[PATCH v4 1/2] dhcpv6: Add --dhcpv6-opt with option type table and value parser

Introduce the --dhcpv6-opt flag that allows setting arbitrary DHCPv6 options from command-line in the form [--dhcpv6-opt CODE,VALUE]. Add a type lookup table mapping option codes to value types (IPv6, IPv6 list, integer, string, vendor class, length-prefixed string list) and dhcpv6_opt_parse() to convert CLI strings to binary wire format. If the same option code is given more than once, the last value wins. Link: https://bugs.passt.top/show_bug.cgi?id=192 Signed-off-by: Anshu Kumari --- v4: - The dhcpv6_opt_code < 1 check was replaced with proper validation: dhcpv6_opt_code == 0 || dhcpv6_opt_code > UINT16_MAX in conf.c - All uint16_t/uint32_t writes to byte buffers now use intermediate variables + memcpy() instead of direct pointer casts. - The DHCPV6_OPT_STR case now uses slen > buf_len instead of slen >= buf_len. - Option 17 (Vendor-specific Info) excluded. - A separate char optbuf[512] was added in conf_print() instead of reusing the small INANY_ADDRSTRLEN-sized buf for option rendering. - inet_ntop() return value checked. - Uses off += strlen(buf + off) instead of off = strlen(buf) in the IPv6 list rendering loop. - Iterator macro added — for_each_in6_off(off, len). - The addr and af variables are declared at function scope in dhcpv6_opt_parse() rather than inside block wrappers. - snprintf() alignment and line formatting. v3: - Use parse_unsigned(), parse_literal(), parse_eoi() from parse.c instead of manual strtoul()/errno/strchr() in dhcpv6_opt_parse() for UINT and VENDOR_CLASS cases. - Store options as pre-parsed binary in a static array indexed by option code, instead of storing raw strings. - Add dhcpv6_opt_to_str() to render binary option values back to printable strings for startup logging in conf_print(). v2: - Renamed custom_v6opts to dhcpv6_opts, MAX_CUSTOM_DHCPV6_OPTS to MAX_DHCPV6_OPTS. - Dropped val/len from ctx struct. - Moved dhcpv6_add_option() to conf.c as static conf_dhcpv6_option(). - Made dhcpv6_opt_parse() non-static, declared in dhcpv6.h - Omitted explicit [256] from dhcpv6_opt_types[]. - Moved chunk declaration into while block. - Removed redundant !slen check in DHCPV6_OPT_STR case. - All errors in dhcpv6_opt_parse() return -1, removed die() calls. --- conf.c | 26 ++++- dhcpv6.c | 339 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ dhcpv6.h | 2 + passt.1 | 31 +++++ 4 files changed, 397 insertions(+), 1 deletion(-) diff --git a/conf.c b/conf.c index faf26814..dba62bf8 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" @@ -632,7 +633,8 @@ 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 CODE to VAL\n"); if (strstr(name, "pasta")) FPRINTF(f, " default: don't use any search list\n"); else @@ -800,6 +802,7 @@ enum passt_modes conf_mode(int argc, char *argv[]) static void conf_print(const struct ctx *c) { char buf[INANY_ADDRSTRLEN]; + char optbuf[512]; int i; if (c->fd_control_listen >= 0) @@ -900,6 +903,10 @@ 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 = 1; i < UINT16_MAX; i++) { + if (dhcpv6_opt_to_str(i, optbuf, sizeof(optbuf))) + info(" option %u: %s", i, optbuf); + } dns6: for (i = 0; i < ARRAY_SIZE(c->ip6.dns); i++) { @@ -1348,6 +1355,7 @@ void conf(struct ctx *c, int argc, char **argv) {"stats", required_argument, NULL, 31 }, {"conf-path", required_argument, NULL, 'c' }, {"chroot-fallback", no_argument, NULL, 32 }, + {"dhcpv6-opt", required_argument, NULL, 35 }, { 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:"; @@ -1589,6 +1597,22 @@ void conf(struct ctx *c, int argc, char **argv) case 32: c->chroot_fallback = true; break; + case 35: { + unsigned long dhcpv6_opt_code; + + p = optarg; + + if (!parse_unsigned(&p, 0, &dhcpv6_opt_code) || + !parse_literal(&p, ",")) + die("--dhcpv6-opt requires CODE,VALUE format"); + + if (dhcpv6_opt_code == 0 || + dhcpv6_opt_code > UINT16_MAX) + die("Invalid DHCPv6 option code: %s", optarg); + + dhcpv6_set_opt(dhcpv6_opt_code, p); + break; + } case 'd': c->debug = 1; c->quiet = 0; diff --git a/dhcpv6.c b/dhcpv6.c index 29c7e320..abc45813 100644 --- a/dhcpv6.c +++ b/dhcpv6.c @@ -31,6 +31,8 @@ #include "passt.h" #include "tap.h" #include "log.h" +#include "inany.h" +#include "parse.h" /** * struct opt_hdr - DHCPv6 option header @@ -63,6 +65,11 @@ struct opt_hdr { #define OPT_MAX_SIZE IPV6_MIN_MTU - (sizeof(struct ipv6hdr) + \ UDP_MSG_HDR_SIZE) +#define for_each_in6_off(off, len) \ + for ((off) = 0; \ + (off) + sizeof(struct in6_addr) <= (unsigned int)(len); \ + (off) += sizeof(struct in6_addr)) + /** * struct opt_client_id - DHCPv6 Client Identifier option * @hdr: Option header @@ -278,6 +285,338 @@ static struct resp_not_on_link_t { { 0, }, }; +/** + * enum dhcpv6_opt_type - DHCPv6 option value types + * @DHCPV6_OPT_NONE: Unsupported or unknown option + * @DHCPV6_OPT_STR: Variable-length string + * @DHCPV6_OPT_IPV6: Single IPv6 address + * @DHCPV6_OPT_IPV6_LIST: Multiple IPv6 addresses, comma-separated + * @DHCPV6_OPT_UINT8: Unsigned 8-bit integer + * @DHCPV6_OPT_UINT16: Unsigned 16-bit integer + * @DHCPV6_OPT_UINT32: Unsigned 32-bit integer + * @DHCPV6_OPT_VENDOR_CLASS: Enterprise number + length-prefixed data + * @DHCPV6_OPT_LEN_STR_LIST: Length-prefixed string list + */ +enum dhcpv6_opt_type { + DHCPV6_OPT_NONE, + DHCPV6_OPT_STR, + DHCPV6_OPT_IPV6, + DHCPV6_OPT_IPV6_LIST, + DHCPV6_OPT_UINT8, + DHCPV6_OPT_UINT16, + DHCPV6_OPT_UINT32, + DHCPV6_OPT_VENDOR_CLASS, + DHCPV6_OPT_LEN_STR_LIST, +}; + +/** + * dhcpv6_opt_types - Maps DHCPv6 option code to value type, indexed by code + * RFC 8415 Options: 7, 15, 16, 32, 82, 83 + * RFC 5970 Options: 59, 60 + * RFC 4075 Options: 31 + */ +static const enum dhcpv6_opt_type dhcpv6_opt_types[] = { + [7] = DHCPV6_OPT_UINT8, /* Preference */ + [15] = DHCPV6_OPT_LEN_STR_LIST, /* User Class */ + [16] = DHCPV6_OPT_VENDOR_CLASS, /* Vendor Class */ + [31] = DHCPV6_OPT_IPV6_LIST, /* SNTP Servers */ + [32] = DHCPV6_OPT_UINT32, /* Information Refresh Time */ + [59] = DHCPV6_OPT_STR, /* Boot File URL */ + [60] = DHCPV6_OPT_LEN_STR_LIST, /* Boot File Params */ + [82] = DHCPV6_OPT_UINT32, /* SOL_MAX_RT */ + [83] = DHCPV6_OPT_UINT32, /* INF_MAX_RT */ +}; + +/** + * dhcpv6_opt_parse() - Parse a DHCPv6 option value string into binary + * @code: DHCPv6 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 dhcpv6_opt_parse(uint16_t code, const char *str, + uint8_t *buf, size_t buf_len) +{ + enum dhcpv6_opt_type type; + union inany_addr addr; + unsigned long val; + uint16_t slen_net; + sa_family_t af; + uint8_t width; + uint32_t ent; + size_t slen; + int len; + + if (!*str) + return -1; + + if (code >= ARRAY_SIZE(dhcpv6_opt_types)) + return -1; + + type = dhcpv6_opt_types[code]; + + switch (type) { + case DHCPV6_OPT_NONE: + return -1; + case DHCPV6_OPT_IPV6: + case DHCPV6_OPT_IPV6_LIST: + len = 0; + + do { + if (len + sizeof(struct in6_addr) > buf_len) + return -1; + + if (!parse_inany_(&str, &addr, &af) || af != AF_INET6) + return -1; + + memcpy(buf + len, &addr.a6, sizeof(struct in6_addr)); + len += sizeof(struct in6_addr); + + if (type == DHCPV6_OPT_IPV6) + break; + } while (parse_literal(&str, ",")); + + if (!len || !parse_eoi(str)) + return -1; + + return len; + case DHCPV6_OPT_UINT8: + case DHCPV6_OPT_UINT16: + case DHCPV6_OPT_UINT32: + if (type == DHCPV6_OPT_UINT8) + width = 1; + else if (type == DHCPV6_OPT_UINT16) + width = 2; + else + width = 4; + + if (buf_len < width) + return -1; + + if (!parse_unsigned(&str, 0, &val) || !parse_eoi(str) || + val >= (1ULL << (width * 8))) + return -1; + + if (type == DHCPV6_OPT_UINT16) { + uint16_t v16 = htons(val); + memcpy(buf, &v16, sizeof(v16)); + } else if (type == DHCPV6_OPT_UINT32) { + uint32_t v32 = htonl(val); + memcpy(buf, &v32, sizeof(v32)); + } else { + buf[0] = val; + } + + return width; + case DHCPV6_OPT_STR: + slen = strlen(str); + + if (slen > buf_len) + return -1; + + memcpy(buf, str, slen); + + return slen; + case DHCPV6_OPT_VENDOR_CLASS: + if (!parse_unsigned(&str, 0, &val) || + !parse_literal(&str, ":") || val > UINT32_MAX) + return -1; + + slen = strlen(str); + if (!slen) + return -1; + + len = sizeof(uint32_t) + sizeof(uint16_t) + slen; + if ((size_t)len > buf_len) + return -1; + + ent = htonl(val); + memcpy(buf, &ent, sizeof(ent)); + + slen_net = htons(slen); + memcpy(buf + sizeof(uint32_t), &slen_net, sizeof(slen_net)); + + memcpy(buf + sizeof(uint32_t) + sizeof(uint16_t), str, slen); + + return len; + case DHCPV6_OPT_LEN_STR_LIST: + len = 0; + + while (*str) { + slen = strcspn(str, ","); + if (!slen) + return -1; + + if (len + (int)(sizeof(uint16_t) + slen) > (int)buf_len) + return -1; + + slen_net = htons(slen); + memcpy(buf + len, &slen_net, sizeof(slen_net)); + len += sizeof(uint16_t); + + memcpy(buf + len, str, slen); + len += slen; + + str += slen; + if (*str == ',') + str++; + } + + if (!len) + return -1; + + return len; + } + + return -1; +} + +/** + * struct dhcpv6_user_opts - User-specified DHCPv6 options from --dhcpv6-opt + * @val: Binary option value in wire format + * @len: Length of @val in bytes, 0 if not set + */ +static struct { + uint8_t val[UINT16_MAX]; + int len; +} dhcpv6_user_opts[ARRAY_SIZE(dhcpv6_opt_types)]; + +/** + * dhcpv6_opt_to_str() - Render a binary DHCPv6 option value to printable string + * @code: DHCPv6 option code + * @buf: Output string buffer + * @buf_len: Size of output buffer + * + * Return: pointer to @buf if option is set, NULL otherwise + */ +const char *dhcpv6_opt_to_str(uint16_t code, char *buf, size_t buf_len) +{ + enum dhcpv6_opt_type type; + unsigned int i; + uint16_t slen; + int off = 0; + + if (code >= ARRAY_SIZE(dhcpv6_user_opts) || + !dhcpv6_user_opts[code].len) + return NULL; + + type = dhcpv6_opt_types[code]; + + switch (type) { + case DHCPV6_OPT_IPV6: + case DHCPV6_OPT_IPV6_LIST: + for_each_in6_off(i, dhcpv6_user_opts[code].len) { + if (off) { + if (off + 1 >= (int)buf_len) + return NULL; + buf[off++] = ','; + } + if (!inet_ntop(AF_INET6, + dhcpv6_user_opts[code].val + i, + buf + off, buf_len - off)) + return NULL; + off += strlen(buf + off); + } + return buf; + case DHCPV6_OPT_UINT8: + case DHCPV6_OPT_UINT16: + case DHCPV6_OPT_UINT32: { + uint32_t val = 0; + + if (dhcpv6_user_opts[code].len == 1) { + val = dhcpv6_user_opts[code].val[0]; + } else if (dhcpv6_user_opts[code].len == 2) { + uint16_t v16; + memcpy(&v16, dhcpv6_user_opts[code].val, sizeof(v16)); + val = ntohs(v16); + } else if (dhcpv6_user_opts[code].len == 4) { + memcpy(&val, dhcpv6_user_opts[code].val, sizeof(val)); + val = ntohl(val); + } + + (void)snprintf(buf, buf_len, "%u", val); + return buf; + } + case DHCPV6_OPT_STR: + (void)snprintf(buf, buf_len, "%.