/*                   Lynx CGI support                              LYCgi.c
**                   ================
**
** Authors
**          GL      George Lindholm <George.Lindholm@ubc.ca>
**
** History
**      15 Jun 95   Created as way to provide a lynx based service with
**                  dynamic pages without the need for a http daemon.  GL
**      27 Jun 95   Added <index> (command line) support.  Various cleanup
**                  and bug fixes. GL
**	04 Sep 97   Added support for PATH_INFO scripts.  JKT
**
** Bugs
**      If the called scripts aborts before sending the mime headers then
**      lynx hangs.
**
**      Should do something about SIGPIPE, (but then it should never happen)
**
**      No support for redirection.  Or mime-types.
**
**      Should try and parse for a HTTP 1.1 header in case we are "calling" a
**      nph- script.
*/

#include <HTUtils.h>
#include <HTTP.h>
#include <HTParse.h>
#include <HTTCP.h>
#include <HTFormat.h>
#include <HTFile.h>
#include <HTAlert.h>
#include <HTMIME.h>
#include <HTAABrow.h>

#include <LYGlobalDefs.h>
#include <LYUtils.h>
#include <HTML.h>
#include <HTInit.h>
#include <LYGetFile.h>
#include <LYBookmark.h>
#include <GridText.h>
#include <LYCgi.h>
#include <LYStrings.h>
#include <LYLocal.h>

#include <LYLeaks.h>

#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif

struct _HTStream
{
  HTStreamClass * isa;
};

PRIVATE char **env = NULL;  /* Environment variables */
PRIVATE int envc_size = 0;  /* Slots in environment array */
PRIVATE int envc = 0;	    /* Slots used so far */
PRIVATE HTList *alloced = NULL;
#ifdef LYNXCGI_LINKS
PRIVATE char *user_agent = NULL;
PRIVATE char *server_software = NULL;
PRIVATE char *accept_language = NULL;
PRIVATE char *post_len = NULL;
#endif /* LYNXCGI_LINKS */

PRIVATE void add_environment_value PARAMS((char *env_value));

#define PERROR(msg) CTRACE((tfp, "LYNXCGI: %s: %s\n", msg, LYStrerror(errno)))

#ifdef LY_FIND_LEAKS
PRIVATE void free_alloced_lynxcgi NOARGS
{
    void *ptr;
    while ((ptr = HTList_removeLastObject(alloced)) != NULL) {
	FREE(ptr);
    }
    FREE(alloced);
#ifdef LYNXCGI_LINKS
    FREE(user_agent);
    FREE(server_software);
#endif
}
#endif /* LY_FIND_LEAKS */

PRIVATE void remember_alloced ARGS1(
    void *,		ptr)
{
    if (!alloced) {
	alloced = HTList_new();
#ifdef LY_FIND_LEAKS
	atexit(free_alloced_lynxcgi);
#endif
    }
    HTList_addObject(alloced, ptr);
}

/*
 * Simple routine for expanding the environment array and adding a value to
 * it
 */
PRIVATE void add_environment_value ARGS1(
	char *,	env_value)
{
    if (envc == envc_size) {   /* Need some more slots */
	envc_size += 10;
	if (env) {
	    env = (char **)realloc(env,
				   sizeof(env[0]) * (envc_size + 2));
						/* + terminator and base 0 */
	} else {
	    env = (char **)malloc(sizeof(env[0]) * (envc_size + 2));
						/* + terminator and base 0 */
	    remember_alloced(env);
	}
	if (env == NULL) {
	    outofmem(__FILE__, "LYCgi");
	}
    }

    env[envc++] = env_value;
    env[envc] = NULL;      /* Make sure it is always properly terminated */
}

/*
 * Add the value of an existing environment variable to those passed on to the
 * lynxcgi script.
 */
PUBLIC void add_lynxcgi_environment ARGS1(
	CONST char *,	variable_name)
{
    char *env_value;

    env_value = getenv(variable_name);
    if (env_value != NULL) {
	char *add_value = NULL;

