Add code to always reply using the queried IP address, if the OS

makes it possible.
2001-03-28 18:24:25 +00:00 · 2001-03-28 18:24:25 +00:00 · ffa45eae76
commit ffa45eae76
parent a24840a364
8 changed files with 569 additions and 106 deletions
--- a/tftpd/recvfrom.c
+++ b/tftpd/recvfrom.c
@ -0,0 +1,139 @@
+/* $Id$ */
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2001 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software available under the same license
+ *   as the "OpenBSD" operating system, distributed at
+ *   http://www.openbsd.org/.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * recvfrom.c
+ *
+ * Emulate recvfrom() using recvmsg(), but try to capture the local address
+ * since some TFTP clients consider it an error to get the reply from another
+ * IP address than the request was sent to.
+ *
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include "../config.h"
+
+#if defined(HAVE_RECVMSG) && defined(HAVE_MSGHDR_MSG_CONTROL)
+
+#include <sys/uio.h>
+
+#ifndef CMSG_LEN
+#define CMSG_LEN(size)	 (sizeof(struct cmsghdr) + (size))
+#endif
+#ifndef CMSG_SPACE
+#define CMSG_SPACE(size) (sizeof(struct cmsghdr) + (size))
+#endif
+
+int
+myrecvfrom(int s, void *buf, int len, unsigned int flags,
+	   struct sockaddr *from, int *fromlen,
+	   struct sockaddr_in *myaddr)
+{
+  struct msghdr msg;
+  struct iovec iov[1];
+  int n;
+  struct cmsghdr *cmptr;
+  union {
+    struct cmsghdr cm;
+#ifdef IP_PKTINFO
+    char control[CMSG_SPACE(sizeof(struct in_addr)) +
+		CMSG_SPACE(sizeof(struct in_pktinfo))];
+#else
+    char control[CMSG_SPACE(sizeof(struct in_addr))];
+#endif
+  } control_un;
+  int on = 1;
+#ifdef IP_PKTINFO
+  struct in_pktinfo pktinfo;
+#endif
+
+  /* Try to enable getting the return address */
+#ifdef IP_RECVDSTADDR
+  setsockopt(s, IPPROTO_IP, IP_RECVDSTADDR, &on, sizeof(on));
+#endif
+#ifdef IP_PKTINFO
+  setsockopt(s, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
+#endif
+
+  msg.msg_control = control_un.control;
+  msg.msg_controllen = sizeof(control_un.control);
+  msg.msg_flags = 0;
+
+  msg.msg_name = from;
+  msg.msg_namelen = *fromlen;
+  iov[0].iov_base = buf;
+  iov[0].iov_len  = len;
+  msg.msg_iov = iov;
+  msg.msg_iovlen = 1;
+
+  if ( (n = recvmsg(s, &msg, flags)) < 0 )
+    return n;			/* Error */
+
+  *fromlen = msg.msg_namelen;
+
+  if ( myaddr ) {
+    bzero(myaddr, sizeof(struct sockaddr_in));
+    myaddr->sin_family = AF_INET;
+
+    if ( msg.msg_controllen < sizeof(struct cmsghdr) ||
+	 (msg.msg_flags & MSG_CTRUNC) )
+      return n;			/* No information available */
+
+    for ( cmptr = CMSG_FIRSTHDR(&msg) ; cmptr != NULL ;
+	  cmptr = CMSG_NXTHDR(&msg, cmptr) ) {
+
+#ifdef IP_RECVSTDADDR
+      if ( cmptr->cmsg_level == IPPROTO_IP &&
+	   cmptr->cmsg_type == IP_RECVDSTADDR ) {
+	memcpy(&myaddr->sin_addr, CMSG_DATA(cmptr),
+	       sizeof(struct in_addr));
+      }
+#endif
+
+#ifdef IP_PKTINFO
+      if ( cmptr->cmsg_level == IPPROTO_IP &&
+	   cmptr->cmsg_type == IP_PKTINFO ) {
+	memcpy(&pktinfo, CMSG_DATA(cmptr), sizeof(struct in_pktinfo));
+	memcpy(&myaddr->sin_addr, &pktinfo.ipi_addr, sizeof(struct in_addr));
+      }
+#endif
+
+    }
+  }
+
+  return n;
+}
+
+#else /* pointless... */
+
+int
+myrecvfrom(int s, void *buf, int len, unsigned int flags,
+	   struct sockaddr *from, int *fromlen,
+	   struct sockaddr_in *myaddr)
+{
+  /* There is no way we can get the local address, fudge it */
+
+  bzero(myaddr, sizeof(struct sockaddr_in));
+  myaddr->sin_family = AF_INET;
+
+  myaddr->sin_port   = htons(IPPORT_TFTP);
+  bzero(&myaddr->sin_addr, sizeof(myaddr->sin_addr));
+
+  return recvfrom(s,buf,len,flags,from,fromlen);
+}
+
+#endif