On Tue, May 26, 2026 at 9:35 PM Laurent Vivier wrote: > On 5/26/26 14:31, Anshu Kumari wrote: > > Add an RFC 2132 type lookup table mapping DHCP option codes to their > > expected value formats, and a dhcp_opt_parse() function that converts > > CLI string values into their binary wire representation. > > > > Wire dhcp_opt_parse() into the --dhcp-opt handler so that values are > > validated and encoded at configuration time. > > > > Link: https://bugs.passt.top/show_bug.cgi?id=192 > > Signed-off-by: Anshu Kumari > > --- > > v2: > > - Replaced struct lookup table + dhcp_opt_type_lookup() function with > flat dhcp_opt_types[256] array indexed by code. > > - Consolidated DHCP_OPT_UINT8/UINT16/UINT32 into single > DHCP_OPT_INTEGER with dhcp_opt_int_width[256] table. > > - Dropped DHCP_OPT_ROUTES / option 121 entirely. > > - Added kerneldoc for enum dhcp_opt_type values. > > - Removed curly braces from switch cases, declarations before switch. > > - Added newlines before return statements. > > - Changed IP list delimiter from space to comma (--dhcp-opt > 6,1.1.1.1,8.8.8.8). > > - Defined DHCP_OPT_PARSE_BUF constant for bare 1024. > > - Added len and val[255] fields to struct here (moved from patch 1). > > - Added kerneldoc for @custom_opts.len and @custom_opts.val. > > - Wired dhcp_opt_parse() into case 32 (--dhcp-boot) to populate > val/len. > > --- > > conf.c | 16 ++++++ > > dhcp.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > dhcp.h | 17 +++++++ > > passt.h | 4 ++ > > 4 files changed, 185 insertions(+) > > > > diff --git a/conf.c b/conf.c > > index ae8ee26..3a5f45d 100644 > > --- a/conf.c > > +++ b/conf.c > > @@ -1266,6 +1266,7 @@ void conf(struct ctx *c, int argc, char **argv) > > char *end; > > uid_t uid; > > gid_t gid; > > + int len; > > I think you don't need to introduce len for --dhcp-opt as you already use > ret for --dhcp-boot > > > > > > if (c->mode == MODE_PASTA) > > @@ -1482,7 +1483,14 @@ void conf(struct ctx *c, int argc, char **argv) > > die("Too many DHCP options (max %d)", > > MAX_CUSTOM_DHCP_OPTS); > > > > + ret = dhcp_opt_parse(67, optarg, > > + > c->custom_opts[c->custom_opts_count].val, > > + > sizeof(c->custom_opts[0].val)); > > + if (ret < 0) > > + die("Invalid boot file value: %s", optarg); > > + > > c->custom_opts[c->custom_opts_count].code = 67; > > + c->custom_opts[c->custom_opts_count].len = ret; > > if > (snprintf_check(c->custom_opts[c->custom_opts_count].str, > > sizeof(c->custom_opts[0].str), > > "%s", optarg)) > > @@ -1503,7 +1511,15 @@ void conf(struct ctx *c, int argc, char **argv) > > die("Too many --dhcp-opt entries (max %d)", > > MAX_CUSTOM_DHCP_OPTS); > > > > + len = dhcp_opt_parse(optcode, comma + 1, > > + > c->custom_opts[c->custom_opts_count].val, > > + > sizeof(c->custom_opts[0].val)); > > you can use "ret" here too > > > + if (len < 0) > > + die("Invalid value for DHCP option %lu: > %s", > > + optcode, comma + 1); > > + > > c->custom_opts[c->custom_opts_count].code = > optcode; > > + c->custom_opts[c->custom_opts_count].len = len; > > if > (snprintf_check(c->custom_opts[c->custom_opts_count].str, > > sizeof(c->custom_opts[0].str), > > "%s", comma + 1)) > > diff --git a/dhcp.c b/dhcp.c > > index 1ff8cba..e1c95ad 100644 > > --- a/dhcp.c > > +++ b/dhcp.c > > @@ -33,6 +33,154 @@ > > #include "log.h" > > #include "dhcp.h" > > > > +/** > > + * dhcp_opt_types - Maps option code to RFC 2132 value type, indexed by > code > > + */ > > +static const enum dhcp_opt_type dhcp_opt_types[256] = { > > + [1] = DHCP_OPT_IPV4, /* Subnet Mask */ > > + [2] = DHCP_OPT_INTEGER, /* Time Offset */ > > + [3] = DHCP_OPT_IPV4_LIST, /* Router */ > > + [4] = DHCP_OPT_IPV4_LIST, /* Time Server */ > > + [5] = DHCP_OPT_IPV4_LIST, /* Name Server */ > > + [6] = DHCP_OPT_IPV4_LIST, /* Domain Name Server */ > > + [7] = DHCP_OPT_IPV4_LIST, /* Log Server */ > > + [8] = DHCP_OPT_IPV4_LIST, /* Cookie Server */ > > + [9] = DHCP_OPT_IPV4_LIST, /* LPR Server */ > > + [10] = DHCP_OPT_IPV4_LIST, /* Impress Server */ > > + [11] = DHCP_OPT_IPV4_LIST, /* Resource Location Server */ > > + [12] = DHCP_OPT_STR, /* Host Name */ > > + [13] = DHCP_OPT_INTEGER, /* Boot File Size */ > > + [15] = DHCP_OPT_STR, /* Domain Name */ > > + [16] = DHCP_OPT_IPV4, /* Swap Server */ > > + [17] = DHCP_OPT_STR, /* Root Path */ > > + [19] = DHCP_OPT_INTEGER, /* IP Forwarding */ > > + [23] = DHCP_OPT_INTEGER, /* Default IP TTL */ > > + [26] = DHCP_OPT_INTEGER, /* Interface MTU */ > > + [28] = DHCP_OPT_IPV4, /* Broadcast Address */ > > + [33] = DHCP_OPT_IPV4_LIST, /* Static Routes */ > > + [37] = DHCP_OPT_INTEGER, /* TCP Default TTL */ > > + [38] = DHCP_OPT_INTEGER, /* TCP Keepalive Interval */ > > + [40] = DHCP_OPT_STR, /* NIS Domain Name */ > > + [41] = DHCP_OPT_IPV4_LIST, /* NIS Servers */ > > + [42] = DHCP_OPT_IPV4_LIST, /* NTP Servers */ > > + [44] = DHCP_OPT_IPV4_LIST, /* NetBIOS Name Server */ > > + [50] = DHCP_OPT_IPV4, /* Requested IP Address */ > > + [51] = DHCP_OPT_INTEGER, /* IP Address Lease Time */ > > + [53] = DHCP_OPT_INTEGER, /* DHCP Message Type */ > > + [54] = DHCP_OPT_IPV4, /* Server Identifier */ > > + [55] = DHCP_OPT_STR, /* Parameter Request List */ > > This is a client option, I don't think we need to manage it. > > > + [57] = DHCP_OPT_INTEGER, /* Max DHCP Message Size */ > > + [58] = DHCP_OPT_INTEGER, /* Renewal (T1) Time */ > > + [59] = DHCP_OPT_INTEGER, /* Rebinding (T2) Time */ > > + [60] = DHCP_OPT_STR, /* Vendor Class Identifier */ > > + [61] = DHCP_OPT_STR, /* Client Identifier */ > > This is also a client option. > > > + [66] = DHCP_OPT_STR, /* TFTP Server Name */ > > + [67] = DHCP_OPT_STR, /* Bootfile Name */ > > + [119] = DHCP_OPT_STR, /* Domain Search List */ > > This is not really a string as this uses the message compression described > in RFC 1035, > 4.1.4. (See also 3. Example in rfc3397). I'm not sure we can encode this > manually on the > command line. And RFC 3396 defines how to encode search string for more > than 255 > characters length > > > + [252] = DHCP_OPT_STR, /* WPAD URL */ > > +}; > > + > > +/** > > + * dhcp_opt_int_width - Integer width in bytes for INTEGER-typed options > > + */ > > +static const uint8_t dhcp_opt_int_width[256] = { > > + [2] = 4, /* Time Offset */ > > + [13] = 2, /* Boot File Size */ > > + [19] = 1, /* IP Forwarding */ > > + [23] = 1, /* Default IP TTL */ > > + [26] = 2, /* Interface MTU */ > > + [37] = 1, /* TCP Default TTL */ > > + [38] = 4, /* TCP Keepalive Interval */ > > + [51] = 4, /* IP Address Lease Time */ > > + [53] = 1, /* DHCP Message Type */ > > + [57] = 2, /* Max DHCP Message Size */ > > + [58] = 4, /* Renewal (T1) Time */ > > + [59] = 4, /* Rebinding (T2) Time */ > > +}; > > + > > +#define DHCP_OPT_PARSE_BUF 1024 > > Do we need 1024 bytes, all options are bounded to 256 bytes. > > + > > +/** > > + * dhcp_opt_parse() - Parse a DHCP option value > > + * @code: DHCP option code > > + * @str: DHCP Value string from command line > > + * @buf: Output buffer > > + * @buf_len: Size of output buffer > > + * > > + * Return: number of bytes written to @buf, or -1 on error > > + */ > > +int dhcp_opt_parse(uint8_t code, const char *str, uint8_t *buf, size_t > buf_len) > > +{ > > + enum dhcp_opt_type type = dhcp_opt_types[code]; > > + char tmp[DHCP_OPT_PARSE_BUF]; > > + char *tok, *saveptr, *end; > > + struct in_addr addr; > > + unsigned long val; > > + unsigned int i; > > + uint8_t width; > > + size_t slen; > > + int len; > > + > > + switch (type) { > > + case DHCP_OPT_NONE: > > + die("Unsupported DHCP option: %u," > > + " see passt(1) for supported codes", code); > > + case DHCP_OPT_IPV4: > > + if (inet_pton(AF_INET, str, &addr) != 1) > > + return -1; > > + > > + if (buf_len < sizeof(addr)) > > + return -1; > > + > > + memcpy(buf, &addr, sizeof(addr)); > > + > > + return sizeof(addr); > > + case DHCP_OPT_IPV4_LIST: > > + len = 0; > > + > > + if (snprintf_check(tmp, sizeof(tmp), "%s", str)) > > + return -1; > > + > > + for (tok = strtok_r(tmp, ",", &saveptr); tok; > > + tok = strtok_r(NULL, ",", &saveptr)) { > > + if (inet_pton(AF_INET, tok, &addr) != 1) > > + return -1; > > + > > + if (len + (int)sizeof(addr) > (int)buf_len) > > + return -1; > > + > > + memcpy(buf + len, &addr, sizeof(addr)); > > + len += sizeof(addr); > > + } > > + return len; > > + case DHCP_OPT_INTEGER: > > + width = dhcp_opt_int_width[code]; > > + val = strtoul(str, &end, 0); > > + > > + if (*end || buf_len < width) > > + return -1; > > + > > + if (width < 4 && val >= (1UL << (width * 8))) > > + return -1; > > + > > + for (i = 0; i < width; i++) > > + buf[i] = (val >> ((width - 1 - i) * 8)) & 0xff; > > + > > + return width; > > + case DHCP_OPT_STR: > > + slen = strlen(str); > > + > > + if (!slen || slen >= buf_len) > > + return -1; > > + > > + strncpy((char *)buf, str, buf_len); > > + > > + return slen; > > + } > > + > > + return -1; > > +} > > + > > /** > > * struct opt - DHCP option > > * @sent: Convenience flag, set while filling replies > > diff --git a/dhcp.h b/dhcp.h > > index cd50c99..3da571c 100644 > > --- a/dhcp.h > > +++ b/dhcp.h > > @@ -6,7 +6,24 @@ > > #ifndef DHCP_H > > #define DHCP_H > > > > +/** > > + * enum dhcp_opt_type - DHCP option value types per RFC 2132 > > + * @DHCP_OPT_NONE: Unsupported or unknown option > > + * @DHCP_OPT_STR: Variable-length string > > + * @DHCP_OPT_IPV4: Single IPv4 address > > + * @DHCP_OPT_IPV4_LIST:Multiple IPv4 addresses, comma-separated > > + * @DHCP_OPT_INTEGER: Unsigned integer (1, 2, or 4 bytes) > > + */ > > +enum dhcp_opt_type { > > + DHCP_OPT_NONE, > > + DHCP_OPT_STR, > > + DHCP_OPT_IPV4, > > + DHCP_OPT_IPV4_LIST, > > + DHCP_OPT_INTEGER, > > +}; > > + > > int dhcp(const struct ctx *c, struct iov_tail *data); > > void dhcp_init(void); > > +int dhcp_opt_parse(uint8_t code, const char *str, uint8_t *buf, size_t > buf_len); > > > > #endif /* DHCP_H */ > > diff --git a/passt.h b/passt.h > > index 3a0816f..751fee3 100644 > > --- a/passt.h > > +++ b/passt.h > > @@ -184,6 +184,8 @@ struct ip6_ctx { > > * @fqdn: Guest FQDN > > * @custom_opts: User-specified DHCP options from --dhcp-opt > > * @custom_opts.code: DHCP option code > > + * @custom_opts.len: Length of binary value in @val > > + * @custom_opts.val: Binary-encoded option value > > * @custom_opts.str: Original string value from command line > > * @custom_opts_count: Number of entries in @custom_opts > > * @ifi6: Template interface for IPv6, -1: none, 0: IPv6 > disabled > > @@ -271,6 +273,8 @@ struct ctx { > > > > struct { > > uint8_t code; > > + uint8_t len; > > + uint8_t val[255]; > > char str[256]; > > Why do we need to keep str[] once the value is encoded into val[]? > To print the option value as entered by user. anskuma@anskuma-thinkpadp1gen7:~/Documents/passt$ ./passt -f --dhcp-opt 60,HTTPClient --dhcp-opt 67,http://192.168.1.1:8080/alpine.iso --dhcp-opt 12,testhost --dhcp-opt 15,test.example.com --dhcp-opt 6,8.8.8.8,8.8.4.4 --dhcp-opt 26,1400 --dhcp-opt 42,192.168.1.1 --dhcp-opt 51,360 --dhcp-opt 6,1.1.1.1,9.9.9.9 UNIX domain socket bound at /tmp/passt_1.socket No IPv6 nameserver available for NDP/DHCPv6 Template interface: wlp9s0f0 (IPv4), wlp9s0f0 (IPv6) MAC: host: 9a:55:9a:55:9a:55 NAT to host 127.0.0.1: 192.168.1.1 DHCP: assign: 192.168.1.9 mask: 255.255.255.0 router: 192.168.1.1 *option 60: HTTPClient option 67: http://192.168.1.1:8080/alpine.iso option 12: testhost option 15: test.example.com option 6: 1.1.1.1,9.9.9.9 option 26: 1400 option 42: 192.168.1.1 option 51: 360* > > > } custom_opts[MAX_CUSTOM_DHCP_OPTS]; > > int custom_opts_count; > > Thanks, > Laurent > >