/*=========================================================================*/
int DHCPGetOptionInfo(unsigned char *dhcpOptCodes, int dhcpOptCodeCnt,
DHCPInfoCallBack *dhcpInfoCB, void *context)
/* Calls dhcpInfoCB once for each requested option in dhcpOptCodes.
Returns - zero on success, non-zero on failure
errno ENOTCONN error during read
ETIME read timed out
ENOMEM out of memory
EINVAL parse error
BOOTP/DHCP packet header format:
Offs Len Name Description
0 1 opcode Message opcode: 1 = BOOTREQUEST, 2 = BOOTREPLY
1 1 htype Hardware address type (eg., 1 = 10mb ethernet)
2 1 hlen Hardware address length (eg., 6 = 10mb ethernet)
3 1 hops Client sets to zero, optionally used by relay agents
4 4 xid Transaction ID, random number chosen by client
8 2 secs Client sets to seconds since start of boot process
10 2 flags Bit 0: broadcast response bit
12 4 ciaddr Client IP address - only filled if client is bound
16 4 yiaddr 'your' (Client) IP address
20 4 siaddr IP address of next server to use in bootstrap
24 4 giaddr Relay agent IP address, used in booting via RA
28 16 chaddr Client hardware address
44 64 sname Optional server host name, null-terminated string
108 128 file Boot file name, null-terminated string
236 var options Optional parameters field
The options field has the following format:
Offs Len Name Description
0 4 cookie 4-byte cookie field: 99.130.83.99 (0x63825363)
Followed by 1-byte option codes and 1-byte option lengths, except
for the two special fixed length options, pad (0) and end (255).
Options are defined in slp_dhcp.h as TAG_XXX values. The two we
really care about here are options TAG_SLP_DA and TAG_SLP_SCOPE,
78 and 79, respectively.
The format for TAG_SLP_DA (starting with the tag) is:
Offs Len Name Description
0 1 tag TAG_SLP_DA - directory agent ip addresses
1 1 length length of remaining data in the option
2 1 mand flag: the use of these DA's is mandatory
3 4 a(0) 4-byte ip address
...
3+n*4 4 a(n) 4-byte ip address
The format for TAG_SLP_SCOPE (starting with the tag) is:
Offs Len Name Description
0 1 tag TAG_SLP_SCOPE - directory scopes to use
1 1 length length of remaining data in the option
2 1 mand flag: the use of these scopes is mandatory
3 var scopes a null-terminated, comma-separated string of scopes
The "DHCP Message Type" option must be included in every DHCP message.
All tags except for TAG_PAD(0) and TAG_END(255) begin with a tag value
followed by a length of remaining data value.
=========================================================================*/
{
UINT32 xid;
time_t timer;
struct timeval tv;
int sockfd, retries;
struct sockaddr_in sendaddr;
unsigned char chaddr[MAX_MACADDR_SIZE];
unsigned char hlen, htype;
unsigned char sndbuf[512];
unsigned char rcvbuf[512];
struct hostent *hep;
unsigned char *p;
size_t rcvbufsz = 0;
char host[256];
/* Get our IP and MAC addresses */
if(gethostname(host, (int)sizeof(host))
|| !(hep = gethostbyname(host))
|| dhcpGetAddressInfo((unsigned char *)hep->h_addr,
chaddr, &hlen, &htype))
return -1;
/* get a reasonably random transaction id value */
xid = (UINT32)time(&timer);
/* BOOTP request header */
memset(sndbuf, 0, 236); /* clear bootp header */
p = sndbuf;
*p++ = BOOTREQUEST; /* opcode */
*p++ = htype;
*p++ = hlen;
p++; /* hops */
ToUINT32(p, xid);
p += 2 * sizeof(UINT32); /* xid, secs, flags */
memcpy(p, hep->h_addr, 4);
p += 4 * sizeof(UINT32); /* ciaddr, yiaddr, siaddr, giaddr */
memcpy(p, chaddr, hlen);
p += 16 + 64 + 128; /* chaddr, sname and file */
*p++ = DHCP_COOKIE1; /* options, cookies 1-4 */
*p++ = DHCP_COOKIE2;
*p++ = DHCP_COOKIE3;
*p++ = DHCP_COOKIE4;
/* DHCP Message Type option */
*p++ = TAG_DHCP_MSG_TYPE;
*p++ = 1; /* option length */
*p++ = DHCP_MSG_INFORM; /* message type is DHCPINFORM */
/* DHCP Parameter Request option */
*p++ = TAG_DHCP_PARAM_REQ; /* request for DHCP parms */
*p++ = (unsigned char)dhcpOptCodeCnt;
memcpy(p, dhcpOptCodes, dhcpOptCodeCnt);
p += dhcpOptCodeCnt;
/* DHCP Client Identifier option */
*p++ = TAG_CLIENT_IDENTIFIER;
*p++ = hlen + 1; /* option length */
*p++ = htype; /* client id is htype/haddr */
memcpy(p, chaddr, hlen);
p += hlen;
/* End option */
*p++ = TAG_END;
/* get a broadcast send/recv socket and address */
if((sockfd = dhcpCreateBCSkt(&sendaddr)) < 0)
return -1;
/* setup select timeout */
tv.tv_sec = 0;
tv.tv_usec = INIT_TMOUT_USECS;
retries = 0;
srand((unsigned)time(&timer));
while (retries++ < MAX_DHCP_RETRIES)
{
if(dhcpSendRequest(sockfd, sndbuf, p - sndbuf,
(struct sockaddr *)&sendaddr, &tv) < 0)
{
if (errno != ETIMEDOUT)
{
closesocket(sockfd);
return -1;
}
}
else if((rcvbufsz = dhcpRecvResponse(sockfd, rcvbuf,
sizeof(rcvbuf), &tv)) < 0)
{
if (errno != ETIMEDOUT)
{
closesocket(sockfd);
return -1;
}
}
else if(rcvbufsz >= 236 && AsUINT32(&rcvbuf[4]) == xid)
break;
/* exponential backoff randomized by a
uniform number between -1 and 1 */
tv.tv_usec = tv.tv_usec * 2 + (rand() % 3) - 1;
tv.tv_sec = tv.tv_usec / USECS_PER_SEC;
tv.tv_usec %= USECS_PER_SEC;
}
closesocket(sockfd);
return rcvbufsz? dhcpProcessOptions(rcvbuf + 236, rcvbufsz - 236,
dhcpInfoCB, context): -1;
}
/** Queries a DHCP server and calls a callback once for each option.