*s", + dhcpv6_user_opts[code].len, + dhcpv6_user_opts[code].val); + return buf; + case DHCPV6_OPT_VENDOR_CLASS: { + uint32_t ent; + int doff; + + if (dhcpv6_user_opts[code].len < + (int)(sizeof(uint32_t) + sizeof(uint16_t))) + return NULL; + + memcpy(&ent, dhcpv6_user_opts[code].val, sizeof(ent)); + memcpy(&slen, dhcpv6_user_opts[code].val + sizeof(uint32_t), + sizeof(slen)); + doff = sizeof(uint32_t) + sizeof(uint16_t); + + (void)snprintf(buf, buf_len, "%u:%.*s", + ntohl(ent), ntohs(slen), + dhcpv6_user_opts[code].val + doff); + return buf; + } + case DHCPV6_OPT_LEN_STR_LIST: + off = 0; + i = 0; + + while (i + sizeof(uint16_t) <= + (unsigned int)dhcpv6_user_opts[code].len) { + memcpy(&slen, dhcpv6_user_opts[code].val + i, + sizeof(slen)); + slen = ntohs(slen); + i += sizeof(uint16_t); + + if (i + slen > (unsigned int)dhcpv6_user_opts[code].len) + break; + + if (off) { + if (off + 1 >= (int)buf_len) + return NULL; + buf[off++] = ','; + } + if (off + slen >= (int)buf_len) + return NULL; + memcpy(buf + off, dhcpv6_user_opts[code].val + i, + slen); + off += slen; + i += slen; + } + buf[off] = '\0'; + return buf; + default: + return NULL; + } +} + +/** + * dhcpv6_set_opt() - Parse and store a user-specified DHCPv6 option + * @code: DHCPv6 option code + * @val_str: Value string from command line + */ +void dhcpv6_set_opt(uint16_t code, const char *val_str) +{ + int ret; + + if (code >= ARRAY_SIZE(dhcpv6_opt_types) || + dhcpv6_opt_types[code] == DHCPV6_OPT_NONE) + die("DHCPv6 option %u is not supported", code); + + ret = dhcpv6_opt_parse(code, val_str, + dhcpv6_user_opts[code].val, + sizeof(dhcpv6_user_opts[code].val)); + if (ret < 0) + die("Invalid value for DHCPv6 option %u: %s", code, val_str); + + dhcpv6_user_opts[code].len = ret; +} + /** * dhcpv6_opt() - Get option from DHCPv6 message * @data: Buffer with options, set to matching option on return diff --git a/dhcpv6.h b/dhcpv6.h index 1015a1a7..973c477c 100644 --- a/dhcpv6.h +++ b/dhcpv6.h @@ -9,5 +9,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data, const struct in6_addr *saddr, const struct in6_addr *daddr); void dhcpv6_init(const struct ctx *c); +void dhcpv6_set_opt(uint16_t code, const char *val_str); +const char *dhcpv6_opt_to_str(uint16_t code, char *buf, size_t buf_len); #endif /* DHCPV6_H */ diff --git a/passt.1 b/passt.1 index 53e072a9..249ed5cf 100644 --- a/passt.1 +++ b/passt.1 @@ -440,6 +440,37 @@ 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 DHCPv6 option \fICODE\fR to \fIVALUE\fR. The value format depends +on the option type and is determined automatically from the option code. +Multiple IPv6 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. +.RS +.TP +.B String options +59 (Boot File URL, RFC 5970) +.TP +.B Length-prefixed string list options (comma-separated entries) +15 (User Class, RFC 8415), 60 (Boot File Params, RFC 5970). +Each comma-separated entry is encoded with a 2-byte length prefix. +Example: \fB\-\-dhcpv6-opt 15,class1,class2\fR. +.TP +.B Vendor class options (ENTERPRISE:DATA format) +16 (Vendor Class, RFC 8415). +VALUE is \fIENTERPRISE\fR:\fIDATA\fR where \fIENTERPRISE\fR is the IANA +Private Enterprise Number and \fIDATA\fR is the vendor class string. +Example: \fB\-\-dhcpv6-opt 16,0:HTTPClient\fR for UEFI HTTP Boot. +.TP +.B IPv6 address list options (comma-separated) +31 (SNTP Servers) +.TP +.B Integer options +7 (Preference, 8-bit), 32 (Information Refresh Time, 32-bit), +82 (SOL_MAX_RT, 32-bit), 83 (INF_MAX_RT, 32-bit) +.RE + .TP .BR \-t ", " \-\-tcp-ports " " \fIspec Configure TCP port forwarding to guest or namespace. \fIspec\fR can be either: -- 2.55.0