[PATCH v3 6/6] doc: Add --dhcp-boot and --dhcp-opt to man page

[Anshu Kumari <anskuma@redhat.com>]

Document the new --dhcp-boot and --dhcp-opt command-line options in
the passt(1) man page, including supported option codes grouped by
value type and usage examples.

Link: https://bugs.passt.top/show_bug.cgi?id=192
Signed-off-by: Anshu Kumari <anskuma@redhat.com>
---
v3:
  - Removed options 33, 55, 61, 119 from supported codes list
  - Added note: "If the same name option code is given more than once,
    the last value wins".

v2:
  - Updated --dhcp-boot description.
  - Highlighted cross-referenced options with \fB...\fR.
  - Updated IP list format from "space-separated within quotes" to "comma-separated".
  - option 121 dropped.
  - Added option 55 to string options list.
  - Removed --dhcp-boot override reference from --dhcp-opt description.
---
 passt.1 | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/passt.1 b/passt.1
index 908fd4a..57e2cc1 100644
--- a/passt.1
+++ b/passt.1
@@ -430,6 +430,47 @@ 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 \-\-dhcp-boot " " \fIurl
+Convenience shorthand for \fB\-\-dhcp-opt\fR 67,\fIurl\fR.
+Sets the boot file name (DHCP option 67) for network boot.
+For UEFI HTTP boot, also set the vendor class identifier using
+\fB\-\-dhcp-opt\fR 60,HTTPClient.
+
+.TP
+.BR \-\-dhcp-opt " " \fICODE\fR,\fIVALUE\fR
+Set a DHCP option by numeric code. The value format is determined automatically
+from the option code. Multiple IPv4 addresses are comma-separated.
+This option can be specified multiple times. If the same option code is
+given more than once, the last value wins. Options set with
+\fB\-\-dhcp-opt\fR override built-in values.
+Only the following option codes are supported (unsupported codes cause an error):
+.RS
+.TP
+.B IPv4 address options
+1 (Subnet Mask), 16 (Swap Server), 28 (Broadcast Address), 50 (Requested IP),
+54 (Server Identifier)
+.TP
+.B IPv4 address list options (comma-separated)
+3 (Router), 4 (Time Server), 5 (Name Server), 6 (DNS), 7 (Log Server),
+8 (Cookie Server), 9 (LPR Server), 10 (Impress Server),
+11 (Resource Location Server), 41 (NIS Servers),
+42 (NTP Servers), 44 (NetBIOS Name Server)
+.TP
+.B Integer options
+2 (Time Offset, 32-bit), 13 (Boot File Size, 16-bit), 19 (IP Forwarding, 8-bit),
+23 (Default IP TTL, 8-bit), 26 (Interface MTU, 16-bit),
+37 (TCP Default TTL, 8-bit), 38 (TCP Keepalive Interval, 32-bit),
+51 (IP Address Lease Time, 32-bit),
+53 (DHCP Message Type, 8-bit), 57 (Max DHCP Message Size, 16-bit),
+58 (Renewal Time, 32-bit), 59 (Rebinding Time, 32-bit)
+.TP
+.B String options
+12 (Host Name), 15 (Domain Name), 17 (Root Path), 40 (NIS Domain Name),
+60 (Vendor Class Identifier), 66 (TFTP Server Name),
+67 (Bootfile Name), 252 (WPAD URL)
+.RE
+
 .TP
 .BR \-t ", " \-\-tcp-ports " " \fIspec
 Configure TCP port forwarding to guest or namespace. \fIspec\fR can be one of:
-- 
2.54.0