Userland: Implement -l, -v, -N, -s, and -p for netcat

1 files changed, 167 insertions, 53 deletions

diff --git a/Userland/nc.cpp b/Userland/nc.cpp
index cb597a2811..e097be0039 100644
--- a/Userland/nc.cpp
+++ b/Userland/nc.cpp
@@ -1,4 +1,6 @@
 #include <arpa/inet.h>
+#include <errno.h>
+#include <getopt.h>
 #include <netinet/in.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -11,68 +13,174 @@
 
 #define max(a, b) ((a > b) ? a : b)
 
+void exit_with_usage(int rc)
+{
+    fprintf(stderr, "Usage: nc [-l] [-v] [-h] [-N] [-s source] [-p source_port] [destination] [port]\n");
+    exit(rc);
+}
+
 int main(int argc, char** argv)
 {
-    if (argc < 3) {
-        fprintf(stderr, "Usage: nc <host> <port>\n");
-        return -1;
+    bool should_listen = false;
+    bool verbose = false;
+    char *source_addr = nullptr;
+    int source_port = 0;
+    bool should_close = false;
+
+    int opt;
+    while ((opt = getopt(argc, argv, "hlvs:p:N")) != -1) {
+        switch (opt) {
+        case 'h':
+            exit_with_usage(0);
+            break;
+        case 'l':
+            should_listen = true;
+            break;
+        case 'v':
+            verbose = true;
+            break;
+        case 's':
+            source_addr = strdup(optarg);
+            break;
+        case 'p':
+            source_port = atoi(optarg);
+            break;
+        case 'N':
+            should_close = true;
+            break;
+        }
     }
 
-    const char* addr_str = argv[1];
-    int port = atoi(argv[2]);
+    int fd;
 
-    int fd = socket(AF_INET, SOCK_STREAM, 0);
-    if (fd < 0) {
-        perror("socket");
-        return 1;
-    }
+    if (should_listen) {
+        int listen_fd = socket(AF_INET, SOCK_STREAM, 0);
+        if (listen_fd < 0) {
+            perror("socket");
+            return 1;
+        }
 
-    struct timeval timeout {
-        3, 0
-    };
-    int rc = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
-    if (rc < 0) {
-        perror("setsockopt");
-        return 1;
-    }
-    rc = setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout));
-    if (rc < 0) {
-        perror("setsockopt");
-        return 1;
-    }
+        struct sockaddr_in sa;
+        memset(&sa, 0, sizeof sa);
+        sa.sin_family = AF_INET;
+        sa.sin_port = htons(source_port);
+        sa.sin_addr.s_addr = htonl(INADDR_ANY);
+        if (source_addr) {
+            if (inet_pton(AF_INET, source_addr, &sa.sin_addr) < 0) {
+                perror("inet_pton");
+                return 1;
+            }
+        }
 
-    struct sockaddr_in dst_addr;
-    memset(&dst_addr, 0, sizeof(dst_addr));
+        if (bind(listen_fd, (struct sockaddr*)&sa, sizeof(sa)) == -1) {
+            perror("bind");
+            return 1;
+        }
 
-    dst_addr.sin_family = AF_INET;
-    dst_addr.sin_port = htons(port);
-    rc = inet_pton(AF_INET, addr_str, &dst_addr.sin_addr);
-    if (rc <= 0) {
-        perror("inet_pton");
-        return 1;
-    }
+        if (listen(listen_fd, 1) == -1) {
+            perror("listen");
+            return 1;
+        }
+
+        char addr_str[100];
+
+        struct sockaddr_in sin;
+        socklen_t len = sizeof(sin);
+
+        if (getsockname(listen_fd, (struct sockaddr*)&sin, &len) == -1) {
+            perror("getsockname");
+            return 1;
+        }
+        if (verbose)
+            fprintf(stderr, "waiting for a connection on %s:%d\n", inet_ntop(sin.sin_family, &sin.sin_addr, addr_str, sizeof(addr_str) - 1), ntohs(sin.sin_port));
+
+        fd = accept(listen_fd, (struct sockaddr*)&sin, &len);
+        if (fd == -1) {
+            perror("accept");
+            return 1;
+        }
+
+        if (verbose)
+            fprintf(stderr, "got connection from %s:%d\n", inet_ntop(sin.sin_family, &sin.sin_addr, addr_str, sizeof(addr_str) - 1), ntohs(sin.sin_port));
+
+        if (close(listen_fd) == -1) {
+            perror("close");
+            return 1;
+        };
+    } else {
+        if ((argc - optind) < 2) {
+            exit_with_usage(-1);
+        }
+
+        const char* addr_arg = argv[optind];
+        int port_arg = atoi(argv[optind + 1]);
+        if (port_arg < 0) {
+            perror("atoi");
+            return 1;
+        }
+
+        fd = socket(AF_INET, SOCK_STREAM, 0);
+        if (fd < 0) {
+            perror("socket");
+            return 1;
+        }
+
+        struct timeval timeout {
+            3, 0
+        };
+        if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)) < 0) {
+            perror("setsockopt");
+            return 1;
+        }
+        if (setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout)) < 0) {
+            perror("setsockopt");
+            return 1;
+        }
+
+        char addr_str[100];
 
