Date: Tue, 19 Jan 2016 21:35:10 +0000 (UTC) From: Ian Lepore <ian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r294343 - stable/10/lib/libstand Message-ID: <201601192135.u0JLZAuf044042@repo.freebsd.org>
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Author: ian Date: Tue Jan 19 21:35:09 2016 New Revision: 294343 URL: https://svnweb.freebsd.org/changeset/base/294343 Log: MFC r292583: Allow dhcp/bootp server-provided values to be overriden from environment variables in loader(8) and other libstand applications. Sometimes a dhcp server provides incorrect information along with the IP address. It would be useful to have a way to override this with locally-supplied information, such as command line parameters passed from a prior-stage bootloader. This change allows pre-existing env vars to take precedence over values delivered by the dhcp or bootp server. The bootp/dhcp code in libstand automatically creates environment variables from the data provided by the server (dhcp.root-path, dhcp.domain-name, etc). It also transcribes the values to some global variables such as 'rootpath' and 'hostname'. This change does two things: When adding dhcp.* vars to the environment, don't replace existing vars/values. When setting the global vars rootpath and hostname, use the dhcp.root-path and dhcp.host-name env var values if they exist. This allows the platform-specific part of loader(8) to obtain override values in some platform-specific way and store them in the environment before opening the network device. The set of values that can be overriden is currently limited to just string options. The values that are delivered as binary data are things that probably shouldn't be overridden (IP, netmask, gateway, etc). The original patch this evolved from was submitted by martymac@ PR: 202098 Relnotes: Yes Modified: stable/10/lib/libstand/bootp.c Directory Properties: stable/10/ (props changed) Modified: stable/10/lib/libstand/bootp.c ============================================================================== --- stable/10/lib/libstand/bootp.c Tue Jan 19 21:27:25 2016 (r294342) +++ stable/10/lib/libstand/bootp.c Tue Jan 19 21:35:09 2016 (r294343) @@ -354,6 +354,7 @@ vend_rfc1048(cp, len) u_char *ep; int size; u_char tag; + const char *val; #ifdef BOOTP_DEBUG if (debug) @@ -380,15 +381,17 @@ vend_rfc1048(cp, len) } if (tag == TAG_SWAPSERVER) { /* let it override bp_siaddr */ - bcopy(cp, &rootip.s_addr, sizeof(swapip.s_addr)); + bcopy(cp, &rootip.s_addr, sizeof(rootip.s_addr)); } if (tag == TAG_ROOTPATH) { - strncpy(rootpath, (char *)cp, sizeof(rootpath)); - rootpath[size] = '\0'; + if ((val = getenv("dhcp.root-path")) == NULL) + val = (const char *)cp; + strlcpy(rootpath, val, sizeof(rootpath)); } if (tag == TAG_HOSTNAME) { - strncpy(hostname, (char *)cp, sizeof(hostname)); - hostname[size] = '\0'; + if ((val = getenv("dhcp.host-name")) == NULL) + val = (const char *)cp; + strlcpy(hostname, val, sizeof(hostname)); } #ifdef SUPPORT_DHCP if (tag == TAG_DHCP_MSGTYPE) { @@ -730,7 +733,11 @@ setenv_(u_char *cp, u_char *ep, struct sprintf(env, op->desc, opts[0].desc, tag); else sprintf(env, "%s%s", opts[0].desc, op->desc); - setenv(env, buf, 1); + /* + * Do not replace existing values in the environment, so that + * locally-obtained values can override server-provided values. + */ + setenv(env, buf, 0); } } if (tp != tags) {
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