X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=libbb%2Fudp_io.c;h=6e3ef484e4a1f4419bdfce8807ba7ec14f922425;hb=045327a418d1cf0a99405ca0b70ed61b5c1a1869;hp=e968ecb6600b177be9c78cec2b63aeaf51ba7a72;hpb=081eb71ebd7954a67287816a9a6fff80e8c5319a;p=oweals%2Fbusybox.git

diff --git a/libbb/udp_io.c b/libbb/udp_io.c
index e968ecb66..6e3ef484e 100644
--- a/libbb/udp_io.c
+++ b/libbb/udp_io.c
@@ -4,49 +4,50 @@
  *
  * Copyright (C) 2007 Denys Vlasenko
  *
- * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
-
 #include "libbb.h"
 
 /*
  * This asks kernel to let us know dst addr/port of incoming packets
  * We don't check for errors here. Not supported == won't be used
  */
-void
-socket_want_pktinfo(int fd)
+void FAST_FUNC
+socket_want_pktinfo(int fd UNUSED_PARAM)
 {
 #ifdef IP_PKTINFO
-	setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &const_int_1, sizeof(int));
+	setsockopt_1(fd, IPPROTO_IP, IP_PKTINFO);
 #endif
 #if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
-	setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &const_int_1, sizeof(int));
+	setsockopt_1(fd, IPPROTO_IPV6, IPV6_PKTINFO);
 #endif
 }
 
 
-ssize_t
+ssize_t FAST_FUNC
 send_to_from(int fd, void *buf, size_t len, int flags,
 		const struct sockaddr *to,
 		const struct sockaddr *from,
 		socklen_t tolen)
 {
 #ifndef IP_PKTINFO
+	(void)from; /* suppress "unused from" warning */
 	return sendto(fd, buf, len, flags, to, tolen);
 #else
 	struct iovec iov[1];
 	struct msghdr msg;
-	char cbuf[sizeof(struct in_pktinfo)
-#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
-		| sizeof(struct in6_pktinfo) /* (a|b) is poor man's max(a,b) */
-#endif
-	];
+	union {
+		char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+		char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
+# endif
+	} u;
 	struct cmsghdr* cmsgptr;
 
 	if (from->sa_family != AF_INET
-#if ENABLE_FEATURE_IPV6
+# if ENABLE_FEATURE_IPV6
 	 && from->sa_family != AF_INET6
-#endif
+# endif
 	) {
 		/* ANY local address */
 		return sendto(fd, buf, len, flags, to, tolen);
@@ -57,38 +58,52 @@ send_to_from(int fd, void *buf, size_t len, int flags,
 	iov[0].iov_base = buf;
 	iov[0].iov_len = len;
 
-	memset(cbuf, 0, sizeof(cbuf));
+	memset(&u, 0, sizeof(u));
 
 	memset(&msg, 0, sizeof(msg));
 	msg.msg_name = (void *)(struct sockaddr *)to; /* or compiler will annoy us */
 	msg.msg_namelen = tolen;
 	msg.msg_iov = iov;
 	msg.msg_iovlen = 1;
-	msg.msg_control = cbuf;
-	msg.msg_controllen = sizeof(cbuf);
+	msg.msg_control = &u;
+	msg.msg_controllen = sizeof(u);
 	msg.msg_flags = flags;
 