-    rc = connect(fd, (struct sockaddr*)&dst_addr, sizeof(dst_addr));
-    if (rc < 0) {
-        perror("connect");
-        return 1;
+        struct sockaddr_in dst_addr;
+        memset(&dst_addr, 0, sizeof(dst_addr));
+
+        dst_addr.sin_family = AF_INET;
+        dst_addr.sin_port = htons(port_arg);
+        if (inet_pton(AF_INET, addr_arg, &dst_addr.sin_addr) < 0) {
+            perror("inet_pton");
+            return 1;
+        }
+
+        if (verbose)
+            fprintf(stderr, "connecting to %s:%d\n", inet_ntop(dst_addr.sin_family, &dst_addr.sin_addr, addr_str, sizeof(addr_str) - 1), ntohs(dst_addr.sin_port));
+        if (connect(fd, (struct sockaddr*)&dst_addr, sizeof(dst_addr)) < 0) {
+            perror("connect");
+            return 1;
+        }
+        if (verbose)
+            fprintf(stderr, "connected!\n");
     }
 
+    bool stdin_closed = false;
+    bool fd_closed = false;
+
     fd_set readfds, writefds, exceptfds;
 
-    for (;;) {
+    while (!stdin_closed || !fd_closed) {
         FD_ZERO(&readfds);
         FD_ZERO(&writefds);
         FD_ZERO(&exceptfds);
 
         int highest_fd = 0;
 
-        FD_SET(STDIN_FILENO, &readfds);
-        FD_SET(STDIN_FILENO, &exceptfds);
-        highest_fd = max(highest_fd, STDIN_FILENO);
-        FD_SET(fd, &readfds);
-        FD_SET(fd, &exceptfds);
-        highest_fd = max(highest_fd, fd);
+        if (!stdin_closed) {
+            FD_SET(STDIN_FILENO, &readfds);
+            FD_SET(STDIN_FILENO, &exceptfds);
+            highest_fd = max(highest_fd, STDIN_FILENO);
+        }
+        if (!fd_closed) {
+            FD_SET(fd, &readfds);
+            FD_SET(fd, &exceptfds);
+            highest_fd = max(highest_fd, fd);
+        }
 
         int ready = select(highest_fd + 1, &readfds, &writefds, &exceptfds, NULL);
         if (ready == -1) {
@@ -83,7 +191,7 @@ int main(int argc, char** argv)
             return 1;
         }
 
-        if (FD_ISSET(STDIN_FILENO, &readfds)) {
+        if (!stdin_closed && FD_ISSET(STDIN_FILENO, &readfds)) {
             char buf[1024];
             int nread = read(STDIN_FILENO, buf, sizeof(buf));
             if (nread < 0) {
@@ -93,16 +201,20 @@ int main(int argc, char** argv)
 
             // stdin closed
             if (nread == 0) {
-                return 0;
-            }
-
-            if (write(fd, buf, nread) < 0) {
+                stdin_closed = true;
+                if (verbose)
+                    fprintf(stderr, "stdin closed\n");
+                if (should_close) {
+                    close(fd);
+                    fd_closed = true;
+                }
+            } else if (write(fd, buf, nread) < 0) {
                 perror("write(fd)");
                 return 1;
             }
         }
 
-        if (FD_ISSET(fd, &readfds)) {
+        if (!fd_closed && FD_ISSET(fd, &readfds)) {
             char buf[1024];
             int nread = read(fd, buf, sizeof(buf));
             if (nread < 0) {
@@ -112,10 +224,12 @@ int main(int argc, char** argv)
 
             // remote end closed
             if (nread == 0) {
-                return 0;
-            }
-
-            if (write(STDOUT_FILENO, buf, nread) < 0) {
+                close(STDIN_FILENO);
+                stdin_closed = true;
+                fd_closed = true;
+                if (verbose)
+                    fprintf(stderr, "remote closed\n");
+            } else if (write(STDOUT_FILENO, buf, nread) < 0) {
                 perror("write(STDOUT_FILENO)");
                 return 1;
             }