Add a --dhcpv6-opt CODE,VALUE option for injecting custom DHCPv6
options into server replies. This patch adds the CLI parsing in conf.c,
storage in struct ctx, and a simple dhcpv6_add_option() that stores the
option code and raw string value.
Signed-off-by: Anshu Kumari
---
conf.c | 26 +++++++++++++++++++++++++-
dhcpv6.c | 37 +++++++++++++++++++++++++++++++++++++
dhcpv6.h | 1 +
passt.1 | 6 ++++++
passt.h | 12 ++++++++++++
5 files changed, 81 insertions(+), 1 deletion(-)
diff --git a/conf.c b/conf.c
index 6f86940..ac7e6e5 100644
--- a/conf.c
+++ b/conf.c
@@ -47,6 +47,7 @@
#include "lineread.h"
#include "isolation.h"
#include "log.h"
+#include "dhcpv6.h"
#include "vhost_user.h"
#include "epoll_ctl.h"
#include "conf.h"
@@ -616,7 +617,8 @@ static void usage(const char *name, FILE *f, int status)
" -S, --search LIST Space-separated list, search domains\n"
" a single, empty option disables the DNS search list\n"
" -H, --hostname NAME Hostname to configure client with\n"
- " --fqdn NAME FQDN to configure client with\n");
+ " --fqdn NAME FQDN to configure client with\n"
+ " --dhcpv6-opt CODE,VAL Set DHCPv6 option by code\n");
if (strstr(name, "pasta"))
FPRINTF(f, " default: don't use any search list\n");
else
@@ -884,6 +886,10 @@ static void conf_print(const struct ctx *c)
info(" our link-local: %s",
inet_ntop(AF_INET6, &c->ip6.our_tap_ll,
buf, sizeof(buf)));
+ for (i = 0; i < c->custom_v6opts_count; i++)
+ info(" v6 option %u: %s",
+ c->custom_v6opts[i].code,
+ c->custom_v6opts[i].str);
dns6:
for (i = 0; i < ARRAY_SIZE(c->ip6.dns); i++) {
@@ -1233,6 +1239,7 @@ void conf(struct ctx *c, int argc, char **argv)
{"migrate-no-linger", no_argument, NULL, 30 },
{"stats", required_argument, NULL, 31 },
{"conf-path", required_argument, NULL, 'c' },
+ {"dhcpv6-opt", required_argument, NULL, 34 },
{ 0 },
};
const char *optstring = "+dqfel:hs:c:F:I:p:P:m:a:n:M:g:i:o:D:S:H:461t:u:T:U:";
@@ -1248,10 +1255,13 @@ void conf(struct ctx *c, int argc, char **argv)
uint8_t prefix_len_from_opt = 0;
unsigned int ifi4 = 0, ifi6 = 0;
const char *logfile = NULL;
+ unsigned long v6optcode;
char *runas = NULL;
size_t logsize = 0;
+ const char *comma;
long fd_tap_opt;
int name, ret;
+ char *end;
uid_t uid;
gid_t gid;
@@ -1465,6 +1475,20 @@ void conf(struct ctx *c, int argc, char **argv)
die("Can't display statistics if not running in foreground");
c->stats = strtol(optarg, NULL, 0);
break;
+ case 34:
+ comma = strchr(optarg, ',');
+ if (!comma)
+ die("--dhcpv6-opt requires CODE,VALUE format");
+
+ errno = 0;
+ v6optcode = strtoul(optarg, &end, 0);
+ if (end != comma || errno ||
+ v6optcode < 1 || v6optcode > 255)
+ die("DHCPv6 option code must be 1-255: %s",
+ optarg);
+
+ dhcpv6_add_option(c, v6optcode, comma + 1);
+ break;
case 'd':
c->debug = 1;
c->quiet = 0;
diff --git a/dhcpv6.c b/dhcpv6.c
index 97c04e2..a0fb77c 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -32,6 +32,43 @@
#include "tap.h"
#include "log.h"
+/**
+ * dhcpv6_add_option() - Add or update a custom DHCPv6 option
+ * @c: Execution context
+ * @code: DHCPv6 option code
+ * @val_str: Value string from command line
+ *
+ * Stores the option code and raw string value. Binary encoding and
+ * injection into DHCPv6 replies are handled by later patches.