	HTSprintf0(&add_value, "%s=%s", variable_name, env_value);
	add_environment_value(add_value);
	remember_alloced(add_value);
    }
}

PRIVATE int LYLoadCGI ARGS4(
	CONST char *, 		arg,
	HTParentAnchor *,	anAnchor,
	HTFormat,		format_out,
	HTStream*,		sink)
{
    int status = 0;
#ifdef LYNXCGI_LINKS
#ifndef VMS
    char *cp;
    struct stat stat_buf;
    char *pgm = NULL;		        /* executable */
    char *pgm_args = NULL;	        /* and its argument(s) */
    int statrv;
    char *orig_pgm = NULL;		/* Path up to ? as given, URL-escaped*/
    char *document_root = NULL;		/* Corrected value of DOCUMENT_ROOT  */
    char *path_info = NULL;             /* PATH_INFO extracted from pgm      */
    char *pgm_buff = NULL;		/* PATH_INFO extraction buffer       */
    char *path_translated;		/* From document_root/path_info      */

    if (!arg || !*arg || strlen(arg) <= 8) {
	HTAlert(BAD_REQUEST);
	status = -2;
	return(status);

    } else {
	if (strncmp(arg, "lynxcgi://localhost", 19) == 0) {
	    StrAllocCopy(pgm, arg+19);
	} else {
	    StrAllocCopy(pgm, arg+8);
	}
	if ((cp=strchr(pgm, '?')) != NULL) { /* Need to terminate executable */
	    *cp++ = '\0';
	    pgm_args = cp;
	}
    }

    StrAllocCopy(orig_pgm, pgm);
    if ((cp=strchr(pgm, '#')) != NULL) {
	/*
	 *  Strip a #fragment from path.  In this case any pgm_args
	 *  found above will also be bogus, since the '?' came after
	 *  the '#' and is part of the fragment.  Note that we don't
	 *  handle the case where a '#' appears after a '?' properly
	 *  according to URL rules. - kw
	 */
	*cp = '\0';
	pgm_args = NULL;
    }
    HTUnEscape(pgm);

    /* BEGIN WebSter Mods */
    /* If pgm is not stat-able, see if PATH_INFO data is at the end of pgm */
    if ((statrv = stat(pgm, &stat_buf)) < 0) {
	StrAllocCopy(pgm_buff, pgm);
	while (statrv < 0 || (statrv = stat(pgm_buff, &stat_buf)) < 0) {
	    if ((cp=strrchr(pgm_buff, '/')) != NULL) {
		*cp = '\0';
		statrv = 999;	/* force new stat()  - kw */
	    } else {
		PERROR("strrchr(pgm_buff, '/') returned NULL");
	    	break;
	    }
        }

	if (statrv < 0) {
	    /* Did not find PATH_INFO data */
	    PERROR("stat() of pgm_buff failed");
	} else {
	    /* Found PATH_INFO data.  Strip it off of pgm and into path_info. */
	    StrAllocCopy(path_info, pgm + strlen(pgm_buff));
	    /* The following is safe since pgm_buff was derived from pgm
	       by stripping stuff off its end and by HTUnEscaping, so we
	       know we have enough memory allocated for pgm.  Note that
	       pgm_args may still point into that memory, so we cannot
	       reallocate pgm here. - kw */
	    strcpy(pgm, pgm_buff);
	    CTRACE((tfp, "LYNXCGI: stat() of %s succeeded, path_info=\"%s\".\n",
			pgm_buff, path_info));
	}
	FREE(pgm_buff);
    }
    /* END WebSter Mods */

    if (statrv != 0) {
	/*
	 *  Neither the path as given nor any components examined by
	 *  backing up were stat()able. - kw
	 */
	HTAlert(gettext("Unable to access cgi script"));
	PERROR("stat() failed");
	status = -4;

