Accept filter maintainance

Update copyrights.

Introduce a new sysctl node:
  net.inet.accf

Although acceptfilters need refcounting to be properly (safely) unloaded
as a temporary hack allow them to be unloaded if the sysctl
net.inet.accf.unloadable is set, this is really for developers who want
to work on thier own filters.

A near complete re-write of the accf_http filter:
  1) Parse check if the request is HTTP/1.0 or HTTP/1.1 if not dump
     to the application.
     Because of the performance implications of this there is a sysctl
     'net.inet.accf.http.parsehttpversion' that when set to non-zero
     parses the HTTP version.
     The default is to parse the version.
  2) Check if a socket has filled and dump to the listener
  3) optimize the way that mbuf boundries are handled using some voodoo
  4) even though you'd expect accept filters to only be used on TCP
     connections that don't use m_nextpkt I've fixed the accept filter
     for socket connections that use this.

This rewrite of accf_http should allow someone to use them and maintain
full HTTP compliance as long as net.inet.accf.http.parsehttpversion is
set.

sys/kern/uipc_accf.c

@@ -1,5 +1,6 @@
-/*-
- * Copyright (c) 2000 Alfred Perlstein <alfred@FreeBSD.org>
+/*
+ * Copyright (c) 2000 Paycounter, Inc.
+ * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -37,6 +38,7 @@
 #include <sys/malloc.h>
 #include <sys/mbuf.h>
 #include <sys/protosw.h>
+#include <sys/sysctl.h>
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/queue.h>
@@ -46,6 +48,13 @@ static SLIST_HEAD(, accept_filter) accept_filtlsthd =
 
 MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
 
+static int unloadable = 0;
+
+SYSCTL_DECL(_net_inet);	/* XXX: some header should do this for me */
+SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
+SYSCTL_INT(_net_inet_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
+	"Allow unload of accept filters (not recommended)");
+
 /*
  * must be passed a malloc'd structure so we don't explode if the kld
  * is unloaded, we leak the struct on deallocation to deal with this,
@@ -121,12 +130,12 @@ accept_filt_generic_mod_event(module_t mod, int event, void *data)
 		 * is a bad thing.  A simple fix would be to track the refcount
 		 * in the struct accept_filter.
 		 */
-#if 0
-		s = splnet();
-		error = accept_filt_del(accfp->accf_name);
-		splx(s);
-#endif
-		error = EOPNOTSUPP;
+		if (unloadable != 0) {
+			s = splnet();
+			error = accept_filt_del(accfp->accf_name);
+			splx(s);
+		} else
+			error = EOPNOTSUPP;
 		break;
 
 	case MOD_SHUTDOWN:

sys/netinet/accf_http.c

@@ -1,5 +1,6 @@
-/*-
- * Copyright (c) 2000 Alfred Perlstein <alfred@FreeBSD.org>
+/*
+ * Copyright (c) 2000 Paycounter, Inc.
+ * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -38,6 +39,7 @@
 #include <sys/file.h>
 #include <sys/fcntl.h>
 #include <sys/protosw.h>
+#include <sys/sysctl.h>
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/stat.h>
@@ -46,16 +48,19 @@
 #include <sys/sysent.h>
 #include <sys/resourcevar.h>
 
-/*
- * XXX: doesn't work with 0.9 requests, make a seperate filter
- * based on this one if you want to decode those.
- */
-
-/* check for GET */
+/* check for GET/HEAD */
 static void sohashttpget(struct socket *so, void *arg, int waitflag);
-/* check for end of HTTP request */
+/* check for HTTP/1.0 or HTTP/1.1 */
+static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
+/* check for end of HTTP/1.x request */
 static void soishttpconnected(struct socket *so, void *arg, int waitflag);
-static char sbindex(struct mbuf **mp, int *begin, int end);
+/* strcmp on an mbuf chain */
+static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
+/* strncmp on an mbuf chain */
+static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
+	int max, char *cmp);
+/* socketbuffer is full */
+static int sbfull(struct sockbuf *sb);
 
 static struct accept_filter accf_http_filter = {
 	"httpready",
@@ -72,45 +77,139 @@ static moduledata_t accf_http_mod = {
 
 DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
 
+static int parse_http_version = 1;
 
-static char
-sbindex(struct mbuf **mp, int *begin, int end)
+SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
+"HTTP accept filter");
+SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
+&parse_http_version, 1,
+"Parse http version so that non 1.x requests work");
+
+#ifdef ACCF_HTTP_DEBUG
+#define DPRINT(fmt, args...) \
+	do {	\
+		printf("%s:%d: " fmt "\n", __func__, __LINE__ , ##args);	\
+	} while (0)
+#else
+#define DPRINT(fmt, args...)
+#endif
+
+static int
+sbfull(struct sockbuf *sb)
 {
-	struct mbuf *m = *mp;
-	int diff = end - *begin + 1;
 