 	cmsgptr = CMSG_FIRSTHDR(&msg);
-	if (to->sa_family == AF_INET && from->sa_family == AF_INET) {
+	/*
+	 * Users report that to->sa_family can be AF_INET6 too,
+	 * if "to" was acquired by recv_from_to(). IOW: recv_from_to()
+	 * was seen showing IPv6 "from" even when the destination
+	 * of received packet (our local address) was IPv4.
+	 */
+	if (/* to->sa_family == AF_INET && */ from->sa_family == AF_INET) {
 		struct in_pktinfo *pktptr;
 		cmsgptr->cmsg_level = IPPROTO_IP;
 		cmsgptr->cmsg_type = IP_PKTINFO;
 		cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
 		pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr));
-		/* pktptr->ipi_ifindex = 0; -- already done by memset(cbuf...) */
+		/*pktptr->ipi_ifindex = 0; -- already done by memset(u...) */
+		/* In general, CMSG_DATA() can be unaligned, but in this case
+		 * we know for sure it is sufficiently aligned:
+		 * CMSG_FIRSTHDR simply returns &u above,
+		 * and CMSG_DATA returns &u + size_t + int + int.
+		 * Thus direct assignment is ok:
+		 */
 		pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr;
 	}
-#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
-	else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) {
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+	else if (/* to->sa_family == AF_INET6 && */ from->sa_family == AF_INET6) {
 		struct in6_pktinfo *pktptr;
 		cmsgptr->cmsg_level = IPPROTO_IPV6;
 		cmsgptr->cmsg_type = IPV6_PKTINFO;
 		cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
 		pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr));
-		/* pktptr->ipi6_ifindex = 0; -- already done by memset(cbuf...) */
+		/* pktptr->ipi6_ifindex = 0; -- already done by memset(u...) */
 		pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr;
 	}
-#endif
+# endif
+	msg.msg_controllen = cmsgptr->cmsg_len;
+
 	return sendmsg(fd, &msg, flags);
 #endif
 }
@@ -97,23 +112,26 @@ send_to_from(int fd, void *buf, size_t len, int flags,
  * _Only_ IP/IPv6 address part of 'to' is _maybe_ modified.
  * Typical usage is to preinit 'to' with "default" value
  * before calling recv_from_to(). */
-ssize_t
+ssize_t FAST_FUNC
 recv_from_to(int fd, void *buf, size_t len, int flags,
 		struct sockaddr *from, struct sockaddr *to,
 		socklen_t sa_size)
 {
 #ifndef IP_PKTINFO
+	(void)to; /* suppress "unused to" warning */
 	return recvfrom(fd, buf, len, flags, from, &sa_size);
 #else
 	/* man recvmsg and man cmsg is needed to make sense of code below */
 	struct iovec iov[1];
 	union {
 		char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
 		char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
+# endif
 	} u;
 	struct cmsghdr *cmsgptr;
 	struct msghdr msg;
-	socklen_t recv_length;
+	ssize_t recv_length;
 
 	iov[0].iov_base = buf;
 	iov[0].iov_len = len;
@@ -130,6 +148,8 @@ recv_from_to(int fd, void *buf, size_t len, int flags,
 	if (recv_length < 0)
 		return recv_length;
 
+# define to4 ((struct sockaddr_in*)to)
+# define to6 ((struct sockaddr_in6*)to)
 	/* Here we try to retrieve destination IP and memorize it */
 	for (cmsgptr = CMSG_FIRSTHDR(&msg);
 			cmsgptr != NULL;
@@ -138,25 +158,27 @@ recv_from_to(int fd, void *buf, size_t len, int flags,
 		if (cmsgptr->cmsg_level == IPPROTO_IP
 		 && cmsgptr->cmsg_type == IP_PKTINFO
 		) {
-#define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )
+			const int IPI_ADDR_OFF = offsetof(struct in_pktinfo, ipi_addr);
 			to->sa_family = AF_INET;
-			((struct sockaddr_in*)to)->sin_addr = pktinfo(cmsgptr)->ipi_addr;
-			/* ((struct sockaddr_in*)to)->sin_port = 123; */
-#undef pktinfo
+			/*# define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
+			/*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */
+			memcpy(&to4->sin_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI_ADDR_OFF, sizeof(to4->sin_addr));
+			/*to4->sin_port = 123; - this data is not supplied by kernel */
 			break;
 		}
-#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
 		if (cmsgptr->cmsg_level == IPPROTO_IPV6
 		 && cmsgptr->cmsg_type == IPV6_PKTINFO
 		) {
-#define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )
+			const int IPI6_ADDR_OFF = offsetof(struct in6_pktinfo, ipi6_addr);
 			to->sa_family = AF_INET6;
-			((struct sockaddr_in6*)to)->sin6_addr = pktinfo(cmsgptr)->ipi6_addr;
-			/* ((struct sockaddr_in6*)to)->sin6_port = 123; */
-#undef pktinfo
+			/*#  define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
+			/*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */
+			memcpy(&to6->sin6_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI6_ADDR_OFF, sizeof(to6->sin6_addr));
+			/*to6->sin6_port = 123; */
 			break;
 		}
-#endif
+# endif
 	}
 	return recv_length;
 #endif