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/*
2 
 * for GET or POST to /magic/save/foo.
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 * add incoming data to foo.data.
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 * send foo.html as reply.
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 *
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 * supports foo.data with "exclusive use" mode to prevent interleaved saves.
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 * thus http://cm.bell-labs.com/magic/save/t?args should access:
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 * -lrw-rw--w- M 21470 ehg web 1533 May 21 18:19 /usr/web/save/t.data
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 * --rw-rw-r-- M 21470 ehg web   73 May 21 18:17 /usr/web/save/t.html
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*/
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#include <u.h>
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#include <libc.h>
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#include <bio.h>
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#include "httpd.h"
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#include "httpsrv.h"
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enum
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{
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	MaxLog		= 24*1024,		/* limit on length of any one log request */
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	LockSecs	= MaxLog/500,		/* seconds to wait before giving up on opening the data file */
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};
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static int
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dangerous(char *s)
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{
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	if(s == nil)
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		return 1;
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	/*
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	 * This check shouldn't be needed;
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	 * filename folding is already supposed to have happened.
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	 * But I'm paranoid.
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	 */
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	while(s = strchr(s,'/')){
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		if(s[1]=='.' && s[2]=='.')
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			return 1;
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		s++;
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	}
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	return 0;
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}
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/*
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 * open a file which might be locked.
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 * if it is, spin until available
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 */
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int
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openLocked(char *file, int mode)
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{
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	char buf[ERRMAX];
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	int tries, fd;
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	for(tries = 0; tries < LockSecs*2; tries++){
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		fd = open(file, mode);
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		if(fd >= 0)
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			return fd;
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		errstr(buf, sizeof buf);
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		if(strstr(buf, "locked") == nil)
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			break;
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		sleep(500);
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	}
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	return -1;
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}
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void
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main(int argc, char **argv)
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{
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	HConnect *c;
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	Dir *dir;
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	Hio *hin, *hout;
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	char *s, *t, *fn;
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	int n, nfn, datafd, htmlfd;
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	c = init(argc, argv);
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75 
	if(dangerous(c->req.uri)){
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		hfail(c, HSyntax);
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		exits("failed");
78 
	}
79 
 
80 
	if(hparseheaders(c, HSTIMEOUT) < 0)
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		exits("failed");
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	hout = &c->hout;
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	if(c->head.expectother){
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		hfail(c, HExpectFail, nil);
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		exits("failed");
86 
	}
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	if(c->head.expectcont){
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		hprint(hout, "100 Continue\r\n");
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		hprint(hout, "\r\n");
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		hflush(hout);
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	}
92 
 
93 
	s = nil;
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	if(strcmp(c->req.meth, "POST") == 0){
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		hin = hbodypush(&c->hin, c->head.contlen, c->head.transenc);
96 
		if(hin != nil){
97 
			alarm(HSTIMEOUT);
98 
			s = hreadbuf(hin, hin->pos);
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			alarm(0);
100 
		}
101 
		if(s == nil){
102 
			hfail(c, HBadReq, nil);
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			exits("failed");
104 
		}
105 
		t = strchr(s, '\n');
106 
		if(t != nil)
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			*t = '\0';
108 
	}else if(strcmp(c->req.meth, "GET") != 0 && strcmp(c->req.meth, "HEAD") != 0){
109 
		hunallowed(c, "GET, HEAD, PUT");
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		exits("unallowed");
111 
	}else
112 
		s = c->req.search;
113 
	if(s == nil){
114 
		hfail(c, HNoData, "save");
115 
		exits("failed");
116 
	}
117 
 
118 
	if(strlen(s) > MaxLog)
119 
		s[MaxLog] = '\0';
120 
	n = snprint(c->xferbuf, HBufSize, "at %ld %s\n", time(0), s);
121 
 
122 
 
123 
	nfn = strlen(c->req.uri) + 64;
124 
	fn = halloc(c, nfn);
125 
 
126 
	/*
127 
	 * open file descriptors & write log line
128 
	 */
129 
	snprint(fn, nfn, "/usr/web/save/%s.html", c->req.uri);
130 
	htmlfd = open(fn, OREAD);
131 
	if(htmlfd < 0 || (dir = dirfstat(htmlfd)) == nil){
132 
		hfail(c, HNotFound, c->req.uri);
133 
		exits("failed");
134 
		return;
135 
	}
136 
 
137 
	snprint(fn, nfn, "/usr/web/save/%s.data", c->req.uri);
138 
	datafd = openLocked(fn, OWRITE);
139 
	if(datafd < 0){
140 
		errstr(c->xferbuf, sizeof c->xferbuf);
141 
		if(strstr(c->xferbuf, "locked") != nil)
142 
			hfail(c, HTempFail, c->req.uri);
143 
		else
144 
			hfail(c, HNotFound, c->req.uri);
145 
		exits("failed");
146 
	}
147 
	seek(datafd, 0, 2);
148 
	write(datafd, c->xferbuf, n);
149 
	close(datafd);
150 
 
151 
	sendfd(c, htmlfd, dir, hmkcontent(c, "text", "html", nil), nil);
152 
 
153 
	exits(nil);
154 
}