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netcat: add --crlf to convert LF into CRLF

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This adds the --crlf option to netcat, which triggers translation of \n
characters into \r\n sequences in the input -> network direction.
The Linux version of nc also supports this functionality with --crlf and
-C. The OpenBSD version uses -C to specify client certificates. Our
version is too old and doesn't have it, but I avoided adding -C anyway
to ease future syncs with upstream.

Attempts to upstream the feature were unsuccessful:
https://marc.info/?t=169282068500001

Differential Revision: https://reviews.freebsd.org/D41489
This commit is contained in:
Pietro Cerutti 2023-08-17 11:42:23 +00:00
parent e4e11c1d07
commit d4b3aefdf9
2 changed files with 43 additions and 12 deletions
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3
contrib/netcat/nc.1
View File

@ -42,6 +42,7 @@
.Op Fl i Ar interval
.Op Fl -no-tcpopt
.Op Fl -sctp
.Op Fl -crlf
.Op Fl O Ar length
.Op Fl P Ar proxy_username
.Op Fl p Ar source_port
@ -104,6 +105,8 @@ to use IPv4 addresses only.
Forces
.Nm
to use IPv6 addresses only.
.It Fl -crlf
Convert LF into CRLF when sending data over the network.
.It Fl D
Enable debugging on the socket.
.It Fl d

52
contrib/netcat/netcat.c
View File

@ -94,6 +94,7 @@ int Nflag; /* shutdown() network socket */
int nflag; /* Don't do name look up */
int FreeBSD_Oflag; /* Do not use TCP options */
int FreeBSD_sctp; /* Use SCTP */
int FreeBSD_crlf; /* Convert LF to CRLF */
char *Pflag; /* Proxy username */
char *pflag; /* Localport flag */
int rflag; /* Random ports flag */
@ -136,7 +137,8 @@ void set_common_sockopts(int, int);
int map_tos(char *, int *);
void report_connect(const struct sockaddr *, socklen_t);
void usage(int);
ssize_t drainbuf(int, unsigned char *, size_t *);
ssize_t write_wrapper(int, const void *, size_t);
ssize_t drainbuf(int, unsigned char *, size_t *, int);
ssize_t fillbuf(int, unsigned char *, size_t *);
#ifdef IPSEC
@ -165,6 +167,7 @@ main(int argc, char *argv[])
struct addrinfo proxyhints;
char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
struct option longopts[] = {
{ "crlf", no_argument, &FreeBSD_crlf, 1 },
{ "no-tcpopt", no_argument, &FreeBSD_Oflag, 1 },
{ "sctp", no_argument, &FreeBSD_sctp, 1 },
{ "tun", required_argument, NULL, FREEBSD_TUN },
@ -972,7 +975,7 @@ readwrite(int net_fd)
/* try to write to network */
if (pfd[POLL_NETOUT].revents & POLLOUT && stdinbufpos > 0) {
ret = drainbuf(pfd[POLL_NETOUT].fd, stdinbuf,
&stdinbufpos);
&stdinbufpos, FreeBSD_crlf);
if (ret == -1)
pfd[POLL_NETOUT].fd = -1;
/* buffer empty - remove self from polling */
@ -1007,7 +1010,7 @@ readwrite(int net_fd)
/* try to write to stdout */
if (pfd[POLL_STDOUT].revents & POLLOUT && netinbufpos > 0) {
ret = drainbuf(pfd[POLL_STDOUT].fd, netinbuf,
&netinbufpos);
&netinbufpos, 0);
if (ret == -1)
pfd[POLL_STDOUT].fd = -1;
/* buffer empty - remove self from polling */
@ -1037,17 +1040,41 @@ readwrite(int net_fd)
}
ssize_t
drainbuf(int fd, unsigned char *buf, size_t *bufpos)
write_wrapper(int fd, const void *buf, size_t buflen)
{
ssize_t n;
ssize_t adjust;
n = write(fd, buf, *bufpos);
ssize_t n = write(fd, buf, buflen);
/* don't treat EAGAIN, EINTR as error */
if (n == -1 && (errno == EAGAIN || errno == EINTR))
n = -2;
if (n <= 0)
return n;
return (n == -1 && (errno == EAGAIN || errno == EINTR)) ? -2 : n;
}
ssize_t
drainbuf(int fd, unsigned char *buf, size_t *bufpos, int crlf)
{
ssize_t n = *bufpos, n2 = 0;
ssize_t adjust;
unsigned char *lf = NULL;
if (crlf) {
lf = memchr(buf, '\n', *bufpos);
if (lf && (lf == buf || *(lf - 1) != '\r'))
n = lf - buf;
else
lf = NULL;
}
if (n != 0) {
n = write_wrapper(fd, buf, n);
if (n <= 0)
return n;
}
if (lf) {
n2 = write_wrapper(fd, "\r\n", 2);
if (n2 <= 0)
return n2;
n += 1;
}
/* adjust buffer */
adjust = *bufpos - n;
if (adjust > 0)
@ -1440,6 +1467,7 @@ help(void)
fprintf(stderr, "\tCommand Summary:\n\
\t-4 Use IPv4\n\
\t-6 Use IPv6\n\
\t--crlf Convert LF into CRLF when sending data over the network\n\
\t-D Enable the debug socket option\n\
\t-d Detach from stdin\n");
#ifdef IPSEC