From 9c3eb4b413cc240680d349c9356c8f9c89d5c7aa Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Fri, 17 May 2024 03:34:34 -0500
Subject: [PATCH] netcat: add -o

---
 lib/lib.h         |  4 ++-
 lib/net.c         |  6 ++--
 toys/net/netcat.c | 82 ++++++++++++++++++++++++++++++++++++++---------
 3 files changed, 73 insertions(+), 19 deletions(-)

diff --git a/lib/lib.h b/lib/lib.h
index 4618a2f0..5bc21f01 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -359,7 +359,9 @@ void xconnect(int fd, const struct sockaddr *sa, socklen_t len);
 int xconnectany(struct addrinfo *ai);
 int xbindany(struct addrinfo *ai);
 int xpoll(struct pollfd *fds, int nfds, int timeout);
-int pollinate(int in1, int in2, int out1, int out2, int timeout, int shutdown_timeout);
+int pollinate(int in1, int in2, int out1, int out2,
+              void (*callback)(int fd, void *buf, size_t len),
+              int timeout, int shutdown_timeout);
 char *ntop(struct sockaddr *sa);
 void xsendto(int sockfd, void *buf, size_t len, struct sockaddr *dest);
 int xrecvwait(int fd, char *buf, int len, union socksaddr *sa, int timeout);
diff --git a/lib/net.c b/lib/net.c
index 16a110e3..8fe006b6 100644
--- a/lib/net.c
+++ b/lib/net.c
@@ -96,7 +96,9 @@ int xpoll(struct pollfd *fds, int nfds, int timeout)
 // Loop forwarding data from in1 to out1 and in2 to out2, handling
 // half-connection shutdown. timeouts return if no data for X ms.
 // Returns 0: both closed, 1 shutdown_timeout, 2 timeout
-int pollinate(int in1, int in2, int out1, int out2, int timeout, int shutdown_timeout)
+int pollinate(int in1, int in2, int out1, int out2,
+              void (*callback)(int fd, void *buf, size_t len),
+              int timeout, int shutdown_timeout)
 {
   struct pollfd pollfds[2];
   int i, pollcount = 2;
@@ -115,7 +117,7 @@ int pollinate(int in1, int in2, int out1, int out2, int timeout, int shutdown_ti
         int len = read(pollfds[i].fd, libbuf, sizeof(libbuf));
         if (len<1) pollfds[i].revents = POLLHUP;
         else {
-          xwrite(i ? out2 : out1, libbuf, len);
+          callback(i ? out2 : out1, libbuf, len);
           continue;
         }
       }
diff --git a/toys/net/netcat.c b/toys/net/netcat.c
index 16cf40f0..7587dac9 100644
--- a/toys/net/netcat.c
+++ b/toys/net/netcat.c
@@ -2,16 +2,16 @@
  *
  * Copyright 2007 Rob Landley <rob@landley.net>
  *
- * TODO: genericize for telnet/microcom/tail-f, fix -t
+ * TODO: genericize for telnet/microcom/tail-f, fix -t with login_tty()
 
-USE_NETCAT(NEWTOY(netcat, "^tElLw#<1W#<1p#<1>65535q#<1s:f:46uUnvz[!tlL][!Lw][!Lu][!46U]", TOYFLAG_BIN))
+USE_NETCAT(NEWTOY(netcat, "^tElLw#<1W#<1p#<1>65535q#<1o:s:f:46uUnz[!tlL][!Lw][!Lu][!46U]", TOYFLAG_BIN))
 USE_NETCAT(OLDTOY(nc, netcat, TOYFLAG_USR|TOYFLAG_BIN))
 
 config NETCAT
   bool "netcat"
   default y
   help
-    usage: netcat [-46ELlntUu] [-pqWw #] [-s addr] {IPADDR PORTNUM|-f FILENAME|COMMAND...}
+    usage: netcat [-46ELlntUu] [-pqWw #] [-s addr] [-o FILE] {IPADDR PORTNUM|-f FILENAME|COMMAND...}
 
     Forward stdin/stdout to a file or network connection.
 
@@ -22,11 +22,11 @@ config NETCAT
     -L	Listen and background each incoming connection (server mode)
     -l	Listen for one incoming connection, then exit
     -n	No DNS lookup
+    -o	Hex dump to FILE (-o- writes hex only to stdout)
     -p	Local port number
     -q	Quit SECONDS after EOF on stdin, even if stdout hasn't closed yet
     -s	Local source address
     -t	Allocate tty
-    -v	Verbose
     -u	Use UDP
     -U	Use a UNIX domain socket
     -W	SECONDS timeout for more data on an idle connection
@@ -49,8 +49,11 @@ config NETCAT
 #include "toys.h"
 
 GLOBALS(
-  char *f, *s;
+  char *f, *s, *o;
   long q, p, W, w;
+
+  unsigned ofd, olast, opos, ocount[2];
+  char obuf[16];
 )
 
 static void timeout(int signum)
@@ -78,6 +81,49 @@ static int usock(char *name, int type, int out)
   return sockfd;
 }
 
