nc: port nc 1.10 to busybox

3 files changed, 166 insertions, 1 deletions

diff --git a/libbb/Kbuild b/libbb/Kbuild
index a3b78ef28..bdf25da09 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -78,6 +78,7 @@ lib-y += skip_whitespace.o
 lib-y += speed_table.o
 lib-y += trim.o
 lib-y += u_signal_names.o
+lib-y += udp_io.o
 lib-y += uuencode.o
 lib-y += vdprintf.o
 lib-y += verror_msg.o
diff --git a/libbb/udp_io.c b/libbb/udp_io.c
new file mode 100644
index 000000000..d834a237b
--- /dev/null
+++ b/libbb/udp_io.c
@@ -0,0 +1,164 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright (C) 2007 Denis Vlasenko
+ *
+ * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ */
+
+#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)
+{
+#ifdef IP_PKTINFO
+        setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &const_int_1, sizeof(int));
+#endif
+#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+        setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &const_int_1, sizeof(int));
+#endif
+}
+
+
+#ifdef UNUSED
+ssize_t
+send_to_from(int fd, void *buf, size_t len, int flags,
+                const struct sockaddr *from, const struct sockaddr *to,
+                socklen_t tolen)
+{
+#ifndef IP_PKTINFO
+        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
+        ];
+        struct cmsghdr* cmsgptr;
+
+        if (from->sa_family != AF_INET
+#if ENABLE_FEATURE_IPV6
+         && from->sa_family != AF_INET6
+#endif
+        ) {
+                /* ANY local address */
+                return sendto(fd, buf, len, flags, to, tolen);
+        }
+        
+        /* man recvmsg and man cmsg is needed to make sense of code below */
+
+        iov[0].iov_base = buf;
+        iov[0].iov_len = len;
+
+        memset(cbuf, 0, sizeof(cbuf));
+
+        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_flags = flags;
+
+        cmsgptr = CMSG_FIRSTHDR(&msg);
+        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_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) {
+                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_addr = ((struct sockaddr_in6*)from)->sin6_addr;
+        }
+#endif
+        return sendmsg(fd, &msg, flags);
+#endif
+}
+#endif /* UNUSED */
+
+/* NB: this will never set port# in 'to'!
+ * _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
+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
+        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))];
+                char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
+        } u;
+        struct cmsghdr *cmsgptr;
+        struct msghdr msg;
+        socklen_t recv_length;
+
+        iov[0].iov_base = buf;
+        iov[0].iov_len = len;
+
+        memset(&msg, 0, sizeof(msg));
+        msg.msg_name = (struct sockaddr *)from;
+        msg.msg_namelen = sa_size;
+        msg.msg_iov = iov;
+        msg.msg_iovlen = 1;
+        msg.msg_control = &u;
+        msg.msg_controllen = sizeof(u);
+
+        recv_length = recvmsg(fd, &msg, flags);
+        if (recv_length < 0)
+                return recv_length;
+
+        /* Here we try to retrieve destination IP and memorize it */
+        for (cmsgptr = CMSG_FIRSTHDR(&msg);
+                        cmsgptr != NULL;
+                        cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)
+        ) {
+                if (cmsgptr->cmsg_level == IPPROTO_IP
+                 && cmsgptr->cmsg_type == IP_PKTINFO
+                ) {
+#define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )
+                        to->sa_family = AF_INET;
+                        ((struct sockaddr_in*)to)->sin_addr = pktinfo(cmsgptr)->ipi_addr;
+                        /* ((struct sockaddr_in*)to)->sin_port = 123; */
+#undef pktinfo
+                        break;
+                }
+#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)) )
+                        to->sa_family = AF_INET6;
+                        ((struct sockaddr_in6*)to)->sin6_addr = pktinfo(cmsgptr)->ipi6_addr;
+                        /* ((struct sockaddr_in6*)to)->sin6_port = 123; */
+#undef pktinfo
+                        break;
+                }
+#endif
+        }
+        return recv_length;
+#endif
+}
diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index 3c1eec943..8466325c7 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -208,7 +208,7 @@ len_and_sockaddr* xdotted2sockaddr(const char *host, int port)
         return str2sockaddr(host, port, AF_UNSPEC, AI_NUMERICHOST | DIE_ON_ERROR);
 }
 
-static int xsocket_type(len_and_sockaddr **lsap, int sock_type)
+int xsocket_type(len_and_sockaddr **lsap, int sock_type)
 {
         len_and_sockaddr *lsa;
         int fd;