    } else
#ifdef _WINDOWS	/* 1998/01/14 (Wed) 09:16:04 */
#define isExecutable(mode) (mode & (S_IXUSR))
#else
#define isExecutable(mode) (mode & (S_IXUSR|S_IXGRP|S_IXOTH))
#endif
    if (!(S_ISREG(stat_buf.st_mode) && isExecutable(stat_buf.st_mode))) {
	/*
	 *  Not a runnable file, See if we can load it using "file:" code.
	 */
	char *new_arg = NULL;

	/*
	 *  But try "file:" only if the file we are looking at is the path
	 *  as given (no path_info was extracted), otherwise it will be
	 *  to confusing to know just what file is loaded. - kw
	 */
	if (path_info) {
	    CTRACE((tfp, "%s is not a file and %s not an executable, giving up.\n",
			orig_pgm, pgm));
	    FREE(path_info);
	    FREE(pgm);
	    FREE(orig_pgm);
	    status = -4;
	    return(status);
	}

	LYLocalFileToURL (&new_arg, orig_pgm);

	CTRACE((tfp, "%s is not an executable file, passing the buck.\n", arg));
	status = HTLoadFile(new_arg, anAnchor, format_out, sink);
	FREE(new_arg);

    } else if (path_info &&
	       anAnchor != HTMainAnchor &&
	       !(reloading && anAnchor->document) &&
	       strcmp(arg, HTLoadedDocumentURL()) &&
	       HText_AreDifferent(anAnchor, arg) &&
	       HTUnEscape(orig_pgm) &&
	       !exec_ok(HTLoadedDocumentURL(), orig_pgm,
			CGI_PATH)) { /* exec_ok gives out msg. */
	/*
	 *  If we have extra path info and are not just reloading
	 *  the current, check the full file path (after unescaping)
	 *  now to catch forbidden segments. - kw
	 */
	status = HT_NOT_LOADED;

    } else if (no_lynxcgi) {
	HTUserMsg(CGI_DISABLED);
	status = HT_NOT_LOADED;

    } else if (no_bookmark_exec &&
	       anAnchor != HTMainAnchor &&
	       !(reloading && anAnchor->document) &&
	       strcmp(arg, HTLoadedDocumentURL()) &&
	       HText_AreDifferent(anAnchor, arg) &&
 	       HTLoadedDocumentBookmark()) {
	/*
	 *  If we are reloading a lynxcgi document that had already been
	 *  loaded, the various checks above should allow it even if
	 *  no_bookmark_exec is TRUE an we are not now coming from a
	 *  bookmark page. - kw
	 */
	HTUserMsg(BOOKMARK_EXEC_DISABLED);
	status = HT_NOT_LOADED;

    } else if (anAnchor != HTMainAnchor &&
	       !(reloading && anAnchor->document) &&
	       strcmp(arg, HTLoadedDocumentURL()) &&
	       HText_AreDifferent(anAnchor, arg) &&
	       !exec_ok(HTLoadedDocumentURL(), pgm,
			CGI_PATH)) { /* exec_ok gives out msg. */
	/*
	 *  If we are reloading a lynxcgi document that had already been
	 *  loaded, the various checks above should allow it even if
	 *  exec_ok() would reject it because we are not now coming from
	 *  a document with a URL allowed by TRUSTED_LYNXCGI rules. - kw
	 */
	status = HT_NOT_LOADED;

    } else {
	HTFormat format_in;
	HTStream *target  = NULL;		/* Unconverted data */
	int fd1[2], fd2[2];
	char buf[1024];
	pid_t pid;
#ifdef HAVE_TYPE_UNIONWAIT
	union wait wstatus;
#else
	int wstatus;
#endif

	if (anAnchor->isHEAD || keep_mime_headers) {

	    /* Show output as plain text */
	    format_in = WWW_PLAINTEXT;
	} else {

	    /* Decode full HTTP response */
	    format_in = HTAtom_for("www/mime");
	}

	target = HTStreamStack(format_in,
			       format_out,
			       sink, anAnchor);

	if (!target || target == NULL) {
	    char *tmp = 0;
	    HTSprintf0(&tmp, CANNOT_CONVERT_I_TO_O,
		       HTAtom_name(format_in),
		       HTAtom_name(format_out));
	    HTAlert(tmp);
	    FREE(tmp);
	    status = HT_NOT_LOADED;

