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Optimize normalizeValue for headers #1194

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Merged
mtdowling merged 1 commit into from
May 19, 2026
Merged

Optimize normalizeValue for headers #1194

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46 changes: 22 additions & 24 deletions http/http-api/src/main/java/software/amazon/smithy/java/http/api/HeaderUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -12,9 +12,6 @@ public final class HeaderUtils {
// Header name lookup table: 0=invalid, 1=valid lower, 2=valid upper.
private static final byte[] HEADER_NAME_TABLE = new byte[128];

// Header value lookup table: true = allowed character
private static final boolean[] VALID_VALUE_CHAR = new boolean[256];

static {
for (char c = 'a'; c <= 'z'; c++) {
HEADER_NAME_TABLE[c] = 1;
Expand All @@ -26,16 +23,6 @@ public final class HeaderUtils {
for (int i = 0; i < validChars.length(); i++) {
HEADER_NAME_TABLE[validChars.charAt(i)] = 1;
}

// Valid value chars per RFC 7230 field-content: SP, HTAB, VCHAR, obs-text
VALID_VALUE_CHAR[' '] = true;
VALID_VALUE_CHAR['\t'] = true;
for (int c = 0x21; c <= 0x7E; c++) {
VALID_VALUE_CHAR[c] = true;
}
for (int c = 0x80; c <= 0xFF; c++) {
VALID_VALUE_CHAR[c] = true;
}
}

private HeaderUtils() {}
Expand Down Expand Up @@ -102,25 +89,36 @@ static String normalizeName(String name) {
* @throws IllegalArgumentException if the value contains invalid characters
*/
public static String normalizeValue(String value) {
// Simulate String.trim(), but we only want to trim leading and trailing ' ' and '\t'.
int len = value.length();
int end = len - 1;
int start = trimStart(value, end);
end = trimEnd(value, start);
if (start > end) {
return "";
if (len == 0) {
return value;
}

for (int i = start; i <= end; i++) {
// Peek at the boundaries to detect whether trimming is needed.
char first = value.charAt(0);
char last = value.charAt(len - 1);
boolean trimNeeded = first == ' ' || first == '\t' || last == ' ' || last == '\t';

// Ensure valid chars match obs-text
for (int i = 0; i < len; i++) {
char c = value.charAt(i);
if (c > 255 || !VALID_VALUE_CHAR[c]) {
if (c > 0xFF || (c < 0x20 && c != '\t') || c == 0x7F) {
throw invalidHeaderValueChar(value);
}
}

return (start == 0 && end == len - 1)
? value
: value.substring(start, end + 1);
if (!trimNeeded) {
return value;
}

int end = len - 1;
int start = trimStart(value, end);
end = trimEnd(value, start);
if (start > end) {
return "";
}

return value.substring(start, end + 1);
}

private static int trimStart(String s, int end) {
Expand Down