On Fri, Jun 12, 2026 at 01:04:41AM +0200, Stefano Brivio wrote: > On Mon, 1 Jun 2026 13:07:53 +0530 > 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 dhcp_add_option() 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 > > --- > > v3: > > - Replaced DHCP_OPT_INTEGER with separate DHCP_OPT_INT8/INT16/INT32 > > enums, removed dhcp_opt_int_width[] array. > > - Shared logic between DHCP_OPT_IPV4 and DHCP_OPT_IPV4_LIST — parse > > both as list, error if >1 in single case. > > - Added errno = 0 before strtoul() and check after. > > - Fixed range check: 1ULL << (width * 8) for all widths including > > width==4. > > - strncpy → memcpy for DHCP_OPT_STR. > > - Moved enum to dhcp.c since not used in other files. > > - Removed options 55, 61 (client-only), 119 (DNS compression, use > > --dhcp-search instead), 33 (IP pairs not supported). > > - DHCP_OPT_PARSE_BUF 1024 → char tmp[256]. > > - Upgraded dhcp_add_option() to call dhcp_opt_parse() and populate > > val[]/len. > > - Aligned array entries for readability. > > - Added tab after @DHCP_OPT_IPV4_LIST: in kerneldoc. > > - Reject empty value strings before parsing > > - Reject leading/trailing/consecutive commas in IP list values. > > > > 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. > > --- > > dhcp.c | 180 +++++++++++++++++++++++++++++++++++++++++++++++++++++++- > > passt.h | 4 ++ > > 2 files changed, 181 insertions(+), 3 deletions(-) > > > > diff --git a/dhcp.c b/dhcp.c > > index c5fbf37..07a42b9 100644 > > --- a/dhcp.c > > +++ b/dhcp.c > > @@ -23,6 +23,7 @@ > > #include > > #include > > #include > > +#include > > > > #include "util.h" > > #include "ip.h" > > @@ -33,6 +34,170 @@ > > #include "log.h" > > #include "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_INT8: Unsigned 8-bit integer > > + * @DHCP_OPT_INT16: Unsigned 16-bit integer > > + * @DHCP_OPT_INT32: Unsigned 32-bit integer > > + */ > > +enum dhcp_opt_type { > > + DHCP_OPT_NONE, > > + DHCP_OPT_STR, > > + DHCP_OPT_IPV4, > > + DHCP_OPT_IPV4_LIST, > > + DHCP_OPT_INT8, > > + DHCP_OPT_INT16, > > + DHCP_OPT_INT32, > > +}; > > + > > +/** > > + * 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_INT32, /* 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_INT16, /* Boot File Size */ > > + [15] = DHCP_OPT_STR, /* Domain Name */ > > + [16] = DHCP_OPT_IPV4, /* Swap Server */ > > + [17] = DHCP_OPT_STR, /* Root Path */ > > + [19] = DHCP_OPT_INT8, /* IP Forwarding */ > > + [23] = DHCP_OPT_INT8, /* Default IP TTL */ > > + [26] = DHCP_OPT_INT16, /* Interface MTU */ > > + [28] = DHCP_OPT_IPV4, /* Broadcast Address */ > > + [37] = DHCP_OPT_INT8, /* TCP Default TTL */ > > + [38] = DHCP_OPT_INT32, /* 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_INT32, /* IP Address Lease Time */ > > + [53] = DHCP_OPT_INT8, /* DHCP Message Type */ > > + [54] = DHCP_OPT_IPV4, /* Server Identifier */ > > + [57] = DHCP_OPT_INT16, /* Max DHCP Message Size */ > > + [58] = DHCP_OPT_INT32, /* Renewal (T1) Time */ > > + [59] = DHCP_OPT_INT32, /* Rebinding (T2) Time */ > > + [60] = DHCP_OPT_STR, /* Vendor Class Identifier */ > > + [66] = DHCP_OPT_STR, /* TFTP Server Name */ > > + [67] = DHCP_OPT_STR, /* Bootfile Name */ > > + [252] = DHCP_OPT_STR, /* WPAD URL */ > > +}; > > + > > +/** > > + * dhcp_opt_parse() - Parse a DHCP option value > > + * @code: DHCP option code > > + * @str: Value string from command line > > + * @buf: Output buffer for binary value > > + * @buf_len: Size of output buffer > > + * > > + * Return: number of bytes written to @buf, or -1 on error > > + */ > > +static 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 *tok, *saveptr, *end; > > + struct in_addr addr; > > + unsigned long val; > > + unsigned int i; > > + uint8_t width; > > + char tmp[256]; > > + size_t slen; > > + int len; > > + > > + if (!