1 /*
2 * for GET or POST to /magic/save/foo.
3 * add incoming data to foo.data.
4 * send foo.html as reply.
5 *
6 * supports foo.data with "exclusive use" mode to prevent interleaved saves.
7 * thus http://cm.bell-labs.com/magic/save/t?args should access:
8 * -lrw-rw--w- M 21470 ehg web 1533 May 21 18:19 /usr/web/save/t.data
9 * --rw-rw-r-- M 21470 ehg web 73 May 21 18:17 /usr/web/save/t.html
10 */
11 #include <u.h>
12 #include <libc.h>
13 #include <bio.h>
14 #include "httpd.h"
15 #include "httpsrv.h"
16
17 enum
18 {
19 MaxLog = 24*1024, /* limit on length of any one log request */
20 LockSecs = MaxLog/500, /* seconds to wait before giving up on opening the data file */
21 };
22
23 static int
dangerous(char * s)24 dangerous(char *s)
25 {
26 if(s == nil)
27 return 1;
28
29 /*
30 * This check shouldn't be needed;
31 * filename folding is already supposed to have happened.
32 * But I'm paranoid.
33 */
34 while(s = strchr(s,'/')){
35 if(s[1]=='.' && s[2]=='.')
36 return 1;
37 s++;
38 }
39 return 0;
40 }
41
42 /*
43 * open a file which might be locked.
44 * if it is, spin until available
45 */
46 int
openLocked(char * file,int mode)47 openLocked(char *file, int mode)
48 {
49 char buf[ERRMAX];
50 int tries, fd;
51
52 for(tries = 0; tries < LockSecs*2; tries++){
53 fd = open(file, mode);
54 if(fd >= 0)
55 return fd;
56 errstr(buf, sizeof buf);
57 if(strstr(buf, "locked") == nil)
58 break;
59 sleep(500);
60 }
61 return -1;
62 }
63
64 void
main(int argc,char ** argv)65 main(int argc, char **argv)
66 {
67 HConnect *c;
68 Dir *dir;
69 Hio *hin, *hout;
70 char *s, *t, *fn;
71 int n, nfn, datafd, htmlfd;
72
73 c = init(argc, argv);
74
75 if(dangerous(c->req.uri)){
76 hfail(c, HSyntax);
77 exits("failed");
78 }
79
80 if(hparseheaders(c, HSTIMEOUT) < 0)
81 exits("failed");
82 hout = &c->hout;
83 if(c->head.expectother){
84 hfail(c, HExpectFail, nil);
85 exits("failed");
86 }
87 if(c->head.expectcont){
88 hprint(hout, "100 Continue\r\n");
89 hprint(hout, "\r\n");
90 hflush(hout);
91 }
92
93 s = nil;
94 if(strcmp(c->req.meth, "POST") == 0){
95 hin = hbodypush(&c->hin, c->head.contlen, c->head.transenc);
96 if(hin != nil){
97 alarm(HSTIMEOUT);
98 s = hreadbuf(hin, hin->pos);
99 alarm(0);
100 }
101 if(s == nil){
102 hfail(c, HBadReq, nil);
103 exits("failed");
104 }
105 t = strchr(s, '\n');
106 if(t != nil)
107 *t = '\0';
108 }else if(strcmp(c->req.meth, "GET") != 0 && strcmp(c->req.meth, "HEAD") != 0){
109 hunallowed(c, "GET, HEAD, PUT");
110 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 }
155