+ *
+ * Return: 0 on success
+ */
+int dhcpv6_add_option(struct ctx *c, uint16_t code, const char *val_str)
+{
+ int idx;
+
+ for (idx = 0; idx < c->custom_v6opts_count; idx++) {
+ if (c->custom_v6opts[idx].code == code)
+ break;
+ }
+
+ if (idx == c->custom_v6opts_count) {
+ if (c->custom_v6opts_count >= MAX_CUSTOM_DHCPV6_OPTS)
+ die("Too many --dhcpv6-opt entries (max %d)",
+ MAX_CUSTOM_DHCPV6_OPTS);
+ c->custom_v6opts_count++;
+ }
+
+ c->custom_v6opts[idx].code = code;
+
+ if (snprintf_check(c->custom_v6opts[idx].str,
+ sizeof(c->custom_v6opts[0].str),
+ "%s", val_str))
+ die("DHCPv6 option value too long: %s", val_str);
+
+ return 0;
+}
+
/**
* struct opt_hdr - DHCPv6 option header
* @t: Option type
diff --git a/dhcpv6.h b/dhcpv6.h
index c706dfd..c01bc36 100644
--- a/dhcpv6.h
+++ b/dhcpv6.h
@@ -9,5 +9,6 @@
int dhcpv6(struct ctx *c, struct iov_tail *data,
struct in6_addr *saddr, struct in6_addr *daddr);
void dhcpv6_init(const struct ctx *c);
+int dhcpv6_add_option(struct ctx *c, uint16_t code, const char *val_str);
#endif /* DHCPV6_H */
diff --git a/passt.1 b/passt.1
index 908fd4a..9c25214 100644
--- a/passt.1
+++ b/passt.1
@@ -430,6 +430,12 @@ Send \fIname\fR as DHCP option 12 (hostname).
FQDN to configure the client with.
Send \fIname\fR as Client FQDN: DHCP option 81 and DHCPv6 option 39.
+.TP
+.BR \-\-dhcpv6-opt " " \fICODE\fR,\fIVALUE\fR
+Set a DHCPv6 option by numeric code. The value format is determined
+automatically from the option code. This option can be specified multiple
+times. If the same option code is given more than once, the last value wins.
+
.TP
.BR \-t ", " \-\-tcp-ports " " \fIspec
Configure TCP port forwarding to guest or namespace. \fIspec\fR can be one of:
diff --git a/passt.h b/passt.h
index 1726965..91509df 100644
--- a/passt.h
+++ b/passt.h
@@ -182,6 +182,10 @@ struct ip6_ctx {
* @dns_search: DNS search list
* @hostname: Guest hostname
* @fqdn: Guest FQDN
+ * @custom_v6opts: User-specified DHCPv6 options from --dhcpv6-opt
+ * @custom_v6opts.code: DHCPv6 option code
+ * @custom_v6opts.str: Original string value from command line
+ * @custom_v6opts_count:Number of entries in @custom_v6opts
* @ifi6: Template interface for IPv6, -1: none, 0: IPv6 disabled
* @ip6: IPv6 configuration
* @pasta_ifn: Name of namespace interface for pasta
@@ -263,6 +267,14 @@ struct ctx {
char hostname[PASST_MAXDNAME];
char fqdn[PASST_MAXDNAME];
+#define MAX_CUSTOM_DHCPV6_OPTS 32
+
+ struct {
+ uint16_t code;
+ char str[256];
+ } custom_v6opts[MAX_CUSTOM_DHCPV6_OPTS];
+ int custom_v6opts_count;
+
int ifi6;
struct ip6_ctx ip6;
--
2.54.0