*str) > > + die("Empty value for DHCP option %u", code); > > + > > + switch (type) { > > + case DHCP_OPT_NONE: > > + die("Unsupported DHCP option: %u," > > + " see passt(1) for supported codes", code); > > + case DHCP_OPT_IPV4: > > + case DHCP_OPT_IPV4_LIST: > > + len = 0; > > + > > + /* Reject empty, leading/trailing, or consecutive commas */ > > + if (!*str || *str == ',' || str[strlen(str) - 1] == ',' || > > + strstr(str, ",,")) > > + return -1; > > + > > + 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); > > + > > + if (type == DHCP_OPT_IPV4) > > + break; > > + } > > + > > + if (type == DHCP_OPT_IPV4 && strtok_r(NULL, ",", &saveptr)) > > + return -1; > > + > > + return len; > > + case DHCP_OPT_INT8: > > + case DHCP_OPT_INT16: > > + case DHCP_OPT_INT32: > > + if (type == DHCP_OPT_INT8) > > + width = 1; > > + else if (type == DHCP_OPT_INT16) > > + width = 2; > > + else > > + width = 4; > > + > > + errno = 0; > > + val = strtoul(str, &end, 0); > > + > > + if (*end || errno) > > + return -1; > > + > > + if (buf_len < width) > > + return -1; > > + > > + if (val >= (1ULL << (width * 8))) > > + return -1; > > + > > + for (i = width; i > 0; i--) { > > + buf[i - 1] = val & 0xff; > > + val >>= 8; > > + } > > + > > + return width; > > + case DHCP_OPT_STR: > > + slen = strlen(str); > > + > > + if (!slen || slen >= buf_len) > > + return -1; > > + > > + memcpy(buf, str, slen); > > + > > + return slen; > > + } > > + > > + return -1; > > +} > > > > /** > > * dhcp_add_option() - Add or update a custom DHCP option > > @@ -40,14 +205,15 @@ > > * @code: DHCP option code > > * @val_str: Value string from command line > > * > > - * If @code was already added, the previous value is overwritten. > > - * Calls die() on any error. > > + * Parses @val_str according to the type registered for @code in > > + * dhcp_opt_types[]. If @code was already added, the previous value > > + * is overwritten. Calls die() on any error. > > * > > * Return: 0 on success > > */ > > int dhcp_add_option(struct ctx *c, uint8_t code, const char *val_str) > > { > > - int idx; > > + int idx, ret; > > > > for (idx = 0; idx < c->custom_opts_count; idx++) { > > if (c->custom_opts[idx].code == code) > > @@ -61,7 +227,15 @@ int dhcp_add_option(struct ctx *c, uint8_t code, const char *val_str) > > c->custom_opts_count++; > > } > > > > + ret = dhcp_opt_parse(code, val_str, > > + c->custom_opts[idx].val, > > + sizeof(c->custom_opts[0].val)); > > + if (ret < 0) > > + die("Invalid value for DHCP option %u: %s", > > + code, val_str); > > + > > c->custom_opts[idx].code = code; > > + c->custom_opts[idx].len = ret; > > > > if (snprintf_check(c->custom_opts[idx].str, > > sizeof(c->custom_opts[0].str), > > 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 > > But we already have struct opt opts[255] in dhcp.c, why don't you use > that directly? It would have the advantage of clearly separating what > belongs to the configuration proper and what belongs to the specific > DHCP encoding. > > Besides, I see the point in maintaining what was set via command line, > but not some temporary value that would just be copied to struct opt[]. > This would be a third copy. Right, that's what I was getting at :). -- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson