Handle more TCP edge cases

.github/workflows/quick.yml

@@ -36,7 +36,7 @@
 
   smoketest_all_opts:
     name: Smoke test With all options turned on
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v4
@@ -75,7 +75,7 @@
       - name: Generate coverage reports
         run: |
           make gcov
-          make cover COVERAGEDIR=coverage/ubuntu-latest
+          make cover COVERAGEDIR=coverage/ubuntu-22.04
         shell: bash
 
       - name: Upload gcovr report artifact
@@ -89,7 +89,7 @@
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
 # TODO: Since windows has a bunch of build differences, it would be good to
 # have a smoketest for it, but it is about 5 times slower than the other
 # quick tests...
 #
@@ -114,7 +114,7 @@
 
   lint:
     name: Code syntax
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v4

doc/Containerfile.example

@@ -0,0 +1,46 @@
+#
+# A simple example of how to build a docker container for n3n-edge
+#
+# Build with the command:
+# podman build \
+#   --device=/dev/net/tun \
+#   --cap-add=NET_ADMIN \
+#   -t=n3n \
+#   -f doc/Containerfile.example \
+#   .
+#
+# Start a n3n session with:
+# podman run \
+#   -it \
+#   --name=n3n \
+#   --device=/dev/net/tun \
+#   --cap-add=NET_ADMIN \
+#   -v $PWD/n3n:/etc/n3n/ \
+#   n3n start -vvvv
+#
+# Note that the build could be done without the --device and --cap-add if
+# the `make test` is omitted
+
+FROM docker.io/library/debian:12 AS builder
+
+RUN apt-get update
+RUN apt-get install -y build-essential autoconf git python3 jq sudo
+
+WORKDIR /n3n
+
+COPY . .
+
+RUN \
+    ./autogen.sh && \
+    ./configure && \
+    make clean all && \
+    make test
+
+
+FROM docker.io/library/debian:12
+
+COPY --from=builder /n3n/apps/n3n-edge /n3n-edge
+
+VOLUME [ "/etc/n3n" ]
+ENTRYPOINT ["/n3n-edge"]
+CMD ["start"]

libs/connslot/connslot.c

@@ -177,7 +177,7 @@ void conn_check_ready(conn_t *conn) {
     return;
 }
 
-void conn_read(conn_t *conn, int fd) {
+ssize_t conn_read(conn_t *conn, int fd) {
     conn->state = CONN_READING;
 
     // If no space available, try increasing our capacity
@@ -195,28 +195,26 @@ void conn_read(conn_t *conn, int fd) {
         // zero-sized read request, the only time we get a zero back is if the
         // far end has closed
         conn->state = CONN_CLOSED;
-        return;
+        return 0;
     }
 
     if (size == -1) {
         if (errno == EWOULDBLOCK || errno == EAGAIN) {
-            conn->state = CONN_EMPTY;
-            return;
+            return 0;
         }
         conn->state = CONN_ERROR;
-        return;
+        return 0;
     }
 
     // This will truncate the time to a int - usually 32bits
     conn->activity = time(NULL);
     conn_check_ready(conn);
+    return size;
 }
 
 ssize_t conn_write(conn_t *conn, int fd) {
     ssize_t sent;
 
-    conn->state = CONN_SENDING;
-
     if (fd == -1) {
         return 0;
     }
@@ -267,11 +265,17 @@ ssize_t conn_write(conn_t *conn, int fd) {
     unsigned int end_pos = sb_len(conn->reply_header) + sb_len(conn->reply);
 #endif
 
+    if (sent == -1) {
+        sent = 0;
+        if (errno != EAGAIN && errno != EWOULDBLOCK) {
+            conn->state = CONN_ERROR;
+        }
+    }
+
     conn->reply_sendpos += sent;
 
     if (conn->reply_sendpos >= end_pos) {
         // We have sent the last bytes of this reply
-        conn->state = CONN_EMPTY;
         conn->reply_sendpos = 0;
         sb_zero(conn->reply_header);
         sb_zero(conn->reply);
@@ -282,13 +286,20 @@ ssize_t conn_write(conn_t *conn, int fd) {
     return sent;
 }
 
-int conn_iswriter(conn_t *conn) {
-    switch (conn->state) {
-        case CONN_SENDING:
-            return 1;
-        default:
-            return 0;
+bool conn_iswriter(conn_t *conn) {
+    int endpos = 0;
+    if (conn->reply_header) {
+        endpos += sb_len(conn->reply_header);
+    }
+    if (conn->reply) {
+        endpos += sb_len(conn->reply);
     }
+
+    // If there are any bytes ready to send, then we are writable
+    if(endpos) {
+        return true;
+    }
+    return false;
 }
 