-	while (m->m_len < diff) {
-		*begin += m->m_len;
-		diff -= m->m_len;
-		if (m->m_next) {
-			m = m->m_next;
-		} else if (m->m_nextpkt) {
-			m = m->m_nextpkt;
-		} else {
-			/* only happens if end > data in socket buffer */
-			panic("sbindex: not enough data");
+	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, mbcnt(%ld) >= mbmax(%ld): %d", 
+		sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
+		sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
+	return(sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
+}
+
+/*
+ * start at mbuf m, (must provide npkt if exists)
+ * starting at offset in m compare characters in mbuf chain for 'cmp'
+ */
+static int
+mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
+{
+	struct mbuf *n;
+
+	for (;m != NULL; m = n) {
+		n = npkt;
+		if (npkt)
+			npkt = npkt->m_nextpkt;
+		for (; m; m = m->m_next) {
+			for (; offset < m->m_len; offset++, cmp++) {
+				if (*cmp == '\0') {
+					return (1);
+				} else if (*cmp != *(mtod(m, char *) + offset)) {
+					return (0);
+				}
+			}
+			offset = 0;
 		}
 	}
-	*mp = m;
-	return *(mtod(m, char *) + diff - 1);
+	return (0);
 }
 
+/*
+ * start at mbuf m, (must provide npkt if exists)
+ * starting at offset in m compare characters in mbuf chain for 'cmp'
+ * stop at 'max' characters
+ */
+static int
+mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
+{
+	struct mbuf *n;
+
+	for (;m != NULL; m = n) {
+		n = npkt;
+		if (npkt)
+			npkt = npkt->m_nextpkt;
+		for (; m; m = m->m_next) {
+			for (; offset < m->m_len; offset++, cmp++, max--) {
+				if (max == 0 || *cmp == '\0') {
+					return (1);
+				} else if (*cmp != *(mtod(m, char *) + offset)) {
+					return (0);
+				}
+			}
+			offset = 0;
+		}
+	}
+	return (0);
+}
+
+#define STRSETUP(sptr, slen, str) \
+	do {	\
+		sptr = str;	\
+		slen = sizeof(str) - 1;	\
+	} while(0)
+
 static void
 sohashttpget(struct socket *so, void *arg, int waitflag)
 {
 
-	if ((so->so_state & SS_CANTRCVMORE) == 0) {
+	if ((so->so_state & SS_CANTRCVMORE) == 0 || !sbfull(&so->so_rcv)) {
 		struct mbuf *m;
+		char *cmp;
+		int	cmplen, cc;
 
-		if (so->so_rcv.sb_cc < 6)
-			return;
 		m = so->so_rcv.sb_mb;
-		if (bcmp(mtod(m, char *), "GET ", 4) == 0) {
-			soishttpconnected(so, arg, waitflag);
+		cc = so->so_rcv.sb_cc - 1;
+		if (cc < 1)
+			return;
+		switch (*mtod(m, char *)) {
+		case 'G':
+			STRSETUP(cmp, cmplen, "ET ");
+			break;
+		case 'H':
+			STRSETUP(cmp, cmplen, "EAD ");
+			break;
+		default:
+			goto fallout;
+		}
+		if (cc < cmplen) {
+			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
+				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
+				return;
+			} else {
+				DPRINT("short cc (%d) mbufstrncmp failed", cc);
+				goto fallout;
+			}
+		}
+		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
+			DPRINT("mbufstrcmp ok");
+			if (parse_http_version == 0)
+				soishttpconnected(so, arg, waitflag);
+			else
+				soparsehttpvers(so, arg, waitflag);
 			return;
 		}
+		DPRINT("mbufstrcmp bad");
 	}
 
+fallout:
+	DPRINT("fallout");
 	so->so_upcall = NULL;
 	so->so_rcv.sb_flags &= ~SB_UPCALL;
 	soisconnected(so);
@@ -118,64 +217,141 @@ sohashttpget(struct socket *so, void *arg, int waitflag)
 }
 
 static void
-soishttpconnected(struct socket *so, void *arg, int waitflag)
+soparsehttpvers(struct socket *so, void *arg, int waitflag)
 {
-	char a, b, c;
-	struct mbuf *y, *z;
+	struct mbuf *m, *n;
+	int	i, cc, spaces, inspaces;
 
-	if ((so->so_state & SS_CANTRCVMORE) == 0) {
-		/* seek to end and keep track of next to last mbuf */
-		y = so->so_rcv.sb_mb;
-		while (y->m_nextpkt)
-			y = y->m_nextpkt;
-		z = y;	
-		while (y->m_next) {
-			z = y;
-			y = y->m_next;
-		}
-			
-		if (z->m_len + y->m_len > 2) {
-			int index = y->m_len - 1;
+	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
+		goto fallout;
 