	} else if (anAnchor->post_data && pipe(fd1) < 0) {
	    HTAlert(CONNECT_SET_FAILED);
	    PERROR("pipe() failed");
	    status = -3;

	} else if (pipe(fd2) < 0) {
	    HTAlert(CONNECT_SET_FAILED);
	    PERROR("pipe() failed");
	    close(fd1[0]);
	    close(fd1[1]);
	    status = -3;

	} else {
	    static BOOL first_time = TRUE;      /* One time setup flag */

	    if (first_time) {	/* Set up static environment variables */
		first_time = FALSE;	/* Only once */

		add_environment_value("REMOTE_HOST=localhost");
		add_environment_value("REMOTE_ADDR=127.0.0.1");

		HTSprintf0(&user_agent, "HTTP_USER_AGENT=%s/%s libwww/%s",
			LYNX_NAME, LYNX_VERSION, HTLibraryVersion);
		add_environment_value(user_agent);

		HTSprintf0(&server_software, "SERVER_SOFTWARE=%s/%s",
			LYNX_NAME, LYNX_VERSION);
		add_environment_value(server_software);
	    }
	    fflush(stdout);
	    fflush(stderr);
	    CTRACE_FLUSH(tfp);

	    if ((pid = fork()) > 0) { /* The good, */
		int chars, total_chars;

		close(fd2[1]);

		if (anAnchor->post_data) {
		    int written, remaining, total_written = 0;
		    close(fd1[0]);

		    /* We have form data to push across the pipe */
		    CTRACE((tfp, "LYNXCGI: Doing post, content-type '%s'\n",
				anAnchor->post_content_type));
		    CTRACE((tfp, "LYNXCGI: Writing:\n%s----------------------------------\n",
				anAnchor->post_data));
		    remaining = strlen(anAnchor->post_data);
		    while ((written = write(fd1[1],
					    anAnchor->post_data + total_written,
					    remaining)) != 0) {
			if (written < 0) {
#ifdef EINTR
			    if (errno == EINTR)
				continue;
#endif /* EINTR */
#ifdef ERESTARTSYS
			    if (errno == ERESTARTSYS)
				continue;
#endif /* ERESTARTSYS */
			    PERROR("write() of POST data failed");
			    break;
			}
			CTRACE((tfp, "LYNXCGI: Wrote %d bytes of POST data.\n",
				    written));
			total_written += written;
			remaining -= written;
			if (remaining == 0)
			    break;
		    }
		    if (remaining != 0) {
			CTRACE((tfp, "LYNXCGI: %d bytes remain unwritten!\n",
				    remaining));
		    }
		    close(fd1[1]);
		}

		HTReadProgress(total_chars = 0, 0);
		while((chars = read(fd2[0], buf, sizeof(buf))) != 0) {
		    if (chars < 0) {
#ifdef EINTR
			if (errno == EINTR)
			    continue;
#endif /* EINTR */
#ifdef ERESTARTSYS
			if (errno == ERESTARTSYS)
			    continue;
#endif /* ERESTARTSYS */
			PERROR("read() of CGI output failed");
			break;
		    }
		    HTReadProgress(total_chars += chars, 0);
		    CTRACE((tfp, "LYNXCGI: Rx: %.*s\n", chars, buf));
		    (*target->isa->put_block)(target, buf, chars);
		}

		if (chars < 0 && total_chars == 0) {
		    status = HT_NOT_LOADED;
		    (*target->isa->_abort)(target, NULL);
		    target = NULL;
		} else if (chars != 0) {
		    status = HT_PARTIAL_CONTENT;
		} else {
		    status = HT_LOADED;
		}

