MINOR: deviceatlas: precompute maxhdrlen to skip oversized headers early

Precompute the maximum header name length from the atlas evidence
headers at init and hot-reload time. Use it in da_haproxy_fetch() to
skip headers early that cannot match any known DeviceAtlas evidence
header, avoiding unnecessary string copies and comparisons.

diff --git a/addons/deviceatlas/da.c b/addons/deviceatlas/da.c
index 2c09c22725b2026596946ee213c1aab091c2cb8a..0c3311b613889e76da9fc6d017a4bea415c4a225 100644 (file)
--- a/addons/deviceatlas/da.c
+++ b/addons/deviceatlas/da.c
@@ -31,6 +31,7 @@ static struct {
        da_atlas_t atlas;
        da_evidence_id_t useragentid;
        da_severity_t loglevel;
+       size_t maxhdrlen;
        char separator;
        unsigned char daset:1;
 } global_deviceatlas = {
@@ -42,6 +43,7 @@ static struct {
        .atlasmap = NULL,
        .atlasfd = -1,
        .useragentid = 0,
+       .maxhdrlen = 0,
        .daset = 0,
        .separator = '|',
 };
@@ -224,6 +226,15 @@ static int init_deviceatlas(void)
 
                global_deviceatlas.useragentid = da_atlas_header_evidence_id(&global_deviceatlas.atlas,
                        "user-agent");
+               {
+                       size_t hi;
+                       global_deviceatlas.maxhdrlen = 16;
+                       for (hi = 0; hi < global_deviceatlas.atlas.header_evidence_count; hi++) {
+                               size_t nl = strlen(global_deviceatlas.atlas.header_priorities[hi].name);
+                               if (nl > global_deviceatlas.maxhdrlen)
+                                       global_deviceatlas.maxhdrlen = nl;
+                       }
+               }
                if ((global_deviceatlas.atlasfd = shm_open(ATLASMAPNM, O_RDWR, 0660)) != -1) {
                        global_deviceatlas.atlasmap = mmap(NULL, ATLASTOKSZ, PROT_READ | PROT_WRITE, MAP_SHARED, global_deviceatlas.atlasfd, 0);
                        if (global_deviceatlas.atlasmap == MAP_FAILED) {
@@ -304,6 +315,15 @@ static void da_haproxy_checkinst(void)
                     free(global_deviceatlas.atlasimgptr);
                     global_deviceatlas.atlasimgptr = cnew;
                     global_deviceatlas.atlas = inst;
+                    {
+                        size_t hi;
+                        global_deviceatlas.maxhdrlen = 16;
+                        for (hi = 0; hi < inst.header_evidence_count; hi++) {
+                            size_t nl = strlen(inst.header_priorities[hi].name);
+                            if (nl > global_deviceatlas.maxhdrlen)
+                                global_deviceatlas.maxhdrlen = nl;
+                        }
+                    }
                     base[0] = 0;
                     ha_notice("deviceatlas : new instance, data file date `%s`.\n",
                         da_getdatacreationiso8601(&global_deviceatlas.atlas));
@@ -464,8 +484,7 @@ static int da_haproxy_fetch(const struct arg *args, struct sample *smp, const ch
                        continue;
                }
 
-               /* The HTTP headers used by the DeviceAtlas API are not longer */
-               if (n.len >= sizeof(hbuf)) {
+               if (n.len > global_deviceatlas.maxhdrlen || n.len >= sizeof(hbuf)) {
                        continue;
                }