-			c = *(mtod(y, char *) + index--);
-			switch (index) {
-			case -1:
-				y = z;
-				index = y->m_len - 1;
-				b = *(mtod(y, char *) + index--);
-				break;
-			case 0:
-				b = *(mtod(y, char *) + index--);
-				y = z;
-				index = y->m_len - 1;
-				break;
-			default:
-				b = *(mtod(y, char *) + index--);
-				break;
+	m = so->so_rcv.sb_mb;
+	cc = so->so_rcv.sb_cc;
+	inspaces = spaces = 0;
+	for (m = so->so_rcv.sb_mb; m; m = n) {
+		n = m->m_nextpkt;
+		for (; m; m = m->m_next) {
+			for (i = 0; i < m->m_len; i++, cc--) {
+				switch (*(mtod(m, char *) + i)) {
+				case ' ':
+					if (!inspaces) {
+						spaces++;
+						inspaces = 1;
+					}
+					break;
+				case '\r':
+				case '\n':
+					DPRINT("newline");
+					goto fallout;
+				default:
+					if (spaces == 2) {
+						/* make sure we have enough data left */
+						if (cc < sizeof("HTTP/1.0") - 1) {
+							if (mbufstrncmp(m, n, i, cc, "HTTP/1.") == 1) {
+								DPRINT("mbufstrncmp ok");
+								goto readmore;
+							} else {
+								DPRINT("mbufstrncmp bad");
+								goto fallout;
+							}
+						} else if (mbufstrcmp(m, n, i, "HTTP/1.0") == 1 ||
+									mbufstrcmp(m, n, i, "HTTP/1.1") == 1) {
+								DPRINT("mbufstrcmp ok");
+								soishttpconnected(so, arg, waitflag);
+								return;
+						} else {
+							DPRINT("mbufstrcmp bad");
+							goto fallout;
+						}
+					}
+					inspaces = 0;
+					break;
+				}
 			}
-			a = *(mtod(y, char *) + index--);
-		} else {
-			int begin = 0;
-			int end = so->so_rcv.sb_cc - 3;
-
-			y = so->so_rcv.sb_mb;
-			a = sbindex(&y, &begin, end++);
-			b = sbindex(&y, &begin, end++);
-			c = sbindex(&y, &begin, end++);
-		}
-
-		if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
-			/* we have all request headers */
-			goto done;
-		} else {
-			/* still need more data */
-			so->so_upcall = soishttpconnected;
-			so->so_rcv.sb_flags |= SB_UPCALL;
-			return;
 		}
 	}
+readmore:
+	DPRINT("readmore");
+	/*
+	 * if we hit here we haven't hit something
+	 * we don't understand or a newline, so try again
+	 */
+	so->so_upcall = soparsehttpvers;
+	so->so_rcv.sb_flags |= SB_UPCALL;
+	return;
 
-done:
+fallout:
+	DPRINT("fallout");
+	so->so_upcall = NULL;
+	so->so_rcv.sb_flags &= ~SB_UPCALL;
+	soisconnected(so);
+	return;
+}
+
+
+#define NCHRS 3
+
+static void
+soishttpconnected(struct socket *so, void *arg, int waitflag)
+{
+	char a, b, c;
+	struct mbuf *m, *n;
+	int ccleft, copied;
+
+	DPRINT("start");
+	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
+		goto gotit;
+
+	/*
+	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
+	 * copied - how much we've copied so far
+	 * ccleft - how many bytes remaining in the socketbuffer
+	 * just loop over the mbufs subtracting from 'ccleft' until we only
+	 * have NCHRS left
+	 */
+	copied = 0;
+	ccleft = so->so_rcv.sb_cc;
+	if (ccleft < NCHRS)
+		goto readmore;
+	a = b = c = '\0';
+	for (m = so->so_rcv.sb_mb; m; m = n) {
+		n = m->m_nextpkt;
+		for (; m; m = m->m_next) {
+			ccleft -= m->m_len;
+			if (ccleft <= NCHRS) {
+				char *src;
+				int tocopy;
+
+				tocopy = (NCHRS - ccleft) - copied;
+				src = mtod(m, char *) + (m->m_len - tocopy);
+
+				while (tocopy--) {
+					switch (copied++) {
+					case 0:
+						a = *src++;
+						break;
+					case 1:
+						b = *src++;
+						break;
+					case 2:
+						c = *src++;
+						break;
+					}
+				}
+			}
+		}
+	}
+	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
+		/* we have all request headers */
+		goto gotit;
+	}
+
+readmore:
+	so->so_upcall = soishttpconnected;
+	so->so_rcv.sb_flags |= SB_UPCALL;
+	return;
+
+gotit:
 	so->so_upcall = NULL;
 	so->so_rcv.sb_flags &= ~SB_UPCALL;
 	soisconnected(so);

sys/sys/socketvar.h

@@ -404,6 +404,7 @@ int	accept_filt_del __P((char *name));
 struct accept_filter *	accept_filt_get __P((char *name));
 #ifdef ACCEPT_FILTER_MOD
 int accept_filt_generic_mod_event __P((module_t mod, int event, void *data));
+SYSCTL_DECL(_net_inet_accf);
 #endif /* ACCEPT_FILTER_MOD */
 
 #endif /* _KERNEL */