#if !HAVE_WAITPID
		while (wait(&wstatus) != pid)
		    ; /* do nothing */
#else
		while (-1 == waitpid(pid, &wstatus, 0)) { /* wait for child */
#ifdef EINTR
		    if (errno == EINTR)
			continue;
#endif /* EINTR */
#ifdef ERESTARTSYS
		    if (errno == ERESTARTSYS)
			continue;
#endif /* ERESTARTSYS */
		    break;
		}
#endif /* !HAVE_WAITPID */
		close(fd2[0]);

	    } else if (pid == 0) { /* The Bad, */
		char **argv = NULL;
		int argv_cnt = 3; /* name, one arg and terminator */
		char **cur_argv = NULL;
		int exec_errno;

		/* Set up output pipe */
		close(fd2[0]);
		dup2(fd2[1], fileno(stdout)); /* Should check success code */
		dup2(fd2[1], fileno(stderr));
		close(fd2[1]);

		if (language && *language) {
		HTSprintf0(&accept_language, "HTTP_ACCEPT_LANGUAGE=%s", language);
		add_environment_value(accept_language);
		}

		if (pref_charset && *pref_charset) {
		    cp = NULL;
		    StrAllocCopy(cp, "HTTP_ACCEPT_CHARSET=");
		    StrAllocCat(cp, pref_charset);
		    add_environment_value(cp);
		}

		if (anAnchor->post_data &&
		    anAnchor->post_content_type) {
		    cp = NULL;
		    StrAllocCopy(cp, "CONTENT_TYPE=");
		    StrAllocCat(cp, anAnchor->post_content_type);
		    add_environment_value(cp);
		}

		if (anAnchor->post_data) { /* post script, read stdin */
		    close(fd1[1]);
		    dup2(fd1[0], fileno(stdin));
		    close(fd1[0]);

		    /* Build environment variables */

		    add_environment_value("REQUEST_METHOD=POST");

		    HTSprintf0(&post_len, "CONTENT_LENGTH=%d",
			    strlen(anAnchor->post_data));
		    add_environment_value(post_len);
		} else {
		    close(fileno(stdin));

		    if (anAnchor->isHEAD) {
			add_environment_value("REQUEST_METHOD=HEAD");
		    }
		}

		/*
		 * Set up argument line, mainly for <index> scripts
		 */
		if (pgm_args != NULL) {
		    for (cp = pgm_args; *cp != '\0'; cp++) {
			if (*cp == '+') {
			    argv_cnt++;
			}
		    }
		}

		argv = (char**)malloc(argv_cnt * sizeof(char*));
		if (argv == NULL) {
		    outofmem(__FILE__, "LYCgi");
		}
		cur_argv = argv + 1;		/* For argv[0] */
		if (pgm_args != NULL) {
		    char *cr;

		    /* Data for a get/search form */
		    if (is_www_index) {
			add_environment_value("REQUEST_METHOD=SEARCH");
		    } else if (!anAnchor->isHEAD && !anAnchor->post_data) {
			add_environment_value("REQUEST_METHOD=GET");
		    }

		    cp = NULL;
		    StrAllocCopy(cp, "QUERY_STRING=");
		    StrAllocCat(cp, pgm_args);
		    add_environment_value(cp);

		    /*
		     * Split up arguments into argv array
		     */
		    cp = pgm_args;
		    cr = cp;
		    while(1) {
			if (*cp == '\0') {
			    *(cur_argv++) = HTUnEscape(cr);
			    break;

			} else if (*cp == '+') {
			    *cp++ = '\0';
			    *(cur_argv++) = HTUnEscape(cr);
			    cr = cp;
			}
			cp++;
		    }
		} else if (!anAnchor->isHEAD && !anAnchor->post_data) {
		    add_environment_value("REQUEST_METHOD=GET");
		}
		*cur_argv = NULL;	/* Terminate argv */
		argv[0] = pgm;

