From 4e867b8a352744eb10aa7032936c96b762f4c144 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Tue, 11 Oct 2016 08:19:41 -0500
Subject: Make netcat work with nommu and factor out poll() loop into
 net/net.c.

---
 lib/lib.h |  1 +
 lib/net.c | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

(limited to 'lib')

diff --git a/lib/lib.h b/lib/lib.h
index 69692b73..2afe558b 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -281,6 +281,7 @@ void xsetsockopt(int fd, int level, int opt, void *val, socklen_t len);
 int xconnect(char *host, char *port, int family, int socktype, int protocol,
   int flags);
 int xpoll(struct pollfd *fds, int nfds, int timeout);
+int pollinate(int in1, int in2, int out1, int out2, int timeout, int shutdown_timeout);
 
 // password.c
 int get_salt(char *salt, char * algo);
diff --git a/lib/net.c b/lib/net.c
index 2e72b268..1a46a5a9 100644
--- a/lib/net.c
+++ b/lib/net.c
@@ -55,3 +55,40 @@ int xpoll(struct pollfd *fds, int nfds, int timeout)
     } else return i;
   }
 }
+
+// Loop forwarding data from in1 to out1 and in2 to out2, handling
+// half-connection shutdown. timeouts return if no data for X miliseconds.
+// Returns 0: both closed, 1 shutdown_timeout, 2 timeout
+int pollinate(int in1, int in2, int out1, int out2, int timeout, int shutdown_timeout)
+{
+  struct pollfd pollfds[2];
+  int i, pollcount = 2;
+
+  memset(pollfds, 0, 2*sizeof(struct pollfd));
+  pollfds[0].events = pollfds[1].events = POLLIN;
+  pollfds[0].fd = in1;
+  pollfds[1].fd = in2;
+
+  // Poll loop copying data from each fd to the other one.
+  for (;;) {
+    if (!xpoll(pollfds, pollcount, timeout)) return pollcount;
+
+    for (i=0; i<pollcount; i++) {
+      if (pollfds[i].revents & POLLIN) {
+        int len = read(pollfds[i].fd, libbuf, sizeof(libbuf));
+        if (len<1) pollfds[i].revents = POLLHUP;
+        else xwrite(i ? out2 : out1, libbuf, len);
+      }
+      if (pollfds[i].revents & POLLHUP) {
+        // Close half-connection.  This is needed for things like
+        // "echo GET / | netcat landley.net 80"
+        // Note that in1 closing triggers timeout, in2 returns now.
+        if (i) {
+          shutdown(pollfds[0].fd, SHUT_WR);
+          pollcount--;
+          timeout = shutdown_timeout;
+        } else return 0;
+      }
+    }
+  }
+}
-- 
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