package runtime import ( "errors" "fmt" "strings" "github.com/grpc-ecosystem/grpc-gateway/utilities" "google.golang.org/grpc/grpclog" ) var ( // ErrNotMatch indicates that the given HTTP request path does not match to the pattern. ErrNotMatch = errors.New("not match to the path pattern") // ErrInvalidPattern indicates that the given definition of Pattern is not valid. ErrInvalidPattern = errors.New("invalid pattern") ) type op struct { code utilities.OpCode operand int } // Pattern is a template pattern of http request paths defined in third_party/googleapis/google/api/http.proto. type Pattern struct { // ops is a list of operations ops []op // pool is a constant pool indexed by the operands or vars. pool []string // vars is a list of variables names to be bound by this pattern vars []string // stacksize is the max depth of the stack stacksize int // tailLen is the length of the fixed-size segments after a deep wildcard tailLen int // verb is the VERB part of the path pattern. It is empty if the pattern does not have VERB part. verb string } // NewPattern returns a new Pattern from the given definition values. // "ops" is a sequence of op codes. "pool" is a constant pool. // "verb" is the verb part of the pattern. It is empty if the pattern does not have the part. // "version" must be 1 for now. // It returns an error if the given definition is invalid. func NewPattern(version int, ops []int, pool []string, verb string) (Pattern, error) { if version != 1 { grpclog.Printf("unsupported version: %d", version) return Pattern{}, ErrInvalidPattern } l := len(ops) if l%2 != 0 { grpclog.Printf("odd number of ops codes: %d", l) return Pattern{}, ErrInvalidPattern } var ( typedOps []op stack, maxstack int tailLen int pushMSeen bool vars []string ) for i := 0; i < l; i += 2 { op := op{code: utilities.OpCode(ops[i]), operand: ops[i+1]} switch op.code { case utilities.OpNop: continue case utilities.OpPush: if pushMSeen { tailLen++ } stack++ case utilities.OpPushM: if pushMSeen { grpclog.Printf("pushM appears twice") return Pattern{}, ErrInvalidPattern } pushMSeen = true stack++ case utilities.OpLitPush: if op.operand < 0 || len(pool) <= op.operand { grpclog.Printf("negative literal index: %d", op.operand) return Pattern{}, ErrInvalidPattern } if pushMSeen { tailLen++ } stack++ case utilities.OpConcatN: if op.operand <= 0 { grpclog.Printf("negative concat size: %d", op.operand) return Pattern{}, ErrInvalidPattern } stack -= op.operand if stack < 0 { grpclog.Print("stack underflow") return Pattern{}, ErrInvalidPattern } stack++ case utilities.OpCapture: if op.operand < 0 || len(pool) <= op.operand { grpclog.Printf("variable name index out of bound: %d", op.operand) return Pattern{}, ErrInvalidPattern } v := pool[op.operand] op.operand = len(vars) vars = append(vars, v) stack-- if stack < 0 { grpclog.Printf("stack underflow") return Pattern{}, ErrInvalidPattern } default: grpclog.Printf("invalid opcode: %d", op.code) return Pattern{}, ErrInvalidPattern } if maxstack < stack { maxstack = stack } typedOps = append(typedOps, op) } return Pattern{ ops: typedOps, pool: pool, vars: vars, stacksize: maxstack, tailLen: tailLen, verb: verb, }, nil } // MustPattern is a helper function which makes it easier to call NewPattern in variable initialization. func MustPattern(p Pattern, err error) Pattern { if err != nil { grpclog.Fatalf("Pattern initialization failed: %v", err) } return p } // Match examines components if it matches to the Pattern. // If it matches, the function returns a mapping from field paths to their captured values. // If otherwise, the function returns an error. func (p Pattern) Match(components []string, verb string) (map[string]string, error) { if p.verb != verb { return nil, ErrNotMatch } var pos int stack := make([]string, 0, p.stacksize) captured := make([]string, len(p.vars)) l := len(components) for _, op := range p.ops { switch op.code { case utilities.OpNop: continue case utilities.OpPush, utilities.OpLitPush: if pos >= l { return nil, ErrNotMatch } c := components[pos] if op.code == utilities.OpLitPush { if lit := p.pool[op.operand]; c != lit { return nil, ErrNotMatch } } stack = append(stack, c) pos++ case utilities.OpPushM: end := len(components) if end < pos+p.tailLen { return nil, ErrNotMatch } end -= p.tailLen stack = append(stack, strings.Join(components[pos:end], "/")) pos = end case utilities.OpConcatN: n := op.operand l := len(stack) - n stack = append(stack[:l], strings.Join(stack[l:], "/")) case utilities.OpCapture: n := len(stack) - 1 captured[op.operand] = stack[n] stack = stack[:n] } } if pos < l { return nil, ErrNotMatch } bindings := make(map[string]string) for i, val := range captured { bindings[p.vars[i]] = val } return bindings, nil } // Verb returns the verb part of the Pattern. func (p Pattern) Verb() string { return p.verb } func (p Pattern) String() string { var stack []string for _, op := range p.ops { switch op.code { case utilities.OpNop: continue case utilities.OpPush: stack = append(stack, "*") case utilities.OpLitPush: stack = append(stack, p.pool[op.operand]) case utilities.OpPushM: stack = append(stack, "**") case utilities.OpConcatN: n := op.operand l := len(stack) - n stack = append(stack[:l], strings.Join(stack[l:], "/")) case utilities.OpCapture: n := len(stack) - 1 stack[n] = fmt.Sprintf("{%s=%s}", p.vars[op.operand], stack[n]) } } segs := strings.Join(stack, "/") if p.verb != "" { return fmt.Sprintf("/%s:%s", segs, p.verb) } return "/" + segs }