*
* Queries the sub-net DHCP server for a specified set of DHCP options
* and then calls a user-supplied callback function once for each of
* the desired options returned by the server.
*
* @param[in] dhcpOptCodes - An array of option codes to query for.
* @param[in] dhcpOptCodeCnt - The number of elements in @p dhcpOptCodes.
* @param[in] dhcpInfoCB - The callback function to call for each option.
* @param[in] context - callback context.
*
* @return Zero on success; non-zero on failure, with errno set to
* ENOTCONN (read error), ETIMEDOUT (read timeout), ENOMEM (out of
* memory), or EINVAL (on parse error).
*/
int DHCPGetOptionInfo(unsigned char * dhcpOptCodes, int dhcpOptCodeCnt,
DHCPInfoCallBack * dhcpInfoCB, void * context)
{
uint32_t xid;
time_t timer;
struct timeval tv;
sockfd_t sockfd;
int retries;
struct sockaddr_storage sendaddr;
unsigned char chaddr[MAX_MACADDR_SIZE];
unsigned char hlen, htype;
uint8_t sndbuf[512];
uint8_t rcvbuf[512];
struct hostent * hep;
uint8_t * p;
int rcvbufsz = 0;
char host[256];
/* Get our IP and MAC addresses */
if (gethostname(host, (int)sizeof(host))
|| (hep = gethostbyname(host)) == 0
|| dhcpGetAddressInfo((unsigned char *)hep->h_addr,
chaddr, &hlen, &htype))
return -1;
/* get a reasonably random transaction id value */
xid = (uint32_t)time(&timer);
/* BOOTP request header */
p = sndbuf;
*p++ = BOOTREQUEST; /* opcode */
*p++ = htype;
*p++ = hlen;
*p++ = 0; /* hops */
PutUINT32(&p, xid);
PutUINT16(&p, 0); /* seconds */
PutUINT16(&p, 0); /* flags */
memcpy(p, hep->h_addr, 4); /* ciaddr */
p += 4;
PutUINT32(&p, 0); /* yiaddr */
PutUINT32(&p, 0); /* siaddr */
PutUINT32(&p, 0); /* giaddr */
memcpy(p, chaddr, hlen); /* chaddr */
p += hlen;
memset(p, 0, 16-hlen); /* remaining chaddr space */
p += 16-hlen;
memset(p, 0, 64 + 128); /* server host name, boot file */
p += 64 + 128;
/* BOOTP options field */
*p++ = DHCP_COOKIE1; /* options, cookies 1-4 */
*p++ = DHCP_COOKIE2;
*p++ = DHCP_COOKIE3;
*p++ = DHCP_COOKIE4;
/* DHCP Message Type option */
*p++ = TAG_DHCP_MSG_TYPE;
*p++ = 1; /* option length */
*p++ = DHCP_MSG_INFORM; /* message type is DHCPINFORM */
/* DHCP Parameter Request option */
*p++ = TAG_DHCP_PARAM_REQ; /* request for DHCP parms */
*p++ = (unsigned char)dhcpOptCodeCnt;
memcpy(p, dhcpOptCodes, dhcpOptCodeCnt);
p += dhcpOptCodeCnt;
/* DHCP Client Identifier option */
*p++ = TAG_CLIENT_IDENTIFIER;
*p++ = hlen + 1; /* option length */
*p++ = htype; /* client id is htype/haddr */
memcpy(p, chaddr, hlen);
p += hlen;
/* End option */
*p++ = TAG_END;
/* get a broadcast send/recv socket and address */
if ((sockfd = dhcpCreateBCSkt(&sendaddr)) == SLP_INVALID_SOCKET)
return -1;
/* setup select timeout */
tv.tv_sec = 0;
tv.tv_usec = INIT_TMOUT_USECS;
retries = 0;
srand((unsigned)time(&timer));
while (retries++ < MAX_DHCP_RETRIES)
{
if (dhcpSendRequest(sockfd, sndbuf, p - sndbuf,
&sendaddr, sizeof(sendaddr), &tv) < 0)
{
if (errno != ETIMEDOUT)
{
closesocket(sockfd);
return -1;
}
}
else if ((rcvbufsz = dhcpRecvResponse(sockfd, rcvbuf,
sizeof(rcvbuf), &tv)) < 0)
{
if (errno != ETIMEDOUT)
{
closesocket(sockfd);
return -1;
}
}
else if (rcvbufsz >= 236 && AS_UINT32(&rcvbuf[4]) == xid)
break;
/* exponential backoff randomized by a
* uniform number between -1 and 1
*/
tv.tv_usec = tv.tv_usec * 2 + (rand() % 3) - 1;
tv.tv_sec = tv.tv_usec / USECS_PER_SEC;
tv.tv_usec %= USECS_PER_SEC;
}
closesocket(sockfd);
return rcvbufsz? dhcpProcessOptions(rcvbuf + 236, rcvbufsz - 236,
dhcpInfoCB, context): -1;
}
