sys/src/cmd/ip/httpd/save.c

   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
  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
  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
  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 }