		/* Begin WebSter Mods  -jkt */
		if (LYCgiDocumentRoot != NULL) {
		    /* Add DOCUMENT_ROOT to env */
		    cp = NULL;
		    StrAllocCopy(cp, "DOCUMENT_ROOT=");
		    StrAllocCat(cp, LYCgiDocumentRoot);
		    add_environment_value(cp);
		}
		if (path_info != NULL ) {
		    /* Add PATH_INFO to env */
		    cp = NULL;
		    StrAllocCopy(cp, "PATH_INFO=");
		    StrAllocCat(cp, path_info);
		    add_environment_value(cp);
		}
		if (LYCgiDocumentRoot != NULL && path_info != NULL ) {
		    /* Construct and add PATH_TRANSLATED to env */
		    StrAllocCopy(document_root, LYCgiDocumentRoot);
		    LYTrimHtmlSep(document_root);
		    path_translated = document_root;
		    StrAllocCat(path_translated, path_info);
		    cp = NULL;
		    StrAllocCopy(cp, "PATH_TRANSLATED=");
		    StrAllocCat(cp, path_translated);
		    add_environment_value(cp);
		    FREE(path_translated);
		}
		/* End WebSter Mods  -jkt */

		execve(argv[0], argv, env);
		exec_errno = errno;
		PERROR("execve failed");
		printf("Content-Type: text/plain\r\n\r\n");
		if (!anAnchor->isHEAD) {
		    printf("exec of %s failed", pgm);
		    printf(": %s.\r\n", LYStrerror(exec_errno));
		}
		fflush(stdout);
		fflush(stderr);
		_exit(1);

	    } else {	/* and the Ugly */
		HTAlert(CONNECT_FAILED);
		PERROR("fork() failed");
		status = HT_NO_DATA;
		close(fd1[0]);
		close(fd1[1]);
		close(fd2[0]);
		close(fd2[1]);
		status = -1;
	    }

	}
	if (target != NULL) {
	    (*target->isa->_free)(target);
	}
    }
    FREE(path_info);
    FREE(pgm);
    FREE(orig_pgm);
#else  /* VMS */
    HTStream *target;
    char *buf = 0;

    target = HTStreamStack(WWW_HTML,
			   format_out,
			   sink, anAnchor);

    HTSprintf0(&buf, "<head>\n<title>%s</title>\n</head>\n<body>\n", gettext("Good Advice"));
    (*target->isa->put_block)(target, buf, strlen(buf));

    HTSprintf0(&buf, "<h1>%s</h1>\n", gettext("Good Advice"));
    (*target->isa->put_block)(target, buf, strlen(buf));

    HTSprintf0(&buf, "%s <a\n", gettext("An excellent http server for VMS is available via"));
    (*target->isa->put_block)(target, buf, strlen(buf));

    HTSprintf0(&buf,
	       "href=\"http://kcgl1.eng.ohio-state.edu/www/doc/serverinfo.html\"\n");
    (*target->isa->put_block)(target, buf, strlen(buf));

    HTSprintf0(&buf, ">%s</a>.\n", gettext("this link"));
    (*target->isa->put_block)(target, buf, strlen(buf));

    HTSprintf0(&buf, "<p>%s\n",
	       gettext("It provides state of the art CGI script support.\n"));
    (*target->isa->put_block)(target, buf, strlen(buf));

    HTSprintf0(&buf,"</body>\n");
    (*target->isa->put_block)(target, buf, strlen(buf));

    (*target->isa->_free)(target);
    FREE(buf);
    status = HT_LOADED;
#endif /* VMS */
#else /* LYNXCGI_LINKS */
    HTUserMsg(CGI_NOT_COMPILED);
    status = HT_NOT_LOADED;
#endif /* LYNXCGI_LINKS */
    return(status);
}

#ifdef GLOBALDEF_IS_MACRO
#define _LYCGI_C_GLOBALDEF_1_INIT { "lynxcgi", LYLoadCGI, 0 }
GLOBALDEF (HTProtocol,LYLynxCGI,_LYCGI_C_GLOBALDEF_1_INIT);
#else
GLOBALDEF PUBLIC HTProtocol LYLynxCGI = { "lynxcgi", LYLoadCGI, 0 };
#endif /* GLOBALDEF_IS_MACRO */
