)
{
freeurl(u, 1);
continue;
}
/* We decide the direction of conversion according to whether
a URL was downloaded. Downloaded URLs will be converted
ABS2REL, whereas non-downloaded will be converted REL2ABS.
Note: not yet implemented; only ABS2REL works. */
for (l2 = urls_downloaded; l2; l2 = l2->next)
if (!strcmp(l2->url, u->url))
{
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile,
"%s flagged for conversion, local %s\n",
l2->url, l2->local_name);
#endif
break;
}
/* Clear the flags. */
l1->flags &= ~(UABS2REL | UREL2ABS);
/* Decide on the conversion direction. */
if (l2)
{
l1->flags |= UABS2REL;
l1->local_name = nstrdup(l2->local_name);
}
else
{
l1->flags |= UREL2ABS;
l1->local_name = NULL;
}
freeurl(u, 1);
}
/* Convert the links in the file. */
convert_links(html->string, urls);
/* Free the data. */
free_urlpos(urls);
}
}
/*******************
* Robots support:
*******************/
/* Construct the robots URL. */
urlinfo *
robots_url(const char *url, const char *robots_filename)
{
urlinfo *u = newurl();
uerr_t err;
err = parseurl(url, u, 0);
assert(err == URLOK && u->proto == URLHTTP);
free(u->file);
free(u->dir);
free(u->url);
u->dir = nstrdup("");
u->file = nstrdup(robots_filename);
u->url = str_url(u, 0);
return u;
}
/* Retrieves the robots_filename from the root server directory, if
possible. Returns ROBOTSOK if robots were retrieved OK, and
NOROBOTS if robots could not be retrieved for any reason. */
uerr_t
retrieve_robots(const char *url, const char *robots_filename)
{
int dt;
uerr_t err;
urlinfo *u;
u = robots_url(url, robots_filename);
if (opt.verbose)
fprintf(opt.lfile, "Loading robots.txt; please ignore errors.\n");
err = retrieve_url(u->url, NULL, NULL, NULL, &dt);
freeurl(u, 1);
if (err == RETROK)
return ROBOTSOK;
else
return NOROBOTS;
}
/* Parses the robots_filename returning the disallowed filenames in a
malloc-ed vector of character pointers.
It should be fully compliant with the syntax as described in the
file norobots.txt, adopted by the robots mailing list
(robots@webcrawler.com). */
char **
parse_robots(const char *robots_filename)
{
FILE *fp;
char **entries;
char *line, *cmd, *str, *p;
char *base_version, *version;
int len, num, i;
int wgetmatched; /* Is the part meant for Wget? */
entries = NULL;
num = 0;
fp = fopen(robots_filename, "r");
if (!fp)
return NULL;
/* Kill version number. */
base_version = nstrdup(version_string);
version = nstrdup(version_string);
for (p = version; *p; p++)
*p = tolower(*p);
for (p = base_version; *p && *p != '/'; p++)
*p = tolower(*p);
*p = '\0';
/* Setting this to 1 means that Wget considers itself under
restrictions by default, even if the User-Agent field is not
present. However, if it finds the user-agent set to something
other than Wget, the rest will be ignored (up to the following
User-Agent field). Thus you may have something like:
Disallow: 1
Disallow: 2
User-Agent: stupid-robot
Disallow: 3
Disallow: 4
User-Agent: Wget*
Disallow: 5
Disallow: 6
User-Agent: *
Disallow: 7
In this case the 1, 2, 5, 6 and 7 disallow lines will be
stored. */
wgetmatched = 1;
while ((line = read_whole_line(fp)))
{
len = strlen(line);
/* Destroy <CR> if there is one. */
if (len && line[len - 1] == '\r')
line[len - 1] = '\0';
/* According to specifications, optional space may be at the
end... */
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile, "Line: %s\n", line);
#endif
/* Skip spaces. */
for (cmd = line; *cmd && isspace(*cmd); cmd++);
if (!*cmd)
{
free(line);
DEBUGP("(chucked out)\n");
continue;
}
/* Look for ':'. */
for (str = cmd; *str && *str != ':'; str++);
if (!*str)
{
free(line);
DEBUGP("(chucked out)\n");
continue;
}
/* Zero-terminate the command. */
*str++ = '\0';
/* Look for the string beginning... */
for (; *str && isspace(*str); str++);
/* Look for comments and kill them off. */
for (p = str; *p && !isspace(*p); p++);
if (isspace(*p) && *(p + 1) == '#')
*p = '\0';
if (!strcasecmp(cmd, "User-agent"))
{
int match = 0;
/* Lowercase the agent string. */
for (p = str; *p; p++)
*p = tolower(*p);
/* If the string is '*', it matches. */
if (*str == '*' && !*(str + 1))
match = 1;
else
{
/* If the string contains wildcards, we'll run it through
fnmatch(). */
if (has_wildcards(str))
{
/* If the string contains '/', compare with the full
version. Else, compare it to base_version. */
if (strchr(str, '/'))
match = !fnmatch(str, version, 0);
else
match = !fnmatch(str, base_version, 0);
}
else /* Substring search */
{
if (strstr(version, str))
match = 1;
else
match = 0;
}
}
/* If Wget is not matched, skip all the entries up to the
next User-agent field. */
wgetmatched = match;
}
else if (!wgetmatched)
{
free(line);
DEBUGP("(chucking out since it is not applicable for Wget)\n");
continue;
}
else if (!strcasecmp(cmd, "Disallow"))
{
/* If "Disallow" is empty, the robot is welcome. */
if (!*str)
{
free_vec(entries);
entries = (char **)nmalloc(sizeof(char *));
*entries = NULL;
}
else
{
entries = (char **)nrealloc(entries, (num + 2)* sizeof(char *));
entries[num] = nstrdup(str);
entries[++num] = NULL;
/* Strip trailing spaces, according to specifications. */
for (i = strlen(str); i >= 0 && isspace(str[i]); i--)
if (isspace(str[i]))
str[i] = '\0';
}
}
else
{
/* unknown command */
DEBUGP("(chucked out)\n");
}
free(line);
}
fclose(fp);
free(base_version);
free(version);
return entries;
}
/* May the URL url be loaded according to disallowing rules stored in
forbidden? */
int
robots_match(urlinfo *u, char **forbidden)
{
int l;
if (!forbidden)
return 1;
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile, "Matching %s against: ", u->path);
#endif
for (; *forbidden; forbidden++)
{
#ifdef DEBUG
if (opt.debug)
fprintf(opt.lfile, "%s ", *forbidden);
#endif
l = strlen(*forbidden);
/* If dir is forbidden, we may not load the file. */
if (strncmp(u->path, *forbidden, l) == 0)
{
DEBUGP("matched.\n");
return 0; /* Matches, i.e. does not load... */
}
}
DEBUGP("not matched.\n");
return 1;
}