📄 webls.c
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#include <u.h>#include <libc.h>#include <ctype.h>#include <bio.h>#include <regexp.h>#include <fcall.h>#include "httpd.h"#include "httpsrv.h"static Hio *hout;static Hio houtb;static HConnect *connect;static int vermaj, gidwidth, uidwidth, lenwidth, devwidth;static Biobuf *aio, *dio;static voiddoctype(void){ hprint(hout, "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\"\n"); hprint(hout, " \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">\n");}voiderror(char *title, char *fmt, ...){ va_list arg; char buf[1024], *out; va_start(arg, fmt); out = vseprint(buf, buf+sizeof(buf), fmt, arg); va_end(arg); *out = 0; hprint(hout, "%s 404 %s\r\n", hversion, title); hprint(hout, "Date: %D\r\n", time(nil)); hprint(hout, "Server: Plan9\r\n"); hprint(hout, "Content-type: text/html\r\n"); hprint(hout, "\r\n"); doctype(); hprint(hout, "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n"); hprint(hout, "<head><title>%s</title></head>\n", title); hprint(hout, "<body>\n"); hprint(hout, "<h1>%s</h1>\n", title); hprint(hout, "%s\n", buf); hprint(hout, "</body>\n"); hprint(hout, "</html>\n"); hflush(hout); writelog(connect, "Reply: 404\nReason: %s\n", title); exits(nil);}/* * Are we actually allowed to look in here? * * Rules: * 1) If neither allowed nor denied files exist, access is granted. * 2) If allowed exists and denied does not, dir *must* be in allowed * for access to be granted, otherwise, access is denied. * 3) If denied exists and allowed does not, dir *must not* be in * denied for access to be granted, otherwise, access is enied. * 4) If both exist, okay if either (a) file is not in denied, or * (b) in denied and in allowed. Otherwise, access is denied. */static Reprog *getre(Biobuf *buf){ Reprog *re; char *p, *t; char *bbuf; int n; if (buf == nil) return(nil); for ( ; ; free(p)) { p = Brdstr(buf, '\n', 0); if (p == nil) return(nil); t = strchr(p, '#'); if (t != nil) *t = '\0'; t = p + strlen(p); while (--t > p && isspace(*t)) *t = '\0'; n = strlen(p); if (n == 0) continue; /* root the regular expresssion */ bbuf = malloc(n+2); if(bbuf == nil) sysfatal("out of memory"); bbuf[0] = '^'; strcpy(bbuf+1, p); re = regcomp(bbuf); free(bbuf); if (re == nil) continue; free(p); return(re); }}static intallowed(char *dir){ Reprog *re; int okay; Resub match; if (strcmp(dir, "..") == 0 || strncmp(dir, "../", 3) == 0) return(0); if (aio == nil) return(0); if (aio != nil) Bseek(aio, 0, 0); if (dio != nil) Bseek(dio, 0, 0); /* if no deny list, assume everything is denied */ okay = (dio != nil); /* go through denials till we find a match */ while (okay && (re = getre(dio)) != nil) { memset(&match, 0, sizeof(match)); okay = (regexec(re, dir, &match, 1) != 1); free(re); } /* go through accepts till we have a match */ if (aio == nil) return(okay); while (!okay && (re = getre(aio)) != nil) { memset(&match, 0, sizeof(match)); okay = (regexec(re, dir, &match, 1) == 1); free(re); } return(okay);}/* * Comparison routine for sorting the directory. */static intcompar(Dir *a, Dir *b){ return(strcmp(a->name, b->name));}/* * These is for formating; how wide are variable-length * fields? */static voidmaxwidths(Dir *dp, long n){ long i; char scratch[64]; for (i = 0; i < n; i++) { if (snprint(scratch, sizeof scratch, "%ud", dp[i].dev) > devwidth) devwidth = strlen(scratch); if (strlen(dp[i].uid) > uidwidth) uidwidth = strlen(dp[i].uid); if (strlen(dp[i].gid) > gidwidth) gidwidth = strlen(dp[i].gid); if (snprint(scratch, sizeof scratch, "%lld", dp[i].length) > lenwidth) lenwidth = strlen(scratch); }}/* * Do an actual directory listing. * asciitime is lifted directly out of ls. */char *asciitime(long l){ ulong clk; static char buf[32]; char *t; clk = time(nil); t = ctime(l); /* 6 months in the past or a day in the future */ if(l<clk-180L*24*60*60 || clk+24L*60*60<l){ memmove(buf, t+4, 7); /* month and day */ memmove(buf+7, t+23, 5); /* year */ }else memmove(buf, t+4, 12); /* skip day of week */ buf[12] = 0; return buf;}static voiddols(char *dir){ Dir *d; char *f, *p,*nm; long i, n; int fd; cleanname(dir); // expands "" to "."; ``dir+1'' access below depends on that if (!allowed(dir)) { error("Permission denied", "<p>Cannot list directory %s: Access prohibited</p>", dir); return; } fd = open(dir, OREAD); if (fd < 0) { error("Cannot read directory", "<p>Cannot read directory %s: %r</p>", dir); return; } if (vermaj) { hokheaders(connect); hprint(hout, "Content-type: text/html\r\n"); hprint(hout, "\r\n"); } doctype(); hprint(hout, "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n"); hprint(hout, "<head><title>Index of %s</title></head>\n", dir); hprint(hout, "<body>\n"); hprint(hout, "<h1>Index of "); nm = dir; while((p = strchr(nm, '/')) != nil){ *p = '\0'; f = (*dir == '\0') ? "/" : dir; if (!(*dir == '\0' && *(dir+1) == '\0') && allowed(f)) hprint(hout, "<a href=\"/magic/webls?dir=%H\">%s/</a>", f, nm); else hprint(hout, "%s/", nm); *p = '/'; nm = p+1; } hprint(hout, "%s</h1>\n", nm); n = dirreadall(fd, &d); close(fd); maxwidths(d, n); qsort(d, n, sizeof(Dir), (int (*)(void *, void *))compar); hprint(hout, "<pre>\n"); for (i = 0; i < n; i++) { f = smprint("%s/%s", dir, d[i].name); cleanname(f); if (d[i].mode & DMDIR) { p = smprint("/magic/webls?dir=%H", f); free(f); f = p; } hprint(hout, "%M %C %*ud %-*s %-*s %*lld %s <a href=\"%s\">%s</a>\n", d[i].mode, d[i].type, devwidth, d[i].dev, uidwidth, d[i].uid, gidwidth, d[i].gid, lenwidth, d[i].length, asciitime(d[i].mtime), f, d[i].name); free(f); } f = smprint("%s/..", dir); cleanname(f); if (strcmp(f, dir) != 0 && allowed(f)) hprint(hout, "\nGo to <a href=\"/magic/webls?dir=%H\">parent</a> directory\n", f); else hprint(hout, "\nEnd of directory listing\n"); free(f); hprint(hout, "</pre>\n</body>\n</html>\n"); hflush(hout); free(d);}/* * Handle unpacking the request in the URI and * invoking the actual handler. */static voiddosearch(char *search){ if (strncmp(search, "dir=", 4) == 0){ search = hurlunesc(connect, search+4); dols(search); return; } /* * Otherwise, we've gotten an illegal request. * spit out a non-apologetic error. */ search = hurlunesc(connect, search); error("Bad directory listing request", "<p>Illegal formatted directory listing request:</p>\n" "<p>%H</p>", search);}voidmain(int argc, char **argv){ fmtinstall('H', httpfmt); fmtinstall('U', hurlfmt); fmtinstall('M', dirmodefmt); aio = Bopen("/sys/lib/webls.allowed", OREAD); dio = Bopen("/sys/lib/webls.denied", OREAD); if(argc == 2){ hinit(&houtb, 1, Hwrite); hout = &houtb; dols(argv[1]); exits(nil); } close(2); connect = init(argc, argv); hout = &connect->hout; vermaj = connect->req.vermaj; if(hparseheaders(connect, HSTIMEOUT) < 0) exits("failed"); if(strcmp(connect->req.meth, "GET") != 0 && strcmp(connect->req.meth, "HEAD") != 0){ hunallowed(connect, "GET, HEAD"); exits("not allowed"); } if(connect->head.expectother || connect->head.expectcont){ hfail(connect, HExpectFail, nil); exits("failed"); } bind("/usr/web", "/", MREPL); if(connect->req.search != nil) dosearch(connect->req.search); else error("Bad argument", "<p>Need a search argument</p>"); hflush(hout); writelog(connect, "200 webls %ld %ld\n", hout->seek, hout->seek); exits(nil);}⌨️ 快捷键说明
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