#include <u.h>#include <libc.h>#include "httpd.h"#include "httpsrv.h" // htmlquote//   escape < as &lt; to avoid cross-site scripting//   escape > as &gt; because some browsers "helpfully" insert < when seeing a >//   <META ... charset=ISO-8859-1"> because UTF-7 has other ways to write <//   and escape & as &amp; for appearance sake// caller should freestatic char *hq(char *text){	int textlen = strlen(text), escapedlen = textlen;	char *escaped, *s, *w; 	for(s = text; *s; s++)		if(*s=='<' || *s=='>' || *s=='&')			escapedlen += 4;	escaped = ezalloc(escapedlen+1);	for(s = text, w = escaped; *s; s++){		if(*s == '<'){			strcpy(w, "&lt;");			w += 4;		}else if(*s == '>'){			strcpy(w, "&gt;");			w += 4;		}else if(*s == '&'){			strcpy(w, "&amp;");			w += 5;		}else{			*w++ = *s;		}	}	return escaped;} static voidhqwrite(Hio *hout, char *s, int n){	char *buf = ezalloc(n+1), *esc; 	memcpy(buf, s, n);	buf[n] = 0;	esc = hq(buf);	hwrite(hout, esc, strlen(esc));	free(esc);	free(buf);} voidmain(int argc, char **argv){	HConnect *c;	HSPriv *hp;	Hio *hout, *hin;	char *s; 	c = init(argc, argv);	if(hparseheaders(c, 15*60*1000) < 0)		exits("failed");	hout = &c->hout;	if(c->head.expectother){		hfail(c, HExpectFail, nil);		exits("failed");	}	if(c->head.expectcont){		hprint(hout, "100 Continue\r\n");		hprint(hout, "\r\n");		hflush(hout);	}	if(c->req.vermaj){		hokheaders(c);		hprint(hout, "Content-type: text/html\r\n");		hprint(hout, "\r\n");	}	hprint(hout, "<HEAD><META http-equiv=\"Content-Type\" content=\"text/html; charset=ISO-8859-1\"><TITLE>Echo</TITLE></HEAD><BODY><h1>Echo</h1>\r\n");	hp = c->private;	hprint(hout, "You connected from sys %s, serv %s\r\n",		hp->remotesys, hp->remoteserv);	hprint(hout, "<p>You requested a %s, version HTTP/%d.%d on %s",		hq(c->req.meth), c->req.vermaj, c->req.vermin, hq(c->req.uri));	if(c->req.search)		hprint(hout, " with search string %s", hq(c->req.search));	hprint(hout, ".\r\n"); 	hprint(hout, "<p>Your client sent the following headers:<p><PRE>\r\n");	hqwrite(hout, (char*)(c->header), c->hstop - c->header); 	if(strcmp(c->req.meth, "POST") == 0){		hin = hbodypush(&c->hin, c->head.contlen, c->head.transenc);		if(hin == nil)			hprint(hout, "<p>With an invalid or unsupported body length specification.<p>");		else{			hprint(hout, "with POSTed data:<p><PRE>\n'");			alarm(15*60*1000);			for(; s = hreadbuf(hin, hin->pos); hin->pos = hin->stop)				hqwrite(hout, s, hbuflen(hin, s));			alarm(0);			hprint(hout, "'\n</PRE>");		}	} 	hprint(hout, "</PRE></BODY>\n");	hflush(hout);	writelog(c, "Reply: 200 echo %ld %ld\n", hout->seek, hout->seek);	exits(nil);}