irC

commit 1c58927f7c75430f54b660733fc7d10a01b592cc
parent eefee86b3c900f92f6ab090b7f494c04b6b99f90
Author: aabacchus <ben@bvnf.space>
Date:   Tue,  5 Oct 2021 11:04:16 +0100

make nc utility

Diffstat:
M
.gitignore
 | 
1
+
M
Makefile
 | 
12
++++++++----
A
nc.c
 | 
137
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 146 insertions(+), 4 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -1,2 +1,3 @@
 irC
 *.o
+nc
diff --git a/Makefile b/Makefile
@@ -1,7 +1,11 @@
-CFLAGS += -Wall -Wextra -Wpedantic
-LDFLAGS += -static
+.POSIX:
+
+XCFLAGS = $(CFLAGS) -Wall -Wextra -Wpedantic -g -Og -D_XOPEN_SOURCE=700
+
 irC: main.c
-	$(CC) -g $(CFLAGS) $(LDFLAGS) main.c -o $@
+	$(CC) $(XCFLAGS) $(LDFLAGS) main.c -o $@
+nc: nc.c
+	$(CC) $(XCFLAGS) $(LDFLAGS) nc.c -o $@
 
 clean:
-	rm irC
+	rm -f irC nc
diff --git a/nc.c b/nc.c
@@ -0,0 +1,137 @@
+/*
+ * This file is in the public domain.
+ * Author: Ben Fuller
+ *
+ * Basic netcat-like utility to create a connection on the specified
+ * address and port, using stdin and stdout.
+ *
+ */
+#include <stdio.h>
+#include <errno.h>
+#include <poll.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <netdb.h>
+
+#define BUF_LEN 1024
+
+void usage(const char *);
+int sock_write(int, char *);
+int sock_read(int);
+
+int main(int argc, char *argv[]) {
+    int s, sfd;
+    struct addrinfo hints, *result, *rp;
+    if (argc < 3) {
+        usage(argv[0]);
+    }
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_UNSPEC;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_PASSIVE;
+    hints.ai_protocol = 0;
+
+
+    s = getaddrinfo(argv[1], argv[2], &hints, &result);
+    if (s != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(s));
+        return 1;
+    }
+
+    sfd = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
+    for (rp = result; rp != NULL; rp = rp->ai_next) {
+        sfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+        if (sfd == -1)
+            continue;
+
+        if (connect(sfd, rp->ai_addr, rp->ai_addrlen) == 0)
+            break;
+
+        if (close(sfd) == -1) {
+            perror("close");
+            return 1;
+        }
+    }
+
+    freeaddrinfo(result);
+
+    if (rp == NULL)
+        return 1;
+
+    size_t linelen = 0;
+
+    int pollret;
+    struct pollfd fds[2];
+    fds[0].fd = 0;
+    fds[0].events = POLLIN;
+    fds[1].fd = sfd;
+    fds[1].events = POLLIN | POLLWRBAND;
+
+    while (1) {
+        pollret = poll(fds, 2, -1);
+        if (pollret <= 0) {
+            if (pollret == 0 || errno == EAGAIN)
+                continue;
+            perror("poll");
+            return 1;
+        }
+        if (fds[1].revents & POLLIN)
+            if (sock_read(sfd) != 0)
+                return 1;
+        if (fds[0].revents & POLLIN) {
+            char *line = NULL;
+            if (getline(&line, &linelen, stdin) == -1) {
+                free(line);
+                break;
+            }
+            if (sock_write(sfd, line) != 0) {
+                free(line);
+                return 1;
+            }
+            free(line);
+        }
+        fds[0].revents = 0;
+        fds[1].revents = 0;
+    }
+
+    if (close(sfd) == -1) {
+        perror("close");
+        return 1;
+    }
+    return 0;
+}
+
+void usage(const char *argv0){
+    fprintf(stderr, "usage: %s host port\n", argv0);
+    exit(1);
+}
+
+int sock_write(int sfd, char *msg){
+    ssize_t ret;
+    int len = strlen(msg);
+    ret = send(sfd, msg, len, 0);
+    if (ret != (ssize_t) len) {
+        perror("sock_write");
+        return 1;
+    }
+    return 0;
+}
+
+int sock_read(int sfd){
+    char buff[BUF_LEN];
+    memset(&buff, 0, sizeof buff);
+    ssize_t ret;
+
+    ret = recv(sfd, buff, BUF_LEN, 0);
+
+    if (ret < 0) {
+        perror("sock_read");
+        return 1;
+    }
+    printf("%s", buff);
+    return 0;
+}