diff options
Diffstat (limited to 'networking/udhcp')
| -rw-r--r-- | networking/udhcp/common.c | 96 | ||||
| -rw-r--r-- | networking/udhcp/common.h | 8 |
2 files changed, 62 insertions, 42 deletions
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c index 16bf697..20d843b 100644 --- a/networking/udhcp/common.c +++ b/networking/udhcp/common.c @@ -15,7 +15,7 @@ const uint8_t MAC_BCAST_ADDR[6] ALIGN2 = { }; #if ENABLE_UDHCPC || ENABLE_UDHCPD -/* Supported options are easily added here. +/* Supported options are easily added here, they need to be sorted. * See RFC2132 for more options. * OPTION_REQ: these options are requested by udhcpc (unless -o). */ @@ -222,79 +222,91 @@ unsigned FAST_FUNC udhcp_option_idx(const char *name, const char *option_strings } } -/* Get an option with bounds checking (warning, result is not aligned) */ -uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) +/* Initialize state to be used between subsequent udhcp_scan_options calls */ +void FAST_FUNC init_scan_state(struct dhcp_packet *packet, struct dhcp_scan_state *scan_state) +{ + scan_state->overload = 0; + scan_state->rem = sizeof(packet->options); + scan_state->optionptr = packet->options; +} + +/* Iterate over packet's options, each call returning the next option. + * scan_state needs to be initialized with init_scan_state beforehand. + * Warning, result is not aligned. */ +uint8_t* FAST_FUNC udhcp_scan_options(struct dhcp_packet *packet, struct dhcp_scan_state *scan_state) { - uint8_t *optionptr; int len; - int rem; - int overload = 0; enum { FILE_FIELD101 = FILE_FIELD * 0x101, SNAME_FIELD101 = SNAME_FIELD * 0x101, }; /* option bytes: [code][len][data1][data2]..[dataLEN] */ - optionptr = packet->options; - rem = sizeof(packet->options); while (1) { - if (rem <= 0) { + if (scan_state->rem <= 0) { complain: bb_simple_error_msg("bad packet, malformed option field"); return NULL; } /* DHCP_PADDING and DHCP_END have no [len] byte */ - if (optionptr[OPT_CODE] == DHCP_PADDING) { - rem--; - optionptr++; + if (scan_state->optionptr[OPT_CODE] == DHCP_PADDING) { + scan_state->rem--; + scan_state->optionptr++; continue; } - if (optionptr[OPT_CODE] == DHCP_END) { - if ((overload & FILE_FIELD101) == FILE_FIELD) { + if (scan_state->optionptr[OPT_CODE] == DHCP_END) { + if ((scan_state->overload & FILE_FIELD101) == FILE_FIELD) { /* can use packet->file, and didn't look at it yet */ - overload |= FILE_FIELD101; /* "we looked at it" */ - optionptr = packet->file; - rem = sizeof(packet->file); + scan_state->overload |= FILE_FIELD101; /* "we looked at it" */ + scan_state->optionptr = packet->file; + scan_state->rem = sizeof(packet->file); continue; } - if ((overload & SNAME_FIELD101) == SNAME_FIELD) { + if ((scan_state->overload & SNAME_FIELD101) == SNAME_FIELD) { /* can use packet->sname, and didn't look at it yet */ - overload |= SNAME_FIELD101; /* "we looked at it" */ - optionptr = packet->sname; - rem = sizeof(packet->sname); + scan_state->overload |= SNAME_FIELD101; /* "we looked at it" */ + scan_state->optionptr = packet->sname; + scan_state->rem = sizeof(packet->sname); continue; } break; } - if (rem <= OPT_LEN) + if (scan_state->rem <= OPT_LEN) goto complain; /* complain and return NULL */ - len = 2 + optionptr[OPT_LEN]; - rem -= len; - if (rem < 0) + len = 2 + scan_state->optionptr[OPT_LEN]; + scan_state->rem -= len; + /* So far no valid option with length 0 known. */ + if (scan_state->rem < 0 || scan_state->optionptr[OPT_LEN] == 0) goto complain; /* complain and return NULL */ - if (optionptr[OPT_CODE] == code) { - if (optionptr[OPT_LEN] == 0) { - /* So far no valid option with length 0 known. - * Having this check means that searching - * for DHCP_MESSAGE_TYPE need not worry - * that returned pointer might be unsafe - * to dereference. - */ - goto complain; /* complain and return NULL */ - } - log_option("option found", optionptr); - return optionptr + OPT_DATA; + if (scan_state->optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) { + if (len >= 3) + scan_state->overload |= scan_state->optionptr[OPT_DATA]; + } else { + uint8_t *return_ptr = scan_state->optionptr; + scan_state->optionptr += len; + return return_ptr; } + scan_state->optionptr += len; + } - if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) { - if (len >= 3) - overload |= optionptr[OPT_DATA]; - /* fall through */ + return NULL; +} + +/* Get an option with bounds checking (warning, result is not aligned) */ +uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) +{ + uint8_t *optptr; + struct dhcp_scan_state scan_state; + + init_scan_state(packet, &scan_state); + while ((optptr = udhcp_scan_options(packet, &scan_state)) != NULL) { + if (optptr[OPT_CODE] == code) { + log_option("option found", optptr); + return optptr + OPT_DATA; } - optionptr += len; } /* log3 because udhcpc uses it a lot - very noisy */ diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h index 6214db0..81c1dcb 100644 --- a/networking/udhcp/common.h +++ b/networking/udhcp/common.h @@ -107,6 +107,12 @@ enum { OPTION_LIST = 0x20, }; +struct dhcp_scan_state { + int overload; + int rem; + uint8_t *optionptr; +}; + /* DHCP option codes (partial list). See RFC 2132 and * http://www.iana.org/assignments/bootp-dhcp-parameters/ * Commented out options are handled by common option machinery, @@ -206,6 +212,8 @@ extern const uint8_t dhcp_option_lengths[] ALIGN1; unsigned FAST_FUNC udhcp_option_idx(const char *name, const char *option_strings); +void init_scan_state(struct dhcp_packet *packet, struct dhcp_scan_state *scan_state) FAST_FUNC; +uint8_t *udhcp_scan_options(struct dhcp_packet *packet, struct dhcp_scan_state *scan_state) FAST_FUNC; uint8_t *udhcp_get_option(struct dhcp_packet *packet, int code) FAST_FUNC; /* Same as above + ensures that option length is 4 bytes * (returns NULL if size is different) |