+// Hex dump accumulated buffer data
+void oflush(void)
+{
+  char *s = toybuf;
+  unsigned *oc = TT.ocount+(TT.olast==1), uu;
+
+  if (!TT.opos) return;
+  s += sprintf(toybuf, "%c %08x", 60+2*(TT.olast==1), *oc);
+  for (uu = 0; uu<16; uu++) {
+    s += sprintf(s, uu<TT.opos ? " %02x" : "   ", TT.obuf[uu]);
+    if (TT.obuf[uu]-32u>95) TT.obuf[uu] = '.';
+  }
+  dprintf(TT.ofd, "%s # %.*s\n", toybuf, TT.opos, TT.obuf);
+  *oc += TT.opos;
+  TT.opos = 0;
+}
+
+// Write data to output, and hex dump to -o if enabled.
+void ohexwrite(int fd, void *buf, size_t len)
+{
+  // Hex dump if -o specified. Output is always to fd 1, input != 1.
+  if (TT.ofd) {
+    int i = 0, j;
+
+    if (TT.olast != fd) oflush();
+    TT.olast = fd;
+
+    while (i<len) {
+      j = minof(16-TT.opos, len-i);
+      memcpy(TT.obuf+TT.opos, buf+i, j);
+      TT.opos += j;
+      i += j;
+      if (TT.opos == 16) oflush();
+    }
+
+    // Don't write data to stdout when -o goes to stdout.
+    if (TT.ofd==1 && fd==1) return;
+  }
+
+  // Pass along raw data
+  xwrite(fd, buf, len);
+}
+
 void netcat_main(void)
 {
   int sockfd = -1, in1 = 0, in2 = 0, out1 = 1, out2 = 1, family = AF_UNSPEC,
@@ -85,7 +131,14 @@ void netcat_main(void)
   socklen_t len;
   pid_t child;
 
-  // Addjust idle and quit_delay to ms or -1 for no timeout
+  // -o - disables normal writes to stdout, just gives hex dump.
+  if (TT.o) {
+    if (!strcmp(TT.o, "-")) TT.ofd = 1;
+    else TT.ofd = xcreate(TT.o, O_CREAT|O_TRUNC|O_WRONLY, 0666);
+    sigatexit(oflush);
+  }
+
+  // Adjust idle and quit_delay to ms or -1 for no timeout
   TT.W = TT.W ? TT.W*1000 : -1;
   TT.q = TT.q ? TT.q*1000 : -1;
 
@@ -107,16 +160,13 @@ void netcat_main(void)
   if (TT.f) {
     in1 = out2 = xopen(TT.f, O_RDWR);
     alarm(0);
-    pollinate(in1, in2, out1, out2, TT.W, TT.q);
+    pollinate(in1, in2, out1, out2, ohexwrite, TT.W, TT.q);
   } else {
     // Setup socket
     if (!FLAG(l) && !FLAG(L)) {
-      char *host = toys.optargs[0];
-      char *port = toys.optargs[1];
-      if (FLAG(U)) sockfd = usock(host, type, 1);
-      else sockfd = xconnectany(xgetaddrinfo(host, port, family, type, 0, AI_NUMERICHOST*FLAG(n)));
-
-      if (FLAG(v)) printf("%s:%s [open]\n", host, port);
+      if (FLAG(U)) sockfd = usock(toys.optargs[0], type, 1);
+      else sockfd = xconnectany(xgetaddrinfo(toys.optargs[0], toys.optargs[1],
+        family, type, 0, AI_NUMERICHOST*FLAG(n)));
 
       // Do not perform any I/O in zero mode
       if (FLAG(z)) goto cleanup;
@@ -124,7 +174,7 @@ void netcat_main(void)
       // We have a connection. Disarm timeout and start poll/send loop.
       alarm(0);
       in1 = out2 = sockfd;
-      pollinate(in1, in2, out1, out2, TT.W, TT.q);
+      pollinate(in1, in2, out1, out2, ohexwrite, TT.W, TT.q);
     } else {
       // Listen for incoming connections
       if (FLAG(U)) {
@@ -155,7 +205,7 @@ void netcat_main(void)
       }
 
       do {
-       len = sizeof(struct sockaddr_storage);
+        len = sizeof(struct sockaddr_storage);
         if (FLAG(u)) {
           if (-1 == recvfrom(in1 = dup(sockfd), &child, 1, MSG_PEEK,
             (void *)toybuf, &len)) perror_exit("recvfrom");
@@ -191,7 +241,7 @@ void netcat_main(void)
 
         // Copy stdin/out
         } else {
-          pollinate(in1, in2, out1, out2, TT.W, TT.q);
+          pollinate(in1, in2, out1, out2, ohexwrite, TT.W, TT.q);
           close(in1);
         }
       } while (FLAG(L));
-- 
2.39.2