 void conn_close(conn_t *conn, int fd) {

libs/connslot/connslot.h

@@ -29,7 +29,6 @@ enum __attribute__((__packed__)) conn_state {
     CONN_EMPTY = 0,
     CONN_READING = 1,
     CONN_READY = 2,
-    CONN_SENDING = 3,
     CONN_CLOSED = 4,
     CONN_ERROR = 5,
 };
@@ -64,9 +63,9 @@ void conn_zero(conn_t *);
 int conn_init(conn_t *, size_t, size_t);
 void conn_accept(conn_t *, int, enum conn_proto);
 void conn_check_ready(conn_t *);
-void conn_read(conn_t *, int);
+ssize_t conn_read(conn_t *, int);
 ssize_t conn_write(conn_t *, int);
-int conn_iswriter(conn_t *);
+bool conn_iswriter(conn_t *);
 void conn_close(conn_t *, int);
 bool conn_closeidle(conn_t *, int, int, int);
 void conn_dump(strbuf_t **, conn_t *);

src/edge_utils.c

@@ -1630,11 +1630,13 @@ void update_supernode_reg (struct n3n_runtime_data * eee, time_t now) {
         if(eee->conf.bind_address) {
             // do not explicitly disconnect every time as the condition described is rare, so ...
             // ... check that there are no external peers (indicating a working socket) ...
-            HASH_ITER(hh, eee->known_peers, peer, tmp_peer)
-            if(!peer->local) {
-                cnt++;
-                break;
+            HASH_ITER(hh, eee->known_peers, peer, tmp_peer) {
+                if(!peer->local) {
+                    cnt++;
+                    break;
+                }
             }
+
             if(!cnt) {
                 // ... and then count the connection retries
                 (eee->close_socket_counter)++;
@@ -2297,7 +2299,7 @@ void process_udp (struct n3n_runtime_data *eee,
     via_multicast = (in_sock == eee->udp_multicast_sock);
 #endif
 
-    traceEvent(TRACE_DEBUG, "Rx N2N_UDP of size %d from [%s]",
+    traceEvent(TRACE_DEBUG, "Rx VPN packet of size %d from [%s]",
                (signed int)udp_size, sock_to_cstr(sockbuf1, &sender));
 
     if(eee->conf.header_encryption == HEADER_ENCRYPTION_ENABLED) {

src/mainloop.c

@@ -226,6 +226,10 @@ static int fdlist_allocslot (int fd, enum fd_info_proto proto) {
 
 static void fdlist_freefd (int fd) {
     int slot = 0;
+    if(fd == -1) {
+        // Cannot release an error fd!
+        return;
+    }
     while(slot < MAX_HANDLES) {
         if(fdlist[slot].fd != fd) {
             slot++;
@@ -331,7 +335,6 @@ static void handle_fd (const time_t now, const struct fd_info info, struct n3n_r
             switch(conn->state) {
                 case CONN_EMPTY:
                 case CONN_READING:
-                case CONN_SENDING:
                     // These states dont require us to do anything
                     // TODO:
                     // - handle reading/sending simultaneous?
@@ -402,7 +405,6 @@ static void handle_fd (const time_t now, const struct fd_info info, struct n3n_r
             switch(conn->state) {
                 case CONN_EMPTY:
                 case CONN_READING:
-                case CONN_SENDING:
                     // These states dont require us to do anything
                     // TODO:
                     // - handle reading/sending simultaneous?

src/n2n.c

@@ -62,8 +62,41 @@ SOCKET open_socket (struct sockaddr *local_address, socklen_t addrlen, int type
     /* fcntl(sock_fd, F_SETFL, O_NONBLOCK); */
 #endif
 
+    int result;
+
     sockopt = 1;
-    setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, (char *)&sockopt, sizeof(sockopt));
+    result = setsockopt(
+        sock_fd,
+        SOL_SOCKET,
+        SO_REUSEADDR,
+        (char *)&sockopt,
+        sizeof(sockopt)
+    );
+    if(result == -1) {
+        traceEvent(
+            TRACE_ERROR,
+            "SO_REUSEADDR fd=%i, error=%s\n",
+            sock_fd,
+            strerror(errno)
+        );
+    }
+#ifdef SO_REUSEPORT /* no SO_REUSEPORT in Windows / old linux versions */
+    result = setsockopt(
+        sock_fd,
+        SOL_SOCKET,
+        SO_REUSEPORT,
+        (char *)&sockopt,
+        sizeof(sockopt)
+    );
+    if(result == -1) {
+        traceEvent(
+            TRACE_ERROR,
+            "SO_REUSEPORT fd=%i, error=%s\n",
+            sock_fd,
+            strerror(errno)
+        );
+    }
+#endif
 
     if(!local_address) {
         // skip binding if we dont have the right details

tools/crypto_helper.c

@@ -96,7 +96,10 @@ static void cmd_header_decrypt (int argc, char **argv, void *conf) {
         exit(1);
     }
 
-    write(1, &buf, size);
+    int r = write(1, &buf, size);
+    if(r != size) {
+        printf("Short write\n");
+    }
     exit(0);
 
 }
@@ -130,7 +133,10 @@ static void cmd_pearson_128 (int argc, char **argv, void *conf) {
     unsigned char hash[16];
     size = read(0, &buf, sizeof(buf));
     pearson_hash_128(hash, buf, size);
-    write(1, &hash, sizeof(hash));
+    int r = write(1, &hash, sizeof(hash));
+    if(r != sizeof(hash)) {
+        printf("Short write\n");
+    }
     exit(0);
 }